xnu-6153.141.1.tar.gz

[apple/xnu.git] / bsd / nfs / nfs_vnops.c

/*
 * Copyright (c) 2000-2019 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rick Macklem at The University of Guelph.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)nfs_vnops.c 8.16 (Berkeley) 5/27/95
 * FreeBSD-Id: nfs_vnops.c,v 1.72 1997/11/07 09:20:48 phk Exp $
 */

#include <nfs/nfs_conf.h>
#if CONFIG_NFS_CLIENT

/*
 * vnode op calls for Sun NFS version 2 and 3
 */
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/resourcevar.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/mount_internal.h>
#include <sys/malloc.h>
#include <sys/kpi_mbuf.h>
#include <sys/conf.h>
#include <sys/vnode_internal.h>
#include <sys/dirent.h>
#include <sys/fcntl.h>
#include <sys/lockf.h>
#include <sys/ubc_internal.h>
#include <sys/attr.h>
#include <sys/signalvar.h>
#include <sys/uio_internal.h>
#include <sys/xattr.h>

#include <vfs/vfs_support.h>

#include <sys/vm.h>

#include <sys/time.h>
#include <kern/clock.h>
#include <libkern/OSAtomic.h>

#include <miscfs/fifofs/fifo.h>
#include <miscfs/specfs/specdev.h>

#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfs/nfs.h>
#include <nfs/nfsnode.h>
#include <nfs/nfs_gss.h>
#include <nfs/nfsmount.h>
#include <nfs/nfs_lock.h>
#include <nfs/xdr_subs.h>
#include <nfs/nfsm_subs.h>

#include <net/if.h>
#include <netinet/in.h>
#include <netinet/in_var.h>

#include <vm/vm_kern.h>
#include <vm/vm_pageout.h>

#include <kern/task.h>
#include <kern/sched_prim.h>

#define NFS_VNOP_DBG(...) NFS_DBG(NFS_FAC_VNOP, 7, ## __VA_ARGS__)
#define DEFAULT_READLINK_NOCACHE 0

/*
 * NFS vnode ops
 */
int     nfs_vnop_lookup(struct vnop_lookup_args *);
int     nfsspec_vnop_read(struct vnop_read_args *);
int     nfsspec_vnop_write(struct vnop_write_args *);
int     nfsspec_vnop_close(struct vnop_close_args *);
#if FIFO
int     nfsfifo_vnop_read(struct vnop_read_args *);
int     nfsfifo_vnop_write(struct vnop_write_args *);
int     nfsfifo_vnop_close(struct vnop_close_args *);
#endif
int     nfs_vnop_ioctl(struct vnop_ioctl_args *);
int     nfs_vnop_select(struct vnop_select_args *);
int     nfs_vnop_setattr(struct vnop_setattr_args *);
int     nfs_vnop_fsync(struct vnop_fsync_args *);
int     nfs_vnop_rename(struct vnop_rename_args *);
int     nfs_vnop_readdir(struct vnop_readdir_args *);
int     nfs_vnop_readlink(struct vnop_readlink_args *);
int     nfs_vnop_pathconf(struct vnop_pathconf_args *);
int     nfs_vnop_pagein(struct vnop_pagein_args *);
int     nfs_vnop_pageout(struct vnop_pageout_args *);
int     nfs_vnop_blktooff(struct vnop_blktooff_args *);
int     nfs_vnop_offtoblk(struct vnop_offtoblk_args *);
int     nfs_vnop_blockmap(struct vnop_blockmap_args *);
int     nfs_vnop_monitor(struct vnop_monitor_args *);

int     nfs3_vnop_create(struct vnop_create_args *);
int     nfs3_vnop_mknod(struct vnop_mknod_args *);
int     nfs3_vnop_getattr(struct vnop_getattr_args *);
int     nfs3_vnop_link(struct vnop_link_args *);
int     nfs3_vnop_mkdir(struct vnop_mkdir_args *);
int     nfs3_vnop_rmdir(struct vnop_rmdir_args *);
int     nfs3_vnop_symlink(struct vnop_symlink_args *);


vnop_t **nfsv2_vnodeop_p;
static const struct vnodeopv_entry_desc nfsv2_vnodeop_entries[] = {
        { .opve_op = &vnop_default_desc, .opve_impl = (vnop_t *)vn_default_error },
        { .opve_op = &vnop_lookup_desc, .opve_impl = (vnop_t *)nfs_vnop_lookup },       /* lookup */
        { .opve_op = &vnop_create_desc, .opve_impl = (vnop_t *)nfs3_vnop_create },      /* create */
        { .opve_op = &vnop_mknod_desc, .opve_impl = (vnop_t *)nfs3_vnop_mknod },        /* mknod */
        { .opve_op = &vnop_open_desc, .opve_impl = (vnop_t *)nfs_vnop_open },           /* open */
        { .opve_op = &vnop_close_desc, .opve_impl = (vnop_t *)nfs_vnop_close },         /* close */
        { .opve_op = &vnop_access_desc, .opve_impl = (vnop_t *)nfs_vnop_access },       /* access */
        { .opve_op = &vnop_getattr_desc, .opve_impl = (vnop_t *)nfs3_vnop_getattr },    /* getattr */
        { .opve_op = &vnop_setattr_desc, .opve_impl = (vnop_t *)nfs_vnop_setattr },     /* setattr */
        { .opve_op = &vnop_read_desc, .opve_impl = (vnop_t *)nfs_vnop_read },           /* read */
        { .opve_op = &vnop_write_desc, .opve_impl = (vnop_t *)nfs_vnop_write },         /* write */
        { .opve_op = &vnop_ioctl_desc, .opve_impl = (vnop_t *)nfs_vnop_ioctl },         /* ioctl */
        { .opve_op = &vnop_select_desc, .opve_impl = (vnop_t *)nfs_vnop_select },       /* select */
        { .opve_op = &vnop_revoke_desc, .opve_impl = (vnop_t *)nfs_vnop_revoke },       /* revoke */
        { .opve_op = &vnop_mmap_desc, .opve_impl = (vnop_t *)nfs_vnop_mmap },           /* mmap */
        { .opve_op = &vnop_mnomap_desc, .opve_impl = (vnop_t *)nfs_vnop_mnomap },       /* mnomap */
        { .opve_op = &vnop_fsync_desc, .opve_impl = (vnop_t *)nfs_vnop_fsync },         /* fsync */
        { .opve_op = &vnop_remove_desc, .opve_impl = (vnop_t *)nfs_vnop_remove },       /* remove */
        { .opve_op = &vnop_link_desc, .opve_impl = (vnop_t *)nfs3_vnop_link },          /* link */
        { .opve_op = &vnop_rename_desc, .opve_impl = (vnop_t *)nfs_vnop_rename },       /* rename */
        { .opve_op = &vnop_mkdir_desc, .opve_impl = (vnop_t *)nfs3_vnop_mkdir },        /* mkdir */
        { .opve_op = &vnop_rmdir_desc, .opve_impl = (vnop_t *)nfs3_vnop_rmdir },        /* rmdir */
        { .opve_op = &vnop_symlink_desc, .opve_impl = (vnop_t *)nfs3_vnop_symlink },    /* symlink */
        { .opve_op = &vnop_readdir_desc, .opve_impl = (vnop_t *)nfs_vnop_readdir },     /* readdir */
        { .opve_op = &vnop_readlink_desc, .opve_impl = (vnop_t *)nfs_vnop_readlink },   /* readlink */
        { .opve_op = &vnop_inactive_desc, .opve_impl = (vnop_t *)nfs_vnop_inactive },   /* inactive */
        { .opve_op = &vnop_reclaim_desc, .opve_impl = (vnop_t *)nfs_vnop_reclaim },     /* reclaim */
        { .opve_op = &vnop_strategy_desc, .opve_impl = (vnop_t *)err_strategy },        /* strategy */
        { .opve_op = &vnop_pathconf_desc, .opve_impl = (vnop_t *)nfs_vnop_pathconf },   /* pathconf */
        { .opve_op = &vnop_advlock_desc, .opve_impl = (vnop_t *)nfs_vnop_advlock },     /* advlock */
        { .opve_op = &vnop_bwrite_desc, .opve_impl = (vnop_t *)err_bwrite },            /* bwrite */
        { .opve_op = &vnop_pagein_desc, .opve_impl = (vnop_t *)nfs_vnop_pagein },       /* Pagein */
        { .opve_op = &vnop_pageout_desc, .opve_impl = (vnop_t *)nfs_vnop_pageout },     /* Pageout */
        { .opve_op = &vnop_copyfile_desc, .opve_impl = (vnop_t *)err_copyfile },        /* Copyfile */
        { .opve_op = &vnop_blktooff_desc, .opve_impl = (vnop_t *)nfs_vnop_blktooff },   /* blktooff */
        { .opve_op = &vnop_offtoblk_desc, .opve_impl = (vnop_t *)nfs_vnop_offtoblk },   /* offtoblk */
        { .opve_op = &vnop_blockmap_desc, .opve_impl = (vnop_t *)nfs_vnop_blockmap },   /* blockmap */
        { .opve_op = &vnop_monitor_desc, .opve_impl = (vnop_t *)nfs_vnop_monitor },     /* monitor */
        { .opve_op = NULL, .opve_impl = NULL }
};
const struct vnodeopv_desc nfsv2_vnodeop_opv_desc =
{ &nfsv2_vnodeop_p, nfsv2_vnodeop_entries };


#if CONFIG_NFS4
vnop_t **nfsv4_vnodeop_p;
static const struct vnodeopv_entry_desc nfsv4_vnodeop_entries[] = {
        { &vnop_default_desc, (vnop_t *)vn_default_error },
        { &vnop_lookup_desc, (vnop_t *)nfs_vnop_lookup },       /* lookup */
        { &vnop_create_desc, (vnop_t *)nfs4_vnop_create },      /* create */
        { &vnop_mknod_desc, (vnop_t *)nfs4_vnop_mknod },        /* mknod */
        { &vnop_open_desc, (vnop_t *)nfs_vnop_open },           /* open */
        { &vnop_close_desc, (vnop_t *)nfs_vnop_close },         /* close */
        { &vnop_access_desc, (vnop_t *)nfs_vnop_access },       /* access */
        { &vnop_getattr_desc, (vnop_t *)nfs4_vnop_getattr },    /* getattr */
        { &vnop_setattr_desc, (vnop_t *)nfs_vnop_setattr },     /* setattr */
        { &vnop_read_desc, (vnop_t *)nfs_vnop_read },           /* read */
        { &vnop_write_desc, (vnop_t *)nfs_vnop_write },         /* write */
        { &vnop_ioctl_desc, (vnop_t *)nfs_vnop_ioctl },         /* ioctl */
        { &vnop_select_desc, (vnop_t *)nfs_vnop_select },       /* select */
        { &vnop_revoke_desc, (vnop_t *)nfs_vnop_revoke },       /* revoke */
        { &vnop_mmap_desc, (vnop_t *)nfs_vnop_mmap },           /* mmap */
        { &vnop_mnomap_desc, (vnop_t *)nfs_vnop_mnomap },       /* mnomap */
        { &vnop_fsync_desc, (vnop_t *)nfs_vnop_fsync },         /* fsync */
        { &vnop_remove_desc, (vnop_t *)nfs_vnop_remove },       /* remove */
        { &vnop_link_desc, (vnop_t *)nfs4_vnop_link },          /* link */
        { &vnop_rename_desc, (vnop_t *)nfs_vnop_rename },       /* rename */
        { &vnop_mkdir_desc, (vnop_t *)nfs4_vnop_mkdir },        /* mkdir */
        { &vnop_rmdir_desc, (vnop_t *)nfs4_vnop_rmdir },        /* rmdir */
        { &vnop_symlink_desc, (vnop_t *)nfs4_vnop_symlink },    /* symlink */
        { &vnop_readdir_desc, (vnop_t *)nfs_vnop_readdir },     /* readdir */
        { &vnop_readlink_desc, (vnop_t *)nfs_vnop_readlink },   /* readlink */
        { &vnop_inactive_desc, (vnop_t *)nfs_vnop_inactive },   /* inactive */
        { &vnop_reclaim_desc, (vnop_t *)nfs_vnop_reclaim },     /* reclaim */
        { &vnop_strategy_desc, (vnop_t *)err_strategy },        /* strategy */
        { &vnop_pathconf_desc, (vnop_t *)nfs_vnop_pathconf },   /* pathconf */
        { &vnop_advlock_desc, (vnop_t *)nfs_vnop_advlock },     /* advlock */
        { &vnop_bwrite_desc, (vnop_t *)err_bwrite },            /* bwrite */
        { &vnop_pagein_desc, (vnop_t *)nfs_vnop_pagein },       /* Pagein */
        { &vnop_pageout_desc, (vnop_t *)nfs_vnop_pageout },     /* Pageout */
        { &vnop_copyfile_desc, (vnop_t *)err_copyfile },        /* Copyfile */
        { &vnop_blktooff_desc, (vnop_t *)nfs_vnop_blktooff },   /* blktooff */
        { &vnop_offtoblk_desc, (vnop_t *)nfs_vnop_offtoblk },   /* offtoblk */
        { &vnop_blockmap_desc, (vnop_t *)nfs_vnop_blockmap },   /* blockmap */
        { &vnop_getxattr_desc, (vnop_t *)nfs4_vnop_getxattr },  /* getxattr */
        { &vnop_setxattr_desc, (vnop_t *)nfs4_vnop_setxattr },  /* setxattr */
        { &vnop_removexattr_desc, (vnop_t *)nfs4_vnop_removexattr },/* removexattr */
        { &vnop_listxattr_desc, (vnop_t *)nfs4_vnop_listxattr },/* listxattr */
#if NAMEDSTREAMS
        { &vnop_getnamedstream_desc, (vnop_t *)nfs4_vnop_getnamedstream },      /* getnamedstream */
        { &vnop_makenamedstream_desc, (vnop_t *)nfs4_vnop_makenamedstream },    /* makenamedstream */
        { &vnop_removenamedstream_desc, (vnop_t *)nfs4_vnop_removenamedstream },/* removenamedstream */
#endif
        { &vnop_monitor_desc, (vnop_t *)nfs_vnop_monitor },     /* monitor */
        { NULL, NULL }
};
const struct vnodeopv_desc nfsv4_vnodeop_opv_desc =
{ &nfsv4_vnodeop_p, nfsv4_vnodeop_entries };
#endif

/*
 * Special device vnode ops
 */
vnop_t **spec_nfsv2nodeop_p;
static const struct vnodeopv_entry_desc spec_nfsv2nodeop_entries[] = {
        { &vnop_default_desc, (vnop_t *)vn_default_error },
        { &vnop_lookup_desc, (vnop_t *)spec_lookup },           /* lookup */
        { &vnop_create_desc, (vnop_t *)spec_create },           /* create */
        { &vnop_mknod_desc, (vnop_t *)spec_mknod },             /* mknod */
        { &vnop_open_desc, (vnop_t *)spec_open },               /* open */
        { &vnop_close_desc, (vnop_t *)nfsspec_vnop_close },     /* close */
        { &vnop_getattr_desc, (vnop_t *)nfs3_vnop_getattr },    /* getattr */
        { &vnop_setattr_desc, (vnop_t *)nfs_vnop_setattr },     /* setattr */
        { &vnop_read_desc, (vnop_t *)nfsspec_vnop_read },       /* read */
        { &vnop_write_desc, (vnop_t *)nfsspec_vnop_write },     /* write */
        { &vnop_ioctl_desc, (vnop_t *)spec_ioctl },             /* ioctl */
        { &vnop_select_desc, (vnop_t *)spec_select },           /* select */
        { &vnop_revoke_desc, (vnop_t *)spec_revoke },           /* revoke */
        { &vnop_mmap_desc, (vnop_t *)spec_mmap },               /* mmap */
        { &vnop_fsync_desc, (vnop_t *)nfs_vnop_fsync },         /* fsync */
        { &vnop_remove_desc, (vnop_t *)spec_remove },           /* remove */
        { &vnop_link_desc, (vnop_t *)spec_link },               /* link */
        { &vnop_rename_desc, (vnop_t *)spec_rename },           /* rename */
        { &vnop_mkdir_desc, (vnop_t *)spec_mkdir },             /* mkdir */
        { &vnop_rmdir_desc, (vnop_t *)spec_rmdir },             /* rmdir */
        { &vnop_symlink_desc, (vnop_t *)spec_symlink },         /* symlink */
        { &vnop_readdir_desc, (vnop_t *)spec_readdir },         /* readdir */
        { &vnop_readlink_desc, (vnop_t *)spec_readlink },       /* readlink */
        { &vnop_inactive_desc, (vnop_t *)nfs_vnop_inactive },   /* inactive */
        { &vnop_reclaim_desc, (vnop_t *)nfs_vnop_reclaim },     /* reclaim */
        { &vnop_strategy_desc, (vnop_t *)spec_strategy },       /* strategy */
        { &vnop_pathconf_desc, (vnop_t *)spec_pathconf },       /* pathconf */
        { &vnop_advlock_desc, (vnop_t *)spec_advlock },         /* advlock */
        { &vnop_bwrite_desc, (vnop_t *)vn_bwrite },             /* bwrite */
        { &vnop_pagein_desc, (vnop_t *)nfs_vnop_pagein },       /* Pagein */
        { &vnop_pageout_desc, (vnop_t *)nfs_vnop_pageout },     /* Pageout */
        { &vnop_blktooff_desc, (vnop_t *)nfs_vnop_blktooff },   /* blktooff */
        { &vnop_offtoblk_desc, (vnop_t *)nfs_vnop_offtoblk },   /* offtoblk */
        { &vnop_blockmap_desc, (vnop_t *)nfs_vnop_blockmap },   /* blockmap */
        { &vnop_monitor_desc, (vnop_t *)nfs_vnop_monitor },     /* monitor */
        { NULL, NULL }
};
const struct vnodeopv_desc spec_nfsv2nodeop_opv_desc =
{ &spec_nfsv2nodeop_p, spec_nfsv2nodeop_entries };
#if CONFIG_NFS4
vnop_t **spec_nfsv4nodeop_p;
static const struct vnodeopv_entry_desc spec_nfsv4nodeop_entries[] = {
        { &vnop_default_desc, (vnop_t *)vn_default_error },
        { &vnop_lookup_desc, (vnop_t *)spec_lookup },           /* lookup */
        { &vnop_create_desc, (vnop_t *)spec_create },           /* create */
        { &vnop_mknod_desc, (vnop_t *)spec_mknod },             /* mknod */
        { &vnop_open_desc, (vnop_t *)spec_open },               /* open */
        { &vnop_close_desc, (vnop_t *)nfsspec_vnop_close },     /* close */
        { &vnop_getattr_desc, (vnop_t *)nfs4_vnop_getattr },    /* getattr */
        { &vnop_setattr_desc, (vnop_t *)nfs_vnop_setattr },     /* setattr */
        { &vnop_read_desc, (vnop_t *)nfsspec_vnop_read },       /* read */
        { &vnop_write_desc, (vnop_t *)nfsspec_vnop_write },     /* write */
        { &vnop_ioctl_desc, (vnop_t *)spec_ioctl },             /* ioctl */
        { &vnop_select_desc, (vnop_t *)spec_select },           /* select */
        { &vnop_revoke_desc, (vnop_t *)spec_revoke },           /* revoke */
        { &vnop_mmap_desc, (vnop_t *)spec_mmap },               /* mmap */
        { &vnop_fsync_desc, (vnop_t *)nfs_vnop_fsync },         /* fsync */
        { &vnop_remove_desc, (vnop_t *)spec_remove },           /* remove */
        { &vnop_link_desc, (vnop_t *)spec_link },               /* link */
        { &vnop_rename_desc, (vnop_t *)spec_rename },           /* rename */
        { &vnop_mkdir_desc, (vnop_t *)spec_mkdir },             /* mkdir */
        { &vnop_rmdir_desc, (vnop_t *)spec_rmdir },             /* rmdir */
        { &vnop_symlink_desc, (vnop_t *)spec_symlink },         /* symlink */
        { &vnop_readdir_desc, (vnop_t *)spec_readdir },         /* readdir */
        { &vnop_readlink_desc, (vnop_t *)spec_readlink },       /* readlink */
        { &vnop_inactive_desc, (vnop_t *)nfs_vnop_inactive },   /* inactive */
        { &vnop_reclaim_desc, (vnop_t *)nfs_vnop_reclaim },     /* reclaim */
        { &vnop_strategy_desc, (vnop_t *)spec_strategy },       /* strategy */
        { &vnop_pathconf_desc, (vnop_t *)spec_pathconf },       /* pathconf */
        { &vnop_advlock_desc, (vnop_t *)spec_advlock },         /* advlock */
        { &vnop_bwrite_desc, (vnop_t *)vn_bwrite },             /* bwrite */
        { &vnop_pagein_desc, (vnop_t *)nfs_vnop_pagein },       /* Pagein */
        { &vnop_pageout_desc, (vnop_t *)nfs_vnop_pageout },     /* Pageout */
        { &vnop_blktooff_desc, (vnop_t *)nfs_vnop_blktooff },   /* blktooff */
        { &vnop_offtoblk_desc, (vnop_t *)nfs_vnop_offtoblk },   /* offtoblk */
        { &vnop_blockmap_desc, (vnop_t *)nfs_vnop_blockmap },   /* blockmap */
        { &vnop_getxattr_desc, (vnop_t *)nfs4_vnop_getxattr },  /* getxattr */
        { &vnop_setxattr_desc, (vnop_t *)nfs4_vnop_setxattr },  /* setxattr */
        { &vnop_removexattr_desc, (vnop_t *)nfs4_vnop_removexattr },/* removexattr */
        { &vnop_listxattr_desc, (vnop_t *)nfs4_vnop_listxattr },/* listxattr */
#if NAMEDSTREAMS
        { &vnop_getnamedstream_desc, (vnop_t *)nfs4_vnop_getnamedstream },      /* getnamedstream */
        { &vnop_makenamedstream_desc, (vnop_t *)nfs4_vnop_makenamedstream },    /* makenamedstream */
        { &vnop_removenamedstream_desc, (vnop_t *)nfs4_vnop_removenamedstream },/* removenamedstream */
#endif
        { &vnop_monitor_desc, (vnop_t *)nfs_vnop_monitor },     /* monitor */
        { NULL, NULL }
};
const struct vnodeopv_desc spec_nfsv4nodeop_opv_desc =
{ &spec_nfsv4nodeop_p, spec_nfsv4nodeop_entries };
#endif /* CONFIG_NFS4 */

#if FIFO
vnop_t **fifo_nfsv2nodeop_p;
static const struct vnodeopv_entry_desc fifo_nfsv2nodeop_entries[] = {
        { &vnop_default_desc, (vnop_t *)vn_default_error },
        { &vnop_lookup_desc, (vnop_t *)fifo_lookup },           /* lookup */
        { &vnop_create_desc, (vnop_t *)fifo_create },           /* create */
        { &vnop_mknod_desc, (vnop_t *)fifo_mknod },             /* mknod */
        { &vnop_open_desc, (vnop_t *)fifo_open },               /* open */
        { &vnop_close_desc, (vnop_t *)nfsfifo_vnop_close },     /* close */
        { &vnop_getattr_desc, (vnop_t *)nfs3_vnop_getattr },    /* getattr */
        { &vnop_setattr_desc, (vnop_t *)nfs_vnop_setattr },     /* setattr */
        { &vnop_read_desc, (vnop_t *)nfsfifo_vnop_read },       /* read */
        { &vnop_write_desc, (vnop_t *)nfsfifo_vnop_write },     /* write */
        { &vnop_ioctl_desc, (vnop_t *)fifo_ioctl },             /* ioctl */
        { &vnop_select_desc, (vnop_t *)fifo_select },           /* select */
        { &vnop_revoke_desc, (vnop_t *)fifo_revoke },           /* revoke */
        { &vnop_mmap_desc, (vnop_t *)fifo_mmap },               /* mmap */
        { &vnop_fsync_desc, (vnop_t *)nfs_vnop_fsync },         /* fsync */
        { &vnop_remove_desc, (vnop_t *)fifo_remove },           /* remove */
        { &vnop_link_desc, (vnop_t *)fifo_link },               /* link */
        { &vnop_rename_desc, (vnop_t *)fifo_rename },           /* rename */
        { &vnop_mkdir_desc, (vnop_t *)fifo_mkdir },             /* mkdir */
        { &vnop_rmdir_desc, (vnop_t *)fifo_rmdir },             /* rmdir */
        { &vnop_symlink_desc, (vnop_t *)fifo_symlink },         /* symlink */
        { &vnop_readdir_desc, (vnop_t *)fifo_readdir },         /* readdir */
        { &vnop_readlink_desc, (vnop_t *)fifo_readlink },       /* readlink */
        { &vnop_inactive_desc, (vnop_t *)nfs_vnop_inactive },   /* inactive */
        { &vnop_reclaim_desc, (vnop_t *)nfs_vnop_reclaim },     /* reclaim */
        { &vnop_strategy_desc, (vnop_t *)fifo_strategy },       /* strategy */
        { &vnop_pathconf_desc, (vnop_t *)fifo_pathconf },       /* pathconf */
        { &vnop_advlock_desc, (vnop_t *)fifo_advlock },         /* advlock */
        { &vnop_bwrite_desc, (vnop_t *)vn_bwrite },             /* bwrite */
        { &vnop_pagein_desc, (vnop_t *)nfs_vnop_pagein },       /* Pagein */
        { &vnop_pageout_desc, (vnop_t *)nfs_vnop_pageout },     /* Pageout */
        { &vnop_blktooff_desc, (vnop_t *)nfs_vnop_blktooff },   /* blktooff */
        { &vnop_offtoblk_desc, (vnop_t *)nfs_vnop_offtoblk },   /* offtoblk */
        { &vnop_blockmap_desc, (vnop_t *)nfs_vnop_blockmap },   /* blockmap */
        { &vnop_monitor_desc, (vnop_t *)nfs_vnop_monitor },     /* monitor */
        { NULL, NULL }
};
const struct vnodeopv_desc fifo_nfsv2nodeop_opv_desc =
{ &fifo_nfsv2nodeop_p, fifo_nfsv2nodeop_entries };
#endif

#if CONFIG_NFS4
#if FIFO
vnop_t **fifo_nfsv4nodeop_p;
static const struct vnodeopv_entry_desc fifo_nfsv4nodeop_entries[] = {
        { &vnop_default_desc, (vnop_t *)vn_default_error },
        { &vnop_lookup_desc, (vnop_t *)fifo_lookup },           /* lookup */
        { &vnop_create_desc, (vnop_t *)fifo_create },           /* create */
        { &vnop_mknod_desc, (vnop_t *)fifo_mknod },             /* mknod */
        { &vnop_open_desc, (vnop_t *)fifo_open },               /* open */
        { &vnop_close_desc, (vnop_t *)nfsfifo_vnop_close },     /* close */
        { &vnop_getattr_desc, (vnop_t *)nfs4_vnop_getattr },    /* getattr */
        { &vnop_setattr_desc, (vnop_t *)nfs_vnop_setattr },     /* setattr */
        { &vnop_read_desc, (vnop_t *)nfsfifo_vnop_read },       /* read */
        { &vnop_write_desc, (vnop_t *)nfsfifo_vnop_write },     /* write */
        { &vnop_ioctl_desc, (vnop_t *)fifo_ioctl },             /* ioctl */
        { &vnop_select_desc, (vnop_t *)fifo_select },           /* select */
        { &vnop_revoke_desc, (vnop_t *)fifo_revoke },           /* revoke */
        { &vnop_mmap_desc, (vnop_t *)fifo_mmap },               /* mmap */
        { &vnop_fsync_desc, (vnop_t *)nfs_vnop_fsync },         /* fsync */
        { &vnop_remove_desc, (vnop_t *)fifo_remove },           /* remove */
        { &vnop_link_desc, (vnop_t *)fifo_link },               /* link */
        { &vnop_rename_desc, (vnop_t *)fifo_rename },           /* rename */
        { &vnop_mkdir_desc, (vnop_t *)fifo_mkdir },             /* mkdir */
        { &vnop_rmdir_desc, (vnop_t *)fifo_rmdir },             /* rmdir */
        { &vnop_symlink_desc, (vnop_t *)fifo_symlink },         /* symlink */
        { &vnop_readdir_desc, (vnop_t *)fifo_readdir },         /* readdir */
        { &vnop_readlink_desc, (vnop_t *)fifo_readlink },       /* readlink */
        { &vnop_inactive_desc, (vnop_t *)nfs_vnop_inactive },   /* inactive */
        { &vnop_reclaim_desc, (vnop_t *)nfs_vnop_reclaim },     /* reclaim */
        { &vnop_strategy_desc, (vnop_t *)fifo_strategy },       /* strategy */
        { &vnop_pathconf_desc, (vnop_t *)fifo_pathconf },       /* pathconf */
        { &vnop_advlock_desc, (vnop_t *)fifo_advlock },         /* advlock */
        { &vnop_bwrite_desc, (vnop_t *)vn_bwrite },             /* bwrite */
        { &vnop_pagein_desc, (vnop_t *)nfs_vnop_pagein },       /* Pagein */
        { &vnop_pageout_desc, (vnop_t *)nfs_vnop_pageout },     /* Pageout */
        { &vnop_blktooff_desc, (vnop_t *)nfs_vnop_blktooff },   /* blktooff */
        { &vnop_offtoblk_desc, (vnop_t *)nfs_vnop_offtoblk },   /* offtoblk */
        { &vnop_blockmap_desc, (vnop_t *)nfs_vnop_blockmap },   /* blockmap */
        { &vnop_getxattr_desc, (vnop_t *)nfs4_vnop_getxattr },  /* getxattr */
        { &vnop_setxattr_desc, (vnop_t *)nfs4_vnop_setxattr },  /* setxattr */
        { &vnop_removexattr_desc, (vnop_t *)nfs4_vnop_removexattr },/* removexattr */
        { &vnop_listxattr_desc, (vnop_t *)nfs4_vnop_listxattr },/* listxattr */
#if NAMEDSTREAMS
        { &vnop_getnamedstream_desc, (vnop_t *)nfs4_vnop_getnamedstream },      /* getnamedstream */
        { &vnop_makenamedstream_desc, (vnop_t *)nfs4_vnop_makenamedstream },    /* makenamedstream */
        { &vnop_removenamedstream_desc, (vnop_t *)nfs4_vnop_removenamedstream },/* removenamedstream */
#endif
        { &vnop_monitor_desc, (vnop_t *)nfs_vnop_monitor },     /* monitor */
        { NULL, NULL }
};
const struct vnodeopv_desc fifo_nfsv4nodeop_opv_desc =
{ &fifo_nfsv4nodeop_p, fifo_nfsv4nodeop_entries };
#endif /* FIFO */
#endif /* CONFIG_NFS4 */

int     nfs_sillyrename(nfsnode_t, nfsnode_t, struct componentname *, vfs_context_t);
int     nfs_getattr_internal(nfsnode_t, struct nfs_vattr *, vfs_context_t, int);
int     nfs_refresh_fh(nfsnode_t, vfs_context_t);


/*
 * Update nfsnode attributes to avoid extra getattr calls for each direntry.
 * This function should be called only if RDIRPLUS flag is enabled.
 */
void
nfs_rdirplus_update_node_attrs(nfsnode_t dnp, struct direntry *dp, fhandle_t *fhp, struct nfs_vattr *nvattrp, uint64_t *savedxidp)
{
        nfsnode_t np;
        struct componentname cn;
        int isdot = (dp->d_namlen == 1) && (dp->d_name[0] == '.');
        int isdotdot = (dp->d_namlen == 2) && (dp->d_name[0] == '.') && (dp->d_name[1] == '.');

        if (isdot || isdotdot) {
                return;
        }

        np = NULL;
        bzero(&cn, sizeof(cn));
        cn.cn_nameptr = dp->d_name;
        cn.cn_namelen = dp->d_namlen;
        cn.cn_nameiop = LOOKUP;

        nfs_nget(NFSTOMP(dnp), dnp, &cn, fhp->fh_data, fhp->fh_len, nvattrp, savedxidp, RPCAUTH_UNKNOWN, NG_NOCREATE, &np);
        if (np) {
                nfs_node_unlock(np);
                vnode_put(NFSTOV(np));
        }
}

/*
 * Find the slot in the access cache for this UID.
 * If adding and no existing slot is found, reuse slots in FIFO order.
 * The index of the next slot to use is kept in the last entry of the n_access array.
 */
int
nfs_node_access_slot(nfsnode_t np, uid_t uid, int add)
{
        int slot;

        for (slot = 0; slot < NFS_ACCESS_CACHE_SIZE; slot++) {
                if (np->n_accessuid[slot] == uid) {
                        break;
                }
        }
        if (slot == NFS_ACCESS_CACHE_SIZE) {
                if (!add) {
                        return -1;
                }
                slot = np->n_access[NFS_ACCESS_CACHE_SIZE];
                np->n_access[NFS_ACCESS_CACHE_SIZE] = (slot + 1) % NFS_ACCESS_CACHE_SIZE;
        }
        return slot;
}

int
nfs3_access_rpc(nfsnode_t np, u_int32_t *access, int rpcflags, vfs_context_t ctx)
{
        int error = 0, lockerror = ENOENT, status, slot;
        uint32_t access_result = 0;
        u_int64_t xid;
        struct nfsm_chain nmreq, nmrep;
        struct nfsmount *nmp;
        struct timeval now;
        uid_t uid;

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq, NFSX_FH(NFS_VER3) + NFSX_UNSIGNED);
        nfsm_chain_add_fh(error, &nmreq, NFS_VER3, np->n_fhp, np->n_fhsize);
        nfsm_chain_add_32(error, &nmreq, *access);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request2(np, NULL, &nmreq, NFSPROC_ACCESS,
            vfs_context_thread(ctx), vfs_context_ucred(ctx),
            NULL, rpcflags, &nmrep, &xid, &status);
        if ((lockerror = nfs_node_lock(np))) {
                error = lockerror;
        }
        nfsm_chain_postop_attr_update(error, &nmrep, np, &xid);
        if (!error) {
                error = status;
        }
        nfsm_chain_get_32(error, &nmrep, access_result);
        nfsmout_if(error);

        /* XXXab do we really need mount here, also why are we doing access cache management here? */
        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                error = ENXIO;
        }
        nfsmout_if(error);

#if CONFIG_NFS_GSS
        if (auth_is_kerberized(np->n_auth) || auth_is_kerberized(nmp->nm_auth)) {
                uid = nfs_cred_getasid2uid(vfs_context_ucred(ctx));
        } else {
                uid = kauth_cred_getuid(vfs_context_ucred(ctx));
        }
#else
        uid = kauth_cred_getuid(vfs_context_ucred(ctx));
#endif /* CONFIG_NFS_GSS */
        slot = nfs_node_access_slot(np, uid, 1);
        np->n_accessuid[slot] = uid;
        microuptime(&now);
        np->n_accessstamp[slot] = now.tv_sec;
        np->n_access[slot] = access_result;

        /*
         * If we asked for DELETE but didn't get it, the server
         * may simply not support returning that bit (possible
         * on UNIX systems).  So, we'll assume that it is OK,
         * and just let any subsequent delete action fail if it
         * really isn't deletable.
         */
        if ((*access & NFS_ACCESS_DELETE) &&
            !(np->n_access[slot] & NFS_ACCESS_DELETE)) {
                np->n_access[slot] |= NFS_ACCESS_DELETE;
        }
        /* ".zfs" subdirectories may erroneously give a denied answer for add/remove */
        if (nfs_access_dotzfs && (np->n_flag & NISDOTZFSCHILD)) {
                np->n_access[slot] |= (NFS_ACCESS_MODIFY | NFS_ACCESS_EXTEND | NFS_ACCESS_DELETE);
        }
        /* pass back the access returned with this request */
        *access = np->n_access[slot];
nfsmout:
        if (!lockerror) {
                nfs_node_unlock(np);
        }
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        return error;
}


/*
 * NFS access vnode op.
 * For NFS version 2, just return ok. File accesses may fail later.
 * For NFS version 3+, use the access RPC to check accessibility. If file
 * permissions are changed on the server, accesses might still fail later.
 */
int
nfs_vnop_access(
        struct vnop_access_args /* {
                                 *  struct vnodeop_desc *a_desc;
                                 *  vnode_t a_vp;
                                 *  int a_action;
                                 *  vfs_context_t a_context;
                                 *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t vp = ap->a_vp;
        int error = 0, slot, dorpc, rpcflags = 0;
        u_int32_t access, waccess;
        nfsnode_t np = VTONFS(vp);
        struct nfsmount *nmp;
        int nfsvers;
        struct timeval now;
        uid_t uid;

        nmp = VTONMP(vp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;


        if (nfsvers == NFS_VER2 || NMFLAG(nmp, NOOPAQUE_AUTH)) {
                if ((ap->a_action & KAUTH_VNODE_WRITE_RIGHTS) &&
                    vfs_isrdonly(vnode_mount(vp))) {
                        return EROFS;
                }
                return 0;
        }

        /*
         * For NFS v3, do an access rpc, otherwise you are stuck emulating
         * ufs_access() locally using the vattr. This may not be correct,
         * since the server may apply other access criteria such as
         * client uid-->server uid mapping that we do not know about, but
         * this is better than just returning anything that is lying about
         * in the cache.
         */

        /*
         * Convert KAUTH primitives to NFS access rights.
         */
        access = 0;
        if (vnode_isdir(vp)) {
                /* directory */
                if (ap->a_action &
                    (KAUTH_VNODE_LIST_DIRECTORY |
                    KAUTH_VNODE_READ_EXTATTRIBUTES)) {
                        access |= NFS_ACCESS_READ;
                }
                if (ap->a_action & KAUTH_VNODE_SEARCH) {
                        access |= NFS_ACCESS_LOOKUP;
                }
                if (ap->a_action &
                    (KAUTH_VNODE_ADD_FILE |
                    KAUTH_VNODE_ADD_SUBDIRECTORY)) {
                        access |= NFS_ACCESS_MODIFY | NFS_ACCESS_EXTEND;
                }
                if (ap->a_action & KAUTH_VNODE_DELETE_CHILD) {
                        access |= NFS_ACCESS_MODIFY;
                }
        } else {
                /* file */
                if (ap->a_action &
                    (KAUTH_VNODE_READ_DATA |
                    KAUTH_VNODE_READ_EXTATTRIBUTES)) {
                        access |= NFS_ACCESS_READ;
                }
                if (ap->a_action & KAUTH_VNODE_WRITE_DATA) {
                        access |= NFS_ACCESS_MODIFY | NFS_ACCESS_EXTEND;
                }
                if (ap->a_action & KAUTH_VNODE_APPEND_DATA) {
                        access |= NFS_ACCESS_EXTEND;
                }
                if (ap->a_action & KAUTH_VNODE_EXECUTE) {
                        access |= NFS_ACCESS_EXECUTE;
                }
        }
        /* common */
        if (ap->a_action & KAUTH_VNODE_DELETE) {
                access |= NFS_ACCESS_DELETE;
        }
        if (ap->a_action &
            (KAUTH_VNODE_WRITE_ATTRIBUTES |
            KAUTH_VNODE_WRITE_EXTATTRIBUTES |
            KAUTH_VNODE_WRITE_SECURITY)) {
                access |= NFS_ACCESS_MODIFY;
        }
        /* XXX this is pretty dubious */
        if (ap->a_action & KAUTH_VNODE_CHANGE_OWNER) {
                access |= NFS_ACCESS_MODIFY;
        }

        /* if caching, always ask for every right */
        if (nfs_access_cache_timeout > 0) {
                waccess = NFS_ACCESS_READ | NFS_ACCESS_MODIFY |
                    NFS_ACCESS_EXTEND | NFS_ACCESS_EXECUTE |
                    NFS_ACCESS_DELETE | NFS_ACCESS_LOOKUP;
        } else {
                waccess = access;
        }

        if ((error = nfs_node_lock(np))) {
                return error;
        }

        /*
         * Does our cached result allow us to give a definite yes to
         * this request?
         */
#if CONFIG_NFS_GSS
        if (auth_is_kerberized(np->n_auth) || auth_is_kerberized(nmp->nm_auth)) {
                uid = nfs_cred_getasid2uid(vfs_context_ucred(ctx));
        } else {
                uid = kauth_cred_getuid(vfs_context_ucred(ctx));
        }
#else
        uid = kauth_cred_getuid(vfs_context_ucred(ctx));
#endif /* CONFIG_NFS_GSS */
        slot = nfs_node_access_slot(np, uid, 0);
        dorpc = 1;
        if (access == 0) {
                /* not asking for any rights understood by NFS, so don't bother doing an RPC */
                /* OSAddAtomic(1, &nfsstats.accesscache_hits); */
                dorpc = 0;
                waccess = 0;
        } else if (NACCESSVALID(np, slot)) {
                microuptime(&now);
                if (((now.tv_sec < (np->n_accessstamp[slot] + nfs_access_cache_timeout)) &&
                    ((np->n_access[slot] & access) == access)) || nfs_use_cache(nmp)) {
                        /* OSAddAtomic(1, &nfsstats.accesscache_hits); */
                        dorpc = 0;
                        waccess = np->n_access[slot];
                }
        }
        nfs_node_unlock(np);
        if (dorpc) {
                /* Either a no, or a don't know.  Go to the wire. */
                /* OSAddAtomic(1, &nfsstats.accesscache_misses); */

                /*
                 * Allow an access call to timeout if we have it cached
                 * so we won't hang if the server isn't responding.
                 */
                if (NACCESSVALID(np, slot)) {
                        rpcflags |= R_SOFT;
                }

                error = nmp->nm_funcs->nf_access_rpc(np, &waccess, rpcflags, ctx);

                /*
                 * If the server didn't respond return the cached access.
                 */
                if ((error == ETIMEDOUT) && (rpcflags & R_SOFT)) {
                        error = 0;
                        waccess = np->n_access[slot];
                }
        }
        if (!error && ((waccess & access) != access)) {
                error = EACCES;
        }

        return error;
}


/*
 * NFS open vnode op
 *
 * Perform various update/invalidation checks and then add the
 * open to the node.  Regular files will have an open file structure
 * on the node and, for NFSv4, perform an OPEN request on the server.
 */
int
nfs_vnop_open(
        struct vnop_open_args /* {
                               *  struct vnodeop_desc *a_desc;
                               *  vnode_t a_vp;
                               *  int a_mode;
                               *  vfs_context_t a_context;
                               *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t vp = ap->a_vp;
        nfsnode_t np = VTONFS(vp);
        struct nfsmount *nmp;
        int error, accessMode, denyMode, opened = 0;
        struct nfs_open_owner *noop = NULL;
        struct nfs_open_file *nofp = NULL;
        enum vtype vtype;

        if (!(ap->a_mode & (FREAD | FWRITE))) {
                return EINVAL;
        }

        nmp = VTONMP(vp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        if (np->n_flag & NREVOKE) {
                return EIO;
        }

        vtype = vnode_vtype(vp);
        if ((vtype != VREG) && (vtype != VDIR) && (vtype != VLNK)) {
                return EACCES;
        }

        /* First, check if we need to update/invalidate */
        if (ISSET(np->n_flag, NUPDATESIZE)) {
                nfs_data_update_size(np, 0);
        }
        if ((error = nfs_node_lock(np))) {
                return error;
        }
        if (np->n_flag & NNEEDINVALIDATE) {
                np->n_flag &= ~NNEEDINVALIDATE;
                if (vtype == VDIR) {
                        nfs_invaldir(np);
                }
                nfs_node_unlock(np);
                nfs_vinvalbuf(vp, V_SAVE | V_IGNORE_WRITEERR, ctx, 1);
                if ((error = nfs_node_lock(np))) {
                        return error;
                }
        }
        if (vtype == VREG) {
                np->n_lastrahead = -1;
        }
        if (np->n_flag & NMODIFIED) {
                if (vtype == VDIR) {
                        nfs_invaldir(np);
                }
                nfs_node_unlock(np);
                if ((error = nfs_vinvalbuf(vp, V_SAVE | V_IGNORE_WRITEERR, ctx, 1))) {
                        return error;
                }
        } else {
                nfs_node_unlock(np);
        }

        /* nfs_getattr() will check changed and purge caches */
        if ((error = nfs_getattr(np, NULL, ctx, NGA_UNCACHED))) {
                return error;
        }

        if (vtype != VREG) {
                /* Just mark that it was opened */
                lck_mtx_lock(&np->n_openlock);
                np->n_openrefcnt++;
                lck_mtx_unlock(&np->n_openlock);
                return 0;
        }

        /* mode contains some combination of: FREAD, FWRITE, O_SHLOCK, O_EXLOCK */
        accessMode = 0;
        if (ap->a_mode & FREAD) {
                accessMode |= NFS_OPEN_SHARE_ACCESS_READ;
        }
        if (ap->a_mode & FWRITE) {
                accessMode |= NFS_OPEN_SHARE_ACCESS_WRITE;
        }
        if (ap->a_mode & O_EXLOCK) {
                denyMode = NFS_OPEN_SHARE_DENY_BOTH;
        } else if (ap->a_mode & O_SHLOCK) {
                denyMode = NFS_OPEN_SHARE_DENY_WRITE;
        } else {
                denyMode = NFS_OPEN_SHARE_DENY_NONE;
        }
        // XXX don't do deny modes just yet (and never do it for !v4)
        denyMode = NFS_OPEN_SHARE_DENY_NONE;

        noop = nfs_open_owner_find(nmp, vfs_context_ucred(ctx), 1);
        if (!noop) {
                return ENOMEM;
        }

restart:
        error = nfs_mount_state_in_use_start(nmp, vfs_context_thread(ctx));
        if (error) {
                nfs_open_owner_rele(noop);
                return error;
        }
        if (np->n_flag & NREVOKE) {
                error = EIO;
                nfs_mount_state_in_use_end(nmp, 0);
                nfs_open_owner_rele(noop);
                return error;
        }

        error = nfs_open_file_find(np, noop, &nofp, accessMode, denyMode, 1);
        if (!error && (nofp->nof_flags & NFS_OPEN_FILE_LOST)) {
                NP(np, "nfs_vnop_open: LOST %d", kauth_cred_getuid(nofp->nof_owner->noo_cred));
                error = EIO;
        }
#if CONFIG_NFS4
        if (!error && (nofp->nof_flags & NFS_OPEN_FILE_REOPEN)) {
                nfs_mount_state_in_use_end(nmp, 0);
                error = nfs4_reopen(nofp, vfs_context_thread(ctx));
                nofp = NULL;
                if (!error) {
                        goto restart;
                }
        }
#endif
        if (!error) {
                error = nfs_open_file_set_busy(nofp, vfs_context_thread(ctx));
        }
        if (error) {
                nofp = NULL;
                goto out;
        }

        if (nmp->nm_vers < NFS_VER4) {
                /*
                 * NFS v2/v3 opens are always allowed - so just add it.
                 */
                nfs_open_file_add_open(nofp, accessMode, denyMode, 0);
                goto out;
        }

        /*
         * If we just created the file and the modes match, then we simply use
         * the open performed in the create.  Otherwise, send the request.
         */
        if ((nofp->nof_flags & NFS_OPEN_FILE_CREATE) &&
            (nofp->nof_creator == current_thread()) &&
            (accessMode == NFS_OPEN_SHARE_ACCESS_BOTH) &&
            (denyMode == NFS_OPEN_SHARE_DENY_NONE)) {
                nofp->nof_flags &= ~NFS_OPEN_FILE_CREATE;
                nofp->nof_creator = NULL;
        } else {
#if CONFIG_NFS4
                if (!opened) {
                        error = nfs4_open(np, nofp, accessMode, denyMode, ctx);
                }
#endif
                if ((error == EACCES) && (nofp->nof_flags & NFS_OPEN_FILE_CREATE) &&
                    (nofp->nof_creator == current_thread())) {
                        /*
                         * Ugh.  This can happen if we just created the file with read-only
                         * perms and we're trying to open it for real with different modes
                         * (e.g. write-only or with a deny mode) and the server decides to
                         * not allow the second open because of the read-only perms.
                         * The best we can do is to just use the create's open.
                         * We may have access we don't need or we may not have a requested
                         * deny mode.  We may log complaints later, but we'll try to avoid it.
                         */
                        if (denyMode != NFS_OPEN_SHARE_DENY_NONE) {
                                NP(np, "nfs_vnop_open: deny mode foregone on create, %d", kauth_cred_getuid(nofp->nof_owner->noo_cred));
                        }
                        nofp->nof_creator = NULL;
                        error = 0;
                }
                if (error) {
                        goto out;
                }
                opened = 1;
                /*
                 * If we had just created the file, we already had it open.
                 * If the actual open mode is less than what we grabbed at
                 * create time, then we'll downgrade the open here.
                 */
                if ((nofp->nof_flags & NFS_OPEN_FILE_CREATE) &&
                    (nofp->nof_creator == current_thread())) {
                        error = nfs_close(np, nofp, NFS_OPEN_SHARE_ACCESS_BOTH, NFS_OPEN_SHARE_DENY_NONE, ctx);
                        if (error) {
                                NP(np, "nfs_vnop_open: create close error %d, %d", error, kauth_cred_getuid(nofp->nof_owner->noo_cred));
                        }
                        if (!nfs_mount_state_error_should_restart(error)) {
                                error = 0;
                                nofp->nof_flags &= ~NFS_OPEN_FILE_CREATE;
                        }
                }
        }

out:
        if (nofp) {
                nfs_open_file_clear_busy(nofp);
        }
        if (nfs_mount_state_in_use_end(nmp, error)) {
                nofp = NULL;
                goto restart;
        }
        if (error) {
                NP(np, "nfs_vnop_open: error %d, %d", error, kauth_cred_getuid(noop->noo_cred));
        }
        if (noop) {
                nfs_open_owner_rele(noop);
        }
        if (!error && vtype == VREG && (ap->a_mode & FWRITE)) {
                lck_mtx_lock(&nmp->nm_lock);
                nmp->nm_state &= ~NFSSTA_SQUISHY;
                nmp->nm_curdeadtimeout = nmp->nm_deadtimeout;
                if (nmp->nm_curdeadtimeout <= 0) {
                        nmp->nm_deadto_start = 0;
                }
                nmp->nm_writers++;
                lck_mtx_unlock(&nmp->nm_lock);
        }

        return error;
}

static uint32_t
nfs_no_of_open_file_writers(nfsnode_t np)
{
        uint32_t writers = 0;
        struct nfs_open_file *nofp;

        TAILQ_FOREACH(nofp, &np->n_opens, nof_link) {
                writers += nofp->nof_w + nofp->nof_rw + nofp->nof_w_dw + nofp->nof_rw_dw +
                    nofp->nof_w_drw + nofp->nof_rw_drw + nofp->nof_d_w_dw +
                    nofp->nof_d_rw_dw + nofp->nof_d_w_drw + nofp->nof_d_rw_drw +
                    nofp->nof_d_w + nofp->nof_d_rw;
        }

        return writers;
}

/*
 * NFS close vnode op
 *
 * What an NFS client should do upon close after writing is a debatable issue.
 * Most NFS clients push delayed writes to the server upon close, basically for
 * two reasons:
 * 1 - So that any write errors may be reported back to the client process
 *     doing the close system call. By far the two most likely errors are
 *     NFSERR_NOSPC and NFSERR_DQUOT to indicate space allocation failure.
 * 2 - To put a worst case upper bound on cache inconsistency between
 *     multiple clients for the file.
 * There is also a consistency problem for Version 2 of the protocol w.r.t.
 * not being able to tell if other clients are writing a file concurrently,
 * since there is no way of knowing if the changed modify time in the reply
 * is only due to the write for this client.
 * (NFS Version 3 provides weak cache consistency data in the reply that
 *  should be sufficient to detect and handle this case.)
 *
 * The current code does the following:
 * for NFS Version 2 - play it safe and flush/invalidate all dirty buffers
 * for NFS Version 3 - flush dirty buffers to the server but don't invalidate them.
 * for NFS Version 4 - basically the same as NFSv3
 */
int
nfs_vnop_close(
        struct vnop_close_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_vp;
                                *  int a_fflag;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t vp = ap->a_vp;
        nfsnode_t np = VTONFS(vp);
        struct nfsmount *nmp;
        int error = 0, error1, nfsvers;
        int fflag = ap->a_fflag;
        enum vtype vtype;
        int accessMode, denyMode;
        struct nfs_open_owner *noop = NULL;
        struct nfs_open_file *nofp = NULL;

        nmp = VTONMP(vp);
        if (!nmp) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        vtype = vnode_vtype(vp);

        /* First, check if we need to update/flush/invalidate */
        if (ISSET(np->n_flag, NUPDATESIZE)) {
                nfs_data_update_size(np, 0);
        }
        nfs_node_lock_force(np);
        if (np->n_flag & NNEEDINVALIDATE) {
                np->n_flag &= ~NNEEDINVALIDATE;
                nfs_node_unlock(np);
                nfs_vinvalbuf(vp, V_SAVE | V_IGNORE_WRITEERR, ctx, 1);
                nfs_node_lock_force(np);
        }
        if ((vtype == VREG) && (np->n_flag & NMODIFIED) && (fflag & FWRITE)) {
                /* we're closing an open for write and the file is modified, so flush it */
                nfs_node_unlock(np);
                if (nfsvers != NFS_VER2) {
                        error = nfs_flush(np, MNT_WAIT, vfs_context_thread(ctx), 0);
                } else {
                        error = nfs_vinvalbuf(vp, V_SAVE, ctx, 1);
                }
                nfs_node_lock_force(np);
                NATTRINVALIDATE(np);
        }
        if (np->n_flag & NWRITEERR) {
                np->n_flag &= ~NWRITEERR;
                error = np->n_error;
        }
        nfs_node_unlock(np);

        if (vtype != VREG) {
                /* Just mark that it was closed */
                lck_mtx_lock(&np->n_openlock);
                if (np->n_openrefcnt == 0) {
                        if (fflag & (FREAD | FWRITE)) {
                                NP(np, "nfs_vnop_close: open reference underrun");
                                error = EINVAL;
                        }
                } else if (fflag & (FREAD | FWRITE)) {
                        np->n_openrefcnt--;
                } else {
                        /* No FREAD/FWRITE set - probably the final close */
                        np->n_openrefcnt = 0;
                }
                lck_mtx_unlock(&np->n_openlock);
                return error;
        }
        error1 = error;

        /* fflag should contain some combination of: FREAD, FWRITE, FHASLOCK */
        accessMode = 0;
        if (fflag & FREAD) {
                accessMode |= NFS_OPEN_SHARE_ACCESS_READ;
        }
        if (fflag & FWRITE) {
                accessMode |= NFS_OPEN_SHARE_ACCESS_WRITE;
        }
// XXX It would be nice if we still had the O_EXLOCK/O_SHLOCK flags that were on the open
//      if (fflag & O_EXLOCK)
//              denyMode = NFS_OPEN_SHARE_DENY_BOTH;
//      else if (fflag & O_SHLOCK)
//              denyMode = NFS_OPEN_SHARE_DENY_WRITE;
//      else
//              denyMode = NFS_OPEN_SHARE_DENY_NONE;
#if 0  // Not yet
        if (fflag & FHASLOCK) {
                /* XXX assume FHASLOCK is for the deny mode and not flock */
                /* FHASLOCK flock will be unlocked in the close path, but the flag is not cleared. */
                if (nofp->nof_deny & NFS_OPEN_SHARE_DENY_READ) {
                        denyMode = NFS_OPEN_SHARE_DENY_BOTH;
                } else if (nofp->nof_deny & NFS_OPEN_SHARE_DENY_WRITE) {
                        denyMode = NFS_OPEN_SHARE_DENY_WRITE;
                } else {
                        denyMode = NFS_OPEN_SHARE_DENY_NONE;
                }
        } else {
                denyMode = NFS_OPEN_SHARE_DENY_NONE;
        }
#else
        // XXX don't do deny modes just yet (and never do it for !v4)
        denyMode = NFS_OPEN_SHARE_DENY_NONE;
#endif

        if (!accessMode) {
                /*
                 * No mode given to close?
                 * Guess this is the final close.
                 * We should unlock all locks and close all opens.
                 */
                uint32_t writers;
                mount_t mp = vnode_mount(vp);
                int force = (!mp || vfs_isforce(mp));

                writers = nfs_no_of_open_file_writers(np);
                nfs_release_open_state_for_node(np, force);
                if (writers) {
                        lck_mtx_lock(&nmp->nm_lock);
                        if (writers > nmp->nm_writers) {
                                NP(np, "nfs_vnop_close: number of write opens for mount underrun. Node has %d"
                                    " opens for write. Mount has total of %d opens for write\n",
                                    writers, nmp->nm_writers);
                                nmp->nm_writers = 0;
                        } else {
                                nmp->nm_writers -= writers;
                        }
                        lck_mtx_unlock(&nmp->nm_lock);
                }

                return error;
        } else if (fflag & FWRITE) {
                lck_mtx_lock(&nmp->nm_lock);
                if (nmp->nm_writers == 0) {
                        NP(np, "nfs_vnop_close: removing open writer from mount, but mount has no files open for writing");
                } else {
                        nmp->nm_writers--;
                }
                lck_mtx_unlock(&nmp->nm_lock);
        }


        noop = nfs_open_owner_find(nmp, vfs_context_ucred(ctx), 0);
        if (!noop) {
                // printf("nfs_vnop_close: can't get open owner!\n");
                return EIO;
        }

restart:
        error = nfs_mount_state_in_use_start(nmp, NULL);
        if (error) {
                nfs_open_owner_rele(noop);
                return error;
        }

        error = nfs_open_file_find(np, noop, &nofp, 0, 0, 0);
#if CONFIG_NFS4
        if (!error && (nofp->nof_flags & NFS_OPEN_FILE_REOPEN)) {
                nfs_mount_state_in_use_end(nmp, 0);
                error = nfs4_reopen(nofp, NULL);
                nofp = NULL;
                if (!error) {
                        goto restart;
                }
        }
#endif
        if (error) {
                NP(np, "nfs_vnop_close: no open file for owner, error %d, %d", error, kauth_cred_getuid(noop->noo_cred));
                error = EBADF;
                goto out;
        }
        error = nfs_open_file_set_busy(nofp, NULL);
        if (error) {
                nofp = NULL;
                goto out;
        }

        error = nfs_close(np, nofp, accessMode, denyMode, ctx);
        if (error) {
                NP(np, "nfs_vnop_close: close error %d, %d", error, kauth_cred_getuid(noop->noo_cred));
        }

out:
        if (nofp) {
                nfs_open_file_clear_busy(nofp);
        }
        if (nfs_mount_state_in_use_end(nmp, error)) {
                nofp = NULL;
                goto restart;
        }
        if (!error) {
                error = error1;
        }
        if (error) {
                NP(np, "nfs_vnop_close: error %d, %d", error, kauth_cred_getuid(noop->noo_cred));
        }
        if (noop) {
                nfs_open_owner_rele(noop);
        }
        return error;
}

/*
 * nfs_close(): common function that does all the heavy lifting of file closure
 *
 * Takes an open file structure and a set of access/deny modes and figures out how
 * to update the open file structure (and the state on the server) appropriately.
 */
int
nfs_close(
        nfsnode_t np,
        struct nfs_open_file *nofp,
        uint32_t accessMode,
        uint32_t denyMode,
        __unused vfs_context_t ctx)
{
#if CONFIG_NFS4
        struct nfs_lock_owner *nlop;
#endif
        int error = 0, changed = 0, delegated = 0, closed = 0, downgrade = 0;
        uint32_t newAccessMode, newDenyMode;

        /* warn if modes don't match current state */
        if (((accessMode & nofp->nof_access) != accessMode) || ((denyMode & nofp->nof_deny) != denyMode)) {
                NP(np, "nfs_close: mode mismatch %d %d, current %d %d, %d",
                    accessMode, denyMode, nofp->nof_access, nofp->nof_deny,
                    kauth_cred_getuid(nofp->nof_owner->noo_cred));
        }

        /*
         * If we're closing a write-only open, we may not have a write-only count
         * if we also grabbed read access.  So, check the read-write count.
         */
        if (denyMode == NFS_OPEN_SHARE_DENY_NONE) {
                if ((accessMode == NFS_OPEN_SHARE_ACCESS_WRITE) &&
                    (nofp->nof_w == 0) && (nofp->nof_d_w == 0) &&
                    (nofp->nof_rw || nofp->nof_d_rw)) {
                        accessMode = NFS_OPEN_SHARE_ACCESS_BOTH;
                }
        } else if (denyMode == NFS_OPEN_SHARE_DENY_WRITE) {
                if ((accessMode == NFS_OPEN_SHARE_ACCESS_WRITE) &&
                    (nofp->nof_w_dw == 0) && (nofp->nof_d_w_dw == 0) &&
                    (nofp->nof_rw_dw || nofp->nof_d_rw_dw)) {
                        accessMode = NFS_OPEN_SHARE_ACCESS_BOTH;
                }
        } else { /* NFS_OPEN_SHARE_DENY_BOTH */
                if ((accessMode == NFS_OPEN_SHARE_ACCESS_WRITE) &&
                    (nofp->nof_w_drw == 0) && (nofp->nof_d_w_drw == 0) &&
                    (nofp->nof_rw_drw || nofp->nof_d_rw_drw)) {
                        accessMode = NFS_OPEN_SHARE_ACCESS_BOTH;
                }
        }

        nfs_open_file_remove_open_find(nofp, accessMode, denyMode, &newAccessMode, &newDenyMode, &delegated);
        if ((newAccessMode != nofp->nof_access) || (newDenyMode != nofp->nof_deny)) {
                changed = 1;
        } else {
                changed = 0;
        }

        if (NFSTONMP(np)->nm_vers < NFS_VER4) {
                /* NFS v2/v3 closes simply need to remove the open. */
                goto v3close;
        }
#if CONFIG_NFS4
        if ((newAccessMode == 0) || (nofp->nof_opencnt == 1)) {
                /*
                 * No more access after this close, so clean up and close it.
                 * Don't send a close RPC if we're closing a delegated open.
                 */
                nfs_wait_bufs(np);
                closed = 1;
                if (!delegated && !(nofp->nof_flags & NFS_OPEN_FILE_LOST)) {
                        error = nfs4_close_rpc(np, nofp, vfs_context_thread(ctx), vfs_context_ucred(ctx), 0);
                }
                if (error == NFSERR_LOCKS_HELD) {
                        /*
                         * Hmm... the server says we have locks we need to release first
                         * Find the lock owner and try to unlock everything.
                         */
                        nlop = nfs_lock_owner_find(np, vfs_context_proc(ctx), 0);
                        if (nlop) {
                                nfs4_unlock_rpc(np, nlop, F_WRLCK, 0, UINT64_MAX,
                                    0, vfs_context_thread(ctx), vfs_context_ucred(ctx));
                                nfs_lock_owner_rele(nlop);
                        }
                        error = nfs4_close_rpc(np, nofp, vfs_context_thread(ctx), vfs_context_ucred(ctx), 0);
                }
        } else if (changed) {
                /*
                 * File is still open but with less access, so downgrade the open.
                 * Don't send a downgrade RPC if we're closing a delegated open.
                 */
                if (!delegated && !(nofp->nof_flags & NFS_OPEN_FILE_LOST)) {
                        downgrade = 1;
                        /*
                         * If we have delegated opens, we should probably claim them before sending
                         * the downgrade because the server may not know the open we are downgrading to.
                         */
                        if (nofp->nof_d_rw_drw || nofp->nof_d_w_drw || nofp->nof_d_r_drw ||
                            nofp->nof_d_rw_dw || nofp->nof_d_w_dw || nofp->nof_d_r_dw ||
                            nofp->nof_d_rw || nofp->nof_d_w || nofp->nof_d_r) {
                                nfs4_claim_delegated_state_for_open_file(nofp, 0);
                        }
                        /* need to remove the open before sending the downgrade */
                        nfs_open_file_remove_open(nofp, accessMode, denyMode);
                        error = nfs4_open_downgrade_rpc(np, nofp, ctx);
                        if (error) { /* Hmm.. that didn't work. Add the open back in. */
                                nfs_open_file_add_open(nofp, accessMode, denyMode, delegated);
                        }
                }
        }
#endif
v3close:
        if (error) {
                NP(np, "nfs_close: error %d, %d", error, kauth_cred_getuid(nofp->nof_owner->noo_cred));
                return error;
        }

        if (!downgrade) {
                nfs_open_file_remove_open(nofp, accessMode, denyMode);
        }

        if (closed) {
                lck_mtx_lock(&nofp->nof_lock);
                if (nofp->nof_r || nofp->nof_d_r || nofp->nof_w || nofp->nof_d_w || nofp->nof_d_rw ||
                    (nofp->nof_rw && !((nofp->nof_flags & NFS_OPEN_FILE_CREATE) && !nofp->nof_creator && (nofp->nof_rw == 1))) ||
                    nofp->nof_r_dw || nofp->nof_d_r_dw || nofp->nof_w_dw || nofp->nof_d_w_dw ||
                    nofp->nof_rw_dw || nofp->nof_d_rw_dw || nofp->nof_r_drw || nofp->nof_d_r_drw ||
                    nofp->nof_w_drw || nofp->nof_d_w_drw || nofp->nof_rw_drw || nofp->nof_d_rw_drw) {
                        NP(np, "nfs_close: unexpected count: %u.%u %u.%u %u.%u dw %u.%u %u.%u %u.%u drw %u.%u %u.%u %u.%u flags 0x%x, %d",
                            nofp->nof_r, nofp->nof_d_r, nofp->nof_w, nofp->nof_d_w,
                            nofp->nof_rw, nofp->nof_d_rw, nofp->nof_r_dw, nofp->nof_d_r_dw,
                            nofp->nof_w_dw, nofp->nof_d_w_dw, nofp->nof_rw_dw, nofp->nof_d_rw_dw,
                            nofp->nof_r_drw, nofp->nof_d_r_drw, nofp->nof_w_drw, nofp->nof_d_w_drw,
                            nofp->nof_rw_drw, nofp->nof_d_rw_drw, nofp->nof_flags,
                            kauth_cred_getuid(nofp->nof_owner->noo_cred));
                }
                /* clear out all open info, just to be safe */
                nofp->nof_access = nofp->nof_deny = 0;
                nofp->nof_mmap_access = nofp->nof_mmap_deny = 0;
                nofp->nof_r = nofp->nof_d_r = 0;
                nofp->nof_w = nofp->nof_d_w = 0;
                nofp->nof_rw = nofp->nof_d_rw = 0;
                nofp->nof_r_dw = nofp->nof_d_r_dw = 0;
                nofp->nof_w_dw = nofp->nof_d_w_dw = 0;
                nofp->nof_rw_dw = nofp->nof_d_rw_dw = 0;
                nofp->nof_r_drw = nofp->nof_d_r_drw = 0;
                nofp->nof_w_drw = nofp->nof_d_w_drw = 0;
                nofp->nof_rw_drw = nofp->nof_d_rw_drw = 0;
                nofp->nof_flags &= ~NFS_OPEN_FILE_CREATE;
                lck_mtx_unlock(&nofp->nof_lock);
                /* XXX we may potentially want to clean up idle/unused open file structures */
        }
        if (nofp->nof_flags & NFS_OPEN_FILE_LOST) {
                error = EIO;
                NP(np, "nfs_close: LOST%s, %d", !nofp->nof_opencnt ? " (last)" : "",
                    kauth_cred_getuid(nofp->nof_owner->noo_cred));
        }

        return error;
}


int
nfs3_getattr_rpc(
        nfsnode_t np,
        mount_t mp,
        u_char *fhp,
        size_t fhsize,
        int flags,
        vfs_context_t ctx,
        struct nfs_vattr *nvap,
        u_int64_t *xidp)
{
        struct nfsmount *nmp = mp ? VFSTONFS(mp) : NFSTONMP(np);
        int error = 0, status, nfsvers, rpcflags = 0;
        struct nfsm_chain nmreq, nmrep;

        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        if (flags & NGA_MONITOR) { /* vnode monitor requests should be soft */
                rpcflags = R_RECOVER;
        }

        if (flags & NGA_SOFT) { /* Return ETIMEDOUT if server not responding */
                rpcflags |= R_SOFT;
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq, NFSX_FH(nfsvers));
        if (nfsvers != NFS_VER2) {
                nfsm_chain_add_32(error, &nmreq, fhsize);
        }
        nfsm_chain_add_opaque(error, &nmreq, fhp, fhsize);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request2(np, mp, &nmreq, NFSPROC_GETATTR,
            vfs_context_thread(ctx), vfs_context_ucred(ctx),
            NULL, rpcflags, &nmrep, xidp, &status);
        if (!error) {
                error = status;
        }
        nfsmout_if(error);
        error = nfs_parsefattr(nmp, &nmrep, nfsvers, nvap);
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        return error;
}

/*
 * nfs_refresh_fh will attempt to update the file handle for the node.
 *
 * It only does this for symbolic links and regular files that are not currently opened.
 *
 * On Success returns 0 and the nodes file handle is updated, or ESTALE on failure.
 */
int
nfs_refresh_fh(nfsnode_t np, vfs_context_t ctx)
{
        vnode_t dvp, vp = NFSTOV(np);
        nfsnode_t dnp;
        const char *v_name = vnode_getname(vp);
        char *name;
        int namelen, fhsize, refreshed;
        int error, wanted = 0;
        uint8_t *fhp;
        struct timespec ts = {.tv_sec = 2, .tv_nsec = 0};

        NFS_VNOP_DBG("vnode is %d\n", vnode_vtype(vp));

        dvp = vnode_parent(vp);
        if ((vnode_vtype(vp) != VREG && vnode_vtype(vp) != VLNK) ||
            v_name == NULL || *v_name == '\0' || dvp == NULL) {
                if (v_name != NULL) {
                        vnode_putname(v_name);
                }
                return ESTALE;
        }
        dnp = VTONFS(dvp);

        namelen = strlen(v_name);
        MALLOC(name, char *, namelen + 1, M_TEMP, M_WAITOK);
        if (name == NULL) {
                vnode_putname(v_name);
                return ESTALE;
        }
        bcopy(v_name, name, namelen + 1);
        NFS_VNOP_DBG("Trying to refresh %s : %s\n", v_name, name);
        vnode_putname(v_name);

        /* Allocate the maximum size file handle */
        MALLOC(fhp, uint8_t *, NFS4_FHSIZE, M_TEMP, M_WAITOK);
        if (fhp == NULL) {
                FREE(name, M_TEMP);
                return ESTALE;
        }

        if ((error = nfs_node_lock(np))) {
                FREE(name, M_TEMP);
                FREE(fhp, M_TEMP);
                return ESTALE;
        }

        fhsize = np->n_fhsize;
        bcopy(np->n_fhp, fhp, fhsize);
        while (ISSET(np->n_flag, NREFRESH)) {
                SET(np->n_flag, NREFRESHWANT);
                NFS_VNOP_DBG("Waiting for refresh of %s\n", name);
                msleep(np, &np->n_lock, PZERO - 1, "nfsrefreshwant", &ts);
                if ((error = nfs_sigintr(NFSTONMP(np), NULL, vfs_context_thread(ctx), 0))) {
                        break;
                }
        }
        refreshed = error ? 0 : !NFS_CMPFH(np, fhp, fhsize);
        SET(np->n_flag, NREFRESH);
        nfs_node_unlock(np);

        NFS_VNOP_DBG("error = %d, refreshed = %d\n", error, refreshed);
        if (error || refreshed) {
                goto nfsmout;
        }

        /* Check that there are no open references for this file */
        lck_mtx_lock(&np->n_openlock);
        if (np->n_openrefcnt || !TAILQ_EMPTY(&np->n_opens) || !TAILQ_EMPTY(&np->n_lock_owners)) {
                int cnt = 0;
                struct nfs_open_file *ofp;

                TAILQ_FOREACH(ofp, &np->n_opens, nof_link) {
                        cnt += ofp->nof_opencnt;
                }
                if (cnt) {
                        lck_mtx_unlock(&np->n_openlock);
                        NFS_VNOP_DBG("Can not refresh file handle for %s with open state\n", name);
                        NFS_VNOP_DBG("\topenrefcnt = %d, opens = %d lock_owners = %d\n",
                            np->n_openrefcnt, cnt, !TAILQ_EMPTY(&np->n_lock_owners));
                        error = ESTALE;
                        goto nfsmout;
                }
        }
        lck_mtx_unlock(&np->n_openlock);
        /*
         * Since the FH is currently stale we should not be able to
         * establish any open state until the FH is refreshed.
         */

        error = nfs_node_lock(np);
        nfsmout_if(error);
        /*
         * Symlinks should never need invalidations and are holding
         * the one and only nfsbuf in an uncached acquired state
         * trying to do a readlink. So we will hang if we invalidate
         * in that case. Only in in the VREG case do we need to
         * invalidate.
         */
        if (vnode_vtype(vp) == VREG) {
                np->n_flag &= ~NNEEDINVALIDATE;
                nfs_node_unlock(np);
                error = nfs_vinvalbuf(vp, V_IGNORE_WRITEERR, ctx, 1);
                if (error) {
                        NFS_VNOP_DBG("nfs_vinvalbuf returned %d\n", error);
                }
                nfsmout_if(error);
        } else {
                nfs_node_unlock(np);
        }

        NFS_VNOP_DBG("Looking up %s\n", name);
        error = nfs_lookitup(dnp, name, namelen, ctx, &np);
        if (error) {
                NFS_VNOP_DBG("nfs_lookitup returned %d\n", error);
        }

nfsmout:
        nfs_node_lock_force(np);
        wanted = ISSET(np->n_flag, NREFRESHWANT);
        CLR(np->n_flag, NREFRESH | NREFRESHWANT);
        nfs_node_unlock(np);
        if (wanted) {
                wakeup(np);
        }

        if (error == 0) {
                NFS_VNOP_DBG("%s refreshed file handle\n", name);
        }

        FREE(name, M_TEMP);
        FREE(fhp, M_TEMP);

        return error ? ESTALE : 0;
}

int
nfs_getattr(nfsnode_t np, struct nfs_vattr *nvap, vfs_context_t ctx, int flags)
{
        int error;

retry:
        error = nfs_getattr_internal(np, nvap, ctx, flags);
        if (error == ESTALE) {
                error = nfs_refresh_fh(np, ctx);
                if (!error) {
                        goto retry;
                }
        }
        return error;
}

int
nfs_getattr_internal(nfsnode_t np, struct nfs_vattr *nvap, vfs_context_t ctx, int flags)
{
        struct nfsmount *nmp;
        int error = 0, nfsvers, inprogset = 0, wanted = 0, avoidfloods;
        struct nfs_vattr nvattr;
        struct timespec ts = { .tv_sec = 2, .tv_nsec = 0 };
        u_int64_t xid;

        FSDBG_TOP(513, np->n_size, np, np->n_vattr.nva_size, np->n_flag);

        nmp = NFSTONMP(np);

        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        if (!nvap) {
                nvap = &nvattr;
        }
        NVATTR_INIT(nvap);

        /* Update local times for special files. */
        if (np->n_flag & (NACC | NUPD)) {
                nfs_node_lock_force(np);
                np->n_flag |= NCHG;
                nfs_node_unlock(np);
        }
        /* Update size, if necessary */
        if (ISSET(np->n_flag, NUPDATESIZE)) {
                nfs_data_update_size(np, 0);
        }

        error = nfs_node_lock(np);
        nfsmout_if(error);
        if (!(flags & (NGA_UNCACHED | NGA_MONITOR)) || ((nfsvers >= NFS_VER4) && (np->n_openflags & N_DELEG_MASK))) {
                /*
                 * Use the cache or wait for any getattr in progress if:
                 * - it's a cached request, or
                 * - we have a delegation, or
                 * - the server isn't responding
                 */
                while (1) {
                        error = nfs_getattrcache(np, nvap, flags);
                        if (!error || (error != ENOENT)) {
                                nfs_node_unlock(np);
                                goto nfsmout;
                        }
                        error = 0;
                        if (!ISSET(np->n_flag, NGETATTRINPROG)) {
                                break;
                        }
                        if (flags & NGA_MONITOR) {
                                /* no need to wait if a request is pending */
                                error = EINPROGRESS;
                                nfs_node_unlock(np);
                                goto nfsmout;
                        }
                        SET(np->n_flag, NGETATTRWANT);
                        msleep(np, &np->n_lock, PZERO - 1, "nfsgetattrwant", &ts);
                        if ((error = nfs_sigintr(NFSTONMP(np), NULL, vfs_context_thread(ctx), 0))) {
                                nfs_node_unlock(np);
                                goto nfsmout;
                        }
                }
                SET(np->n_flag, NGETATTRINPROG);
                inprogset = 1;
        } else if (!ISSET(np->n_flag, NGETATTRINPROG)) {
                SET(np->n_flag, NGETATTRINPROG);
                inprogset = 1;
        } else if (flags & NGA_MONITOR) {
                /* no need to make a request if one is pending */
                error = EINPROGRESS;
        }
        nfs_node_unlock(np);

        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                error = ENXIO;
        }
        if (error) {
                goto nfsmout;
        }

        /*
         * Return cached attributes if they are valid,
         * if the server doesn't respond, and this is
         * some softened up style of mount.
         */
        if (NATTRVALID(np) && nfs_use_cache(nmp)) {
                flags |= NGA_SOFT;
        }

        /*
         * We might want to try to get both the attributes and access info by
         * making an ACCESS call and seeing if it returns updated attributes.
         * But don't bother if we aren't caching access info or if the
         * attributes returned wouldn't be cached.
         */
        if (!(flags & NGA_ACL) && (nfsvers != NFS_VER2) && nfs_access_for_getattr && (nfs_access_cache_timeout > 0)) {
                if (nfs_attrcachetimeout(np) > 0) {
                        /*  OSAddAtomic(1, &nfsstats.accesscache_misses); */
                        u_int32_t access = NFS_ACCESS_ALL;
                        int rpcflags = 0;

                        /* Return cached attrs if server doesn't respond */
                        if (flags & NGA_SOFT) {
                                rpcflags |= R_SOFT;
                        }

                        error = nmp->nm_funcs->nf_access_rpc(np, &access, rpcflags, ctx);

                        if (error == ETIMEDOUT) {
                                goto returncached;
                        }

                        if (error) {
                                goto nfsmout;
                        }
                        nfs_node_lock_force(np);
                        error = nfs_getattrcache(np, nvap, flags);
                        nfs_node_unlock(np);
                        if (!error || (error != ENOENT)) {
                                goto nfsmout;
                        }
                        /* Well, that didn't work... just do a getattr... */
                        error = 0;
                }
        }

        avoidfloods = 0;

tryagain:
        error = nmp->nm_funcs->nf_getattr_rpc(np, NULL, np->n_fhp, np->n_fhsize, flags, ctx, nvap, &xid);
        if (!error) {
                nfs_node_lock_force(np);
                error = nfs_loadattrcache(np, nvap, &xid, 0);
                nfs_node_unlock(np);
        }

        /*
         * If the server didn't respond, return cached attributes.
         */
returncached:
        if ((flags & NGA_SOFT) && (error == ETIMEDOUT)) {
                nfs_node_lock_force(np);
                error = nfs_getattrcache(np, nvap, flags);
                if (!error || (error != ENOENT)) {
                        nfs_node_unlock(np);
                        goto nfsmout;
                }
                nfs_node_unlock(np);
        }
        nfsmout_if(error);

        if (!xid) { /* out-of-order rpc - attributes were dropped */
                FSDBG(513, -1, np, np->n_xid >> 32, np->n_xid);
                if (avoidfloods++ < 20) {
                        goto tryagain;
                }
                /* avoidfloods>1 is bizarre.  at 20 pull the plug */
                /* just return the last attributes we got */
        }
nfsmout:
        nfs_node_lock_force(np);
        if (inprogset) {
                wanted = ISSET(np->n_flag, NGETATTRWANT);
                CLR(np->n_flag, (NGETATTRINPROG | NGETATTRWANT));
        }
        if (!error) {
                /* check if the node changed on us */
                vnode_t vp = NFSTOV(np);
                enum vtype vtype = vnode_vtype(vp);
                if ((vtype == VDIR) && NFS_CHANGED_NC(nfsvers, np, nvap)) {
                        FSDBG(513, -1, np, 0, np);
                        np->n_flag &= ~NNEGNCENTRIES;
                        cache_purge(vp);
                        np->n_ncgen++;
                        NFS_CHANGED_UPDATE_NC(nfsvers, np, nvap);
                        NFS_VNOP_DBG("Purge directory 0x%llx\n",
                            (uint64_t)VM_KERNEL_ADDRPERM(vp));
                }
                if (NFS_CHANGED(nfsvers, np, nvap)) {
                        FSDBG(513, -1, np, -1, np);
                        if (vtype == VDIR) {
                                NFS_VNOP_DBG("Invalidate directory 0x%llx\n",
                                    (uint64_t)VM_KERNEL_ADDRPERM(vp));
                                nfs_invaldir(np);
                        }
                        nfs_node_unlock(np);
                        if (wanted) {
                                wakeup(np);
                        }
                        error = nfs_vinvalbuf(vp, V_SAVE, ctx, 1);
                        FSDBG(513, -1, np, -2, error);
                        if (!error) {
                                nfs_node_lock_force(np);
                                NFS_CHANGED_UPDATE(nfsvers, np, nvap);
                                nfs_node_unlock(np);
                        }
                } else {
                        nfs_node_unlock(np);
                        if (wanted) {
                                wakeup(np);
                        }
                }
        } else {
                nfs_node_unlock(np);
                if (wanted) {
                        wakeup(np);
                }
        }

        if (nvap == &nvattr) {
                NVATTR_CLEANUP(nvap);
        } else if (!(flags & NGA_ACL)) {
                /* make sure we don't return an ACL if it wasn't asked for */
                NFS_BITMAP_CLR(nvap->nva_bitmap, NFS_FATTR_ACL);
                if (nvap->nva_acl) {
                        kauth_acl_free(nvap->nva_acl);
                        nvap->nva_acl = NULL;
                }
        }
        FSDBG_BOT(513, np->n_size, error, np->n_vattr.nva_size, np->n_flag);
        return error;
}


/*
 * NFS getattr call from vfs.
 */

/*
 * The attributes we support over the wire.
 * We also get fsid but the vfs layer gets it out of the mount
 * structure after this calling us so there's no need to return it,
 * and Finder expects to call getattrlist just looking for the FSID
 * with out hanging on a non responsive server.
 */
#define NFS3_SUPPORTED_VATTRS \
        (VNODE_ATTR_va_rdev |           \
         VNODE_ATTR_va_nlink |          \
         VNODE_ATTR_va_data_size |      \
         VNODE_ATTR_va_data_alloc |     \
         VNODE_ATTR_va_uid |            \
         VNODE_ATTR_va_gid |            \
         VNODE_ATTR_va_mode |           \
         VNODE_ATTR_va_modify_time |    \
         VNODE_ATTR_va_change_time |    \
         VNODE_ATTR_va_access_time |    \
         VNODE_ATTR_va_fileid |         \
         VNODE_ATTR_va_type)


int
nfs3_vnop_getattr(
        struct vnop_getattr_args /* {
                                  *  struct vnodeop_desc *a_desc;
                                  *  vnode_t a_vp;
                                  *  struct vnode_attr *a_vap;
                                  *  vfs_context_t a_context;
                                  *  } */*ap)
{
        int error;
        nfsnode_t np;
        uint64_t supported_attrs;
        struct nfs_vattr nva;
        struct vnode_attr *vap = ap->a_vap;
        struct nfsmount *nmp;
        dev_t rdev;

        nmp = VTONMP(ap->a_vp);

        /*
         * Lets don't go over the wire if we don't support any of the attributes.
         * Just fall through at the VFS layer and let it cons up what it needs.
         */
        /* Return the io size no matter what, since we don't go over the wire for this */
        VATTR_RETURN(vap, va_iosize, nfs_iosize);

        supported_attrs = NFS3_SUPPORTED_VATTRS;

        if ((vap->va_active & supported_attrs) == 0) {
                return 0;
        }

        if (VATTR_IS_ACTIVE(ap->a_vap, va_name)) {
                NFS_VNOP_DBG("Getting attrs for 0x%llx, vname is %s\n",
                    (uint64_t)VM_KERNEL_ADDRPERM(ap->a_vp),
                    ap->a_vp->v_name ? ap->a_vp->v_name : "empty");
        }

        /*
         * We should not go over the wire if only fileid was requested and has ever been populated.
         */
        if ((vap->va_active & supported_attrs) == VNODE_ATTR_va_fileid) {
                np = VTONFS(ap->a_vp);
                if (np->n_attrstamp) {
                        VATTR_RETURN(vap, va_fileid, np->n_vattr.nva_fileid);
                        return 0;
                }
        }

        error = nfs_getattr(VTONFS(ap->a_vp), &nva, ap->a_context, NGA_CACHED);
        if (error) {
                return error;
        }

        /* copy nva to *a_vap */
        VATTR_RETURN(vap, va_type, nva.nva_type);
        VATTR_RETURN(vap, va_mode, nva.nva_mode);
        rdev = makedev(nva.nva_rawdev.specdata1, nva.nva_rawdev.specdata2);
        VATTR_RETURN(vap, va_rdev, rdev);
        VATTR_RETURN(vap, va_uid, nva.nva_uid);
        VATTR_RETURN(vap, va_gid, nva.nva_gid);
        VATTR_RETURN(vap, va_nlink, nva.nva_nlink);
        VATTR_RETURN(vap, va_fileid, nva.nva_fileid);
        VATTR_RETURN(vap, va_data_size, nva.nva_size);
        VATTR_RETURN(vap, va_data_alloc, nva.nva_bytes);
        vap->va_access_time.tv_sec = nva.nva_timesec[NFSTIME_ACCESS];
        vap->va_access_time.tv_nsec = nva.nva_timensec[NFSTIME_ACCESS];
        VATTR_SET_SUPPORTED(vap, va_access_time);
        vap->va_modify_time.tv_sec = nva.nva_timesec[NFSTIME_MODIFY];
        vap->va_modify_time.tv_nsec = nva.nva_timensec[NFSTIME_MODIFY];
        VATTR_SET_SUPPORTED(vap, va_modify_time);
        vap->va_change_time.tv_sec = nva.nva_timesec[NFSTIME_CHANGE];
        vap->va_change_time.tv_nsec = nva.nva_timensec[NFSTIME_CHANGE];
        VATTR_SET_SUPPORTED(vap, va_change_time);


        // VATTR_RETURN(vap, va_encoding, 0xffff /* kTextEncodingUnknown */);
        return error;
}

/*
 * NFS setattr call.
 */
int
nfs_vnop_setattr(
        struct vnop_setattr_args /* {
                                  *  struct vnodeop_desc *a_desc;
                                  *  vnode_t a_vp;
                                  *  struct vnode_attr *a_vap;
                                  *  vfs_context_t a_context;
                                  *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t vp = ap->a_vp;
        nfsnode_t np = VTONFS(vp);
        struct nfsmount *nmp;
        struct vnode_attr *vap = ap->a_vap;
        int error = 0;
        int biosize, nfsvers, namedattrs;
        u_quad_t origsize, vapsize;
        struct nfs_dulookup dul;
        nfsnode_t dnp = NULL;
        int dul_in_progress = 0;
        vnode_t dvp = NULL;
        const char *vname = NULL;
#if CONFIG_NFS4
        struct nfs_open_owner *noop = NULL;
        struct nfs_open_file *nofp = NULL;
#endif
        nmp = VTONMP(vp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        namedattrs = (nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_NAMED_ATTR);
        biosize = nmp->nm_biosize;

        /* Disallow write attempts if the filesystem is mounted read-only. */
        if (vnode_vfsisrdonly(vp)) {
                return EROFS;
        }

        origsize = np->n_size;
        if (VATTR_IS_ACTIVE(vap, va_data_size)) {
                switch (vnode_vtype(vp)) {
                case VDIR:
                        return EISDIR;
                case VCHR:
                case VBLK:
                case VSOCK:
                case VFIFO:
                        if (!VATTR_IS_ACTIVE(vap, va_modify_time) &&
                            !VATTR_IS_ACTIVE(vap, va_access_time) &&
                            !VATTR_IS_ACTIVE(vap, va_mode) &&
                            !VATTR_IS_ACTIVE(vap, va_uid) &&
                            !VATTR_IS_ACTIVE(vap, va_gid)) {
                                return 0;
                        }
                        VATTR_CLEAR_ACTIVE(vap, va_data_size);
                        break;
                default:
                        /*
                         * Disallow write attempts if the filesystem is
                         * mounted read-only.
                         */
                        if (vnode_vfsisrdonly(vp)) {
                                return EROFS;
                        }
                        FSDBG_TOP(512, np->n_size, vap->va_data_size,
                            np->n_vattr.nva_size, np->n_flag);
                        /* clear NNEEDINVALIDATE, if set */
                        if ((error = nfs_node_lock(np))) {
                                return error;
                        }
                        if (np->n_flag & NNEEDINVALIDATE) {
                                np->n_flag &= ~NNEEDINVALIDATE;
                        }
                        nfs_node_unlock(np);
                        /* flush everything */
                        error = nfs_vinvalbuf(vp, (vap->va_data_size ? V_SAVE : 0), ctx, 1);
                        if (error) {
                                NP(np, "nfs_setattr: nfs_vinvalbuf %d", error);
                                FSDBG_BOT(512, np->n_size, vap->va_data_size, np->n_vattr.nva_size, -1);
                                return error;
                        }
#if CONFIG_NFS4
                        if (nfsvers >= NFS_VER4) {
                                /* setting file size requires having the file open for write access */
                                if (np->n_flag & NREVOKE) {
                                        return EIO;
                                }
                                noop = nfs_open_owner_find(nmp, vfs_context_ucred(ctx), 1);
                                if (!noop) {
                                        return ENOMEM;
                                }
restart:
                                error = nfs_mount_state_in_use_start(nmp, vfs_context_thread(ctx));
                                if (error) {
                                        return error;
                                }
                                if (np->n_flag & NREVOKE) {
                                        nfs_mount_state_in_use_end(nmp, 0);
                                        return EIO;
                                }
                                error = nfs_open_file_find(np, noop, &nofp, 0, 0, 1);
                                if (!error && (nofp->nof_flags & NFS_OPEN_FILE_LOST)) {
                                        error = EIO;
                                }
                                if (!error && (nofp->nof_flags & NFS_OPEN_FILE_REOPEN)) {
                                        nfs_mount_state_in_use_end(nmp, 0);
                                        error = nfs4_reopen(nofp, vfs_context_thread(ctx));
                                        nofp = NULL;
                                        if (!error) {
                                                goto restart;
                                        }
                                }
                                if (!error) {
                                        error = nfs_open_file_set_busy(nofp, vfs_context_thread(ctx));
                                }
                                if (error) {
                                        nfs_open_owner_rele(noop);
                                        return error;
                                }
                                if (!(nofp->nof_access & NFS_OPEN_SHARE_ACCESS_WRITE)) {
                                        /* we don't have the file open for write access, so open it */
                                        error = nfs4_open(np, nofp, NFS_OPEN_SHARE_ACCESS_WRITE, NFS_OPEN_SHARE_DENY_NONE, ctx);
                                        if (!error) {
                                                nofp->nof_flags |= NFS_OPEN_FILE_SETATTR;
                                        }
                                        if (nfs_mount_state_error_should_restart(error)) {
                                                nfs_open_file_clear_busy(nofp);
                                                nofp = NULL;
                                                if (nfs_mount_state_in_use_end(nmp, error)) {
                                                        goto restart;
                                                }
                                        }
                                }
                        }
#endif
                        nfs_data_lock(np, NFS_DATA_LOCK_EXCLUSIVE);
                        if (np->n_size > vap->va_data_size) { /* shrinking? */
                                daddr64_t obn, bn;
                                int neweofoff, mustwrite;
                                struct nfsbuf *bp;

                                obn = (np->n_size - 1) / biosize;
                                bn = vap->va_data_size / biosize;
                                for (; obn >= bn; obn--) {
                                        if (!nfs_buf_is_incore(np, obn)) {
                                                continue;
                                        }
                                        error = nfs_buf_get(np, obn, biosize, NULL, NBLK_READ, &bp);
                                        if (error) {
                                                continue;
                                        }
                                        if (obn != bn) {
                                                FSDBG(512, bp, bp->nb_flags, 0, obn);
                                                SET(bp->nb_flags, NB_INVAL);
                                                nfs_buf_release(bp, 1);
                                                continue;
                                        }
                                        mustwrite = 0;
                                        neweofoff = vap->va_data_size - NBOFF(bp);
                                        /* check for any dirty data before the new EOF */
                                        if ((bp->nb_dirtyend > 0) && (bp->nb_dirtyoff < neweofoff)) {
                                                /* clip dirty range to EOF */
                                                if (bp->nb_dirtyend > neweofoff) {
                                                        bp->nb_dirtyend = neweofoff;
                                                        if (bp->nb_dirtyoff >= bp->nb_dirtyend) {
                                                                bp->nb_dirtyoff = bp->nb_dirtyend = 0;
                                                        }
                                                }
                                                if ((bp->nb_dirtyend > 0) && (bp->nb_dirtyoff < neweofoff)) {
                                                        mustwrite++;
                                                }
                                        }
                                        bp->nb_dirty &= (1 << round_page_32(neweofoff) / PAGE_SIZE) - 1;
                                        if (bp->nb_dirty) {
                                                mustwrite++;
                                        }
                                        if (!mustwrite) {
                                                FSDBG(512, bp, bp->nb_flags, 0, obn);
                                                SET(bp->nb_flags, NB_INVAL);
                                                nfs_buf_release(bp, 1);
                                                continue;
                                        }
                                        /* gotta write out dirty data before invalidating */
                                        /* (NB_STABLE indicates that data writes should be FILESYNC) */
                                        /* (NB_NOCACHE indicates buffer should be discarded) */
                                        CLR(bp->nb_flags, (NB_DONE | NB_ERROR | NB_INVAL | NB_ASYNC | NB_READ));
                                        SET(bp->nb_flags, NB_STABLE | NB_NOCACHE);
                                        if (!IS_VALID_CRED(bp->nb_wcred)) {
                                                kauth_cred_t cred = vfs_context_ucred(ctx);
                                                kauth_cred_ref(cred);
                                                bp->nb_wcred = cred;
                                        }
                                        error = nfs_buf_write(bp);
                                        // Note: bp has been released
                                        if (error) {
                                                FSDBG(512, bp, 0xd00dee, 0xbad, error);
                                                nfs_node_lock_force(np);
                                                np->n_error = error;
                                                np->n_flag |= NWRITEERR;
                                                /*
                                                 * There was a write error and we need to
                                                 * invalidate attrs and flush buffers in
                                                 * order to sync up with the server.
                                                 * (if this write was extending the file,
                                                 * we may no longer know the correct size)
                                                 */
                                                NATTRINVALIDATE(np);
                                                nfs_node_unlock(np);
                                                nfs_data_unlock(np);
                                                nfs_vinvalbuf(vp, V_SAVE | V_IGNORE_WRITEERR, ctx, 1);
                                                nfs_data_lock(np, NFS_DATA_LOCK_EXCLUSIVE);
                                                error = 0;
                                        }
                                }
                        }
                        if (vap->va_data_size != np->n_size) {
                                ubc_setsize(vp, (off_t)vap->va_data_size); /* XXX error? */
                        }
                        origsize = np->n_size;
                        np->n_size = np->n_vattr.nva_size = vap->va_data_size;
                        nfs_node_lock_force(np);
                        CLR(np->n_flag, NUPDATESIZE);
                        nfs_node_unlock(np);
                        FSDBG(512, np, np->n_size, np->n_vattr.nva_size, 0xf00d0001);
                }
        } else if (VATTR_IS_ACTIVE(vap, va_modify_time) ||
            VATTR_IS_ACTIVE(vap, va_access_time) ||
            (vap->va_vaflags & VA_UTIMES_NULL)) {
                if ((error = nfs_node_lock(np))) {
                        return error;
                }
                if ((np->n_flag & NMODIFIED) && (vnode_vtype(vp) == VREG)) {
                        nfs_node_unlock(np);
                        error = nfs_vinvalbuf(vp, V_SAVE, ctx, 1);
                        if (error == EINTR) {
                                return error;
                        }
                } else {
                        nfs_node_unlock(np);
                }
        }
        if ((VATTR_IS_ACTIVE(vap, va_mode) || VATTR_IS_ACTIVE(vap, va_uid) || VATTR_IS_ACTIVE(vap, va_gid) ||
            VATTR_IS_ACTIVE(vap, va_acl) || VATTR_IS_ACTIVE(vap, va_uuuid) || VATTR_IS_ACTIVE(vap, va_guuid)) &&
            !(error = nfs_node_lock(np))) {
                NACCESSINVALIDATE(np);
                nfs_node_unlock(np);
                if (!namedattrs) {
                        dvp = vnode_getparent(vp);
                        vname = vnode_getname(vp);
                        dnp = (dvp && vname) ? VTONFS(dvp) : NULL;
                        if (dnp) {
                                if (nfs_node_set_busy(dnp, vfs_context_thread(ctx))) {
                                        vnode_put(dvp);
                                        vnode_putname(vname);
                                } else {
                                        nfs_dulookup_init(&dul, dnp, vname, strlen(vname), ctx);
                                        nfs_dulookup_start(&dul, dnp, ctx);
                                        dul_in_progress = 1;
                                }
                        } else {
                                if (dvp) {
                                        vnode_put(dvp);
                                }
                                if (vname) {
                                        vnode_putname(vname);
                                }
                        }
                }
        }

        if (!error) {
                error = nmp->nm_funcs->nf_setattr_rpc(np, vap, ctx);
        }

        if (dul_in_progress) {
                nfs_dulookup_finish(&dul, dnp, ctx);
                nfs_node_clear_busy(dnp);
                vnode_put(dvp);
                vnode_putname(vname);
        }

        FSDBG_BOT(512, np->n_size, vap->va_data_size, np->n_vattr.nva_size, error);
        if (VATTR_IS_ACTIVE(vap, va_data_size)) {
                if (error && (origsize != np->n_size) &&
                    ((nfsvers < NFS_VER4) || !nfs_mount_state_error_should_restart(error))) {
                        /* make every effort to resync file size w/ server... */
                        /* (don't bother if we'll be restarting the operation) */
                        int err; /* preserve "error" for return */
                        np->n_size = np->n_vattr.nva_size = origsize;
                        nfs_node_lock_force(np);
                        CLR(np->n_flag, NUPDATESIZE);
                        nfs_node_unlock(np);
                        FSDBG(512, np, np->n_size, np->n_vattr.nva_size, 0xf00d0002);
                        ubc_setsize(vp, (off_t)np->n_size); /* XXX check error */
                        vapsize = vap->va_data_size;
                        vap->va_data_size = origsize;
                        err = nmp->nm_funcs->nf_setattr_rpc(np, vap, ctx);
                        if (err) {
                                NP(np, "nfs_vnop_setattr: nfs%d_setattr_rpc %d %d", nfsvers, error, err);
                        }
                        vap->va_data_size = vapsize;
                }
                nfs_node_lock_force(np);
                /*
                 * The size was just set.  If the size is already marked for update, don't
                 * trust the newsize (it may have been set while the setattr was in progress).
                 * Clear the update flag and make sure we fetch new attributes so we are sure
                 * we have the latest size.
                 */
                if (ISSET(np->n_flag, NUPDATESIZE)) {
                        CLR(np->n_flag, NUPDATESIZE);
                        NATTRINVALIDATE(np);
                        nfs_node_unlock(np);
                        nfs_getattr(np, NULL, ctx, NGA_UNCACHED);
                } else {
                        nfs_node_unlock(np);
                }
                nfs_data_unlock(np);
#if CONFIG_NFS4
                if (nfsvers >= NFS_VER4) {
                        if (nofp) {
                                /* don't close our setattr open if we'll be restarting... */
                                if (!nfs_mount_state_error_should_restart(error) &&
                                    (nofp->nof_flags & NFS_OPEN_FILE_SETATTR)) {
                                        int err = nfs_close(np, nofp, NFS_OPEN_SHARE_ACCESS_WRITE, NFS_OPEN_SHARE_DENY_NONE, ctx);
                                        if (err) {
                                                NP(np, "nfs_vnop_setattr: close error: %d", err);
                                        }
                                        nofp->nof_flags &= ~NFS_OPEN_FILE_SETATTR;
                                }
                                nfs_open_file_clear_busy(nofp);
                                nofp = NULL;
                        }
                        if (nfs_mount_state_in_use_end(nmp, error)) {
                                goto restart;
                        }
                        nfs_open_owner_rele(noop);
                }
#endif
        }
        return error;
}

/*
 * Do an NFS setattr RPC.
 */
int
nfs3_setattr_rpc(
        nfsnode_t np,
        struct vnode_attr *vap,
        vfs_context_t ctx)
{
        struct nfsmount *nmp = NFSTONMP(np);
        int error = 0, lockerror = ENOENT, status, wccpostattr = 0, nfsvers;
        u_int64_t xid, nextxid;
        struct nfsm_chain nmreq, nmrep;

        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        VATTR_SET_SUPPORTED(vap, va_mode);
        VATTR_SET_SUPPORTED(vap, va_uid);
        VATTR_SET_SUPPORTED(vap, va_gid);
        VATTR_SET_SUPPORTED(vap, va_data_size);
        VATTR_SET_SUPPORTED(vap, va_access_time);
        VATTR_SET_SUPPORTED(vap, va_modify_time);


        if (VATTR_IS_ACTIVE(vap, va_flags)
            ) {
                if (vap->va_flags) {    /* we don't support setting flags */
                        if (vap->va_active & ~VNODE_ATTR_va_flags) {
                                return EINVAL;        /* return EINVAL if other attributes also set */
                        } else {
                                return ENOTSUP;       /* return ENOTSUP for chflags(2) */
                        }
                }
                /* no flags set, so we'll just ignore it */
                if (!(vap->va_active & ~VNODE_ATTR_va_flags)) {
                        return 0; /* no (other) attributes to set, so nothing to do */
                }
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + NFSX_SATTR(nfsvers));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, np->n_fhp, np->n_fhsize);
        if (nfsvers == NFS_VER3) {
                if (VATTR_IS_ACTIVE(vap, va_mode)) {
                        nfsm_chain_add_32(error, &nmreq, TRUE);
                        nfsm_chain_add_32(error, &nmreq, vap->va_mode);
                } else {
                        nfsm_chain_add_32(error, &nmreq, FALSE);
                }
                if (VATTR_IS_ACTIVE(vap, va_uid)) {
                        nfsm_chain_add_32(error, &nmreq, TRUE);
                        nfsm_chain_add_32(error, &nmreq, vap->va_uid);
                } else {
                        nfsm_chain_add_32(error, &nmreq, FALSE);
                }
                if (VATTR_IS_ACTIVE(vap, va_gid)) {
                        nfsm_chain_add_32(error, &nmreq, TRUE);
                        nfsm_chain_add_32(error, &nmreq, vap->va_gid);
                } else {
                        nfsm_chain_add_32(error, &nmreq, FALSE);
                }
                if (VATTR_IS_ACTIVE(vap, va_data_size)) {
                        nfsm_chain_add_32(error, &nmreq, TRUE);
                        nfsm_chain_add_64(error, &nmreq, vap->va_data_size);
                } else {
                        nfsm_chain_add_32(error, &nmreq, FALSE);
                }
                if (vap->va_vaflags & VA_UTIMES_NULL) {
                        nfsm_chain_add_32(error, &nmreq, NFS_TIME_SET_TO_SERVER);
                        nfsm_chain_add_32(error, &nmreq, NFS_TIME_SET_TO_SERVER);
                } else {
                        if (VATTR_IS_ACTIVE(vap, va_access_time)) {
                                nfsm_chain_add_32(error, &nmreq, NFS_TIME_SET_TO_CLIENT);
                                nfsm_chain_add_32(error, &nmreq, vap->va_access_time.tv_sec);
                                nfsm_chain_add_32(error, &nmreq, vap->va_access_time.tv_nsec);
                        } else {
                                nfsm_chain_add_32(error, &nmreq, NFS_TIME_DONT_CHANGE);
                        }
                        if (VATTR_IS_ACTIVE(vap, va_modify_time)) {
                                nfsm_chain_add_32(error, &nmreq, NFS_TIME_SET_TO_CLIENT);
                                nfsm_chain_add_32(error, &nmreq, vap->va_modify_time.tv_sec);
                                nfsm_chain_add_32(error, &nmreq, vap->va_modify_time.tv_nsec);
                        } else {
                                nfsm_chain_add_32(error, &nmreq, NFS_TIME_DONT_CHANGE);
                        }
                }
                nfsm_chain_add_32(error, &nmreq, FALSE);
        } else {
                nfsm_chain_add_32(error, &nmreq, VATTR_IS_ACTIVE(vap, va_mode) ?
                    vtonfsv2_mode(vnode_vtype(NFSTOV(np)), vap->va_mode) : -1);
                nfsm_chain_add_32(error, &nmreq, VATTR_IS_ACTIVE(vap, va_uid) ?
                    vap->va_uid : (uint32_t)-1);
                nfsm_chain_add_32(error, &nmreq, VATTR_IS_ACTIVE(vap, va_gid) ?
                    vap->va_gid : (uint32_t)-1);
                nfsm_chain_add_32(error, &nmreq, VATTR_IS_ACTIVE(vap, va_data_size) ?
                    vap->va_data_size : (uint32_t)-1);
                if (VATTR_IS_ACTIVE(vap, va_access_time)) {
                        nfsm_chain_add_32(error, &nmreq, vap->va_access_time.tv_sec);
                        nfsm_chain_add_32(error, &nmreq, (vap->va_access_time.tv_nsec != -1) ?
                            ((uint32_t)vap->va_access_time.tv_nsec / 1000) : 0xffffffff);
                } else {
                        nfsm_chain_add_32(error, &nmreq, -1);
                        nfsm_chain_add_32(error, &nmreq, -1);
                }
                if (VATTR_IS_ACTIVE(vap, va_modify_time)) {
                        nfsm_chain_add_32(error, &nmreq, vap->va_modify_time.tv_sec);
                        nfsm_chain_add_32(error, &nmreq, (vap->va_modify_time.tv_nsec != -1) ?
                            ((uint32_t)vap->va_modify_time.tv_nsec / 1000) : 0xffffffff);
                } else {
                        nfsm_chain_add_32(error, &nmreq, -1);
                        nfsm_chain_add_32(error, &nmreq, -1);
                }
        }
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request(np, NULL, &nmreq, NFSPROC_SETATTR, ctx, NULL, &nmrep, &xid, &status);
        if ((lockerror = nfs_node_lock(np))) {
                error = lockerror;
        }
        if (nfsvers == NFS_VER3) {
                struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
                nfsm_chain_get_wcc_data(error, &nmrep, np, &premtime, &wccpostattr, &xid);
                nfsmout_if(error);
                /* if file hadn't changed, update cached mtime */
                if (nfstimespeccmp(&np->n_mtime, &premtime, ==)) {
                        NFS_CHANGED_UPDATE(nfsvers, np, &np->n_vattr);
                }
                /* if directory hadn't changed, update namecache mtime */
                if ((vnode_vtype(NFSTOV(np)) == VDIR) &&
                    nfstimespeccmp(&np->n_ncmtime, &premtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, np, &np->n_vattr);
                }
                if (!wccpostattr) {
                        NATTRINVALIDATE(np);
                }
                error = status;
        } else {
                if (!error) {
                        error = status;
                }
                nfsm_chain_loadattr(error, &nmrep, np, nfsvers, &xid);
        }
        /*
         * We just changed the attributes and we want to make sure that we
         * see the latest attributes.  Get the next XID.  If it's not the
         * next XID after the SETATTR XID, then it's possible that another
         * RPC was in flight at the same time and it might put stale attributes
         * in the cache.  In that case, we invalidate the attributes and set
         * the attribute cache XID to guarantee that newer attributes will
         * get loaded next.
         */
        nextxid = 0;
        nfs_get_xid(&nextxid);
        if (nextxid != (xid + 1)) {
                np->n_xid = nextxid;
                NATTRINVALIDATE(np);
        }
nfsmout:
        if (!lockerror) {
                nfs_node_unlock(np);
        }
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        return error;
}

/*
 * NFS lookup call, one step at a time...
 * First look in cache
 * If not found, unlock the directory nfsnode and do the RPC
 */
int
nfs_vnop_lookup(
        struct vnop_lookup_args /* {
                                 *  struct vnodeop_desc *a_desc;
                                 *  vnode_t a_dvp;
                                 *  vnode_t *a_vpp;
                                 *  struct componentname *a_cnp;
                                 *  vfs_context_t a_context;
                                 *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        struct componentname *cnp = ap->a_cnp;
        vnode_t dvp = ap->a_dvp;
        vnode_t *vpp = ap->a_vpp;
        int flags = cnp->cn_flags;
        vnode_t newvp;
        nfsnode_t dnp, np;
        struct nfsmount *nmp;
        mount_t mp;
        int nfsvers, error, busyerror = ENOENT, isdot, isdotdot, negnamecache;
        u_int64_t xid;
        struct nfs_vattr nvattr;
        int ngflags;
        struct vnop_access_args naa;
        fhandle_t fh;
        struct nfsreq rq, *req = &rq;

        *vpp = NULLVP;

        dnp = VTONFS(dvp);
        NVATTR_INIT(&nvattr);

        mp = vnode_mount(dvp);
        nmp = VFSTONFS(mp);
        if (nfs_mount_gone(nmp)) {
                error = ENXIO;
                goto error_return;
        }
        nfsvers = nmp->nm_vers;
        negnamecache = !NMFLAG(nmp, NONEGNAMECACHE);

        if ((error = busyerror = nfs_node_set_busy(dnp, vfs_context_thread(ctx)))) {
                goto error_return;
        }
        /* nfs_getattr() will check changed and purge caches */
        if ((error = nfs_getattr(dnp, NULL, ctx, NGA_CACHED))) {
                goto error_return;
        }

        error = cache_lookup(dvp, vpp, cnp);
        switch (error) {
        case ENOENT:
                /* negative cache entry */
                goto error_return;
        case 0:
                /* cache miss */
                if ((nfsvers > NFS_VER2) && NMFLAG(nmp, RDIRPLUS)) {
                        /* if rdirplus, try dir buf cache lookup */
                        error = nfs_dir_buf_cache_lookup(dnp, &np, cnp, ctx, 0);
                        if (!error && np) {
                                /* dir buf cache hit */
                                *vpp = NFSTOV(np);
                                error = -1;
                        }
                }
                if (error != -1) { /* cache miss */
                        break;
                }
        /* FALLTHROUGH */
        case -1:
                /* cache hit, not really an error */
                OSAddAtomic64(1, &nfsstats.lookupcache_hits);

                nfs_node_clear_busy(dnp);
                busyerror = ENOENT;

                /* check for directory access */
                naa.a_desc = &vnop_access_desc;
                naa.a_vp = dvp;
                naa.a_action = KAUTH_VNODE_SEARCH;
                naa.a_context = ctx;

                /* compute actual success/failure based on accessibility */
                error = nfs_vnop_access(&naa);
        /* FALLTHROUGH */
        default:
                /* unexpected error from cache_lookup */
                goto error_return;
        }

        /* skip lookup, if we know who we are: "." or ".." */
        isdot = isdotdot = 0;
        if (cnp->cn_nameptr[0] == '.') {
                if (cnp->cn_namelen == 1) {
                        isdot = 1;
                }
                if ((cnp->cn_namelen == 2) && (cnp->cn_nameptr[1] == '.')) {
                        isdotdot = 1;
                }
        }
        if (isdotdot || isdot) {
                fh.fh_len = 0;
                goto found;
        }
#if CONFIG_NFS4
        if ((nfsvers >= NFS_VER4) && (dnp->n_vattr.nva_flags & NFS_FFLAG_TRIGGER)) {
                /* we should never be looking things up in a trigger directory, return nothing */
                error = ENOENT;
                goto error_return;
        }
#endif

        /* do we know this name is too long? */
        nmp = VTONMP(dvp);
        if (nfs_mount_gone(nmp)) {
                error = ENXIO;
                goto error_return;
        }
        if (NFS_BITMAP_ISSET(nmp->nm_fsattr.nfsa_bitmap, NFS_FATTR_MAXNAME) &&
            (cnp->cn_namelen > (int)nmp->nm_fsattr.nfsa_maxname)) {
                error = ENAMETOOLONG;
                goto error_return;
        }

        error = 0;
        newvp = NULLVP;

        OSAddAtomic64(1, &nfsstats.lookupcache_misses);

        error = nmp->nm_funcs->nf_lookup_rpc_async(dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx, &req);
        nfsmout_if(error);
        error = nmp->nm_funcs->nf_lookup_rpc_async_finish(dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx, req, &xid, &fh, &nvattr);
        nfsmout_if(error);

        /* is the file handle the same as this directory's file handle? */
        isdot = NFS_CMPFH(dnp, fh.fh_data, fh.fh_len);

found:
        if (flags & ISLASTCN) {
                switch (cnp->cn_nameiop) {
                case DELETE:
                        cnp->cn_flags &= ~MAKEENTRY;
                        break;
                case RENAME:
                        cnp->cn_flags &= ~MAKEENTRY;
                        if (isdot) {
                                error = EISDIR;
                                goto error_return;
                        }
                        break;
                }
        }

        if (isdotdot) {
                newvp = vnode_getparent(dvp);
                if (!newvp) {
                        error = ENOENT;
                        goto error_return;
                }
        } else if (isdot) {
                error = vnode_get(dvp);
                if (error) {
                        goto error_return;
                }
                newvp = dvp;
                nfs_node_lock_force(dnp);
                if (fh.fh_len && (dnp->n_xid <= xid)) {
                        nfs_loadattrcache(dnp, &nvattr, &xid, 0);
                }
                nfs_node_unlock(dnp);
        } else {
                ngflags = (cnp->cn_flags & MAKEENTRY) ? NG_MAKEENTRY : 0;
                error = nfs_nget(mp, dnp, cnp, fh.fh_data, fh.fh_len, &nvattr, &xid, rq.r_auth, ngflags, &np);
                if (error) {
                        goto error_return;
                }
                newvp = NFSTOV(np);
                nfs_node_unlock(np);
        }
        *vpp = newvp;

nfsmout:
        if (error) {
                if (((cnp->cn_nameiop == CREATE) || (cnp->cn_nameiop == RENAME)) &&
                    (flags & ISLASTCN) && (error == ENOENT)) {
                        if (vnode_mount(dvp) && vnode_vfsisrdonly(dvp)) {
                                error = EROFS;
                        } else {
                                error = EJUSTRETURN;
                        }
                }
        }
        if ((error == ENOENT) && (cnp->cn_flags & MAKEENTRY) &&
            (cnp->cn_nameiop != CREATE) && negnamecache) {
                /* add a negative entry in the name cache */
                nfs_node_lock_force(dnp);
                cache_enter(dvp, NULL, cnp);
                dnp->n_flag |= NNEGNCENTRIES;
                nfs_node_unlock(dnp);
        }
error_return:
        NVATTR_CLEANUP(&nvattr);
        if (!busyerror) {
                nfs_node_clear_busy(dnp);
        }
        if (error && *vpp) {
                vnode_put(*vpp);
                *vpp = NULLVP;
        }
        return error;
}

int nfs_readlink_nocache = DEFAULT_READLINK_NOCACHE;

/*
 * NFS readlink call
 */
int
nfs_vnop_readlink(
        struct vnop_readlink_args /* {
                                   *  struct vnodeop_desc *a_desc;
                                   *  vnode_t a_vp;
                                   *  struct uio *a_uio;
                                   *  vfs_context_t a_context;
                                   *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        nfsnode_t np = VTONFS(ap->a_vp);
        struct nfsmount *nmp;
        int error = 0, nfsvers;
        uint32_t buflen;
        uio_t uio = ap->a_uio;
        struct nfsbuf *bp = NULL;
        struct timespec ts;
        int timeo;

        if (vnode_vtype(ap->a_vp) != VLNK) {
                return EPERM;
        }

        if (uio_resid(uio) == 0) {
                return 0;
        }
        if (uio_offset(uio) < 0) {
                return EINVAL;
        }

        nmp = VTONMP(ap->a_vp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;


        /* nfs_getattr() will check changed and purge caches */
        if ((error = nfs_getattr(np, NULL, ctx, nfs_readlink_nocache ? NGA_UNCACHED : NGA_CACHED))) {
                FSDBG(531, np, 0xd1e0001, 0, error);
                return error;
        }

        if (nfs_readlink_nocache) {
                timeo = nfs_attrcachetimeout(np);
                nanouptime(&ts);
        }

retry:
        OSAddAtomic64(1, &nfsstats.biocache_readlinks);
        error = nfs_buf_get(np, 0, NFS_MAXPATHLEN, vfs_context_thread(ctx), NBLK_META, &bp);
        if (error) {
                FSDBG(531, np, 0xd1e0002, 0, error);
                return error;
        }

        if (nfs_readlink_nocache) {
                NFS_VNOP_DBG("timeo = %d ts.tv_sec = %ld need refresh = %d cached = %d\n", timeo, ts.tv_sec,
                    (np->n_rltim.tv_sec + timeo) < ts.tv_sec || nfs_readlink_nocache > 1,
                    ISSET(bp->nb_flags, NB_CACHE) == NB_CACHE);
                /* n_rltim is synchronized by the associated nfs buf */
                if (ISSET(bp->nb_flags, NB_CACHE) && ((nfs_readlink_nocache > 1) || ((np->n_rltim.tv_sec + timeo) < ts.tv_sec))) {
                        SET(bp->nb_flags, NB_INVAL);
                        nfs_buf_release(bp, 0);
                        goto retry;
                }
        }
        if (!ISSET(bp->nb_flags, NB_CACHE)) {
readagain:
                OSAddAtomic64(1, &nfsstats.readlink_bios);
                buflen = bp->nb_bufsize;
                error = nmp->nm_funcs->nf_readlink_rpc(np, bp->nb_data, &buflen, ctx);
                if (error) {
                        if (error == ESTALE) {
                                NFS_VNOP_DBG("Stale FH from readlink rpc\n");
                                error = nfs_refresh_fh(np, ctx);
                                if (error == 0) {
                                        goto readagain;
                                }
                        }
                        SET(bp->nb_flags, NB_ERROR);
                        bp->nb_error = error;
                        NFS_VNOP_DBG("readlink failed %d\n", error);
                } else {
                        bp->nb_validoff = 0;
                        bp->nb_validend = buflen;
                        np->n_rltim = ts;
                        NFS_VNOP_DBG("readlink of %.*s\n", bp->nb_validend, (char *)bp->nb_data);
                }
        } else {
                NFS_VNOP_DBG("got cached link of %.*s\n", bp->nb_validend, (char *)bp->nb_data);
        }

        if (!error && (bp->nb_validend > 0)) {
                error = uiomove(bp->nb_data, bp->nb_validend, uio);
        }
        FSDBG(531, np, bp->nb_validend, 0, error);
        nfs_buf_release(bp, 1);
        return error;
}

/*
 * Do a readlink RPC.
 */
int
nfs3_readlink_rpc(nfsnode_t np, char *buf, uint32_t *buflenp, vfs_context_t ctx)
{
        struct nfsmount *nmp;
        int error = 0, lockerror = ENOENT, nfsvers, status;
        uint32_t len;
        u_int64_t xid;
        struct nfsm_chain nmreq, nmrep;

        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq, NFSX_FH(nfsvers));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, np->n_fhp, np->n_fhsize);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request(np, NULL, &nmreq, NFSPROC_READLINK, ctx, NULL, &nmrep, &xid, &status);
        if ((lockerror = nfs_node_lock(np))) {
                error = lockerror;
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_postop_attr_update(error, &nmrep, np, &xid);
        }
        if (!error) {
                error = status;
        }
        nfsm_chain_get_32(error, &nmrep, len);
        nfsmout_if(error);
        if ((nfsvers == NFS_VER2) && (len > *buflenp)) {
                error = EBADRPC;
                goto nfsmout;
        }
        if (len >= *buflenp) {
                if (np->n_size && (np->n_size < *buflenp)) {
                        len = np->n_size;
                } else {
                        len = *buflenp - 1;
                }
        }
        nfsm_chain_get_opaque(error, &nmrep, len, buf);
        if (!error) {
                *buflenp = len;
        }
nfsmout:
        if (!lockerror) {
                nfs_node_unlock(np);
        }
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        return error;
}

/*
 * NFS read RPC call
 * Ditto above
 */
int
nfs_read_rpc(nfsnode_t np, uio_t uio, vfs_context_t ctx)
{
        struct nfsmount *nmp;
        int error = 0, nfsvers, eof = 0;
        size_t nmrsize, len, retlen;
        user_ssize_t tsiz;
        off_t txoffset;
        struct nfsreq rq, *req = &rq;
#if CONFIG_NFS4
        uint32_t stategenid = 0, restart = 0;
#endif
        FSDBG_TOP(536, np, uio_offset(uio), uio_resid(uio), 0);
        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        nmrsize = nmp->nm_rsize;

        txoffset = uio_offset(uio);
        tsiz = uio_resid(uio);
        if ((nfsvers == NFS_VER2) && ((uint64_t)(txoffset + tsiz) > 0xffffffffULL)) {
                FSDBG_BOT(536, np, uio_offset(uio), uio_resid(uio), EFBIG);
                return EFBIG;
        }

        while (tsiz > 0) {
                len = retlen = (tsiz > (user_ssize_t)nmrsize) ? nmrsize : (size_t)tsiz;
                FSDBG(536, np, txoffset, len, 0);
                if (np->n_flag & NREVOKE) {
                        error = EIO;
                        break;
                }
#if CONFIG_NFS4
                if (nmp->nm_vers >= NFS_VER4) {
                        stategenid = nmp->nm_stategenid;
                }
#endif
                error = nmp->nm_funcs->nf_read_rpc_async(np, txoffset, len,
                    vfs_context_thread(ctx), vfs_context_ucred(ctx), NULL, &req);
                if (!error) {
                        error = nmp->nm_funcs->nf_read_rpc_async_finish(np, req, uio, &retlen, &eof);
                }
#if CONFIG_NFS4
                if ((nmp->nm_vers >= NFS_VER4) && nfs_mount_state_error_should_restart(error) &&
                    (++restart <= nfs_mount_state_max_restarts(nmp))) { /* guard against no progress */
                        lck_mtx_lock(&nmp->nm_lock);
                        if ((error != NFSERR_GRACE) && (stategenid == nmp->nm_stategenid)) {
                                NP(np, "nfs_read_rpc: error %d, initiating recovery", error);
                                nfs_need_recover(nmp, error);
                        }
                        lck_mtx_unlock(&nmp->nm_lock);
                        if (np->n_flag & NREVOKE) {
                                error = EIO;
                        } else {
                                if (error == NFSERR_GRACE) {
                                        tsleep(&nmp->nm_state, (PZERO - 1), "nfsgrace", 2 * hz);
                                }
                                if (!(error = nfs_mount_state_wait_for_recovery(nmp))) {
                                        continue;
                                }
                        }
                }
#endif
                if (error) {
                        break;
                }
                txoffset += retlen;
                tsiz -= retlen;
                if (nfsvers != NFS_VER2) {
                        if (eof || (retlen == 0)) {
                                tsiz = 0;
                        }
                } else if (retlen < len) {
                        tsiz = 0;
                }
        }

        FSDBG_BOT(536, np, eof, uio_resid(uio), error);
        return error;
}

int
nfs3_read_rpc_async(
        nfsnode_t np,
        off_t offset,
        size_t len,
        thread_t thd,
        kauth_cred_t cred,
        struct nfsreq_cbinfo *cb,
        struct nfsreq **reqp)
{
        struct nfsmount *nmp;
        int error = 0, nfsvers;
        struct nfsm_chain nmreq;

        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        nfsm_chain_null(&nmreq);
        nfsm_chain_build_alloc_init(error, &nmreq, NFSX_FH(nfsvers) + 3 * NFSX_UNSIGNED);
        nfsm_chain_add_fh(error, &nmreq, nfsvers, np->n_fhp, np->n_fhsize);
        if (nfsvers == NFS_VER3) {
                nfsm_chain_add_64(error, &nmreq, offset);
                nfsm_chain_add_32(error, &nmreq, len);
        } else {
                nfsm_chain_add_32(error, &nmreq, offset);
                nfsm_chain_add_32(error, &nmreq, len);
                nfsm_chain_add_32(error, &nmreq, 0);
        }
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request_async(np, NULL, &nmreq, NFSPROC_READ, thd, cred, NULL, 0, cb, reqp);
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        return error;
}

int
nfs3_read_rpc_async_finish(
        nfsnode_t np,
        struct nfsreq *req,
        uio_t uio,
        size_t *lenp,
        int *eofp)
{
        int error = 0, lockerror, nfsvers, status, eof = 0;
        size_t retlen = 0;
        uint64_t xid;
        struct nfsmount *nmp;
        struct nfsm_chain nmrep;

        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                nfs_request_async_cancel(req);
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        nfsm_chain_null(&nmrep);

        error = nfs_request_async_finish(req, &nmrep, &xid, &status);
        if (error == EINPROGRESS) { /* async request restarted */
                return error;
        }

        if ((lockerror = nfs_node_lock(np))) {
                error = lockerror;
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_postop_attr_update(error, &nmrep, np, &xid);
        }
        if (!error) {
                error = status;
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_adv(error, &nmrep, NFSX_UNSIGNED);
                nfsm_chain_get_32(error, &nmrep, eof);
        } else {
                nfsm_chain_loadattr(error, &nmrep, np, nfsvers, &xid);
        }
        if (!lockerror) {
                nfs_node_unlock(np);
        }
        nfsm_chain_get_32(error, &nmrep, retlen);
        if ((nfsvers == NFS_VER2) && (retlen > *lenp)) {
                error = EBADRPC;
        }
        nfsmout_if(error);
        error = nfsm_chain_get_uio(&nmrep, MIN(retlen, *lenp), uio);
        if (eofp) {
                if (nfsvers == NFS_VER3) {
                        if (!eof && !retlen) {
                                eof = 1;
                        }
                } else if (retlen < *lenp) {
                        eof = 1;
                }
                *eofp = eof;
        }
        *lenp = MIN(retlen, *lenp);
nfsmout:
        nfsm_chain_cleanup(&nmrep);
        return error;
}

/*
 * NFS write call
 */
int
nfs_vnop_write(
        struct vnop_write_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_vp;
                                *  struct uio *a_uio;
                                *  int a_ioflag;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        uio_t uio = ap->a_uio;
        vnode_t vp = ap->a_vp;
        nfsnode_t np = VTONFS(vp);
        int ioflag = ap->a_ioflag;
        struct nfsbuf *bp;
        struct nfsmount *nmp = VTONMP(vp);
        daddr64_t lbn;
        int biosize;
        int n, on, error = 0;
        off_t boff, start, end;
        uio_t auio;
        char auio_buf[UIO_SIZEOF(1)];
        thread_t thd;
        kauth_cred_t cred;

        FSDBG_TOP(515, np, uio_offset(uio), uio_resid(uio), ioflag);

        if (vnode_vtype(vp) != VREG) {
                FSDBG_BOT(515, np, uio_offset(uio), uio_resid(uio), EIO);
                return EIO;
        }

        thd = vfs_context_thread(ctx);
        cred = vfs_context_ucred(ctx);

        nfs_data_lock(np, NFS_DATA_LOCK_SHARED);

        if ((error = nfs_node_lock(np))) {
                nfs_data_unlock(np);
                FSDBG_BOT(515, np, uio_offset(uio), uio_resid(uio), error);
                return error;
        }
        np->n_wrbusy++;

        if (np->n_flag & NWRITEERR) {
                error = np->n_error;
                np->n_flag &= ~NWRITEERR;
        }
        if (np->n_flag & NNEEDINVALIDATE) {
                np->n_flag &= ~NNEEDINVALIDATE;
                nfs_node_unlock(np);
                nfs_data_unlock(np);
                nfs_vinvalbuf(vp, V_SAVE | V_IGNORE_WRITEERR, ctx, 1);
                nfs_data_lock(np, NFS_DATA_LOCK_SHARED);
        } else {
                nfs_node_unlock(np);
        }
        if (error) {
                goto out;
        }

        biosize = nmp->nm_biosize;

        if (ioflag & (IO_APPEND | IO_SYNC)) {
                nfs_node_lock_force(np);
                if (np->n_flag & NMODIFIED) {
                        NATTRINVALIDATE(np);
                        nfs_node_unlock(np);
                        nfs_data_unlock(np);
                        error = nfs_vinvalbuf(vp, V_SAVE, ctx, 1);
                        nfs_data_lock(np, NFS_DATA_LOCK_SHARED);
                        if (error) {
                                FSDBG(515, np, uio_offset(uio), 0x10bad01, error);
                                goto out;
                        }
                } else {
                        nfs_node_unlock(np);
                }
                if (ioflag & IO_APPEND) {
                        nfs_data_unlock(np);
                        /* nfs_getattr() will check changed and purge caches */
                        error = nfs_getattr(np, NULL, ctx, NGA_UNCACHED);
                        /* we'll be extending the file, so take the data lock exclusive */
                        nfs_data_lock(np, NFS_DATA_LOCK_EXCLUSIVE);
                        if (error) {
                                FSDBG(515, np, uio_offset(uio), 0x10bad02, error);
                                goto out;
                        }
                        uio_setoffset(uio, np->n_size);
                }
        }
        if (uio_offset(uio) < 0) {
                error = EINVAL;
                FSDBG_BOT(515, np, uio_offset(uio), 0xbad0ff, error);
                goto out;
        }
        if (uio_resid(uio) == 0) {
                goto out;
        }

        if (((uio_offset(uio) + uio_resid(uio)) > (off_t)np->n_size) && !(ioflag & IO_APPEND)) {
                /*
                 * It looks like we'll be extending the file, so take the data lock exclusive.
                 */
                nfs_data_unlock(np);
                nfs_data_lock(np, NFS_DATA_LOCK_EXCLUSIVE);

                /*
                 * Also, if the write begins after the previous EOF buffer, make sure to zero
                 * and validate the new bytes in that buffer.
                 */
                struct nfsbuf *eofbp = NULL;
                daddr64_t eofbn = np->n_size / biosize;
                int eofoff = np->n_size % biosize;
                lbn = uio_offset(uio) / biosize;

                if (eofoff && (eofbn < lbn)) {
                        if ((error = nfs_buf_get(np, eofbn, biosize, thd, NBLK_WRITE | NBLK_ONLYVALID, &eofbp))) {
                                goto out;
                        }
                        np->n_size += (biosize - eofoff);
                        nfs_node_lock_force(np);
                        CLR(np->n_flag, NUPDATESIZE);
                        np->n_flag |= NMODIFIED;
                        nfs_node_unlock(np);
                        FSDBG(516, np, np->n_size, np->n_vattr.nva_size, 0xf00d0001);
                        ubc_setsize(vp, (off_t)np->n_size); /* XXX errors */
                        if (eofbp) {
                                /*
                                 * For the old last page, don't zero bytes if there
                                 * are invalid bytes in that page (i.e. the page isn't
                                 * currently valid).
                                 * For pages after the old last page, zero them and
                                 * mark them as valid.
                                 */
                                char *d;
                                int i;
                                if (ioflag & IO_NOCACHE) {
                                        SET(eofbp->nb_flags, NB_NOCACHE);
                                }
                                NFS_BUF_MAP(eofbp);
                                FSDBG(516, eofbp, eofoff, biosize - eofoff, 0xe0fff01e);
                                d = eofbp->nb_data;
                                i = eofoff / PAGE_SIZE;
                                while (eofoff < biosize) {
                                        int poff = eofoff & PAGE_MASK;
                                        if (!poff || NBPGVALID(eofbp, i)) {
                                                bzero(d + eofoff, PAGE_SIZE - poff);
                                                NBPGVALID_SET(eofbp, i);
                                        }
                                        eofoff += PAGE_SIZE - poff;
                                        i++;
                                }
                                nfs_buf_release(eofbp, 1);
                        }
                }
        }

        do {
                OSAddAtomic64(1, &nfsstats.biocache_writes);
                lbn = uio_offset(uio) / biosize;
                on = uio_offset(uio) % biosize;
                n = biosize - on;
                if (uio_resid(uio) < n) {
                        n = uio_resid(uio);
                }
again:
                /*
                 * Get a cache block for writing.  The range to be written is
                 * (off..off+n) within the block.  We ensure that the block
                 * either has no dirty region or that the given range is
                 * contiguous with the existing dirty region.
                 */
                error = nfs_buf_get(np, lbn, biosize, thd, NBLK_WRITE, &bp);
                if (error) {
                        goto out;
                }
                /* map the block because we know we're going to write to it */
                NFS_BUF_MAP(bp);

                if (ioflag & IO_NOCACHE) {
                        SET(bp->nb_flags, NB_NOCACHE);
                }

                if (!IS_VALID_CRED(bp->nb_wcred)) {
                        kauth_cred_ref(cred);
                        bp->nb_wcred = cred;
                }

                /*
                 * If there's already a dirty range AND dirty pages in this block we
                 * need to send a commit AND write the dirty pages before continuing.
                 *
                 * If there's already a dirty range OR dirty pages in this block
                 * and the new write range is not contiguous with the existing range,
                 * then force the buffer to be written out now.
                 * (We used to just extend the dirty range to cover the valid,
                 * but unwritten, data in between also.  But writing ranges
                 * of data that weren't actually written by an application
                 * risks overwriting some other client's data with stale data
                 * that's just masquerading as new written data.)
                 */
                if (bp->nb_dirtyend > 0) {
                        if (on > bp->nb_dirtyend || (on + n) < bp->nb_dirtyoff || bp->nb_dirty) {
                                FSDBG(515, np, uio_offset(uio), bp, 0xd15c001);
                                /* write/commit buffer "synchronously" */
                                /* (NB_STABLE indicates that data writes should be FILESYNC) */
                                CLR(bp->nb_flags, (NB_DONE | NB_ERROR | NB_INVAL));
                                SET(bp->nb_flags, (NB_ASYNC | NB_STABLE));
                                error = nfs_buf_write(bp);
                                if (error) {
                                        goto out;
                                }
                                goto again;
                        }
                } else if (bp->nb_dirty) {
                        int firstpg, lastpg;
                        u_int32_t pagemask;
                        /* calculate write range pagemask */
                        firstpg = on / PAGE_SIZE;
                        lastpg = (on + n - 1) / PAGE_SIZE;
                        pagemask = ((1 << (lastpg + 1)) - 1) & ~((1 << firstpg) - 1);
                        /* check if there are dirty pages outside the write range */
                        if (bp->nb_dirty & ~pagemask) {
                                FSDBG(515, np, uio_offset(uio), bp, 0xd15c002);
                                /* write/commit buffer "synchronously" */
                                /* (NB_STABLE indicates that data writes should be FILESYNC) */
                                CLR(bp->nb_flags, (NB_DONE | NB_ERROR | NB_INVAL));
                                SET(bp->nb_flags, (NB_ASYNC | NB_STABLE));
                                error = nfs_buf_write(bp);
                                if (error) {
                                        goto out;
                                }
                                goto again;
                        }
                        /* if the first or last pages are already dirty */
                        /* make sure that the dirty range encompasses those pages */
                        if (NBPGDIRTY(bp, firstpg) || NBPGDIRTY(bp, lastpg)) {
                                FSDBG(515, np, uio_offset(uio), bp, 0xd15c003);
                                bp->nb_dirtyoff = min(on, firstpg * PAGE_SIZE);
                                if (NBPGDIRTY(bp, lastpg)) {
                                        bp->nb_dirtyend = (lastpg + 1) * PAGE_SIZE;
                                        /* clip to EOF */
                                        if (NBOFF(bp) + bp->nb_dirtyend > (off_t)np->n_size) {
                                                bp->nb_dirtyend = np->n_size - NBOFF(bp);
                                                if (bp->nb_dirtyoff >= bp->nb_dirtyend) {
                                                        bp->nb_dirtyoff = bp->nb_dirtyend = 0;
                                                }
                                        }
                                } else {
                                        bp->nb_dirtyend = on + n;
                                }
                        }
                }

                /*
                 * Are we extending the size of the file with this write?
                 * If so, update file size now that we have the block.
                 * If there was a partial buf at the old eof, validate
                 * and zero the new bytes.
                 */
                if ((uio_offset(uio) + n) > (off_t)np->n_size) {
                        daddr64_t eofbn = np->n_size / biosize;
                        int neweofoff = (uio_offset(uio) + n) % biosize;

                        FSDBG(515, 0xb1ffa000, uio_offset(uio) + n, eofoff, neweofoff);

                        /* if we're extending within the same last block */
                        /* and the block is flagged as being cached... */
                        if ((lbn == eofbn) && ISSET(bp->nb_flags, NB_CACHE)) {
                                /* ...check that all pages in buffer are valid */
                                int endpg = ((neweofoff ? neweofoff : biosize) - 1) / PAGE_SIZE;
                                u_int32_t pagemask;
                                /* pagemask only has to extend to last page being written to */
                                pagemask = (1 << (endpg + 1)) - 1;
                                FSDBG(515, 0xb1ffa001, bp->nb_valid, pagemask, 0);
                                if ((bp->nb_valid & pagemask) != pagemask) {
                                        /* zerofill any hole */
                                        if (on > bp->nb_validend) {
                                                int i;
                                                for (i = bp->nb_validend / PAGE_SIZE; i <= (on - 1) / PAGE_SIZE; i++) {
                                                        NBPGVALID_SET(bp, i);
                                                }
                                                NFS_BUF_MAP(bp);
                                                FSDBG(516, bp, bp->nb_validend, on - bp->nb_validend, 0xf01e);
                                                bzero((char *)bp->nb_data + bp->nb_validend,
                                                    on - bp->nb_validend);
                                        }
                                        /* zerofill any trailing data in the last page */
                                        if (neweofoff) {
                                                NFS_BUF_MAP(bp);
                                                FSDBG(516, bp, neweofoff, PAGE_SIZE - (neweofoff & PAGE_MASK), 0xe0f);
                                                bzero((char *)bp->nb_data + neweofoff,
                                                    PAGE_SIZE - (neweofoff & PAGE_MASK));
                                        }
                                }
                        }
                        np->n_size = uio_offset(uio) + n;
                        nfs_node_lock_force(np);
                        CLR(np->n_flag, NUPDATESIZE);
                        np->n_flag |= NMODIFIED;
                        nfs_node_unlock(np);
                        FSDBG(516, np, np->n_size, np->n_vattr.nva_size, 0xf00d0001);
                        ubc_setsize(vp, (off_t)np->n_size); /* XXX errors */
                }
                /*
                 * If dirtyend exceeds file size, chop it down.  This should
                 * not occur unless there is a race.
                 */
                if (NBOFF(bp) + bp->nb_dirtyend > (off_t)np->n_size) {
                        bp->nb_dirtyend = np->n_size - NBOFF(bp);
                        if (bp->nb_dirtyoff >= bp->nb_dirtyend) {
                                bp->nb_dirtyoff = bp->nb_dirtyend = 0;
                        }
                }
                /*
                 * UBC doesn't handle partial pages, so we need to make sure
                 * that any pages left in the page cache are completely valid.
                 *
                 * Writes that are smaller than a block are delayed if they
                 * don't extend to the end of the block.
                 *
                 * If the block isn't (completely) cached, we may need to read
                 * in some parts of pages that aren't covered by the write.
                 * If the write offset (on) isn't page aligned, we'll need to
                 * read the start of the first page being written to.  Likewise,
                 * if the offset of the end of the write (on+n) isn't page aligned,
                 * we'll need to read the end of the last page being written to.
                 *
                 * Notes:
                 * We don't want to read anything we're just going to write over.
                 * We don't want to read anything we're just going drop when the
                 *   I/O is complete (i.e. don't do reads for NOCACHE requests).
                 * We don't want to issue multiple I/Os if we don't have to
                 *   (because they're synchronous rpcs).
                 * We don't want to read anything we already have modified in the
                 *   page cache.
                 */
                if (!ISSET(bp->nb_flags, NB_CACHE) && (n < biosize)) {
                        int firstpg, lastpg, dirtypg;
                        int firstpgoff, lastpgoff;
                        start = end = -1;
                        firstpg = on / PAGE_SIZE;
                        firstpgoff = on & PAGE_MASK;
                        lastpg = (on + n - 1) / PAGE_SIZE;
                        lastpgoff = (on + n) & PAGE_MASK;
                        if (firstpgoff && !NBPGVALID(bp, firstpg)) {
                                /* need to read start of first page */
                                start = firstpg * PAGE_SIZE;
                                end = start + firstpgoff;
                        }
                        if (lastpgoff && !NBPGVALID(bp, lastpg)) {
                                /* need to read end of last page */
                                if (start < 0) {
                                        start = (lastpg * PAGE_SIZE) + lastpgoff;
                                }
                                end = (lastpg + 1) * PAGE_SIZE;
                        }
                        if (ISSET(bp->nb_flags, NB_NOCACHE)) {
                                /*
                                 * For nocache writes, if there is any partial page at the
                                 * start or end of the write range, then we do the write
                                 * synchronously to make sure that we can drop the data
                                 * from the cache as soon as the WRITE finishes.  Normally,
                                 * we would do an unstable write and not drop the data until
                                 * it was committed.  But doing that here would risk allowing
                                 * invalid data to be read from the cache between the WRITE
                                 * and the COMMIT.
                                 * (NB_STABLE indicates that data writes should be FILESYNC)
                                 */
                                if (end > start) {
                                        SET(bp->nb_flags, NB_STABLE);
                                }
                                goto skipread;
                        }
                        if (end > start) {
                                /* need to read the data in range: start...end-1 */

                                /* first, check for dirty pages in between */
                                /* if there are, we'll have to do two reads because */
                                /* we don't want to overwrite the dirty pages. */
                                for (dirtypg = start / PAGE_SIZE; dirtypg <= (end - 1) / PAGE_SIZE; dirtypg++) {
                                        if (NBPGDIRTY(bp, dirtypg)) {
                                                break;
                                        }
                                }

                                /* if start is at beginning of page, try */
                                /* to get any preceeding pages as well. */
                                if (!(start & PAGE_MASK)) {
                                        /* stop at next dirty/valid page or start of block */
                                        for (; start > 0; start -= PAGE_SIZE) {
                                                if (NBPGVALID(bp, ((start - 1) / PAGE_SIZE))) {
                                                        break;
                                                }
                                        }
                                }

                                NFS_BUF_MAP(bp);
                                /* setup uio for read(s) */
                                boff = NBOFF(bp);
                                auio = uio_createwithbuffer(1, 0, UIO_SYSSPACE, UIO_READ,
                                    &auio_buf, sizeof(auio_buf));

                                if (dirtypg <= (end - 1) / PAGE_SIZE) {
                                        /* there's a dirty page in the way, so just do two reads */
                                        /* we'll read the preceding data here */
                                        uio_reset(auio, boff + start, UIO_SYSSPACE, UIO_READ);
                                        uio_addiov(auio, CAST_USER_ADDR_T(bp->nb_data + start), on - start);
                                        error = nfs_read_rpc(np, auio, ctx);
                                        if (error) {
                                                /* couldn't read the data, so treat buffer as synchronous NOCACHE */
                                                SET(bp->nb_flags, (NB_NOCACHE | NB_STABLE));
                                                goto skipread;
                                        }
                                        if (uio_resid(auio) > 0) {
                                                FSDBG(516, bp, (caddr_t)uio_curriovbase(auio) - bp->nb_data, uio_resid(auio), 0xd00dee01);
                                                bzero(CAST_DOWN(caddr_t, uio_curriovbase(auio)), uio_resid(auio));
                                        }
                                        if (!error) {
                                                /* update validoff/validend if necessary */
                                                if ((bp->nb_validoff < 0) || (bp->nb_validoff > start)) {
                                                        bp->nb_validoff = start;
                                                }
                                                if ((bp->nb_validend < 0) || (bp->nb_validend < on)) {
                                                        bp->nb_validend = on;
                                                }
                                                if ((off_t)np->n_size > boff + bp->nb_validend) {
                                                        bp->nb_validend = min(np->n_size - (boff + start), biosize);
                                                }
                                                /* validate any pages before the write offset */
                                                for (; start < on / PAGE_SIZE; start += PAGE_SIZE) {
                                                        NBPGVALID_SET(bp, start / PAGE_SIZE);
                                                }
                                        }
                                        /* adjust start to read any trailing data */
                                        start = on + n;
                                }

                                /* if end is at end of page, try to */
                                /* get any following pages as well. */
                                if (!(end & PAGE_MASK)) {
                                        /* stop at next valid page or end of block */
                                        for (; end < biosize; end += PAGE_SIZE) {
                                                if (NBPGVALID(bp, end / PAGE_SIZE)) {
                                                        break;
                                                }
                                        }
                                }

                                if (((boff + start) >= (off_t)np->n_size) ||
                                    ((start >= on) && ((boff + on + n) >= (off_t)np->n_size))) {
                                        /*
                                         * Either this entire read is beyond the current EOF
                                         * or the range that we won't be modifying (on+n...end)
                                         * is all beyond the current EOF.
                                         * No need to make a trip across the network to
                                         * read nothing.  So, just zero the buffer instead.
                                         */
                                        FSDBG(516, bp, start, end - start, 0xd00dee00);
                                        bzero(bp->nb_data + start, end - start);
                                        error = 0;
                                } else {
                                        /* now we'll read the (rest of the) data */
                                        uio_reset(auio, boff + start, UIO_SYSSPACE, UIO_READ);
                                        uio_addiov(auio, CAST_USER_ADDR_T(bp->nb_data + start), end - start);
                                        error = nfs_read_rpc(np, auio, ctx);
                                        if (error) {
                                                /* couldn't read the data, so treat buffer as synchronous NOCACHE */
                                                SET(bp->nb_flags, (NB_NOCACHE | NB_STABLE));
                                                goto skipread;
                                        }
                                        if (uio_resid(auio) > 0) {
                                                FSDBG(516, bp, (caddr_t)uio_curriovbase(auio) - bp->nb_data, uio_resid(auio), 0xd00dee02);
                                                bzero(CAST_DOWN(caddr_t, uio_curriovbase(auio)), uio_resid(auio));
                                        }
                                }
                                if (!error) {
                                        /* update validoff/validend if necessary */
                                        if ((bp->nb_validoff < 0) || (bp->nb_validoff > start)) {
                                                bp->nb_validoff = start;
                                        }
                                        if ((bp->nb_validend < 0) || (bp->nb_validend < end)) {
                                                bp->nb_validend = end;
                                        }
                                        if ((off_t)np->n_size > boff + bp->nb_validend) {
                                                bp->nb_validend = min(np->n_size - (boff + start), biosize);
                                        }
                                        /* validate any pages before the write offset's page */
                                        for (; start < (off_t)trunc_page_32(on); start += PAGE_SIZE) {
                                                NBPGVALID_SET(bp, start / PAGE_SIZE);
                                        }
                                        /* validate any pages after the range of pages being written to */
                                        for (; (end - 1) > (off_t)round_page_32(on + n - 1); end -= PAGE_SIZE) {
                                                NBPGVALID_SET(bp, (end - 1) / PAGE_SIZE);
                                        }
                                }
                                /* Note: pages being written to will be validated when written */
                        }
                }
skipread:

                if (ISSET(bp->nb_flags, NB_ERROR)) {
                        error = bp->nb_error;
                        nfs_buf_release(bp, 1);
                        goto out;
                }

                nfs_node_lock_force(np);
                np->n_flag |= NMODIFIED;
                nfs_node_unlock(np);

                NFS_BUF_MAP(bp);
                error = uiomove((char *)bp->nb_data + on, n, uio);
                if (error) {
                        SET(bp->nb_flags, NB_ERROR);
                        nfs_buf_release(bp, 1);
                        goto out;
                }

                /* validate any pages written to */
                start = on & ~PAGE_MASK;
                for (; start < on + n; start += PAGE_SIZE) {
                        NBPGVALID_SET(bp, start / PAGE_SIZE);
                        /*
                         * This may seem a little weird, but we don't actually set the
                         * dirty bits for writes.  This is because we keep the dirty range
                         * in the nb_dirtyoff/nb_dirtyend fields.  Also, particularly for
                         * delayed writes, when we give the pages back to the VM we don't
                         * want to keep them marked dirty, because when we later write the
                         * buffer we won't be able to tell which pages were written dirty
                         * and which pages were mmapped and dirtied.
                         */
                }
                if (bp->nb_dirtyend > 0) {
                        bp->nb_dirtyoff = min(on, bp->nb_dirtyoff);
                        bp->nb_dirtyend = max((on + n), bp->nb_dirtyend);
                } else {
                        bp->nb_dirtyoff = on;
                        bp->nb_dirtyend = on + n;
                }
                if (bp->nb_validend <= 0 || bp->nb_validend < bp->nb_dirtyoff ||
                    bp->nb_validoff > bp->nb_dirtyend) {
                        bp->nb_validoff = bp->nb_dirtyoff;
                        bp->nb_validend = bp->nb_dirtyend;
                } else {
                        bp->nb_validoff = min(bp->nb_validoff, bp->nb_dirtyoff);
                        bp->nb_validend = max(bp->nb_validend, bp->nb_dirtyend);
                }
                if (!ISSET(bp->nb_flags, NB_CACHE)) {
                        nfs_buf_normalize_valid_range(np, bp);
                }

                /*
                 * Since this block is being modified, it must be written
                 * again and not just committed.
                 */
                if (ISSET(bp->nb_flags, NB_NEEDCOMMIT)) {
                        nfs_node_lock_force(np);
                        if (ISSET(bp->nb_flags, NB_NEEDCOMMIT)) {
                                np->n_needcommitcnt--;
                                CHECK_NEEDCOMMITCNT(np);
                        }
                        CLR(bp->nb_flags, NB_NEEDCOMMIT);
                        nfs_node_unlock(np);
                }

                if (ioflag & IO_SYNC) {
                        error = nfs_buf_write(bp);
                        if (error) {
                                goto out;
                        }
                } else if (((n + on) == biosize) || (ioflag & IO_APPEND) ||
                    (ioflag & IO_NOCACHE) || ISSET(bp->nb_flags, NB_NOCACHE)) {
                        SET(bp->nb_flags, NB_ASYNC);
                        error = nfs_buf_write(bp);
                        if (error) {
                                goto out;
                        }
                } else {
                        /* If the block wasn't already delayed: charge for the write */
                        if (!ISSET(bp->nb_flags, NB_DELWRI)) {
                                proc_t p = vfs_context_proc(ctx);
                                if (p && p->p_stats) {
                                        OSIncrementAtomicLong(&p->p_stats->p_ru.ru_oublock);
                                }
                        }
                        nfs_buf_write_delayed(bp);
                }


                if (np->n_needcommitcnt >= NFS_A_LOT_OF_NEEDCOMMITS) {
                        nfs_flushcommits(np, 1);
                }
        } while (uio_resid(uio) > 0 && n > 0);

out:
        nfs_node_lock_force(np);
        np->n_wrbusy--;
        if ((ioflag & IO_SYNC) && !np->n_wrbusy && !np->n_numoutput) {
                np->n_flag &= ~NMODIFIED;
        }
        nfs_node_unlock(np);
        nfs_data_unlock(np);
        FSDBG_BOT(515, np, uio_offset(uio), uio_resid(uio), error);
        return error;
}


/*
 * NFS write call
 */
int
nfs_write_rpc(
        nfsnode_t np,
        uio_t uio,
        vfs_context_t ctx,
        int *iomodep,
        uint64_t *wverfp)
{
        return nfs_write_rpc2(np, uio, vfs_context_thread(ctx), vfs_context_ucred(ctx), iomodep, wverfp);
}

int
nfs_write_rpc2(
        nfsnode_t np,
        uio_t uio,
        thread_t thd,
        kauth_cred_t cred,
        int *iomodep,
        uint64_t *wverfp)
{
        struct nfsmount *nmp;
        int error = 0, nfsvers;
        int wverfset, commit, committed;
        uint64_t wverf = 0, wverf2;
        size_t nmwsize, totalsize, tsiz, len, rlen;
        struct nfsreq rq, *req = &rq;
#if CONFIG_NFS4
        uint32_t stategenid = 0, restart = 0;
#endif
        uint32_t vrestart = 0;
        uio_t uio_save = NULL;

#if DIAGNOSTIC
        /* XXX limitation based on need to back up uio on short write */
        if (uio_iovcnt(uio) != 1) {
                panic("nfs3_write_rpc: iovcnt > 1");
        }
#endif
        FSDBG_TOP(537, np, uio_offset(uio), uio_resid(uio), *iomodep);
        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        nmwsize = nmp->nm_wsize;

        wverfset = 0;
        committed = NFS_WRITE_FILESYNC;

        totalsize = tsiz = uio_resid(uio);
        if ((nfsvers == NFS_VER2) && ((uint64_t)(uio_offset(uio) + tsiz) > 0xffffffffULL)) {
                FSDBG_BOT(537, np, uio_offset(uio), uio_resid(uio), EFBIG);
                return EFBIG;
        }

        uio_save = uio_duplicate(uio);
        if (uio_save == NULL) {
                return EIO;
        }

        while (tsiz > 0) {
                len = (tsiz > nmwsize) ? nmwsize : tsiz;
                FSDBG(537, np, uio_offset(uio), len, 0);
                if (np->n_flag & NREVOKE) {
                        error = EIO;
                        break;
                }
#if CONFIG_NFS4
                if (nmp->nm_vers >= NFS_VER4) {
                        stategenid = nmp->nm_stategenid;
                }
#endif
                error = nmp->nm_funcs->nf_write_rpc_async(np, uio, len, thd, cred, *iomodep, NULL, &req);
                if (!error) {
                        error = nmp->nm_funcs->nf_write_rpc_async_finish(np, req, &commit, &rlen, &wverf2);
                }
                nmp = NFSTONMP(np);
                if (nfs_mount_gone(nmp)) {
                        error = ENXIO;
                }
#if CONFIG_NFS4
                if ((nmp->nm_vers >= NFS_VER4) && nfs_mount_state_error_should_restart(error) &&
                    (++restart <= nfs_mount_state_max_restarts(nmp))) { /* guard against no progress */
                        lck_mtx_lock(&nmp->nm_lock);
                        if ((error != NFSERR_GRACE) && (stategenid == nmp->nm_stategenid)) {
                                NP(np, "nfs_write_rpc: error %d, initiating recovery", error);
                                nfs_need_recover(nmp, error);
                        }
                        lck_mtx_unlock(&nmp->nm_lock);
                        if (np->n_flag & NREVOKE) {
                                error = EIO;
                        } else {
                                if (error == NFSERR_GRACE) {
                                        tsleep(&nmp->nm_state, (PZERO - 1), "nfsgrace", 2 * hz);
                                }
                                if (!(error = nfs_mount_state_wait_for_recovery(nmp))) {
                                        continue;
                                }
                        }
                }
#endif
                if (error) {
                        break;
                }
                if (nfsvers == NFS_VER2) {
                        tsiz -= len;
                        continue;
                }

                /* check for a short write */
                if (rlen < len) {
                        /* Reset the uio to reflect the actual transfer */
                        *uio = *uio_save;
                        uio_update(uio, totalsize - (tsiz - rlen));
                        len = rlen;
                }

                /* return lowest commit level returned */
                if (commit < committed) {
                        committed = commit;
                }

                tsiz -= len;

                /* check write verifier */
                if (!wverfset) {
                        wverf = wverf2;
                        wverfset = 1;
                } else if (wverf != wverf2) {
                        /* verifier changed, so we need to restart all the writes */
                        if (++vrestart > 100) {
                                /* give up after too many restarts */
                                error = EIO;
                                break;
                        }
                        *uio = *uio_save;       // Reset the uio back to the start
                        committed = NFS_WRITE_FILESYNC;
                        wverfset = 0;
                        tsiz = totalsize;
                }
        }
        if (uio_save) {
                uio_free(uio_save);
        }
        if (wverfset && wverfp) {
                *wverfp = wverf;
        }
        *iomodep = committed;
        if (error) {
                uio_setresid(uio, tsiz);
        }
        FSDBG_BOT(537, np, committed, uio_resid(uio), error);
        return error;
}

int
nfs3_write_rpc_async(
        nfsnode_t np,
        uio_t uio,
        size_t len,
        thread_t thd,
        kauth_cred_t cred,
        int iomode,
        struct nfsreq_cbinfo *cb,
        struct nfsreq **reqp)
{
        struct nfsmount *nmp;
        mount_t mp;
        int error = 0, nfsvers;
        struct nfsm_chain nmreq;

        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        /* for async mounts, don't bother sending sync write requests */
        if ((iomode != NFS_WRITE_UNSTABLE) && nfs_allow_async &&
            ((mp = NFSTOMP(np))) && (vfs_flags(mp) & MNT_ASYNC)) {
                iomode = NFS_WRITE_UNSTABLE;
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + 5 * NFSX_UNSIGNED + nfsm_rndup(len));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, np->n_fhp, np->n_fhsize);
        if (nfsvers == NFS_VER3) {
                nfsm_chain_add_64(error, &nmreq, uio_offset(uio));
                nfsm_chain_add_32(error, &nmreq, len);
                nfsm_chain_add_32(error, &nmreq, iomode);
        } else {
                nfsm_chain_add_32(error, &nmreq, 0);
                nfsm_chain_add_32(error, &nmreq, uio_offset(uio));
                nfsm_chain_add_32(error, &nmreq, 0);
        }
        nfsm_chain_add_32(error, &nmreq, len);
        nfsmout_if(error);
        error = nfsm_chain_add_uio(&nmreq, uio, len);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request_async(np, NULL, &nmreq, NFSPROC_WRITE, thd, cred, NULL, 0, cb, reqp);
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        return error;
}

int
nfs3_write_rpc_async_finish(
        nfsnode_t np,
        struct nfsreq *req,
        int *iomodep,
        size_t *rlenp,
        uint64_t *wverfp)
{
        struct nfsmount *nmp;
        int error = 0, lockerror = ENOENT, nfsvers, status;
        int updatemtime = 0, wccpostattr = 0, rlen, committed = NFS_WRITE_FILESYNC;
        u_int64_t xid, wverf;
        mount_t mp;
        struct nfsm_chain nmrep;

        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                nfs_request_async_cancel(req);
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        nfsm_chain_null(&nmrep);

        error = nfs_request_async_finish(req, &nmrep, &xid, &status);
        if (error == EINPROGRESS) { /* async request restarted */
                return error;
        }
        nmp = NFSTONMP(np);
        if (nfs_mount_gone(nmp)) {
                error = ENXIO;
        }
        if (!error && (lockerror = nfs_node_lock(np))) {
                error = lockerror;
        }
        if (nfsvers == NFS_VER3) {
                struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
                nfsm_chain_get_wcc_data(error, &nmrep, np, &premtime, &wccpostattr, &xid);
                if (nfstimespeccmp(&np->n_mtime, &premtime, ==)) {
                        updatemtime = 1;
                }
                if (!error) {
                        error = status;
                }
                nfsm_chain_get_32(error, &nmrep, rlen);
                nfsmout_if(error);
                *rlenp = rlen;
                if (rlen <= 0) {
                        error = NFSERR_IO;
                }
                nfsm_chain_get_32(error, &nmrep, committed);
                nfsm_chain_get_64(error, &nmrep, wverf);
                nfsmout_if(error);
                if (wverfp) {
                        *wverfp = wverf;
                }
                lck_mtx_lock(&nmp->nm_lock);
                if (!(nmp->nm_state & NFSSTA_HASWRITEVERF)) {
                        nmp->nm_verf = wverf;
                        nmp->nm_state |= NFSSTA_HASWRITEVERF;
                } else if (nmp->nm_verf != wverf) {
                        nmp->nm_verf = wverf;
                }
                lck_mtx_unlock(&nmp->nm_lock);
        } else {
                if (!error) {
                        error = status;
                }
                nfsm_chain_loadattr(error, &nmrep, np, nfsvers, &xid);
                nfsmout_if(error);
        }
        if (updatemtime) {
                NFS_CHANGED_UPDATE(nfsvers, np, &np->n_vattr);
        }
nfsmout:
        if (!lockerror) {
                nfs_node_unlock(np);
        }
        nfsm_chain_cleanup(&nmrep);
        if ((committed != NFS_WRITE_FILESYNC) && nfs_allow_async &&
            ((mp = NFSTOMP(np))) && (vfs_flags(mp) & MNT_ASYNC)) {
                committed = NFS_WRITE_FILESYNC;
        }
        *iomodep = committed;
        return error;
}

/*
 * NFS mknod vnode op
 *
 * For NFS v2 this is a kludge. Use a create RPC but with the IFMT bits of the
 * mode set to specify the file type and the size field for rdev.
 */
int
nfs3_vnop_mknod(
        struct vnop_mknod_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_dvp;
                                *  vnode_t *a_vpp;
                                *  struct componentname *a_cnp;
                                *  struct vnode_attr *a_vap;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        vnode_t dvp = ap->a_dvp;
        vnode_t *vpp = ap->a_vpp;
        struct componentname *cnp = ap->a_cnp;
        struct vnode_attr *vap = ap->a_vap;
        vfs_context_t ctx = ap->a_context;
        vnode_t newvp = NULL;
        nfsnode_t np = NULL;
        struct nfsmount *nmp;
        nfsnode_t dnp = VTONFS(dvp);
        struct nfs_vattr nvattr;
        fhandle_t fh;
        int error = 0, lockerror = ENOENT, busyerror = ENOENT, status, wccpostattr = 0;
        struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
        u_int32_t rdev;
        u_int64_t xid = 0, dxid;
        int nfsvers, gotuid, gotgid;
        struct nfsm_chain nmreq, nmrep;
        struct nfsreq rq, *req = &rq;

        nmp = VTONMP(dvp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        if (!VATTR_IS_ACTIVE(vap, va_type)) {
                return EINVAL;
        }
        if (vap->va_type == VCHR || vap->va_type == VBLK) {
                if (!VATTR_IS_ACTIVE(vap, va_rdev)) {
                        return EINVAL;
                }
                rdev = vap->va_rdev;
        } else if (vap->va_type == VFIFO || vap->va_type == VSOCK) {
                rdev = 0xffffffff;
        } else {
                return ENOTSUP;
        }
        if ((nfsvers == NFS_VER2) && (cnp->cn_namelen > NFS_MAXNAMLEN)) {
                return ENAMETOOLONG;
        }

        nfs_avoid_needless_id_setting_on_create(dnp, vap, ctx);

        VATTR_SET_SUPPORTED(vap, va_mode);
        VATTR_SET_SUPPORTED(vap, va_uid);
        VATTR_SET_SUPPORTED(vap, va_gid);
        VATTR_SET_SUPPORTED(vap, va_data_size);
        VATTR_SET_SUPPORTED(vap, va_access_time);
        VATTR_SET_SUPPORTED(vap, va_modify_time);
        gotuid = VATTR_IS_ACTIVE(vap, va_uid);
        gotgid = VATTR_IS_ACTIVE(vap, va_gid);

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + 4 * NFSX_UNSIGNED +
            nfsm_rndup(cnp->cn_namelen) + NFSX_SATTR(nfsvers));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, dnp->n_fhp, dnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, cnp->cn_nameptr, cnp->cn_namelen, nmp);
        if (nfsvers == NFS_VER3) {
                nfsm_chain_add_32(error, &nmreq, vtonfs_type(vap->va_type, nfsvers));
                nfsm_chain_add_v3sattr(nmp, error, &nmreq, vap);
                if (vap->va_type == VCHR || vap->va_type == VBLK) {
                        nfsm_chain_add_32(error, &nmreq, major(vap->va_rdev));
                        nfsm_chain_add_32(error, &nmreq, minor(vap->va_rdev));
                }
        } else {
                nfsm_chain_add_v2sattr(error, &nmreq, vap, rdev);
        }
        nfsm_chain_build_done(error, &nmreq);
        if (!error) {
                error = busyerror = nfs_node_set_busy(dnp, vfs_context_thread(ctx));
        }
        nfsmout_if(error);

        error = nfs_request_async(dnp, NULL, &nmreq, NFSPROC_MKNOD,
            vfs_context_thread(ctx), vfs_context_ucred(ctx), NULL, 0, NULL, &req);
        if (!error) {
                error = nfs_request_async_finish(req, &nmrep, &xid, &status);
        }

        if ((lockerror = nfs_node_lock(dnp))) {
                error = lockerror;
        }
        /* XXX no EEXIST kludge here? */
        dxid = xid;
        if (!error && !status) {
                if (dnp->n_flag & NNEGNCENTRIES) {
                        dnp->n_flag &= ~NNEGNCENTRIES;
                        cache_purge_negatives(dvp);
                }
                error = nfsm_chain_get_fh_attr(nmp, &nmrep, dnp, ctx, nfsvers, &xid, &fh, &nvattr);
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_get_wcc_data(error, &nmrep, dnp, &premtime, &wccpostattr, &dxid);
        }
        if (!error) {
                error = status;
        }
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);

        if (!lockerror) {
                dnp->n_flag |= NMODIFIED;
                /* if directory hadn't changed, update namecache mtime */
                if (nfstimespeccmp(&dnp->n_ncmtime, &premtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, dnp, &dnp->n_vattr);
                }
                nfs_node_unlock(dnp);
                /* nfs_getattr() will check changed and purge caches */
                nfs_getattr(dnp, NULL, ctx, wccpostattr ? NGA_CACHED : NGA_UNCACHED);
        }

        if (!error && fh.fh_len) {
                error = nfs_nget(NFSTOMP(dnp), dnp, cnp, fh.fh_data, fh.fh_len, &nvattr, &xid, rq.r_auth, NG_MAKEENTRY, &np);
        }
        if (!error && !np) {
                error = nfs_lookitup(dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx, &np);
        }
        if (!error && np) {
                newvp = NFSTOV(np);
        }
        if (!busyerror) {
                nfs_node_clear_busy(dnp);
        }

        if (!error && (gotuid || gotgid) &&
            (!newvp || nfs_getattrcache(np, &nvattr, 0) ||
            (gotuid && (nvattr.nva_uid != vap->va_uid)) ||
            (gotgid && (nvattr.nva_gid != vap->va_gid)))) {
                /* clear ID bits if server didn't use them (or we can't tell) */
                VATTR_CLEAR_SUPPORTED(vap, va_uid);
                VATTR_CLEAR_SUPPORTED(vap, va_gid);
        }
        if (error) {
                if (newvp) {
                        nfs_node_unlock(np);
                        vnode_put(newvp);
                }
        } else {
                *vpp = newvp;
                nfs_node_unlock(np);
        }
        return error;
}

static uint32_t create_verf;
/*
 * NFS file create call
 */
int
nfs3_vnop_create(
        struct vnop_create_args /* {
                                 *  struct vnodeop_desc *a_desc;
                                 *  vnode_t a_dvp;
                                 *  vnode_t *a_vpp;
                                 *  struct componentname *a_cnp;
                                 *  struct vnode_attr *a_vap;
                                 *  vfs_context_t a_context;
                                 *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t dvp = ap->a_dvp;
        struct vnode_attr *vap = ap->a_vap;
        struct componentname *cnp = ap->a_cnp;
        struct nfs_vattr nvattr;
        fhandle_t fh;
        nfsnode_t np = NULL;
        struct nfsmount *nmp;
        nfsnode_t dnp = VTONFS(dvp);
        vnode_t newvp = NULL;
        int error = 0, lockerror = ENOENT, busyerror = ENOENT, status, wccpostattr = 0, fmode = 0;
        struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
        int nfsvers, gotuid, gotgid;
        u_int64_t xid, dxid;
        uint32_t val;
        struct nfsm_chain nmreq, nmrep;
        struct nfsreq rq, *req = &rq;
        struct nfs_dulookup dul;
        int dul_in_progress = 0;
        int namedattrs;

        nmp = VTONMP(dvp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        namedattrs = (nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_NAMED_ATTR);

        if ((nfsvers == NFS_VER2) && (cnp->cn_namelen > NFS_MAXNAMLEN)) {
                return ENAMETOOLONG;
        }

        nfs_avoid_needless_id_setting_on_create(dnp, vap, ctx);

        VATTR_SET_SUPPORTED(vap, va_mode);
        VATTR_SET_SUPPORTED(vap, va_uid);
        VATTR_SET_SUPPORTED(vap, va_gid);
        VATTR_SET_SUPPORTED(vap, va_data_size);
        VATTR_SET_SUPPORTED(vap, va_access_time);
        VATTR_SET_SUPPORTED(vap, va_modify_time);
        gotuid = VATTR_IS_ACTIVE(vap, va_uid);
        gotgid = VATTR_IS_ACTIVE(vap, va_gid);

        if ((vap->va_vaflags & VA_EXCLUSIVE)
            ) {
                fmode |= O_EXCL;
                if (!VATTR_IS_ACTIVE(vap, va_access_time) || !VATTR_IS_ACTIVE(vap, va_modify_time)) {
                        vap->va_vaflags |= VA_UTIMES_NULL;
                }
        }

again:
        error = busyerror = nfs_node_set_busy(dnp, vfs_context_thread(ctx));
        if (!namedattrs) {
                nfs_dulookup_init(&dul, dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx);
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + 2 * NFSX_UNSIGNED +
            nfsm_rndup(cnp->cn_namelen) + NFSX_SATTR(nfsvers));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, dnp->n_fhp, dnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, cnp->cn_nameptr, cnp->cn_namelen, nmp);
        if (nfsvers == NFS_VER3) {
                if (fmode & O_EXCL) {
                        nfsm_chain_add_32(error, &nmreq, NFS_CREATE_EXCLUSIVE);
                        lck_rw_lock_shared(in_ifaddr_rwlock);
                        if (!TAILQ_EMPTY(&in_ifaddrhead)) {
                                val = IA_SIN(in_ifaddrhead.tqh_first)->sin_addr.s_addr;
                        } else {
                                val = create_verf;
                        }
                        lck_rw_done(in_ifaddr_rwlock);
                        nfsm_chain_add_32(error, &nmreq, val);
                        ++create_verf;
                        nfsm_chain_add_32(error, &nmreq, create_verf);
                } else {
                        nfsm_chain_add_32(error, &nmreq, NFS_CREATE_UNCHECKED);
                        nfsm_chain_add_v3sattr(nmp, error, &nmreq, vap);
                }
        } else {
                nfsm_chain_add_v2sattr(error, &nmreq, vap, 0);
        }
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);

        error = nfs_request_async(dnp, NULL, &nmreq, NFSPROC_CREATE,
            vfs_context_thread(ctx), vfs_context_ucred(ctx), NULL, 0, NULL, &req);
        if (!error) {
                if (!namedattrs) {
                        nfs_dulookup_start(&dul, dnp, ctx);
                        dul_in_progress = 1;
                }
                error = nfs_request_async_finish(req, &nmrep, &xid, &status);
        }

        if ((lockerror = nfs_node_lock(dnp))) {
                error = lockerror;
        }
        dxid = xid;
        if (!error && !status) {
                if (dnp->n_flag & NNEGNCENTRIES) {
                        dnp->n_flag &= ~NNEGNCENTRIES;
                        cache_purge_negatives(dvp);
                }
                error = nfsm_chain_get_fh_attr(nmp, &nmrep, dnp, ctx, nfsvers, &xid, &fh, &nvattr);
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_get_wcc_data(error, &nmrep, dnp, &premtime, &wccpostattr, &dxid);
        }
        if (!error) {
                error = status;
        }
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);

        if (!lockerror) {
                dnp->n_flag |= NMODIFIED;
                /* if directory hadn't changed, update namecache mtime */
                if (nfstimespeccmp(&dnp->n_ncmtime, &premtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, dnp, &dnp->n_vattr);
                }
                nfs_node_unlock(dnp);
                /* nfs_getattr() will check changed and purge caches */
                nfs_getattr(dnp, NULL, ctx, wccpostattr ? NGA_CACHED : NGA_UNCACHED);
        }

        if (!error && fh.fh_len) {
                error = nfs_nget(NFSTOMP(dnp), dnp, cnp, fh.fh_data, fh.fh_len, &nvattr, &xid, rq.r_auth, NG_MAKEENTRY, &np);
        }
        if (!error && !np) {
                error = nfs_lookitup(dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx, &np);
        }
        if (!error && np) {
                newvp = NFSTOV(np);
        }

        if (dul_in_progress) {
                nfs_dulookup_finish(&dul, dnp, ctx);
        }
        if (!busyerror) {
                nfs_node_clear_busy(dnp);
        }

        if (error) {
                if ((nfsvers == NFS_VER3) && (fmode & O_EXCL) && (error == NFSERR_NOTSUPP)) {
                        fmode &= ~O_EXCL;
                        goto again;
                }
                if (newvp) {
                        nfs_node_unlock(np);
                        vnode_put(newvp);
                }
        } else if ((nfsvers == NFS_VER3) && (fmode & O_EXCL)) {
                nfs_node_unlock(np);
                error = nfs3_setattr_rpc(np, vap, ctx);
                if (error && (gotuid || gotgid)) {
                        /* it's possible the server didn't like our attempt to set IDs. */
                        /* so, let's try it again without those */
                        VATTR_CLEAR_ACTIVE(vap, va_uid);
                        VATTR_CLEAR_ACTIVE(vap, va_gid);
                        error = nfs3_setattr_rpc(np, vap, ctx);
                }
                if (error) {
                        vnode_put(newvp);
                } else {
                        nfs_node_lock_force(np);
                }
        }
        if (!error) {
                *ap->a_vpp = newvp;
        }
        if (!error && (gotuid || gotgid) &&
            (!newvp || nfs_getattrcache(np, &nvattr, 0) ||
            (gotuid && (nvattr.nva_uid != vap->va_uid)) ||
            (gotgid && (nvattr.nva_gid != vap->va_gid)))) {
                /* clear ID bits if server didn't use them (or we can't tell) */
                VATTR_CLEAR_SUPPORTED(vap, va_uid);
                VATTR_CLEAR_SUPPORTED(vap, va_gid);
        }
        if (!error) {
                nfs_node_unlock(np);
        }
        return error;
}

/*
 * NFS file remove call
 * To try and make NFS semantics closer to UFS semantics, a file that has
 * other processes using the vnode is renamed instead of removed and then
 * removed later on the last close.
 * - If vnode_isinuse()
 *        If a rename is not already in the works
 *           call nfs_sillyrename() to set it up
 *     else
 *        do the remove RPC
 */
int
nfs_vnop_remove(
        struct vnop_remove_args /* {
                                 *  struct vnodeop_desc *a_desc;
                                 *  vnode_t a_dvp;
                                 *  vnode_t a_vp;
                                 *  struct componentname *a_cnp;
                                 *  int a_flags;
                                 *  vfs_context_t a_context;
                                 *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t vp = ap->a_vp;
        vnode_t dvp = ap->a_dvp;
        struct componentname *cnp = ap->a_cnp;
        nfsnode_t dnp = VTONFS(dvp);
        nfsnode_t np = VTONFS(vp);
        int error = 0, nfsvers, namedattrs, inuse, gotattr = 0, flushed = 0, setsize = 0;
        struct nfs_vattr nvattr;
        struct nfsmount *nmp;
        struct nfs_dulookup dul;

        /* XXX prevent removing a sillyrenamed file? */

        nmp = NFSTONMP(dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        namedattrs = (nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_NAMED_ATTR);

again_relock:
        error = nfs_node_set_busy2(dnp, np, vfs_context_thread(ctx));
        if (error) {
                return error;
        }

        /* lock the node while we remove the file */
        lck_mtx_lock(nfs_node_hash_mutex);
        while (np->n_hflag & NHLOCKED) {
                np->n_hflag |= NHLOCKWANT;
                msleep(np, nfs_node_hash_mutex, PINOD, "nfs_remove", NULL);
        }
        np->n_hflag |= NHLOCKED;
        lck_mtx_unlock(nfs_node_hash_mutex);

        if (!namedattrs) {
                nfs_dulookup_init(&dul, dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx);
        }
again:
        inuse = vnode_isinuse(vp, 0);
        if ((ap->a_flags & VNODE_REMOVE_NODELETEBUSY) && inuse) {
                /* Caller requested Carbon delete semantics, but file is busy */
                error = EBUSY;
                goto out;
        }
        if (inuse && !gotattr) {
                if (nfs_getattr(np, &nvattr, ctx, NGA_CACHED)) {
                        nvattr.nva_nlink = 1;
                }
                gotattr = 1;
                goto again;
        }
        if (!inuse || (np->n_sillyrename && (nvattr.nva_nlink > 1))) {
                if (!inuse && !flushed) { /* flush all the buffers first */
                        /* unlock the node */
                        lck_mtx_lock(nfs_node_hash_mutex);
                        np->n_hflag &= ~NHLOCKED;
                        if (np->n_hflag & NHLOCKWANT) {
                                np->n_hflag &= ~NHLOCKWANT;
                                wakeup(np);
                        }
                        lck_mtx_unlock(nfs_node_hash_mutex);
                        nfs_node_clear_busy2(dnp, np);
                        error = nfs_vinvalbuf(vp, V_SAVE, ctx, 1);
                        FSDBG(260, np, np->n_size, np->n_vattr.nva_size, 0xf00d0011);
                        flushed = 1;
                        if (error == EINTR) {
                                nfs_node_lock_force(np);
                                NATTRINVALIDATE(np);
                                nfs_node_unlock(np);
                                return error;
                        }
                        if (!namedattrs) {
                                nfs_dulookup_finish(&dul, dnp, ctx);
                        }
                        goto again_relock;
                }
#if CONFIG_NFS4
                if ((nmp->nm_vers >= NFS_VER4) && (np->n_openflags & N_DELEG_MASK)) {
                        nfs4_delegation_return(np, 0, vfs_context_thread(ctx), vfs_context_ucred(ctx));
                }
#endif
                /*
                 * Purge the name cache so that the chance of a lookup for
                 * the name succeeding while the remove is in progress is
                 * minimized.
                 */
                nfs_name_cache_purge(dnp, np, cnp, ctx);

                if (!namedattrs) {
                        nfs_dulookup_start(&dul, dnp, ctx);
                }

                /* Do the rpc */
                error = nmp->nm_funcs->nf_remove_rpc(dnp, cnp->cn_nameptr, cnp->cn_namelen,
                    vfs_context_thread(ctx), vfs_context_ucred(ctx));

                /*
                 * Kludge City: If the first reply to the remove rpc is lost..
                 *   the reply to the retransmitted request will be ENOENT
                 *   since the file was in fact removed
                 *   Therefore, we cheat and return success.
                 */
                if (error == ENOENT) {
                        error = 0;
                }

                if (!error && !inuse && !np->n_sillyrename) {
                        /*
                         * removal succeeded, it's not in use, and not silly renamed so
                         * remove nfsnode from hash now so we can't accidentally find it
                         * again if another object gets created with the same filehandle
                         * before this vnode gets reclaimed
                         */
                        lck_mtx_lock(nfs_node_hash_mutex);
                        if (np->n_hflag & NHHASHED) {
                                LIST_REMOVE(np, n_hash);
                                np->n_hflag &= ~NHHASHED;
                                FSDBG(266, 0, np, np->n_flag, 0xb1eb1e);
                        }
                        lck_mtx_unlock(nfs_node_hash_mutex);
                        /* clear flags now: won't get nfs_vnop_inactive for recycled vnode */
                        /* clear all flags other than these */
                        nfs_node_lock_force(np);
                        np->n_flag &= (NMODIFIED);
                        NATTRINVALIDATE(np);
                        nfs_node_unlock(np);
                        vnode_recycle(vp);
                        setsize = 1;
                } else {
                        nfs_node_lock_force(np);
                        NATTRINVALIDATE(np);
                        nfs_node_unlock(np);
                }
        } else if (!np->n_sillyrename) {
                if (!namedattrs) {
                        nfs_dulookup_start(&dul, dnp, ctx);
                }
                error = nfs_sillyrename(dnp, np, cnp, ctx);
                nfs_node_lock_force(np);
                NATTRINVALIDATE(np);
                nfs_node_unlock(np);
        } else {
                nfs_node_lock_force(np);
                NATTRINVALIDATE(np);
                nfs_node_unlock(np);
                if (!namedattrs) {
                        nfs_dulookup_start(&dul, dnp, ctx);
                }
        }

        /* nfs_getattr() will check changed and purge caches */
        nfs_getattr(dnp, NULL, ctx, NGA_CACHED);
        if (!namedattrs) {
                nfs_dulookup_finish(&dul, dnp, ctx);
        }
out:
        /* unlock the node */
        lck_mtx_lock(nfs_node_hash_mutex);
        np->n_hflag &= ~NHLOCKED;
        if (np->n_hflag & NHLOCKWANT) {
                np->n_hflag &= ~NHLOCKWANT;
                wakeup(np);
        }
        lck_mtx_unlock(nfs_node_hash_mutex);
        nfs_node_clear_busy2(dnp, np);
        if (setsize) {
                ubc_setsize(vp, 0);
        }
        return error;
}

/*
 * NFS silly-renamed file removal function called from nfs_vnop_inactive
 */
int
nfs_removeit(struct nfs_sillyrename *nsp)
{
        struct nfsmount *nmp = NFSTONMP(nsp->nsr_dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        return nmp->nm_funcs->nf_remove_rpc(nsp->nsr_dnp, nsp->nsr_name, nsp->nsr_namlen, NULL, nsp->nsr_cred);
}

/*
 * NFS remove rpc, called from nfs_remove() and nfs_removeit().
 */
int
nfs3_remove_rpc(
        nfsnode_t dnp,
        char *name,
        int namelen,
        thread_t thd,
        kauth_cred_t cred)
{
        int error = 0, lockerror = ENOENT, status, wccpostattr = 0;
        struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
        struct nfsmount *nmp;
        int nfsvers;
        u_int64_t xid;
        struct nfsm_chain nmreq, nmrep;

        nmp = NFSTONMP(dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        if ((nfsvers == NFS_VER2) && (namelen > NFS_MAXNAMLEN)) {
                return ENAMETOOLONG;
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + NFSX_UNSIGNED + nfsm_rndup(namelen));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, dnp->n_fhp, dnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, name, namelen, nmp);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);

        error = nfs_request2(dnp, NULL, &nmreq, NFSPROC_REMOVE, thd, cred, NULL, 0, &nmrep, &xid, &status);

        if ((lockerror = nfs_node_lock(dnp))) {
                error = lockerror;
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_get_wcc_data(error, &nmrep, dnp, &premtime, &wccpostattr, &xid);
        }
        nfsmout_if(error);
        dnp->n_flag |= NMODIFIED;
        /* if directory hadn't changed, update namecache mtime */
        if (nfstimespeccmp(&dnp->n_ncmtime, &premtime, ==)) {
                NFS_CHANGED_UPDATE_NC(nfsvers, dnp, &dnp->n_vattr);
        }
        if (!wccpostattr) {
                NATTRINVALIDATE(dnp);
        }
        if (!error) {
                error = status;
        }
nfsmout:
        if (!lockerror) {
                nfs_node_unlock(dnp);
        }
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        return error;
}

/*
 * NFS file rename call
 */
int
nfs_vnop_rename(
        struct vnop_rename_args  /* {
                                  *  struct vnodeop_desc *a_desc;
                                  *  vnode_t a_fdvp;
                                  *  vnode_t a_fvp;
                                  *  struct componentname *a_fcnp;
                                  *  vnode_t a_tdvp;
                                  *  vnode_t a_tvp;
                                  *  struct componentname *a_tcnp;
                                  *  vfs_context_t a_context;
                                  *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t fdvp = ap->a_fdvp;
        vnode_t fvp = ap->a_fvp;
        vnode_t tdvp = ap->a_tdvp;
        vnode_t tvp = ap->a_tvp;
        nfsnode_t fdnp, fnp, tdnp, tnp;
        struct componentname *tcnp = ap->a_tcnp;
        struct componentname *fcnp = ap->a_fcnp;
        int error, nfsvers, inuse = 0, tvprecycle = 0, locked = 0;
        mount_t fmp, tdmp, tmp;
        struct nfs_vattr nvattr;
        struct nfsmount *nmp;

        fdnp = VTONFS(fdvp);
        fnp = VTONFS(fvp);
        tdnp = VTONFS(tdvp);
        tnp = tvp ? VTONFS(tvp) : NULL;

        nmp = NFSTONMP(fdnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        error = nfs_node_set_busy4(fdnp, fnp, tdnp, tnp, vfs_context_thread(ctx));
        if (error) {
                return error;
        }

        if (tvp && (tvp != fvp)) {
                /* lock the node while we rename over the existing file */
                lck_mtx_lock(nfs_node_hash_mutex);
                while (tnp->n_hflag & NHLOCKED) {
                        tnp->n_hflag |= NHLOCKWANT;
                        msleep(tnp, nfs_node_hash_mutex, PINOD, "nfs_rename", NULL);
                }
                tnp->n_hflag |= NHLOCKED;
                lck_mtx_unlock(nfs_node_hash_mutex);
                locked = 1;
        }

        /* Check for cross-device rename */
        fmp = vnode_mount(fvp);
        tmp = tvp ? vnode_mount(tvp) : NULL;
        tdmp = vnode_mount(tdvp);
        if ((fmp != tdmp) || (tvp && (fmp != tmp))) {
                error = EXDEV;
                goto out;
        }

        /* XXX prevent renaming from/over a sillyrenamed file? */

        /*
         * If the tvp exists and is in use, sillyrename it before doing the
         * rename of the new file over it.
         * XXX Can't sillyrename a directory.
         * Don't sillyrename if source and target are same vnode (hard
         * links or case-variants)
         */
        if (tvp && (tvp != fvp)) {
                inuse = vnode_isinuse(tvp, 0);
        }
        if (inuse && !tnp->n_sillyrename && (vnode_vtype(tvp) != VDIR)) {
                error = nfs_sillyrename(tdnp, tnp, tcnp, ctx);
                if (error) {
                        /* sillyrename failed. Instead of pressing on, return error */
                        goto out; /* should not be ENOENT. */
                } else {
                        /* sillyrename succeeded.*/
                        tvp = NULL;
                }
        }
#if CONFIG_NFS4
        else if (tvp && (nmp->nm_vers >= NFS_VER4) && (tnp->n_openflags & N_DELEG_MASK)) {
                nfs4_delegation_return(tnp, 0, vfs_context_thread(ctx), vfs_context_ucred(ctx));
        }
#endif
        error = nmp->nm_funcs->nf_rename_rpc(fdnp, fcnp->cn_nameptr, fcnp->cn_namelen,
            tdnp, tcnp->cn_nameptr, tcnp->cn_namelen, ctx);

        /*
         * Kludge: Map ENOENT => 0 assuming that it is a reply to a retry.
         */
        if (error == ENOENT) {
                error = 0;
        }

        if (tvp && (tvp != fvp) && !tnp->n_sillyrename) {
                nfs_node_lock_force(tnp);
                tvprecycle = (!error && !vnode_isinuse(tvp, 0) &&
                    (nfs_getattrcache(tnp, &nvattr, 0) || (nvattr.nva_nlink == 1)));
                nfs_node_unlock(tnp);
                lck_mtx_lock(nfs_node_hash_mutex);
                if (tvprecycle && (tnp->n_hflag & NHHASHED)) {
                        /*
                         * remove nfsnode from hash now so we can't accidentally find it
                         * again if another object gets created with the same filehandle
                         * before this vnode gets reclaimed
                         */
                        LIST_REMOVE(tnp, n_hash);
                        tnp->n_hflag &= ~NHHASHED;
                        FSDBG(266, 0, tnp, tnp->n_flag, 0xb1eb1e);
                }
                lck_mtx_unlock(nfs_node_hash_mutex);
        }

        /* purge the old name cache entries and enter the new one */
        nfs_name_cache_purge(fdnp, fnp, fcnp, ctx);
        if (tvp) {
                nfs_name_cache_purge(tdnp, tnp, tcnp, ctx);
                if (tvprecycle) {
                        /* clear flags now: won't get nfs_vnop_inactive for recycled vnode */
                        /* clear all flags other than these */
                        nfs_node_lock_force(tnp);
                        tnp->n_flag &= (NMODIFIED);
                        nfs_node_unlock(tnp);
                        vnode_recycle(tvp);
                }
        }
        if (!error) {
                nfs_node_lock_force(tdnp);
                if (tdnp->n_flag & NNEGNCENTRIES) {
                        tdnp->n_flag &= ~NNEGNCENTRIES;
                        cache_purge_negatives(tdvp);
                }
                nfs_node_unlock(tdnp);
                nfs_node_lock_force(fnp);
                cache_enter(tdvp, fvp, tcnp);
                if (tdvp != fdvp) {     /* update parent pointer */
                        if (fnp->n_parent && !vnode_get(fnp->n_parent)) {
                                /* remove ref from old parent */
                                vnode_rele(fnp->n_parent);
                                vnode_put(fnp->n_parent);
                        }
                        fnp->n_parent = tdvp;
                        if (tdvp && !vnode_get(tdvp)) {
                                /* add ref to new parent */
                                vnode_ref(tdvp);
                                vnode_put(tdvp);
                        } else {
                                fnp->n_parent = NULL;
                        }
                }
                nfs_node_unlock(fnp);
        }
out:
        /* nfs_getattr() will check changed and purge caches */
        nfs_getattr(fdnp, NULL, ctx, NGA_CACHED);
        nfs_getattr(tdnp, NULL, ctx, NGA_CACHED);
        if (locked) {
                /* unlock node */
                lck_mtx_lock(nfs_node_hash_mutex);
                tnp->n_hflag &= ~NHLOCKED;
                if (tnp->n_hflag & NHLOCKWANT) {
                        tnp->n_hflag &= ~NHLOCKWANT;
                        wakeup(tnp);
                }
                lck_mtx_unlock(nfs_node_hash_mutex);
        }
        nfs_node_clear_busy4(fdnp, fnp, tdnp, tnp);
        return error;
}

/*
 * Do an NFS rename rpc. Called from nfs_vnop_rename() and nfs_sillyrename().
 */
int
nfs3_rename_rpc(
        nfsnode_t fdnp,
        char *fnameptr,
        int fnamelen,
        nfsnode_t tdnp,
        char *tnameptr,
        int tnamelen,
        vfs_context_t ctx)
{
        int error = 0, lockerror = ENOENT, status, fwccpostattr = 0, twccpostattr = 0;
        struct timespec fpremtime = { .tv_sec = 0, .tv_nsec = 0 }, tpremtime = { .tv_sec = 0, .tv_nsec = 0 };
        struct nfsmount *nmp;
        int nfsvers;
        u_int64_t xid, txid;
        struct nfsm_chain nmreq, nmrep;

        nmp = NFSTONMP(fdnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        if ((nfsvers == NFS_VER2) &&
            ((fnamelen > NFS_MAXNAMLEN) || (tnamelen > NFS_MAXNAMLEN))) {
                return ENAMETOOLONG;
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            (NFSX_FH(nfsvers) + NFSX_UNSIGNED) * 2 +
            nfsm_rndup(fnamelen) + nfsm_rndup(tnamelen));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, fdnp->n_fhp, fdnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, fnameptr, fnamelen, nmp);
        nfsm_chain_add_fh(error, &nmreq, nfsvers, tdnp->n_fhp, tdnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, tnameptr, tnamelen, nmp);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);

        error = nfs_request(fdnp, NULL, &nmreq, NFSPROC_RENAME, ctx, NULL, &nmrep, &xid, &status);

        if ((lockerror = nfs_node_lock2(fdnp, tdnp))) {
                error = lockerror;
        }
        if (nfsvers == NFS_VER3) {
                txid = xid;
                nfsm_chain_get_wcc_data(error, &nmrep, fdnp, &fpremtime, &fwccpostattr, &xid);
                nfsm_chain_get_wcc_data(error, &nmrep, tdnp, &tpremtime, &twccpostattr, &txid);
        }
        if (!error) {
                error = status;
        }
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        if (!lockerror) {
                fdnp->n_flag |= NMODIFIED;
                /* if directory hadn't changed, update namecache mtime */
                if (nfstimespeccmp(&fdnp->n_ncmtime, &fpremtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, fdnp, &fdnp->n_vattr);
                }
                if (!fwccpostattr) {
                        NATTRINVALIDATE(fdnp);
                }
                tdnp->n_flag |= NMODIFIED;
                /* if directory hadn't changed, update namecache mtime */
                if (nfstimespeccmp(&tdnp->n_ncmtime, &tpremtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, tdnp, &tdnp->n_vattr);
                }
                if (!twccpostattr) {
                        NATTRINVALIDATE(tdnp);
                }
                nfs_node_unlock2(fdnp, tdnp);
        }
        return error;
}

/*
 * NFS hard link create call
 */
int
nfs3_vnop_link(
        struct vnop_link_args /* {
                               *  struct vnodeop_desc *a_desc;
                               *  vnode_t a_vp;
                               *  vnode_t a_tdvp;
                               *  struct componentname *a_cnp;
                               *  vfs_context_t a_context;
                               *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t vp = ap->a_vp;
        vnode_t tdvp = ap->a_tdvp;
        struct componentname *cnp = ap->a_cnp;
        int error = 0, lockerror = ENOENT, status, wccpostattr = 0, attrflag = 0;
        struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
        struct nfsmount *nmp;
        nfsnode_t np = VTONFS(vp);
        nfsnode_t tdnp = VTONFS(tdvp);
        int nfsvers;
        u_int64_t xid, txid;
        struct nfsm_chain nmreq, nmrep;

        if (vnode_mount(vp) != vnode_mount(tdvp)) {
                return EXDEV;
        }

        nmp = VTONMP(vp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        if ((nfsvers == NFS_VER2) && (cnp->cn_namelen > NFS_MAXNAMLEN)) {
                return ENAMETOOLONG;
        }

        /*
         * Push all writes to the server, so that the attribute cache
         * doesn't get "out of sync" with the server.
         * XXX There should be a better way!
         */
        nfs_flush(np, MNT_WAIT, vfs_context_thread(ctx), V_IGNORE_WRITEERR);

        error = nfs_node_set_busy2(tdnp, np, vfs_context_thread(ctx));
        if (error) {
                return error;
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) * 2 + NFSX_UNSIGNED + nfsm_rndup(cnp->cn_namelen));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, np->n_fhp, np->n_fhsize);
        nfsm_chain_add_fh(error, &nmreq, nfsvers, tdnp->n_fhp, tdnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, cnp->cn_nameptr, cnp->cn_namelen, nmp);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request(np, NULL, &nmreq, NFSPROC_LINK, ctx, NULL, &nmrep, &xid, &status);

        if ((lockerror = nfs_node_lock2(tdnp, np))) {
                error = lockerror;
                goto nfsmout;
        }
        if (nfsvers == NFS_VER3) {
                txid = xid;
                nfsm_chain_postop_attr_update_flag(error, &nmrep, np, attrflag, &xid);
                nfsm_chain_get_wcc_data(error, &nmrep, tdnp, &premtime, &wccpostattr, &txid);
        }
        if (!error) {
                error = status;
        }
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        if (!lockerror) {
                if (!attrflag) {
                        NATTRINVALIDATE(np);
                }
                tdnp->n_flag |= NMODIFIED;
                /* if directory hadn't changed, update namecache mtime */
                if (nfstimespeccmp(&tdnp->n_ncmtime, &premtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, tdnp, &tdnp->n_vattr);
                }
                if (!wccpostattr) {
                        NATTRINVALIDATE(tdnp);
                }
                if (!error && (tdnp->n_flag & NNEGNCENTRIES)) {
                        tdnp->n_flag &= ~NNEGNCENTRIES;
                        cache_purge_negatives(tdvp);
                }
                nfs_node_unlock2(tdnp, np);
        }
        nfs_node_clear_busy2(tdnp, np);
        /*
         * Kludge: Map EEXIST => 0 assuming that it is a reply to a retry.
         */
        if (error == EEXIST) {
                error = 0;
        }
        return error;
}

/*
 * NFS symbolic link create call
 */
int
nfs3_vnop_symlink(
        struct vnop_symlink_args /* {
                                  *  struct vnodeop_desc *a_desc;
                                  *  vnode_t a_dvp;
                                  *  vnode_t *a_vpp;
                                  *  struct componentname *a_cnp;
                                  *  struct vnode_attr *a_vap;
                                  *  char *a_target;
                                  *  vfs_context_t a_context;
                                  *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t dvp = ap->a_dvp;
        struct vnode_attr *vap = ap->a_vap;
        struct componentname *cnp = ap->a_cnp;
        struct nfs_vattr nvattr;
        fhandle_t fh;
        int slen, error = 0, lockerror = ENOENT, busyerror = ENOENT, status, wccpostattr = 0;
        struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
        vnode_t newvp = NULL;
        int nfsvers, gotuid, gotgid;
        u_int64_t xid = 0, dxid;
        nfsnode_t np = NULL;
        nfsnode_t dnp = VTONFS(dvp);
        struct nfsmount *nmp;
        struct nfsm_chain nmreq, nmrep;
        struct nfsreq rq, *req = &rq;
        struct nfs_dulookup dul;
        int namedattrs;
        int dul_in_progress = 0;

        nmp = VTONMP(dvp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        namedattrs = (nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_NAMED_ATTR);

        slen = strlen(ap->a_target);
        if ((nfsvers == NFS_VER2) &&
            ((cnp->cn_namelen > NFS_MAXNAMLEN) || (slen > NFS_MAXPATHLEN))) {
                return ENAMETOOLONG;
        }

        nfs_avoid_needless_id_setting_on_create(dnp, vap, ctx);

        VATTR_SET_SUPPORTED(vap, va_mode);
        VATTR_SET_SUPPORTED(vap, va_uid);
        VATTR_SET_SUPPORTED(vap, va_gid);
        VATTR_SET_SUPPORTED(vap, va_data_size);
        VATTR_SET_SUPPORTED(vap, va_access_time);
        VATTR_SET_SUPPORTED(vap, va_modify_time);
        gotuid = VATTR_IS_ACTIVE(vap, va_uid);
        gotgid = VATTR_IS_ACTIVE(vap, va_gid);

        error = busyerror = nfs_node_set_busy(dnp, vfs_context_thread(ctx));
        if (!namedattrs) {
                nfs_dulookup_init(&dul, dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx);
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + 2 * NFSX_UNSIGNED +
            nfsm_rndup(cnp->cn_namelen) + nfsm_rndup(slen) + NFSX_SATTR(nfsvers));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, dnp->n_fhp, dnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, cnp->cn_nameptr, cnp->cn_namelen, nmp);
        if (nfsvers == NFS_VER3) {
                nfsm_chain_add_v3sattr(nmp, error, &nmreq, vap);
        }
        nfsm_chain_add_name(error, &nmreq, ap->a_target, slen, nmp);
        if (nfsvers == NFS_VER2) {
                nfsm_chain_add_v2sattr(error, &nmreq, vap, -1);
        }
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);

        error = nfs_request_async(dnp, NULL, &nmreq, NFSPROC_SYMLINK,
            vfs_context_thread(ctx), vfs_context_ucred(ctx), NULL, 0, NULL, &req);
        if (!error) {
                if (!namedattrs) {
                        nfs_dulookup_start(&dul, dnp, ctx);
                        dul_in_progress = 1;
                }
                error = nfs_request_async_finish(req, &nmrep, &xid, &status);
        }

        if ((lockerror = nfs_node_lock(dnp))) {
                error = lockerror;
        }
        dxid = xid;
        if (!error && !status) {
                if (dnp->n_flag & NNEGNCENTRIES) {
                        dnp->n_flag &= ~NNEGNCENTRIES;
                        cache_purge_negatives(dvp);
                }
                if (nfsvers == NFS_VER3) {
                        error = nfsm_chain_get_fh_attr(nmp, &nmrep, dnp, ctx, nfsvers, &xid, &fh, &nvattr);
                } else {
                        fh.fh_len = 0;
                }
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_get_wcc_data(error, &nmrep, dnp, &premtime, &wccpostattr, &dxid);
        }
        if (!error) {
                error = status;
        }
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);

        if (!lockerror) {
                dnp->n_flag |= NMODIFIED;
                /* if directory hadn't changed, update namecache mtime */
                if (nfstimespeccmp(&dnp->n_ncmtime, &premtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, dnp, &dnp->n_vattr);
                }
                nfs_node_unlock(dnp);
                /* nfs_getattr() will check changed and purge caches */
                nfs_getattr(dnp, NULL, ctx, wccpostattr ? NGA_CACHED : NGA_UNCACHED);
        }

        if (!error && fh.fh_len) {
                error = nfs_nget(NFSTOMP(dnp), dnp, cnp, fh.fh_data, fh.fh_len, &nvattr, &xid, rq.r_auth, NG_MAKEENTRY, &np);
        }
        if (!error && np) {
                newvp = NFSTOV(np);
        }

        if (dul_in_progress) {
                nfs_dulookup_finish(&dul, dnp, ctx);
        }

        /*
         * Kludge: Map EEXIST => 0 assuming that you have a reply to a retry
         * if we can succeed in looking up the symlink.
         */
        if ((error == EEXIST) || (!error && !newvp)) {
                if (newvp) {
                        nfs_node_unlock(np);
                        vnode_put(newvp);
                        newvp = NULL;
                }
                error = nfs_lookitup(dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx, &np);
                if (!error) {
                        newvp = NFSTOV(np);
                        if (vnode_vtype(newvp) != VLNK) {
                                error = EEXIST;
                        }
                }
        }
        if (!busyerror) {
                nfs_node_clear_busy(dnp);
        }
        if (!error && (gotuid || gotgid) &&
            (!newvp || nfs_getattrcache(np, &nvattr, 0) ||
            (gotuid && (nvattr.nva_uid != vap->va_uid)) ||
            (gotgid && (nvattr.nva_gid != vap->va_gid)))) {
                /* clear ID bits if server didn't use them (or we can't tell) */
                VATTR_CLEAR_SUPPORTED(vap, va_uid);
                VATTR_CLEAR_SUPPORTED(vap, va_gid);
        }
        if (error) {
                if (newvp) {
                        nfs_node_unlock(np);
                        vnode_put(newvp);
                }
        } else {
                nfs_node_unlock(np);
                *ap->a_vpp = newvp;
        }
        return error;
}

/*
 * NFS make dir call
 */
int
nfs3_vnop_mkdir(
        struct vnop_mkdir_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_dvp;
                                *  vnode_t *a_vpp;
                                *  struct componentname *a_cnp;
                                *  struct vnode_attr *a_vap;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t dvp = ap->a_dvp;
        struct vnode_attr *vap = ap->a_vap;
        struct componentname *cnp = ap->a_cnp;
        struct nfs_vattr nvattr;
        nfsnode_t np = NULL;
        struct nfsmount *nmp;
        nfsnode_t dnp = VTONFS(dvp);
        vnode_t newvp = NULL;
        int error = 0, lockerror = ENOENT, busyerror = ENOENT, status, wccpostattr = 0;
        struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
        int nfsvers, gotuid, gotgid;
        u_int64_t xid = 0, dxid;
        fhandle_t fh;
        struct nfsm_chain nmreq, nmrep;
        struct nfsreq rq, *req = &rq;
        struct nfs_dulookup dul;
        int namedattrs;
        int dul_in_progress = 0;

        nmp = VTONMP(dvp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        namedattrs = (nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_NAMED_ATTR);

        if ((nfsvers == NFS_VER2) && (cnp->cn_namelen > NFS_MAXNAMLEN)) {
                return ENAMETOOLONG;
        }

        nfs_avoid_needless_id_setting_on_create(dnp, vap, ctx);

        VATTR_SET_SUPPORTED(vap, va_mode);
        VATTR_SET_SUPPORTED(vap, va_uid);
        VATTR_SET_SUPPORTED(vap, va_gid);
        VATTR_SET_SUPPORTED(vap, va_data_size);
        VATTR_SET_SUPPORTED(vap, va_access_time);
        VATTR_SET_SUPPORTED(vap, va_modify_time);
        gotuid = VATTR_IS_ACTIVE(vap, va_uid);
        gotgid = VATTR_IS_ACTIVE(vap, va_gid);

        error = busyerror = nfs_node_set_busy(dnp, vfs_context_thread(ctx));
        if (!namedattrs) {
                nfs_dulookup_init(&dul, dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx);
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + NFSX_UNSIGNED +
            nfsm_rndup(cnp->cn_namelen) + NFSX_SATTR(nfsvers));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, dnp->n_fhp, dnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, cnp->cn_nameptr, cnp->cn_namelen, nmp);
        if (nfsvers == NFS_VER3) {
                nfsm_chain_add_v3sattr(nmp, error, &nmreq, vap);
        } else {
                nfsm_chain_add_v2sattr(error, &nmreq, vap, -1);
        }
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);

        error = nfs_request_async(dnp, NULL, &nmreq, NFSPROC_MKDIR,
            vfs_context_thread(ctx), vfs_context_ucred(ctx), NULL, 0, NULL, &req);
        if (!error) {
                if (!namedattrs) {
                        nfs_dulookup_start(&dul, dnp, ctx);
                        dul_in_progress = 1;
                }
                error = nfs_request_async_finish(req, &nmrep, &xid, &status);
        }

        if ((lockerror = nfs_node_lock(dnp))) {
                error = lockerror;
        }
        dxid = xid;
        if (!error && !status) {
                if (dnp->n_flag & NNEGNCENTRIES) {
                        dnp->n_flag &= ~NNEGNCENTRIES;
                        cache_purge_negatives(dvp);
                }
                error = nfsm_chain_get_fh_attr(nmp, &nmrep, dnp, ctx, nfsvers, &xid, &fh, &nvattr);
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_get_wcc_data(error, &nmrep, dnp, &premtime, &wccpostattr, &dxid);
        }
        if (!error) {
                error = status;
        }
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);

        if (!lockerror) {
                dnp->n_flag |= NMODIFIED;
                /* if directory hadn't changed, update namecache mtime */
                if (nfstimespeccmp(&dnp->n_ncmtime, &premtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, dnp, &dnp->n_vattr);
                }
                nfs_node_unlock(dnp);
                /* nfs_getattr() will check changed and purge caches */
                nfs_getattr(dnp, NULL, ctx, wccpostattr ? NGA_CACHED : NGA_UNCACHED);
        }

        if (!error && fh.fh_len) {
                error = nfs_nget(NFSTOMP(dnp), dnp, cnp, fh.fh_data, fh.fh_len, &nvattr, &xid, rq.r_auth, NG_MAKEENTRY, &np);
        }
        if (!error && np) {
                newvp = NFSTOV(np);
        }

        if (dul_in_progress) {
                nfs_dulookup_finish(&dul, dnp, ctx);
        }

        /*
         * Kludge: Map EEXIST => 0 assuming that you have a reply to a retry
         * if we can succeed in looking up the directory.
         */
        if ((error == EEXIST) || (!error && !newvp)) {
                if (newvp) {
                        nfs_node_unlock(np);
                        vnode_put(newvp);
                        newvp = NULL;
                }
                error = nfs_lookitup(dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx, &np);
                if (!error) {
                        newvp = NFSTOV(np);
                        if (vnode_vtype(newvp) != VDIR) {
                                error = EEXIST;
                        }
                }
        }
        if (!busyerror) {
                nfs_node_clear_busy(dnp);
        }
        if (!error && (gotuid || gotgid) &&
            (!newvp || nfs_getattrcache(np, &nvattr, 0) ||
            (gotuid && (nvattr.nva_uid != vap->va_uid)) ||
            (gotgid && (nvattr.nva_gid != vap->va_gid)))) {
                /* clear ID bits if server didn't use them (or we can't tell) */
                VATTR_CLEAR_SUPPORTED(vap, va_uid);
                VATTR_CLEAR_SUPPORTED(vap, va_gid);
        }
        if (error) {
                if (newvp) {
                        nfs_node_unlock(np);
                        vnode_put(newvp);
                }
        } else {
                nfs_node_unlock(np);
                *ap->a_vpp = newvp;
        }
        return error;
}

/*
 * NFS remove directory call
 */
int
nfs3_vnop_rmdir(
        struct vnop_rmdir_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_dvp;
                                *  vnode_t a_vp;
                                *  struct componentname *a_cnp;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t vp = ap->a_vp;
        vnode_t dvp = ap->a_dvp;
        struct componentname *cnp = ap->a_cnp;
        int error = 0, lockerror = ENOENT, status, wccpostattr = 0;
        struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
        struct nfsmount *nmp;
        nfsnode_t np = VTONFS(vp);
        nfsnode_t dnp = VTONFS(dvp);
        int nfsvers;
        u_int64_t xid;
        struct nfsm_chain nmreq, nmrep;
        struct nfsreq rq, *req = &rq;
        struct nfs_dulookup dul;
        int namedattrs;
        int dul_in_progress = 0;

        nmp = VTONMP(vp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        namedattrs = (nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_NAMED_ATTR);

        if ((nfsvers == NFS_VER2) && (cnp->cn_namelen > NFS_MAXNAMLEN)) {
                return ENAMETOOLONG;
        }

        if ((error = nfs_node_set_busy2(dnp, np, vfs_context_thread(ctx)))) {
                return error;
        }

        if (!namedattrs) {
                nfs_dulookup_init(&dul, dnp, cnp->cn_nameptr, cnp->cn_namelen, ctx);
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + NFSX_UNSIGNED + nfsm_rndup(cnp->cn_namelen));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, dnp->n_fhp, dnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, cnp->cn_nameptr, cnp->cn_namelen, nmp);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);

        error = nfs_request_async(dnp, NULL, &nmreq, NFSPROC_RMDIR,
            vfs_context_thread(ctx), vfs_context_ucred(ctx), NULL, 0, NULL, &req);
        if (!error) {
                if (!namedattrs) {
                        nfs_dulookup_start(&dul, dnp, ctx);
                        dul_in_progress = 1;
                }
                error = nfs_request_async_finish(req, &nmrep, &xid, &status);
        }

        if ((lockerror = nfs_node_lock(dnp))) {
                error = lockerror;
        }
        if (nfsvers == NFS_VER3) {
                nfsm_chain_get_wcc_data(error, &nmrep, dnp, &premtime, &wccpostattr, &xid);
        }
        if (!error) {
                error = status;
        }
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);

        if (!lockerror) {
                dnp->n_flag |= NMODIFIED;
                /* if directory hadn't changed, update namecache mtime */
                if (nfstimespeccmp(&dnp->n_ncmtime, &premtime, ==)) {
                        NFS_CHANGED_UPDATE_NC(nfsvers, dnp, &dnp->n_vattr);
                }
                nfs_node_unlock(dnp);
                nfs_name_cache_purge(dnp, np, cnp, ctx);
                /* nfs_getattr() will check changed and purge caches */
                nfs_getattr(dnp, NULL, ctx, wccpostattr ? NGA_CACHED : NGA_UNCACHED);
        }
        if (dul_in_progress) {
                nfs_dulookup_finish(&dul, dnp, ctx);
        }
        nfs_node_clear_busy2(dnp, np);

        /*
         * Kludge: Map ENOENT => 0 assuming that you have a reply to a retry.
         */
        if (error == ENOENT) {
                error = 0;
        }
        if (!error) {
                /*
                 * remove nfsnode from hash now so we can't accidentally find it
                 * again if another object gets created with the same filehandle
                 * before this vnode gets reclaimed
                 */
                lck_mtx_lock(nfs_node_hash_mutex);
                if (np->n_hflag & NHHASHED) {
                        LIST_REMOVE(np, n_hash);
                        np->n_hflag &= ~NHHASHED;
                        FSDBG(266, 0, np, np->n_flag, 0xb1eb1e);
                }
                lck_mtx_unlock(nfs_node_hash_mutex);
        }
        return error;
}

/*
 * NFS readdir call
 *
 * The incoming "offset" is a directory cookie indicating where in the
 * directory entries should be read from.  A zero cookie means start at
 * the beginning of the directory.  Any other cookie will be a cookie
 * returned from the server.
 *
 * Using that cookie, determine which buffer (and where in that buffer)
 * to start returning entries from.  Buffer logical block numbers are
 * the cookies they start at.  If a buffer is found that is not full,
 * call into the bio/RPC code to fill it.  The RPC code will probably
 * fill several buffers (dropping the first, requiring a re-get).
 *
 * When done copying entries to the buffer, set the offset to the current
 * entry's cookie and enter that cookie in the cookie cache.
 *
 * Note: because the getdirentries(2) API returns a long-typed offset,
 * the incoming offset is a potentially truncated cookie (ptc).
 * The cookie matching code is aware of this and will fall back to
 * matching only 32 bits of the cookie.
 */
int
nfs_vnop_readdir(
        struct vnop_readdir_args /* {
                                  *  struct vnodeop_desc *a_desc;
                                  *  vnode_t a_vp;
                                  *  struct uio *a_uio;
                                  *  int a_flags;
                                  *  int *a_eofflag;
                                  *  int *a_numdirent;
                                  *  vfs_context_t a_context;
                                  *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t dvp = ap->a_vp;
        nfsnode_t dnp = VTONFS(dvp);
        struct nfsmount *nmp;
        uio_t uio = ap->a_uio;
        int error, nfsvers, extended, numdirent, bigcookies, ptc, done, attrcachetimeout;
        uint16_t i, iptc, rlen, nlen;
        uint64_t cookie, nextcookie, lbn = 0;
        struct nfsbuf *bp = NULL;
        struct nfs_dir_buf_header *ndbhp;
        struct direntry *dp, *dpptc;
        struct dirent dent;
        char *cp = NULL;
        struct timeval now;
        thread_t thd;

        nmp = VTONMP(dvp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        bigcookies = (nmp->nm_state & NFSSTA_BIGCOOKIES);
        extended = (ap->a_flags & VNODE_READDIR_EXTENDED);

        if (vnode_vtype(dvp) != VDIR) {
                return EPERM;
        }

        if (ap->a_eofflag) {
                *ap->a_eofflag = 0;
        }

        if (uio_resid(uio) == 0) {
                return 0;
        }
#if CONFIG_NFS4
        if ((nfsvers >= NFS_VER4) && (dnp->n_vattr.nva_flags & NFS_FFLAG_TRIGGER)) {
                /* trigger directories should never be read, return nothing */
                return 0;
        }
#endif
        thd = vfs_context_thread(ctx);
        numdirent = done = 0;
        nextcookie = uio_offset(uio);
        ptc = bigcookies && NFS_DIR_COOKIE_POTENTIALLY_TRUNCATED(nextcookie);

        if ((error = nfs_node_lock(dnp))) {
                goto out;
        }

        if (dnp->n_flag & NNEEDINVALIDATE) {
                dnp->n_flag &= ~NNEEDINVALIDATE;
                nfs_invaldir(dnp);
                nfs_node_unlock(dnp);
                error = nfs_vinvalbuf(dvp, 0, ctx, 1);
                if (!error) {
                        error = nfs_node_lock(dnp);
                }
                if (error) {
                        goto out;
                }
        }

        if (dnp->n_rdirplusstamp_eof && dnp->n_rdirplusstamp_sof) {
                attrcachetimeout = nfs_attrcachetimeout(dnp);
                microuptime(&now);
                if (attrcachetimeout && (now.tv_sec - dnp->n_rdirplusstamp_sof > attrcachetimeout - 1)) {
                        dnp->n_rdirplusstamp_eof = dnp->n_rdirplusstamp_sof = 0;
                        nfs_invaldir(dnp);
                        nfs_node_unlock(dnp);
                        error = nfs_vinvalbuf(dvp, 0, ctx, 1);
                        if (!error) {
                                error = nfs_node_lock(dnp);
                        }
                        if (error) {
                                goto out;
                        }
                }
        }

        /*
         * check for need to invalidate when (re)starting at beginning
         */
        if (!nextcookie) {
                if (dnp->n_flag & NMODIFIED) {
                        nfs_invaldir(dnp);
                        nfs_node_unlock(dnp);
                        if ((error = nfs_vinvalbuf(dvp, 0, ctx, 1))) {
                                goto out;
                        }
                } else {
                        nfs_node_unlock(dnp);
                }
                /* nfs_getattr() will check changed and purge caches */
                if ((error = nfs_getattr(dnp, NULL, ctx, NGA_UNCACHED))) {
                        goto out;
                }
        } else {
                nfs_node_unlock(dnp);
        }

        error = nfs_dir_cookie_to_lbn(dnp, nextcookie, &ptc, &lbn);
        if (error) {
                if (error < 0) { /* just hit EOF cookie */
                        done = 1;
                        error = 0;
                }
                if (ap->a_eofflag) {
                        *ap->a_eofflag = 1;
                }
        }

        while (!error && !done) {
                OSAddAtomic64(1, &nfsstats.biocache_readdirs);
                cookie = nextcookie;
getbuffer:
                error = nfs_buf_get(dnp, lbn, NFS_DIRBLKSIZ, thd, NBLK_READ, &bp);
                if (error) {
                        goto out;
                }
                ndbhp = (struct nfs_dir_buf_header*)bp->nb_data;
                if (!ISSET(bp->nb_flags, NB_CACHE) || !ISSET(ndbhp->ndbh_flags, NDB_FULL)) {
                        if (!ISSET(bp->nb_flags, NB_CACHE)) { /* initialize the buffer */
                                ndbhp->ndbh_flags = 0;
                                ndbhp->ndbh_count = 0;
                                ndbhp->ndbh_entry_end = sizeof(*ndbhp);
                                ndbhp->ndbh_ncgen = dnp->n_ncgen;
                        }
                        error = nfs_buf_readdir(bp, ctx);
                        if (error == NFSERR_DIRBUFDROPPED) {
                                goto getbuffer;
                        }
                        if (error) {
                                nfs_buf_release(bp, 1);
                        }
                        if (error && (error != ENXIO) && (error != ETIMEDOUT) && (error != EINTR) && (error != ERESTART)) {
                                if (!nfs_node_lock(dnp)) {
                                        nfs_invaldir(dnp);
                                        nfs_node_unlock(dnp);
                                }
                                nfs_vinvalbuf(dvp, 0, ctx, 1);
                                if (error == NFSERR_BAD_COOKIE) {
                                        error = ENOENT;
                                }
                        }
                        if (error) {
                                goto out;
                        }
                }

                /* find next entry to return */
                dp = NFS_DIR_BUF_FIRST_DIRENTRY(bp);
                i = 0;
                if ((lbn != cookie) && !(ptc && NFS_DIR_COOKIE_SAME32(lbn, cookie))) {
                        dpptc = NULL;
                        iptc = 0;
                        for (; (i < ndbhp->ndbh_count) && (cookie != dp->d_seekoff); i++) {
                                if (ptc && !dpptc && NFS_DIR_COOKIE_SAME32(cookie, dp->d_seekoff)) {
                                        iptc = i;
                                        dpptc = dp;
                                }
                                nextcookie = dp->d_seekoff;
                                dp = NFS_DIRENTRY_NEXT(dp);
                        }
                        if ((i == ndbhp->ndbh_count) && dpptc) {
                                i = iptc;
                                dp = dpptc;
                        }
                        if (i < ndbhp->ndbh_count) {
                                nextcookie = dp->d_seekoff;
                                dp = NFS_DIRENTRY_NEXT(dp);
                                i++;
                        }
                }
                ptc = 0;  /* only have to deal with ptc on first cookie */

                /* return as many entries as we can */
                for (; i < ndbhp->ndbh_count; i++) {
                        if (extended) {
                                rlen = dp->d_reclen;
                                cp = (char*)dp;
                        } else {
                                if (!cp) {
                                        cp = (char*)&dent;
                                        bzero(cp, sizeof(dent));
                                }
                                if (dp->d_namlen > (sizeof(dent.d_name) - 1)) {
                                        nlen = sizeof(dent.d_name) - 1;
                                } else {
                                        nlen = dp->d_namlen;
                                }
                                rlen = NFS_DIRENT_LEN(nlen);
                                dent.d_reclen = rlen;
                                dent.d_ino = dp->d_ino;
                                dent.d_type = dp->d_type;
                                dent.d_namlen = nlen;
                                strlcpy(dent.d_name, dp->d_name, nlen + 1);
                        }
                        /* check that the record fits */
                        if (rlen > uio_resid(uio)) {
                                done = 1;
                                break;
                        }
                        if ((error = uiomove(cp, rlen, uio))) {
                                break;
                        }
                        numdirent++;
                        nextcookie = dp->d_seekoff;
                        dp = NFS_DIRENTRY_NEXT(dp);
                }

                if (i == ndbhp->ndbh_count) {
                        /* hit end of buffer, move to next buffer */
                        lbn = nextcookie;
                        /* if we also hit EOF, we're done */
                        if (ISSET(ndbhp->ndbh_flags, NDB_EOF)) {
                                done = 1;
                                if (ap->a_eofflag) {
                                        *ap->a_eofflag = 1;
                                }
                        }
                }
                if (!error) {
                        uio_setoffset(uio, nextcookie);
                }
                if (!error && !done && (nextcookie == cookie)) {
                        printf("nfs readdir cookie didn't change 0x%llx, %d/%d\n", cookie, i, ndbhp->ndbh_count);
                        error = EIO;
                }
                nfs_buf_release(bp, 1);
        }

        if (!error) {
                nfs_dir_cookie_cache(dnp, nextcookie, lbn);
        }

        if (ap->a_numdirent) {
                *ap->a_numdirent = numdirent;
        }
out:
        return error;
}


/*
 * Invalidate cached directory information, except for the actual directory
 * blocks (which are invalidated separately).
 */
void
nfs_invaldir(nfsnode_t dnp)
{
        if (vnode_vtype(NFSTOV(dnp)) != VDIR) {
                return;
        }
        dnp->n_eofcookie = 0;
        dnp->n_cookieverf = 0;
        if (!dnp->n_cookiecache) {
                return;
        }
        dnp->n_cookiecache->free = 0;
        dnp->n_cookiecache->mru = -1;
        memset(dnp->n_cookiecache->next, -1, NFSNUMCOOKIES);
}

/*
 * calculate how much space is available for additional directory entries.
 */
uint32_t
nfs_dir_buf_freespace(struct nfsbuf *bp, int rdirplus)
{
        struct nfs_dir_buf_header *ndbhp = (struct nfs_dir_buf_header*)bp->nb_data;
        uint32_t space;

        if (!ndbhp) {
                return 0;
        }
        space = bp->nb_bufsize - ndbhp->ndbh_entry_end;
        if (rdirplus) {
                space -= ndbhp->ndbh_count * sizeof(struct nfs_vattr);
        }
        return space;
}

/*
 * add/update a cookie->lbn entry in the directory cookie cache
 */
void
nfs_dir_cookie_cache(nfsnode_t dnp, uint64_t cookie, uint64_t lbn)
{
        struct nfsdmap *ndcc;
        int8_t i, prev;

        if (!cookie) {
                return;
        }

        if (nfs_node_lock(dnp)) {
                return;
        }

        if (cookie == dnp->n_eofcookie) { /* EOF cookie */
                nfs_node_unlock(dnp);
                return;
        }

        ndcc = dnp->n_cookiecache;
        if (!ndcc) {
                /* allocate the cookie cache structure */
                MALLOC_ZONE(dnp->n_cookiecache, struct nfsdmap *,
                    sizeof(struct nfsdmap), M_NFSDIROFF, M_WAITOK);
                if (!dnp->n_cookiecache) {
                        nfs_node_unlock(dnp);
                        return;
                }
                ndcc = dnp->n_cookiecache;
                ndcc->free = 0;
                ndcc->mru = -1;
                memset(ndcc->next, -1, NFSNUMCOOKIES);
        }

        /*
         * Search the list for this cookie.
         * Keep track of previous and last entries.
         */
        prev = -1;
        i = ndcc->mru;
        while ((i != -1) && (cookie != ndcc->cookies[i].key)) {
                if (ndcc->next[i] == -1) { /* stop on last entry so we can reuse */
                        break;
                }
                prev = i;
                i = ndcc->next[i];
        }
        if ((i != -1) && (cookie == ndcc->cookies[i].key)) {
                /* found it, remove from list */
                if (prev != -1) {
                        ndcc->next[prev] = ndcc->next[i];
                } else {
                        ndcc->mru = ndcc->next[i];
                }
        } else {
                /* not found, use next free entry or reuse last entry */
                if (ndcc->free != NFSNUMCOOKIES) {
                        i = ndcc->free++;
                } else {
                        ndcc->next[prev] = -1;
                }
                ndcc->cookies[i].key = cookie;
                ndcc->cookies[i].lbn = lbn;
        }
        /* insert cookie at head of MRU list */
        ndcc->next[i] = ndcc->mru;
        ndcc->mru = i;
        nfs_node_unlock(dnp);
}

/*
 * Try to map the given directory cookie to a directory buffer (return lbn).
 * If we have a possibly truncated cookie (ptc), check for 32-bit matches too.
 */
int
nfs_dir_cookie_to_lbn(nfsnode_t dnp, uint64_t cookie, int *ptc, uint64_t *lbnp)
{
        struct nfsdmap *ndcc = dnp->n_cookiecache;
        int8_t eofptc, found;
        int i, iptc;
        struct nfsmount *nmp;
        struct nfsbuf *bp, *lastbp;
        struct nfsbuflists blist;
        struct direntry *dp, *dpptc;
        struct nfs_dir_buf_header *ndbhp;

        if (!cookie) {  /* initial cookie */
                *lbnp = 0;
                *ptc = 0;
                return 0;
        }

        if (nfs_node_lock(dnp)) {
                return ENOENT;
        }

        if (cookie == dnp->n_eofcookie) { /* EOF cookie */
                nfs_node_unlock(dnp);
                OSAddAtomic64(1, &nfsstats.direofcache_hits);
                *ptc = 0;
                return -1;
        }
        /* note if cookie is a 32-bit match with the EOF cookie */
        eofptc = *ptc ? NFS_DIR_COOKIE_SAME32(cookie, dnp->n_eofcookie) : 0;
        iptc = -1;

        /* search the list for the cookie */
        for (i = ndcc ? ndcc->mru : -1; i >= 0; i = ndcc->next[i]) {
                if (ndcc->cookies[i].key == cookie) {
                        /* found a match for this cookie */
                        *lbnp = ndcc->cookies[i].lbn;
                        nfs_node_unlock(dnp);
                        OSAddAtomic64(1, &nfsstats.direofcache_hits);
                        *ptc = 0;
                        return 0;
                }
                /* check for 32-bit match */
                if (*ptc && (iptc == -1) && NFS_DIR_COOKIE_SAME32(ndcc->cookies[i].key, cookie)) {
                        iptc = i;
                }
        }
        /* exact match not found */
        if (eofptc) {
                /* but 32-bit match hit the EOF cookie */
                nfs_node_unlock(dnp);
                OSAddAtomic64(1, &nfsstats.direofcache_hits);
                return -1;
        }
        if (iptc >= 0) {
                /* but 32-bit match got a hit */
                *lbnp = ndcc->cookies[iptc].lbn;
                nfs_node_unlock(dnp);
                OSAddAtomic64(1, &nfsstats.direofcache_hits);
                return 0;
        }
        nfs_node_unlock(dnp);

        /*
         * No match found in the cookie cache... hmm...
         * Let's search the directory's buffers for the cookie.
         */
        nmp = NFSTONMP(dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        dpptc = NULL;
        found = 0;

        lck_mtx_lock(nfs_buf_mutex);
        /*
         * Scan the list of buffers, keeping them in order.
         * Note that itercomplete inserts each of the remaining buffers
         * into the head of list (thus reversing the elements).  So, we
         * make sure to iterate through all buffers, inserting them after
         * each other, to keep them in order.
         * Also note: the LIST_INSERT_AFTER(lastbp) is only safe because
         * we don't drop nfs_buf_mutex.
         */
        if (!nfs_buf_iterprepare(dnp, &blist, NBI_CLEAN)) {
                lastbp = NULL;
                while ((bp = LIST_FIRST(&blist))) {
                        LIST_REMOVE(bp, nb_vnbufs);
                        if (!lastbp) {
                                LIST_INSERT_HEAD(&dnp->n_cleanblkhd, bp, nb_vnbufs);
                        } else {
                                LIST_INSERT_AFTER(lastbp, bp, nb_vnbufs);
                        }
                        lastbp = bp;
                        if (found) {
                                continue;
                        }
                        nfs_buf_refget(bp);
                        if (nfs_buf_acquire(bp, NBAC_NOWAIT, 0, 0)) {
                                /* just skip this buffer */
                                nfs_buf_refrele(bp);
                                continue;
                        }
                        nfs_buf_refrele(bp);

                        /* scan the buffer for the cookie */
                        ndbhp = (struct nfs_dir_buf_header*)bp->nb_data;
                        dp = NFS_DIR_BUF_FIRST_DIRENTRY(bp);
                        dpptc = NULL;
                        for (i = 0; (i < ndbhp->ndbh_count) && (cookie != dp->d_seekoff); i++) {
                                if (*ptc && !dpptc && NFS_DIR_COOKIE_SAME32(cookie, dp->d_seekoff)) {
                                        dpptc = dp;
                                        iptc = i;
                                }
                                dp = NFS_DIRENTRY_NEXT(dp);
                        }
                        if ((i == ndbhp->ndbh_count) && dpptc) {
                                /* found only a PTC match */
                                dp = dpptc;
                                i = iptc;
                        } else if (i < ndbhp->ndbh_count) {
                                *ptc = 0;
                        }
                        if (i < (ndbhp->ndbh_count - 1)) {
                                /* next entry is *in* this buffer: return this block */
                                *lbnp = bp->nb_lblkno;
                                found = 1;
                        } else if (i == (ndbhp->ndbh_count - 1)) {
                                /* next entry refers to *next* buffer: return next block */
                                *lbnp = dp->d_seekoff;
                                found = 1;
                        }
                        nfs_buf_drop(bp);
                }
                nfs_buf_itercomplete(dnp, &blist, NBI_CLEAN);
        }
        lck_mtx_unlock(nfs_buf_mutex);
        if (found) {
                OSAddAtomic64(1, &nfsstats.direofcache_hits);
                return 0;
        }

        /* still not found... oh well, just start a new block */
        *lbnp = cookie;
        OSAddAtomic64(1, &nfsstats.direofcache_misses);
        return 0;
}

/*
 * scan a directory buffer for the given name
 * Returns: ESRCH if not found, ENOENT if found invalid, 0 if found
 * Note: should only be called with RDIRPLUS directory buffers
 */

#define NDBS_PURGE      1
#define NDBS_UPDATE     2

int
nfs_dir_buf_search(
        struct nfsbuf *bp,
        struct componentname *cnp,
        fhandle_t *fhp,
        struct nfs_vattr *nvap,
        uint64_t *xidp,
        time_t *attrstampp,
        daddr64_t *nextlbnp,
        int flags)
{
        struct direntry *dp;
        struct nfs_dir_buf_header *ndbhp;
        struct nfs_vattr *nvattrp;
        daddr64_t nextlbn = 0;
        int i, error = ESRCH;
        uint32_t fhlen;

        /* scan the buffer for the name */
        ndbhp = (struct nfs_dir_buf_header*)bp->nb_data;
        dp = NFS_DIR_BUF_FIRST_DIRENTRY(bp);
        for (i = 0; i < ndbhp->ndbh_count; i++) {
                nextlbn = dp->d_seekoff;
                if ((cnp->cn_namelen == dp->d_namlen) && !strcmp(cnp->cn_nameptr, dp->d_name)) {
                        fhlen = dp->d_name[dp->d_namlen + 1];
                        nvattrp = NFS_DIR_BUF_NVATTR(bp, i);
                        if ((ndbhp->ndbh_ncgen != bp->nb_np->n_ncgen) || (fhlen == 0) ||
                            (nvattrp->nva_type == VNON) || (nvattrp->nva_fileid == 0)) {
                                /* entry is not valid */
                                error = ENOENT;
                                break;
                        }
                        if (flags == NDBS_PURGE) {
                                dp->d_fileno = 0;
                                bzero(nvattrp, sizeof(*nvattrp));
                                error = ENOENT;
                                break;
                        }
                        if (flags == NDBS_UPDATE) {
                                /* update direntry's attrs if fh matches */
                                if ((fhp->fh_len == fhlen) && !bcmp(&dp->d_name[dp->d_namlen + 2], fhp->fh_data, fhlen)) {
                                        bcopy(nvap, nvattrp, sizeof(*nvap));
                                        dp->d_fileno = nvattrp->nva_fileid;
                                        nvattrp->nva_fileid = *xidp;
                                        *(time_t*)(&dp->d_name[dp->d_namlen + 2 + fhp->fh_len]) = *attrstampp;
                                }
                                error = 0;
                                break;
                        }
                        /* copy out fh, attrs, attrstamp, and xid */
                        fhp->fh_len = fhlen;
                        bcopy(&dp->d_name[dp->d_namlen + 2], fhp->fh_data, MAX(fhp->fh_len, (int)sizeof(fhp->fh_data)));
                        *attrstampp = *(time_t*)(&dp->d_name[dp->d_namlen + 2 + fhp->fh_len]);
                        bcopy(nvattrp, nvap, sizeof(*nvap));
                        *xidp = nvap->nva_fileid;
                        nvap->nva_fileid = dp->d_fileno;
                        error = 0;
                        break;
                }
                dp = NFS_DIRENTRY_NEXT(dp);
        }
        if (nextlbnp) {
                *nextlbnp = nextlbn;
        }
        return error;
}

/*
 * Look up a name in a directory's buffers.
 * Note: should only be called with RDIRPLUS directory buffers
 */
int
nfs_dir_buf_cache_lookup(nfsnode_t dnp, nfsnode_t *npp, struct componentname *cnp, vfs_context_t ctx, int purge)
{
        nfsnode_t newnp;
        struct nfsmount *nmp;
        int error = 0, i, found = 0, count = 0;
        u_int64_t xid;
        struct nfs_vattr nvattr;
        fhandle_t fh;
        time_t attrstamp = 0;
        thread_t thd = vfs_context_thread(ctx);
        struct nfsbuf *bp, *lastbp, *foundbp;
        struct nfsbuflists blist;
        daddr64_t lbn, nextlbn;
        int dotunder = (cnp->cn_namelen > 2) && (cnp->cn_nameptr[0] == '.') && (cnp->cn_nameptr[1] == '_');
        int isdot = (cnp->cn_namelen == 1) && (cnp->cn_nameptr[0] == '.');
        int isdotdot = (cnp->cn_namelen == 2) && (cnp->cn_nameptr[0] == '.') && (cnp->cn_nameptr[1] == '.');

        nmp = NFSTONMP(dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        if (!purge) {
                *npp = NULL;
        }

        if (isdot || isdotdot) {
                return 0;
        }

        /* first check most recent buffer (and next one too) */
        lbn = dnp->n_lastdbl;
        for (i = 0; i < 2; i++) {
                if ((error = nfs_buf_get(dnp, lbn, NFS_DIRBLKSIZ, thd, NBLK_READ | NBLK_ONLYVALID, &bp))) {
                        return error;
                }
                if (!bp) {
                        break;
                }
                count++;
                error = nfs_dir_buf_search(bp, cnp, &fh, &nvattr, &xid, &attrstamp, &nextlbn, purge ? NDBS_PURGE : 0);
                nfs_buf_release(bp, 0);
                if (error == ESRCH) {
                        error = 0;
                } else {
                        found = 1;
                        break;
                }
                lbn = nextlbn;
        }

        lck_mtx_lock(nfs_buf_mutex);
        if (found) {
                dnp->n_lastdbl = lbn;
                goto done;
        }

        /*
         * Scan the list of buffers, keeping them in order.
         * Note that itercomplete inserts each of the remaining buffers
         * into the head of list (thus reversing the elements).  So, we
         * make sure to iterate through all buffers, inserting them after
         * each other, to keep them in order.
         * Also note: the LIST_INSERT_AFTER(lastbp) is only safe because
         * we don't drop nfs_buf_mutex.
         */
        if (!nfs_buf_iterprepare(dnp, &blist, NBI_CLEAN)) {
                lastbp = foundbp = NULL;
                while ((bp = LIST_FIRST(&blist))) {
                        LIST_REMOVE(bp, nb_vnbufs);
                        if (!lastbp) {
                                LIST_INSERT_HEAD(&dnp->n_cleanblkhd, bp, nb_vnbufs);
                        } else {
                                LIST_INSERT_AFTER(lastbp, bp, nb_vnbufs);
                        }
                        lastbp = bp;
                        if (error || found) {
                                continue;
                        }
                        if (!purge && dotunder && (count > 100)) { /* don't waste too much time looking for ._ files */
                                continue;
                        }
                        nfs_buf_refget(bp);
                        lbn = bp->nb_lblkno;
                        if (nfs_buf_acquire(bp, NBAC_NOWAIT, 0, 0)) {
                                /* just skip this buffer */
                                nfs_buf_refrele(bp);
                                continue;
                        }
                        nfs_buf_refrele(bp);
                        count++;
                        error = nfs_dir_buf_search(bp, cnp, &fh, &nvattr, &xid, &attrstamp, NULL, purge ? NDBS_PURGE : 0);
                        if (error == ESRCH) {
                                error = 0;
                        } else {
                                found = 1;
                                foundbp = bp;
                        }
                        nfs_buf_drop(bp);
                }
                if (found) {
                        LIST_REMOVE(foundbp, nb_vnbufs);
                        LIST_INSERT_HEAD(&dnp->n_cleanblkhd, foundbp, nb_vnbufs);
                        dnp->n_lastdbl = foundbp->nb_lblkno;
                }
                nfs_buf_itercomplete(dnp, &blist, NBI_CLEAN);
        }
done:
        lck_mtx_unlock(nfs_buf_mutex);

        if (!error && found && !purge) {
                error = nfs_nget(NFSTOMP(dnp), dnp, cnp, fh.fh_data, fh.fh_len,
                    &nvattr, &xid, dnp->n_auth, NG_MAKEENTRY, &newnp);
                if (error) {
                        return error;
                }
                newnp->n_attrstamp = attrstamp;
                *npp = newnp;
                nfs_node_unlock(newnp);
                /* check if the dir buffer's attrs are out of date */
                if (!nfs_getattr(newnp, &nvattr, ctx, NGA_CACHED) &&
                    (newnp->n_attrstamp != attrstamp)) {
                        /* they are, so update them */
                        error = nfs_buf_get(dnp, lbn, NFS_DIRBLKSIZ, thd, NBLK_READ | NBLK_ONLYVALID, &bp);
                        if (!error && bp) {
                                attrstamp = newnp->n_attrstamp;
                                xid = newnp->n_xid;
                                nfs_dir_buf_search(bp, cnp, &fh, &nvattr, &xid, &attrstamp, NULL, NDBS_UPDATE);
                                nfs_buf_release(bp, 0);
                        }
                        error = 0;
                }
        }

        return error;
}

/*
 * Purge name cache entries for the given node.
 * For RDIRPLUS, also invalidate the entry in the directory's buffers.
 */
void
nfs_name_cache_purge(nfsnode_t dnp, nfsnode_t np, struct componentname *cnp, vfs_context_t ctx)
{
        struct nfsmount *nmp = NFSTONMP(dnp);

        cache_purge(NFSTOV(np));
        if (nmp && (nmp->nm_vers > NFS_VER2) && NMFLAG(nmp, RDIRPLUS)) {
                nfs_dir_buf_cache_lookup(dnp, NULL, cnp, ctx, 1);
        }
}

/*
 * NFS V3 readdir (plus) RPC.
 */
int
nfs3_readdir_rpc(nfsnode_t dnp, struct nfsbuf *bp, vfs_context_t ctx)
{
        struct nfsmount *nmp;
        int error = 0, lockerror, nfsvers, rdirplus, bigcookies;
        int i, status, attrflag, fhflag, more_entries = 1, eof, bp_dropped = 0;
        uint32_t nmreaddirsize, nmrsize;
        uint32_t namlen, skiplen, fhlen, xlen, attrlen, reclen, space_free, space_needed;
        uint64_t cookie, lastcookie, xid, savedxid, fileno;
        struct nfsm_chain nmreq, nmrep, nmrepsave;
        fhandle_t fh;
        struct nfs_vattr *nvattrp;
        struct nfs_dir_buf_header *ndbhp;
        struct direntry *dp;
        char *padstart, padlen;
        struct timeval now;

        nmp = NFSTONMP(dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;
        nmreaddirsize = nmp->nm_readdirsize;
        nmrsize = nmp->nm_rsize;
        bigcookies = nmp->nm_state & NFSSTA_BIGCOOKIES;
noplus:
        rdirplus = ((nfsvers > NFS_VER2) && NMFLAG(nmp, RDIRPLUS)) ? 1 : 0;

        if ((lockerror = nfs_node_lock(dnp))) {
                return lockerror;
        }

        /* determine cookie to use, and move dp to the right offset */
        ndbhp = (struct nfs_dir_buf_header*)bp->nb_data;
        dp = NFS_DIR_BUF_FIRST_DIRENTRY(bp);
        if (ndbhp->ndbh_count) {
                for (i = 0; i < ndbhp->ndbh_count - 1; i++) {
                        dp = NFS_DIRENTRY_NEXT(dp);
                }
                cookie = dp->d_seekoff;
                dp = NFS_DIRENTRY_NEXT(dp);
        } else {
                cookie = bp->nb_lblkno;
                /* increment with every buffer read */
                OSAddAtomic64(1, &nfsstats.readdir_bios);
        }
        lastcookie = cookie;

        /*
         * Loop around doing readdir(plus) RPCs of size nm_readdirsize until
         * the buffer is full (or we hit EOF).  Then put the remainder of the
         * results in the next buffer(s).
         */
        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);
        while (nfs_dir_buf_freespace(bp, rdirplus) && !(ndbhp->ndbh_flags & NDB_FULL)) {
                nfsm_chain_build_alloc_init(error, &nmreq,
                    NFSX_FH(nfsvers) + NFSX_READDIR(nfsvers) + NFSX_UNSIGNED);
                nfsm_chain_add_fh(error, &nmreq, nfsvers, dnp->n_fhp, dnp->n_fhsize);
                if (nfsvers == NFS_VER3) {
                        /* opaque values don't need swapping, but as long */
                        /* as we are consistent about it, it should be ok */
                        nfsm_chain_add_64(error, &nmreq, cookie);
                        nfsm_chain_add_64(error, &nmreq, dnp->n_cookieverf);
                } else {
                        nfsm_chain_add_32(error, &nmreq, cookie);
                }
                nfsm_chain_add_32(error, &nmreq, nmreaddirsize);
                if (rdirplus) {
                        nfsm_chain_add_32(error, &nmreq, nmrsize);
                }
                nfsm_chain_build_done(error, &nmreq);
                nfs_node_unlock(dnp);
                lockerror = ENOENT;
                nfsmout_if(error);

                error = nfs_request(dnp, NULL, &nmreq,
                    rdirplus ? NFSPROC_READDIRPLUS : NFSPROC_READDIR,
                    ctx, NULL, &nmrep, &xid, &status);

                if ((lockerror = nfs_node_lock(dnp))) {
                        error = lockerror;
                }

                savedxid = xid;
                if (nfsvers == NFS_VER3) {
                        nfsm_chain_postop_attr_update(error, &nmrep, dnp, &xid);
                }
                if (!error) {
                        error = status;
                }
                if (nfsvers == NFS_VER3) {
                        nfsm_chain_get_64(error, &nmrep, dnp->n_cookieverf);
                }
                nfsm_chain_get_32(error, &nmrep, more_entries);

                if (!lockerror) {
                        nfs_node_unlock(dnp);
                        lockerror = ENOENT;
                }
                if (error == NFSERR_NOTSUPP) {
                        /* oops... it doesn't look like readdirplus is supported */
                        lck_mtx_lock(&nmp->nm_lock);
                        NFS_BITMAP_CLR(nmp->nm_flags, NFS_MFLAG_RDIRPLUS);
                        lck_mtx_unlock(&nmp->nm_lock);
                        goto noplus;
                }
                nfsmout_if(error);

                if (rdirplus) {
                        microuptime(&now);
                        if (lastcookie == 0) {
                                dnp->n_rdirplusstamp_sof = now.tv_sec;
                                dnp->n_rdirplusstamp_eof = 0;
                        }
                }

                /* loop through the entries packing them into the buffer */
                while (more_entries) {
                        if (nfsvers == NFS_VER3) {
                                nfsm_chain_get_64(error, &nmrep, fileno);
                        } else {
                                nfsm_chain_get_32(error, &nmrep, fileno);
                        }
                        nfsm_chain_get_32(error, &nmrep, namlen);
                        nfsmout_if(error);
                        /* just truncate names that don't fit in direntry.d_name */
                        if (namlen <= 0) {
                                error = EBADRPC;
                                goto nfsmout;
                        }
                        if (namlen > (sizeof(dp->d_name) - 1)) {
                                skiplen = namlen - sizeof(dp->d_name) + 1;
                                namlen = sizeof(dp->d_name) - 1;
                        } else {
                                skiplen = 0;
                        }
                        /* guess that fh size will be same as parent */
                        fhlen = rdirplus ? (1 + dnp->n_fhsize) : 0;
                        xlen = rdirplus ? (fhlen + sizeof(time_t)) : 0;
                        attrlen = rdirplus ? sizeof(struct nfs_vattr) : 0;
                        reclen = NFS_DIRENTRY_LEN(namlen + xlen);
                        space_needed = reclen + attrlen;
                        space_free = nfs_dir_buf_freespace(bp, rdirplus);
                        if (space_needed > space_free) {
                                /*
                                 * We still have entries to pack, but we've
                                 * run out of room in the current buffer.
                                 * So we need to move to the next buffer.
                                 * The block# for the next buffer is the
                                 * last cookie in the current buffer.
                                 */
nextbuffer:
                                ndbhp->ndbh_flags |= NDB_FULL;
                                nfs_buf_release(bp, 0);
                                bp_dropped = 1;
                                bp = NULL;
                                error = nfs_buf_get(dnp, lastcookie, NFS_DIRBLKSIZ, vfs_context_thread(ctx), NBLK_READ, &bp);
                                nfsmout_if(error);
                                /* initialize buffer */
                                ndbhp = (struct nfs_dir_buf_header*)bp->nb_data;
                                ndbhp->ndbh_flags = 0;
                                ndbhp->ndbh_count = 0;
                                ndbhp->ndbh_entry_end = sizeof(*ndbhp);
                                ndbhp->ndbh_ncgen = dnp->n_ncgen;
                                space_free = nfs_dir_buf_freespace(bp, rdirplus);
                                dp = NFS_DIR_BUF_FIRST_DIRENTRY(bp);
                                /* increment with every buffer read */
                                OSAddAtomic64(1, &nfsstats.readdir_bios);
                        }
                        nmrepsave = nmrep;
                        dp->d_fileno = fileno;
                        dp->d_namlen = namlen;
                        dp->d_reclen = reclen;
                        dp->d_type = DT_UNKNOWN;
                        nfsm_chain_get_opaque(error, &nmrep, namlen, dp->d_name);
                        nfsmout_if(error);
                        dp->d_name[namlen] = '\0';
                        if (skiplen) {
                                nfsm_chain_adv(error, &nmrep,
                                    nfsm_rndup(namlen + skiplen) - nfsm_rndup(namlen));
                        }
                        if (nfsvers == NFS_VER3) {
                                nfsm_chain_get_64(error, &nmrep, cookie);
                        } else {
                                nfsm_chain_get_32(error, &nmrep, cookie);
                        }
                        nfsmout_if(error);
                        dp->d_seekoff = cookie;
                        if (!bigcookies && (cookie >> 32) && (nmp == NFSTONMP(dnp))) {
                                /* we've got a big cookie, make sure flag is set */
                                lck_mtx_lock(&nmp->nm_lock);
                                nmp->nm_state |= NFSSTA_BIGCOOKIES;
                                lck_mtx_unlock(&nmp->nm_lock);
                                bigcookies = 1;
                        }
                        if (rdirplus) {
                                nvattrp = NFS_DIR_BUF_NVATTR(bp, ndbhp->ndbh_count);
                                /* check for attributes */
                                nfsm_chain_get_32(error, &nmrep, attrflag);
                                nfsmout_if(error);
                                if (attrflag) {
                                        /* grab attributes */
                                        error = nfs_parsefattr(nmp, &nmrep, NFS_VER3, nvattrp);
                                        nfsmout_if(error);
                                        dp->d_type = IFTODT(VTTOIF(nvattrp->nva_type));
                                        /* fileid is already in d_fileno, so stash xid in attrs */
                                        nvattrp->nva_fileid = savedxid;
                                } else {
                                        /* mark the attributes invalid */
                                        bzero(nvattrp, sizeof(struct nfs_vattr));
                                }
                                /* check for file handle */
                                nfsm_chain_get_32(error, &nmrep, fhflag);
                                nfsmout_if(error);
                                if (fhflag) {
                                        nfsm_chain_get_fh(error, &nmrep, NFS_VER3, &fh);
                                        nfsmout_if(error);
                                        fhlen = fh.fh_len + 1;
                                        xlen = fhlen + sizeof(time_t);
                                        reclen = NFS_DIRENTRY_LEN(namlen + xlen);
                                        space_needed = reclen + attrlen;
                                        if (space_needed > space_free) {
                                                /* didn't actually have the room... move on to next buffer */
                                                nmrep = nmrepsave;
                                                goto nextbuffer;
                                        }
                                        /* pack the file handle into the record */
                                        dp->d_name[dp->d_namlen + 1] = fh.fh_len;
                                        bcopy(fh.fh_data, &dp->d_name[dp->d_namlen + 2], fh.fh_len);
                                } else {
                                        /* mark the file handle invalid */
                                        fh.fh_len = 0;
                                        fhlen = fh.fh_len + 1;
                                        xlen = fhlen + sizeof(time_t);
                                        reclen = NFS_DIRENTRY_LEN(namlen + xlen);
                                        bzero(&dp->d_name[dp->d_namlen + 1], fhlen);
                                }
                                *(time_t*)(&dp->d_name[dp->d_namlen + 1 + fhlen]) = now.tv_sec;
                                dp->d_reclen = reclen;
                                nfs_rdirplus_update_node_attrs(dnp, dp, &fh, nvattrp, &savedxid);
                        }
                        padstart = dp->d_name + dp->d_namlen + 1 + xlen;
                        ndbhp->ndbh_count++;
                        lastcookie = cookie;
                        /* advance to next direntry in buffer */
                        dp = NFS_DIRENTRY_NEXT(dp);
                        ndbhp->ndbh_entry_end = (char*)dp - bp->nb_data;
                        /* zero out the pad bytes */
                        padlen = (char*)dp - padstart;
                        if (padlen > 0) {
                                bzero(padstart, padlen);
                        }
                        /* check for more entries */
                        nfsm_chain_get_32(error, &nmrep, more_entries);
                        nfsmout_if(error);
                }
                /* Finally, get the eof boolean */
                nfsm_chain_get_32(error, &nmrep, eof);
                nfsmout_if(error);
                if (eof) {
                        ndbhp->ndbh_flags |= (NDB_FULL | NDB_EOF);
                        nfs_node_lock_force(dnp);
                        dnp->n_eofcookie = lastcookie;
                        if (rdirplus) {
                                dnp->n_rdirplusstamp_eof = now.tv_sec;
                        }
                        nfs_node_unlock(dnp);
                } else {
                        more_entries = 1;
                }
                if (bp_dropped) {
                        nfs_buf_release(bp, 0);
                        bp = NULL;
                        break;
                }
                if ((lockerror = nfs_node_lock(dnp))) {
                        error = lockerror;
                }
                nfsmout_if(error);
                nfsm_chain_cleanup(&nmrep);
                nfsm_chain_null(&nmreq);
        }
nfsmout:
        if (bp_dropped && bp) {
                nfs_buf_release(bp, 0);
        }
        if (!lockerror) {
                nfs_node_unlock(dnp);
        }
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        return bp_dropped ? NFSERR_DIRBUFDROPPED : error;
}

/*
 * Silly rename. To make the NFS filesystem that is stateless look a little
 * more like the "ufs" a remove of an active vnode is translated to a rename
 * to a funny looking filename that is removed by nfs_vnop_inactive on the
 * nfsnode. There is the potential for another process on a different client
 * to create the same funny name between when the lookitup() fails and the
 * rename() completes, but...
 */

/* format of "random" silly names - includes a number and pid */
/* (note: shouldn't exceed size of nfs_sillyrename.nsr_name) */
#define NFS_SILLYNAME_FORMAT ".nfs.%08x.%04x"
/* starting from zero isn't silly enough */
static uint32_t nfs_sillyrename_number = 0x20051025;

int
nfs_sillyrename(
        nfsnode_t dnp,
        nfsnode_t np,
        struct componentname *cnp,
        vfs_context_t ctx)
{
        struct nfs_sillyrename *nsp;
        int error;
        short pid;
        kauth_cred_t cred;
        uint32_t num;
        struct nfsmount *nmp;

        nmp = NFSTONMP(dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }

        nfs_name_cache_purge(dnp, np, cnp, ctx);

        MALLOC_ZONE(nsp, struct nfs_sillyrename *,
            sizeof(struct nfs_sillyrename), M_NFSREQ, M_WAITOK);
        if (!nsp) {
                return ENOMEM;
        }
        cred = vfs_context_ucred(ctx);
        kauth_cred_ref(cred);
        nsp->nsr_cred = cred;
        nsp->nsr_dnp = dnp;
        error = vnode_ref(NFSTOV(dnp));
        if (error) {
                goto bad_norele;
        }

        /* Fudge together a funny name */
        pid = vfs_context_pid(ctx);
        num = OSAddAtomic(1, &nfs_sillyrename_number);
        nsp->nsr_namlen = snprintf(nsp->nsr_name, sizeof(nsp->nsr_name),
            NFS_SILLYNAME_FORMAT, num, (pid & 0xffff));
        if (nsp->nsr_namlen >= (int)sizeof(nsp->nsr_name)) {
                nsp->nsr_namlen = sizeof(nsp->nsr_name) - 1;
        }

        /* Try lookitups until we get one that isn't there */
        while (nfs_lookitup(dnp, nsp->nsr_name, nsp->nsr_namlen, ctx, NULL) == 0) {
                num = OSAddAtomic(1, &nfs_sillyrename_number);
                nsp->nsr_namlen = snprintf(nsp->nsr_name, sizeof(nsp->nsr_name),
                    NFS_SILLYNAME_FORMAT, num, (pid & 0xffff));
                if (nsp->nsr_namlen >= (int)sizeof(nsp->nsr_name)) {
                        nsp->nsr_namlen = sizeof(nsp->nsr_name) - 1;
                }
        }

        /* now, do the rename */
        error = nmp->nm_funcs->nf_rename_rpc(dnp, cnp->cn_nameptr, cnp->cn_namelen,
            dnp, nsp->nsr_name, nsp->nsr_namlen, ctx);

        /* Kludge: Map ENOENT => 0 assuming that it is a reply to a retry. */
        if (error == ENOENT) {
                error = 0;
        }
        if (!error) {
                nfs_node_lock_force(dnp);
                if (dnp->n_flag & NNEGNCENTRIES) {
                        dnp->n_flag &= ~NNEGNCENTRIES;
                        cache_purge_negatives(NFSTOV(dnp));
                }
                nfs_node_unlock(dnp);
        }
        FSDBG(267, dnp, np, num, error);
        if (error) {
                goto bad;
        }
        error = nfs_lookitup(dnp, nsp->nsr_name, nsp->nsr_namlen, ctx, &np);
        nfs_node_lock_force(np);
        np->n_sillyrename = nsp;
        nfs_node_unlock(np);
        return 0;
bad:
        vnode_rele(NFSTOV(dnp));
bad_norele:
        nsp->nsr_cred = NOCRED;
        kauth_cred_unref(&cred);
        FREE_ZONE(nsp, sizeof(*nsp), M_NFSREQ);
        return error;
}

int
nfs3_lookup_rpc_async(
        nfsnode_t dnp,
        char *name,
        int namelen,
        vfs_context_t ctx,
        struct nfsreq **reqp)
{
        struct nfsmount *nmp;
        struct nfsm_chain nmreq;
        int error = 0, nfsvers;

        nmp = NFSTONMP(dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        nfsm_chain_null(&nmreq);

        nfsm_chain_build_alloc_init(error, &nmreq,
            NFSX_FH(nfsvers) + NFSX_UNSIGNED + nfsm_rndup(namelen));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, dnp->n_fhp, dnp->n_fhsize);
        nfsm_chain_add_name(error, &nmreq, name, namelen, nmp);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request_async(dnp, NULL, &nmreq, NFSPROC_LOOKUP,
            vfs_context_thread(ctx), vfs_context_ucred(ctx), NULL, 0, NULL, reqp);
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        return error;
}

int
nfs3_lookup_rpc_async_finish(
        nfsnode_t dnp,
        __unused char *name,
        __unused int namelen,
        vfs_context_t ctx,
        struct nfsreq *req,
        u_int64_t *xidp,
        fhandle_t *fhp,
        struct nfs_vattr *nvap)
{
        int error = 0, lockerror = ENOENT, status, nfsvers, attrflag;
        u_int64_t xid;
        struct nfsmount *nmp;
        struct nfsm_chain nmrep;

        nmp = NFSTONMP(dnp);
        if (nmp == NULL) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        nfsm_chain_null(&nmrep);

        error = nfs_request_async_finish(req, &nmrep, xidp, &status);

        if ((lockerror = nfs_node_lock(dnp))) {
                error = lockerror;
        }
        xid = *xidp;
        if (error || status) {
                if (nfsvers == NFS_VER3) {
                        nfsm_chain_postop_attr_update(error, &nmrep, dnp, &xid);
                }
                if (!error) {
                        error = status;
                }
                goto nfsmout;
        }

        nfsmout_if(error || !fhp || !nvap);

        /* get the file handle */
        nfsm_chain_get_fh(error, &nmrep, nfsvers, fhp);

        /* get the attributes */
        if (nfsvers == NFS_VER3) {
                nfsm_chain_postop_attr_get(nmp, error, &nmrep, attrflag, nvap);
                nfsm_chain_postop_attr_update(error, &nmrep, dnp, &xid);
                if (!error && !attrflag) {
                        error = nfs3_getattr_rpc(NULL, NFSTOMP(dnp), fhp->fh_data, fhp->fh_len, 0, ctx, nvap, xidp);
                }
        } else {
                error = nfs_parsefattr(nmp, &nmrep, nfsvers, nvap);
        }
nfsmout:
        if (!lockerror) {
                nfs_node_unlock(dnp);
        }
        nfsm_chain_cleanup(&nmrep);
        return error;
}

/*
 * Look up a file name and optionally either update the file handle or
 * allocate an nfsnode, depending on the value of npp.
 * npp == NULL  --> just do the lookup
 * *npp == NULL --> allocate a new nfsnode and make sure attributes are
 *                      handled too
 * *npp != NULL --> update the file handle in the vnode
 */
int
nfs_lookitup(
        nfsnode_t dnp,
        char *name,
        int namelen,
        vfs_context_t ctx,
        nfsnode_t *npp)
{
        int error = 0;
        nfsnode_t np, newnp = NULL;
        u_int64_t xid;
        fhandle_t fh;
        struct nfsmount *nmp;
        struct nfs_vattr nvattr;
        struct nfsreq rq, *req = &rq;

        nmp = NFSTONMP(dnp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }

        if (NFS_BITMAP_ISSET(nmp->nm_fsattr.nfsa_bitmap, NFS_FATTR_MAXNAME) &&
            (namelen > (int)nmp->nm_fsattr.nfsa_maxname)) {
                return ENAMETOOLONG;
        }

        NVATTR_INIT(&nvattr);

        /* check for lookup of "." */
        if ((name[0] == '.') && (namelen == 1)) {
                /* skip lookup, we know who we are */
                fh.fh_len = 0;
                newnp = dnp;
                goto nfsmout;
        }

        error = nmp->nm_funcs->nf_lookup_rpc_async(dnp, name, namelen, ctx, &req);
        nfsmout_if(error);
        error = nmp->nm_funcs->nf_lookup_rpc_async_finish(dnp, name, namelen, ctx, req, &xid, &fh, &nvattr);
        nfsmout_if(!npp || error);

        if (*npp) {
                np = *npp;
                if (fh.fh_len != np->n_fhsize) {
                        u_char *oldbuf = (np->n_fhsize > NFS_SMALLFH) ? np->n_fhp : NULL;
                        if (fh.fh_len > NFS_SMALLFH) {
                                MALLOC_ZONE(np->n_fhp, u_char *, fh.fh_len, M_NFSBIGFH, M_WAITOK);
                                if (!np->n_fhp) {
                                        np->n_fhp = oldbuf;
                                        error = ENOMEM;
                                        goto nfsmout;
                                }
                        } else {
                                np->n_fhp = &np->n_fh[0];
                        }
                        if (oldbuf) {
                                FREE_ZONE(oldbuf, np->n_fhsize, M_NFSBIGFH);
                        }
                }
                bcopy(fh.fh_data, np->n_fhp, fh.fh_len);
                np->n_fhsize = fh.fh_len;
                nfs_node_lock_force(np);
                error = nfs_loadattrcache(np, &nvattr, &xid, 0);
                nfs_node_unlock(np);
                nfsmout_if(error);
                newnp = np;
        } else if (NFS_CMPFH(dnp, fh.fh_data, fh.fh_len)) {
                nfs_node_lock_force(dnp);
                if (dnp->n_xid <= xid) {
                        error = nfs_loadattrcache(dnp, &nvattr, &xid, 0);
                }
                nfs_node_unlock(dnp);
                nfsmout_if(error);
                newnp = dnp;
        } else {
                struct componentname cn, *cnp = &cn;
                bzero(cnp, sizeof(*cnp));
                cnp->cn_nameptr = name;
                cnp->cn_namelen = namelen;
                error = nfs_nget(NFSTOMP(dnp), dnp, cnp, fh.fh_data, fh.fh_len,
                    &nvattr, &xid, rq.r_auth, NG_MAKEENTRY, &np);
                nfsmout_if(error);
                newnp = np;
        }

nfsmout:
        if (npp && !*npp && !error) {
                *npp = newnp;
        }
        NVATTR_CLEANUP(&nvattr);
        return error;
}

/*
 * set up and initialize a "._" file lookup structure used for
 * performing async lookups.
 */
void
nfs_dulookup_init(struct nfs_dulookup *dulp, nfsnode_t dnp, const char *name, int namelen, vfs_context_t ctx)
{
        int error, du_namelen;
        vnode_t du_vp;
        struct nfsmount *nmp = NFSTONMP(dnp);

        /* check for ._ file in name cache */
        dulp->du_flags = 0;
        bzero(&dulp->du_cn, sizeof(dulp->du_cn));
        du_namelen = namelen + 2;
        if (!nmp || NMFLAG(nmp, NONEGNAMECACHE)) {
                return;
        }
        if ((namelen >= 2) && (name[0] == '.') && (name[1] == '_')) {
                return;
        }
        if (du_namelen >= (int)sizeof(dulp->du_smallname)) {
                MALLOC(dulp->du_cn.cn_nameptr, char *, du_namelen + 1, M_TEMP, M_WAITOK);
        } else {
                dulp->du_cn.cn_nameptr = dulp->du_smallname;
        }
        if (!dulp->du_cn.cn_nameptr) {
                return;
        }
        dulp->du_cn.cn_namelen = du_namelen;
        snprintf(dulp->du_cn.cn_nameptr, du_namelen + 1, "._%s", name);
        dulp->du_cn.cn_nameptr[du_namelen] = '\0';
        dulp->du_cn.cn_nameiop = LOOKUP;
        dulp->du_cn.cn_flags = MAKEENTRY;

        error = cache_lookup(NFSTOV(dnp), &du_vp, &dulp->du_cn);
        if (error == -1) {
                vnode_put(du_vp);
        } else if (!error) {
                nmp = NFSTONMP(dnp);
                if (nmp && (nmp->nm_vers > NFS_VER2) && NMFLAG(nmp, RDIRPLUS)) {
                        /* if rdirplus, try dir buf cache lookup */
                        nfsnode_t du_np = NULL;
                        if (!nfs_dir_buf_cache_lookup(dnp, &du_np, &dulp->du_cn, ctx, 0) && du_np) {
                                /* dir buf cache hit */
                                du_vp = NFSTOV(du_np);
                                vnode_put(du_vp);
                                error = -1;
                        }
                }
                if (!error) {
                        dulp->du_flags |= NFS_DULOOKUP_DOIT;
                }
        }
}

/*
 * start an async "._" file lookup request
 */
void
nfs_dulookup_start(struct nfs_dulookup *dulp, nfsnode_t dnp, vfs_context_t ctx)
{
        struct nfsmount *nmp = NFSTONMP(dnp);
        struct nfsreq *req = &dulp->du_req;

        if (!nmp || !(dulp->du_flags & NFS_DULOOKUP_DOIT) || (dulp->du_flags & NFS_DULOOKUP_INPROG)) {
                return;
        }
        if (!nmp->nm_funcs->nf_lookup_rpc_async(dnp, dulp->du_cn.cn_nameptr,
            dulp->du_cn.cn_namelen, ctx, &req)) {
                dulp->du_flags |= NFS_DULOOKUP_INPROG;
        }
}

/*
 * finish an async "._" file lookup request and clean up the structure
 */
void
nfs_dulookup_finish(struct nfs_dulookup *dulp, nfsnode_t dnp, vfs_context_t ctx)
{
        struct nfsmount *nmp = NFSTONMP(dnp);
        int error;
        nfsnode_t du_np;
        u_int64_t xid;
        fhandle_t fh;
        struct nfs_vattr nvattr;

        if (!nmp || !(dulp->du_flags & NFS_DULOOKUP_INPROG)) {
                goto out;
        }

        NVATTR_INIT(&nvattr);
        error = nmp->nm_funcs->nf_lookup_rpc_async_finish(dnp, dulp->du_cn.cn_nameptr,
            dulp->du_cn.cn_namelen, ctx, &dulp->du_req, &xid, &fh, &nvattr);
        dulp->du_flags &= ~NFS_DULOOKUP_INPROG;
        if (error == ENOENT) {
                /* add a negative entry in the name cache */
                nfs_node_lock_force(dnp);
                cache_enter(NFSTOV(dnp), NULL, &dulp->du_cn);
                dnp->n_flag |= NNEGNCENTRIES;
                nfs_node_unlock(dnp);
        } else if (!error) {
                error = nfs_nget(NFSTOMP(dnp), dnp, &dulp->du_cn, fh.fh_data, fh.fh_len,
                    &nvattr, &xid, dulp->du_req.r_auth, NG_MAKEENTRY, &du_np);
                if (!error) {
                        nfs_node_unlock(du_np);
                        vnode_put(NFSTOV(du_np));
                }
        }
        NVATTR_CLEANUP(&nvattr);
out:
        if (dulp->du_flags & NFS_DULOOKUP_INPROG) {
                nfs_request_async_cancel(&dulp->du_req);
        }
        if (dulp->du_cn.cn_nameptr && (dulp->du_cn.cn_nameptr != dulp->du_smallname)) {
                FREE(dulp->du_cn.cn_nameptr, M_TEMP);
        }
}


/*
 * NFS Version 3 commit RPC
 */
int
nfs3_commit_rpc(
        nfsnode_t np,
        uint64_t offset,
        uint64_t count,
        kauth_cred_t cred,
        uint64_t wverf)
{
        struct nfsmount *nmp;
        int error = 0, lockerror, status, wccpostattr = 0, nfsvers;
        struct timespec premtime = { .tv_sec = 0, .tv_nsec = 0 };
        u_int64_t xid, newwverf;
        uint32_t count32;
        struct nfsm_chain nmreq, nmrep;

        nmp = NFSTONMP(np);
        FSDBG(521, np, offset, count, nmp ? nmp->nm_state : 0);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        if (!(nmp->nm_state & NFSSTA_HASWRITEVERF)) {
                return 0;
        }
        nfsvers = nmp->nm_vers;

        if (count > UINT32_MAX) {
                count32 = 0;
        } else {
                count32 = count;
        }

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        nfsm_chain_build_alloc_init(error, &nmreq, NFSX_FH(NFS_VER3));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, np->n_fhp, np->n_fhsize);
        nfsm_chain_add_64(error, &nmreq, offset);
        nfsm_chain_add_32(error, &nmreq, count32);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request2(np, NULL, &nmreq, NFSPROC_COMMIT,
            current_thread(), cred, NULL, 0, &nmrep, &xid, &status);
        if ((lockerror = nfs_node_lock(np))) {
                error = lockerror;
        }
        /* can we do anything useful with the wcc info? */
        nfsm_chain_get_wcc_data(error, &nmrep, np, &premtime, &wccpostattr, &xid);
        if (!lockerror) {
                nfs_node_unlock(np);
        }
        if (!error) {
                error = status;
        }
        nfsm_chain_get_64(error, &nmrep, newwverf);
        nfsmout_if(error);
        lck_mtx_lock(&nmp->nm_lock);
        if (nmp->nm_verf != newwverf) {
                nmp->nm_verf = newwverf;
        }
        if (wverf != newwverf) {
                error = NFSERR_STALEWRITEVERF;
        }
        lck_mtx_unlock(&nmp->nm_lock);
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        return error;
}


int
nfs_vnop_blockmap(
        __unused struct vnop_blockmap_args /* {
                                            *  struct vnodeop_desc *a_desc;
                                            *  vnode_t a_vp;
                                            *  off_t a_foffset;
                                            *  size_t a_size;
                                            *  daddr64_t *a_bpn;
                                            *  size_t *a_run;
                                            *  void *a_poff;
                                            *  int a_flags;
                                            *  } */*ap)
{
        return ENOTSUP;
}


/*
 * fsync vnode op. Just call nfs_flush().
 */
/* ARGSUSED */
int
nfs_vnop_fsync(
        struct vnop_fsync_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_vp;
                                *  int a_waitfor;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        return nfs_flush(VTONFS(ap->a_vp), ap->a_waitfor, vfs_context_thread(ap->a_context), 0);
}


/*
 * Do an NFS pathconf RPC.
 */
int
nfs3_pathconf_rpc(
        nfsnode_t np,
        struct nfs_fsattr *nfsap,
        vfs_context_t ctx)
{
        u_int64_t xid;
        int error = 0, lockerror, status, nfsvers;
        struct nfsm_chain nmreq, nmrep;
        struct nfsmount *nmp = NFSTONMP(np);
        uint32_t val = 0;

        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        nfsvers = nmp->nm_vers;

        nfsm_chain_null(&nmreq);
        nfsm_chain_null(&nmrep);

        /* fetch pathconf info from server */
        nfsm_chain_build_alloc_init(error, &nmreq, NFSX_FH(NFS_VER3));
        nfsm_chain_add_fh(error, &nmreq, nfsvers, np->n_fhp, np->n_fhsize);
        nfsm_chain_build_done(error, &nmreq);
        nfsmout_if(error);
        error = nfs_request(np, NULL, &nmreq, NFSPROC_PATHCONF, ctx, NULL, &nmrep, &xid, &status);
        if ((lockerror = nfs_node_lock(np))) {
                error = lockerror;
        }
        nfsm_chain_postop_attr_update(error, &nmrep, np, &xid);
        if (!lockerror) {
                nfs_node_unlock(np);
        }
        if (!error) {
                error = status;
        }
        nfsm_chain_get_32(error, &nmrep, nfsap->nfsa_maxlink);
        nfsm_chain_get_32(error, &nmrep, nfsap->nfsa_maxname);
        nfsap->nfsa_flags &= ~(NFS_FSFLAG_NO_TRUNC | NFS_FSFLAG_CHOWN_RESTRICTED | NFS_FSFLAG_CASE_INSENSITIVE | NFS_FSFLAG_CASE_PRESERVING);
        nfsm_chain_get_32(error, &nmrep, val);
        if (val) {
                nfsap->nfsa_flags |= NFS_FSFLAG_NO_TRUNC;
        }
        nfsm_chain_get_32(error, &nmrep, val);
        if (val) {
                nfsap->nfsa_flags |= NFS_FSFLAG_CHOWN_RESTRICTED;
        }
        nfsm_chain_get_32(error, &nmrep, val);
        if (val) {
                nfsap->nfsa_flags |= NFS_FSFLAG_CASE_INSENSITIVE;
        }
        nfsm_chain_get_32(error, &nmrep, val);
        if (val) {
                nfsap->nfsa_flags |= NFS_FSFLAG_CASE_PRESERVING;
        }
        NFS_BITMAP_SET(nfsap->nfsa_bitmap, NFS_FATTR_MAXLINK);
        NFS_BITMAP_SET(nfsap->nfsa_bitmap, NFS_FATTR_MAXNAME);
        NFS_BITMAP_SET(nfsap->nfsa_bitmap, NFS_FATTR_NO_TRUNC);
        NFS_BITMAP_SET(nfsap->nfsa_bitmap, NFS_FATTR_CHOWN_RESTRICTED);
        NFS_BITMAP_SET(nfsap->nfsa_bitmap, NFS_FATTR_CASE_INSENSITIVE);
        NFS_BITMAP_SET(nfsap->nfsa_bitmap, NFS_FATTR_CASE_PRESERVING);
nfsmout:
        nfsm_chain_cleanup(&nmreq);
        nfsm_chain_cleanup(&nmrep);
        return error;
}

/* save pathconf info for NFSv3 mount */
void
nfs3_pathconf_cache(struct nfsmount *nmp, struct nfs_fsattr *nfsap)
{
        nmp->nm_fsattr.nfsa_maxlink = nfsap->nfsa_maxlink;
        nmp->nm_fsattr.nfsa_maxname = nfsap->nfsa_maxname;
        nmp->nm_fsattr.nfsa_flags &= ~(NFS_FSFLAG_NO_TRUNC | NFS_FSFLAG_CHOWN_RESTRICTED | NFS_FSFLAG_CASE_INSENSITIVE | NFS_FSFLAG_CASE_PRESERVING);
        nmp->nm_fsattr.nfsa_flags |= nfsap->nfsa_flags & NFS_FSFLAG_NO_TRUNC;
        nmp->nm_fsattr.nfsa_flags |= nfsap->nfsa_flags & NFS_FSFLAG_CHOWN_RESTRICTED;
        nmp->nm_fsattr.nfsa_flags |= nfsap->nfsa_flags & NFS_FSFLAG_CASE_INSENSITIVE;
        nmp->nm_fsattr.nfsa_flags |= nfsap->nfsa_flags & NFS_FSFLAG_CASE_PRESERVING;
        NFS_BITMAP_SET(nmp->nm_fsattr.nfsa_bitmap, NFS_FATTR_MAXLINK);
        NFS_BITMAP_SET(nmp->nm_fsattr.nfsa_bitmap, NFS_FATTR_MAXNAME);
        NFS_BITMAP_SET(nmp->nm_fsattr.nfsa_bitmap, NFS_FATTR_NO_TRUNC);
        NFS_BITMAP_SET(nmp->nm_fsattr.nfsa_bitmap, NFS_FATTR_CHOWN_RESTRICTED);
        NFS_BITMAP_SET(nmp->nm_fsattr.nfsa_bitmap, NFS_FATTR_CASE_INSENSITIVE);
        NFS_BITMAP_SET(nmp->nm_fsattr.nfsa_bitmap, NFS_FATTR_CASE_PRESERVING);
        nmp->nm_state |= NFSSTA_GOTPATHCONF;
}

/*
 * Return POSIX pathconf information applicable to nfs.
 *
 * The NFS V2 protocol doesn't support this, so just return EINVAL
 * for V2.
 */
/* ARGSUSED */
int
nfs_vnop_pathconf(
        struct vnop_pathconf_args /* {
                                   *  struct vnodeop_desc *a_desc;
                                   *  vnode_t a_vp;
                                   *  int a_name;
                                   *  int32_t *a_retval;
                                   *  vfs_context_t a_context;
                                   *  } */*ap)
{
        vnode_t vp = ap->a_vp;
        nfsnode_t np = VTONFS(vp);
        struct nfsmount *nmp;
        struct nfs_fsattr nfsa, *nfsap;
        int error = 0;
        uint64_t maxFileSize;
        uint nbits;

        nmp = VTONMP(vp);
        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }

        switch (ap->a_name) {
        case _PC_LINK_MAX:
        case _PC_NAME_MAX:
        case _PC_CHOWN_RESTRICTED:
        case _PC_NO_TRUNC:
        case _PC_CASE_SENSITIVE:
        case _PC_CASE_PRESERVING:
                break;
        case _PC_FILESIZEBITS:
                if (nmp->nm_vers == NFS_VER2) {
                        *ap->a_retval = 32;
                        return 0;
                }
                break;
        case _PC_XATTR_SIZE_BITS:
                /* Do we support xattrs natively? */
                if (nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_NAMED_ATTR) {
                        break;  /* Yes */
                }
        /* No... so just return an error */
        /* FALLTHROUGH */
        default:
                /* don't bother contacting the server if we know the answer */
                return EINVAL;
        }

        if (nmp->nm_vers == NFS_VER2) {
                return EINVAL;
        }

        lck_mtx_lock(&nmp->nm_lock);
        if (nmp->nm_vers == NFS_VER3) {
                if (!(nmp->nm_state & NFSSTA_GOTPATHCONF)) {
                        /* no pathconf info cached */
                        lck_mtx_unlock(&nmp->nm_lock);
                        NFS_CLEAR_ATTRIBUTES(nfsa.nfsa_bitmap);
                        error = nfs3_pathconf_rpc(np, &nfsa, ap->a_context);
                        if (error) {
                                return error;
                        }
                        nmp = VTONMP(vp);
                        if (nfs_mount_gone(nmp)) {
                                return ENXIO;
                        }
                        lck_mtx_lock(&nmp->nm_lock);
                        if (nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_HOMOGENEOUS) {
                                /* all files have the same pathconf info, */
                                /* so cache a copy of the results */
                                nfs3_pathconf_cache(nmp, &nfsa);
                        }
                        nfsap = &nfsa;
                } else {
                        nfsap = &nmp->nm_fsattr;
                }
        }
#if CONFIG_NFS4
        else if (!(nmp->nm_fsattr.nfsa_flags & NFS_FSFLAG_HOMOGENEOUS)) {
                /* no pathconf info cached */
                lck_mtx_unlock(&nmp->nm_lock);
                NFS_CLEAR_ATTRIBUTES(nfsa.nfsa_bitmap);
                error = nfs4_pathconf_rpc(np, &nfsa, ap->a_context);
                if (error) {
                        return error;
                }
                nmp = VTONMP(vp);
                if (nfs_mount_gone(nmp)) {
                        return ENXIO;
                }
                lck_mtx_lock(&nmp->nm_lock);
                nfsap = &nfsa;
        }
#endif
        else {
                nfsap = &nmp->nm_fsattr;
        }
        switch (ap->a_name) {
        case _PC_LINK_MAX:
                if (NFS_BITMAP_ISSET(nfsap->nfsa_bitmap, NFS_FATTR_MAXLINK)) {
                        *ap->a_retval = nfsap->nfsa_maxlink;
#if CONFIG_NFS4
                } else if ((nmp->nm_vers == NFS_VER4) && NFS_BITMAP_ISSET(np->n_vattr.nva_bitmap, NFS_FATTR_MAXLINK)) {
                        *ap->a_retval = np->n_vattr.nva_maxlink;
#endif
                } else {
                        error = EINVAL;
                }
                break;
        case _PC_NAME_MAX:
                if (NFS_BITMAP_ISSET(nfsap->nfsa_bitmap, NFS_FATTR_MAXNAME)) {
                        *ap->a_retval = nfsap->nfsa_maxname;
                } else {
                        error = EINVAL;
                }
                break;
        case _PC_CHOWN_RESTRICTED:
                if (NFS_BITMAP_ISSET(nfsap->nfsa_bitmap, NFS_FATTR_CHOWN_RESTRICTED)) {
                        *ap->a_retval = (nfsap->nfsa_flags & NFS_FSFLAG_CHOWN_RESTRICTED) ? 200112 /* _POSIX_CHOWN_RESTRICTED */ : 0;
                } else {
                        error = EINVAL;
                }
                break;
        case _PC_NO_TRUNC:
                if (NFS_BITMAP_ISSET(nfsap->nfsa_bitmap, NFS_FATTR_NO_TRUNC)) {
                        *ap->a_retval = (nfsap->nfsa_flags & NFS_FSFLAG_NO_TRUNC) ? 200112 /* _POSIX_NO_TRUNC */ : 0;
                } else {
                        error = EINVAL;
                }
                break;
        case _PC_CASE_SENSITIVE:
                if (NFS_BITMAP_ISSET(nfsap->nfsa_bitmap, NFS_FATTR_CASE_INSENSITIVE)) {
                        *ap->a_retval = (nfsap->nfsa_flags & NFS_FSFLAG_CASE_INSENSITIVE) ? 0 : 1;
                } else {
                        error = EINVAL;
                }
                break;
        case _PC_CASE_PRESERVING:
                if (NFS_BITMAP_ISSET(nfsap->nfsa_bitmap, NFS_FATTR_CASE_PRESERVING)) {
                        *ap->a_retval = (nfsap->nfsa_flags & NFS_FSFLAG_CASE_PRESERVING) ? 1 : 0;
                } else {
                        error = EINVAL;
                }
                break;
        case _PC_XATTR_SIZE_BITS: /* same as file size bits if named attrs supported */
        case _PC_FILESIZEBITS:
                if (!NFS_BITMAP_ISSET(nfsap->nfsa_bitmap, NFS_FATTR_MAXFILESIZE)) {
                        *ap->a_retval = 64;
                        error = 0;
                        break;
                }
                maxFileSize = nfsap->nfsa_maxfilesize;
                nbits = 1;
                if (maxFileSize & 0xffffffff00000000ULL) {
                        nbits += 32;
                        maxFileSize >>= 32;
                }
                if (maxFileSize & 0xffff0000) {
                        nbits += 16;
                        maxFileSize >>= 16;
                }
                if (maxFileSize & 0xff00) {
                        nbits += 8;
                        maxFileSize >>= 8;
                }
                if (maxFileSize & 0xf0) {
                        nbits += 4;
                        maxFileSize >>= 4;
                }
                if (maxFileSize & 0xc) {
                        nbits += 2;
                        maxFileSize >>= 2;
                }
                if (maxFileSize & 0x2) {
                        nbits += 1;
                }
                *ap->a_retval = nbits;
                break;
        default:
                error = EINVAL;
        }

        lck_mtx_unlock(&nmp->nm_lock);

        return error;
}

/*
 * Read wrapper for special devices.
 */
int
nfsspec_vnop_read(
        struct vnop_read_args /* {
                               *  struct vnodeop_desc *a_desc;
                               *  vnode_t a_vp;
                               *  struct uio *a_uio;
                               *  int a_ioflag;
                               *  vfs_context_t a_context;
                               *  } */*ap)
{
        nfsnode_t np = VTONFS(ap->a_vp);
        struct timespec now;
        int error;

        /*
         * Set access flag.
         */
        if ((error = nfs_node_lock(np))) {
                return error;
        }
        np->n_flag |= NACC;
        nanotime(&now);
        np->n_atim.tv_sec = now.tv_sec;
        np->n_atim.tv_nsec = now.tv_nsec;
        nfs_node_unlock(np);
        return VOCALL(spec_vnodeop_p, VOFFSET(vnop_read), ap);
}

/*
 * Write wrapper for special devices.
 */
int
nfsspec_vnop_write(
        struct vnop_write_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_vp;
                                *  struct uio *a_uio;
                                *  int a_ioflag;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        nfsnode_t np = VTONFS(ap->a_vp);
        struct timespec now;
        int error;

        /*
         * Set update flag.
         */
        if ((error = nfs_node_lock(np))) {
                return error;
        }
        np->n_flag |= NUPD;
        nanotime(&now);
        np->n_mtim.tv_sec = now.tv_sec;
        np->n_mtim.tv_nsec = now.tv_nsec;
        nfs_node_unlock(np);
        return VOCALL(spec_vnodeop_p, VOFFSET(vnop_write), ap);
}

/*
 * Close wrapper for special devices.
 *
 * Update the times on the nfsnode then do device close.
 */
int
nfsspec_vnop_close(
        struct vnop_close_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_vp;
                                *  int a_fflag;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        vnode_t vp = ap->a_vp;
        nfsnode_t np = VTONFS(vp);
        struct vnode_attr vattr;
        mount_t mp;
        int error;

        if ((error = nfs_node_lock(np))) {
                return error;
        }
        if (np->n_flag & (NACC | NUPD)) {
                np->n_flag |= NCHG;
                if (!vnode_isinuse(vp, 0) && (mp = vnode_mount(vp)) && !vfs_isrdonly(mp)) {
                        VATTR_INIT(&vattr);
                        if (np->n_flag & NACC) {
                                vattr.va_access_time = np->n_atim;
                                VATTR_SET_ACTIVE(&vattr, va_access_time);
                        }
                        if (np->n_flag & NUPD) {
                                vattr.va_modify_time = np->n_mtim;
                                VATTR_SET_ACTIVE(&vattr, va_modify_time);
                        }
                        nfs_node_unlock(np);
                        vnode_setattr(vp, &vattr, ap->a_context);
                } else {
                        nfs_node_unlock(np);
                }
        } else {
                nfs_node_unlock(np);
        }
        return VOCALL(spec_vnodeop_p, VOFFSET(vnop_close), ap);
}

#if FIFO
extern vnop_t **fifo_vnodeop_p;

/*
 * Read wrapper for fifos.
 */
int
nfsfifo_vnop_read(
        struct vnop_read_args /* {
                               *  struct vnodeop_desc *a_desc;
                               *  vnode_t a_vp;
                               *  struct uio *a_uio;
                               *  int a_ioflag;
                               *  vfs_context_t a_context;
                               *  } */*ap)
{
        nfsnode_t np = VTONFS(ap->a_vp);
        struct timespec now;
        int error;

        /*
         * Set access flag.
         */
        if ((error = nfs_node_lock(np))) {
                return error;
        }
        np->n_flag |= NACC;
        nanotime(&now);
        np->n_atim.tv_sec = now.tv_sec;
        np->n_atim.tv_nsec = now.tv_nsec;
        nfs_node_unlock(np);
        return VOCALL(fifo_vnodeop_p, VOFFSET(vnop_read), ap);
}

/*
 * Write wrapper for fifos.
 */
int
nfsfifo_vnop_write(
        struct vnop_write_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_vp;
                                *  struct uio *a_uio;
                                *  int a_ioflag;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        nfsnode_t np = VTONFS(ap->a_vp);
        struct timespec now;
        int error;

        /*
         * Set update flag.
         */
        if ((error = nfs_node_lock(np))) {
                return error;
        }
        np->n_flag |= NUPD;
        nanotime(&now);
        np->n_mtim.tv_sec = now.tv_sec;
        np->n_mtim.tv_nsec = now.tv_nsec;
        nfs_node_unlock(np);
        return VOCALL(fifo_vnodeop_p, VOFFSET(vnop_write), ap);
}

/*
 * Close wrapper for fifos.
 *
 * Update the times on the nfsnode then do fifo close.
 */
int
nfsfifo_vnop_close(
        struct vnop_close_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_vp;
                                *  int a_fflag;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        vnode_t vp = ap->a_vp;
        nfsnode_t np = VTONFS(vp);
        struct vnode_attr vattr;
        struct timespec now;
        mount_t mp;
        int error;

        if ((error = nfs_node_lock(np))) {
                return error;
        }
        if (np->n_flag & (NACC | NUPD)) {
                nanotime(&now);
                if (np->n_flag & NACC) {
                        np->n_atim.tv_sec = now.tv_sec;
                        np->n_atim.tv_nsec = now.tv_nsec;
                }
                if (np->n_flag & NUPD) {
                        np->n_mtim.tv_sec = now.tv_sec;
                        np->n_mtim.tv_nsec = now.tv_nsec;
                }
                np->n_flag |= NCHG;
                if (!vnode_isinuse(vp, 1) && (mp = vnode_mount(vp)) && !vfs_isrdonly(mp)) {
                        VATTR_INIT(&vattr);
                        if (np->n_flag & NACC) {
                                vattr.va_access_time = np->n_atim;
                                VATTR_SET_ACTIVE(&vattr, va_access_time);
                        }
                        if (np->n_flag & NUPD) {
                                vattr.va_modify_time = np->n_mtim;
                                VATTR_SET_ACTIVE(&vattr, va_modify_time);
                        }
                        nfs_node_unlock(np);
                        vnode_setattr(vp, &vattr, ap->a_context);
                } else {
                        nfs_node_unlock(np);
                }
        } else {
                nfs_node_unlock(np);
        }
        return VOCALL(fifo_vnodeop_p, VOFFSET(vnop_close), ap);
}
#endif /* FIFO */

/*ARGSUSED*/
int
nfs_vnop_ioctl(
        struct vnop_ioctl_args /* {
                                *  struct vnodeop_desc *a_desc;
                                *  vnode_t a_vp;
                                *  u_int32_t a_command;
                                *  caddr_t a_data;
                                *  int a_fflag;
                                *  vfs_context_t a_context;
                                *  } */*ap)
{
        vfs_context_t ctx = ap->a_context;
        vnode_t vp = ap->a_vp;
        struct nfsmount *mp = VTONMP(vp);
        int error = ENOTTY;
#if CONFIG_NFS_GSS
        struct user_nfs_gss_principal gprinc = {};
        uint32_t len;
#endif

        if (mp == NULL) {
                return ENXIO;
        }
        switch (ap->a_command) {
        case F_FULLFSYNC:
                if (vnode_vfsisrdonly(vp)) {
                        return EROFS;
                }
                error = nfs_flush(VTONFS(vp), MNT_WAIT, vfs_context_thread(ctx), 0);
                break;
#if CONFIG_NFS_GSS
        case NFS_IOC_DESTROY_CRED:
                if (!auth_is_kerberized(mp->nm_auth)) {
                        return ENOTSUP;
                }
                error = nfs_gss_clnt_ctx_remove(mp, vfs_context_ucred(ctx));
                break;
        case NFS_IOC_SET_CRED:
        case NFS_IOC_SET_CRED64:
                if (!auth_is_kerberized(mp->nm_auth)) {
                        return ENOTSUP;
                }
                if ((ap->a_command == NFS_IOC_SET_CRED && vfs_context_is64bit(ctx)) ||
                    (ap->a_command == NFS_IOC_SET_CRED64 && !vfs_context_is64bit(ctx))) {
                        return EINVAL;
                }
                if (vfs_context_is64bit(ctx)) {
                        gprinc = *(struct user_nfs_gss_principal *)ap->a_data;
                } else {
                        struct nfs_gss_principal *tp;
                        tp = (struct nfs_gss_principal *)ap->a_data;
                        gprinc.princlen = tp->princlen;
                        gprinc.nametype = tp->nametype;
                        gprinc.principal = CAST_USER_ADDR_T(tp->principal);
                }
                NFS_DBG(NFS_FAC_GSS, 7, "Enter NFS_FSCTL_SET_CRED (64-bit=%d): principal length %d name type %d usr pointer 0x%llx\n", vfs_context_is64bit(ctx), gprinc.princlen, gprinc.nametype, (unsigned long long)gprinc.principal);
                if (gprinc.princlen > MAXPATHLEN) {
                        return EINVAL;
                }
                uint8_t *p;
                MALLOC(p, uint8_t *, gprinc.princlen + 1, M_TEMP, M_WAITOK | M_ZERO);
                if (p == NULL) {
                        return ENOMEM;
                }
                error = copyin(gprinc.principal, p, gprinc.princlen);
                if (error) {
                        NFS_DBG(NFS_FAC_GSS, 7, "NFS_FSCTL_SET_CRED could not copy in princiapl data of len %d: %d\n",
                            gprinc.princlen, error);
                        FREE(p, M_TEMP);
                        return error;
                }
                NFS_DBG(NFS_FAC_GSS, 7, "Seting credential to principal %s\n", p);
                error = nfs_gss_clnt_ctx_set_principal(mp, ctx, p, gprinc.princlen, gprinc.nametype);
                NFS_DBG(NFS_FAC_GSS, 7, "Seting credential to principal %s returned %d\n", p, error);
                FREE(p, M_TEMP);
                break;
        case NFS_IOC_GET_CRED:
        case NFS_IOC_GET_CRED64:
                if (!auth_is_kerberized(mp->nm_auth)) {
                        return ENOTSUP;
                }
                if ((ap->a_command == NFS_IOC_GET_CRED && vfs_context_is64bit(ctx)) ||
                    (ap->a_command == NFS_IOC_GET_CRED64 && !vfs_context_is64bit(ctx))) {
                        return EINVAL;
                }
                error = nfs_gss_clnt_ctx_get_principal(mp, ctx, &gprinc);
                if (error) {
                        break;
                }
                if (vfs_context_is64bit(ctx)) {
                        struct user_nfs_gss_principal *upp = (struct user_nfs_gss_principal *)ap->a_data;
                        len = upp->princlen;
                        if (gprinc.princlen < len) {
                                len = gprinc.princlen;
                        }
                        upp->princlen = gprinc.princlen;
                        upp->nametype = gprinc.nametype;
                        upp->flags = gprinc.flags;
                        if (gprinc.principal) {
                                error = copyout((void *)gprinc.principal, upp->principal, len);
                        } else {
                                upp->principal = USER_ADDR_NULL;
                        }
                } else {
                        struct nfs_gss_principal *u32pp = (struct nfs_gss_principal *)ap->a_data;
                        len = u32pp->princlen;
                        if (gprinc.princlen < len) {
                                len = gprinc.princlen;
                        }
                        u32pp->princlen = gprinc.princlen;
                        u32pp->nametype = gprinc.nametype;
                        u32pp->flags = gprinc.flags;
                        if (gprinc.principal) {
                                error = copyout((void *)gprinc.principal, u32pp->principal, len);
                        } else {
                                u32pp->principal = (user32_addr_t)0;
                        }
                }
                if (error) {
                        NFS_DBG(NFS_FAC_GSS, 7, "NFS_FSCTL_GET_CRED could not copy out princiapl data of len %d: %d\n",
                            gprinc.princlen, error);
                }
                if (gprinc.principal) {
                        FREE(gprinc.principal, M_TEMP);
                }
#endif /* CONFIG_NFS_GSS */
        }

        return error;
}

/*ARGSUSED*/
int
nfs_vnop_select(
        __unused struct vnop_select_args /* {
                                          *  struct vnodeop_desc *a_desc;
                                          *  vnode_t a_vp;
                                          *  int a_which;
                                          *  int a_fflags;
                                          *  void *a_wql;
                                          *  vfs_context_t a_context;
                                          *  } */*ap)
{
        /*
         * We were once bogusly seltrue() which returns 1.  Is this right?
         */
        return 1;
}

/*
 * vnode OP for pagein using UPL
 *
 * No buffer I/O, just RPCs straight into the mapped pages.
 */
int
nfs_vnop_pagein(
        struct vnop_pagein_args /* {
                                 *  struct vnodeop_desc *a_desc;
                                 *  vnode_t a_vp;
                                 *  upl_t a_pl;
                                 *  vm_offset_t a_pl_offset;
                                 *  off_t a_f_offset;
                                 *  size_t a_size;
                                 *  int a_flags;
                                 *  vfs_context_t a_context;
                                 *  } */*ap)
{
        vnode_t vp = ap->a_vp;
        upl_t pl = ap->a_pl;
        size_t size = ap->a_size;
        off_t f_offset = ap->a_f_offset;
        vm_offset_t pl_offset = ap->a_pl_offset;
        int flags = ap->a_flags;
        thread_t thd;
        kauth_cred_t cred;
        nfsnode_t np = VTONFS(vp);
        size_t nmrsize, iosize, txsize, rxsize, retsize;
        off_t txoffset;
        struct nfsmount *nmp;
        int error = 0;
        vm_offset_t ioaddr, rxaddr;
        uio_t uio;
        char uio_buf[UIO_SIZEOF(1)];
        int nofreeupl = flags & UPL_NOCOMMIT;
        upl_page_info_t *plinfo;
#define MAXPAGINGREQS   16      /* max outstanding RPCs for pagein/pageout */
        struct nfsreq *req[MAXPAGINGREQS];
        int nextsend, nextwait;
#if CONFIG_NFS4
        uint32_t stategenid = 0;
#endif
        uint32_t restart = 0;
        kern_return_t kret;

        FSDBG(322, np, f_offset, size, flags);
        if (pl == (upl_t)NULL) {
                panic("nfs_pagein: no upl");
        }

        if (size <= 0) {
                printf("nfs_pagein: invalid size %ld", size);
                if (!nofreeupl) {
                        (void) ubc_upl_abort_range(pl, pl_offset, size, 0);
                }
                return EINVAL;
        }
        if (f_offset < 0 || f_offset >= (off_t)np->n_size || (f_offset & PAGE_MASK_64)) {
                if (!nofreeupl) {
                        ubc_upl_abort_range(pl, pl_offset, size,
                            UPL_ABORT_ERROR | UPL_ABORT_FREE_ON_EMPTY);
                }
                return EINVAL;
        }

        thd = vfs_context_thread(ap->a_context);
        cred = ubc_getcred(vp);
        if (!IS_VALID_CRED(cred)) {
                cred = vfs_context_ucred(ap->a_context);
        }

        uio = uio_createwithbuffer(1, f_offset, UIO_SYSSPACE, UIO_READ,
            &uio_buf, sizeof(uio_buf));

        nmp = VTONMP(vp);
        if (nfs_mount_gone(nmp)) {
                if (!nofreeupl) {
                        ubc_upl_abort_range(pl, pl_offset, size,
                            UPL_ABORT_ERROR | UPL_ABORT_FREE_ON_EMPTY);
                }
                return ENXIO;
        }
        nmrsize = nmp->nm_rsize;

        plinfo = ubc_upl_pageinfo(pl);
        kret = ubc_upl_map(pl, &ioaddr);
        if (kret != KERN_SUCCESS) {
                panic("nfs_vnop_pagein: ubc_upl_map() failed with (%d)", kret);
        }
        ioaddr += pl_offset;

tryagain:
#if CONFIG_NFS4
        if (nmp->nm_vers >= NFS_VER4) {
                stategenid = nmp->nm_stategenid;
        }
#endif
        txsize = rxsize = size;
        txoffset = f_offset;
        rxaddr = ioaddr;

        bzero(req, sizeof(req));
        nextsend = nextwait = 0;
        do {
                if (np->n_flag & NREVOKE) {
                        error = EIO;
                        break;
                }
                /* send requests while we need to and have available slots */
                while ((txsize > 0) && (req[nextsend] == NULL)) {
                        iosize = MIN(nmrsize, txsize);
                        if ((error = nmp->nm_funcs->nf_read_rpc_async(np, txoffset, iosize, thd, cred, NULL, &req[nextsend]))) {
                                req[nextsend] = NULL;
                                break;
                        }
                        txoffset += iosize;
                        txsize -= iosize;
                        nextsend = (nextsend + 1) % MAXPAGINGREQS;
                }
                /* wait while we need to and break out if more requests to send */
                while ((rxsize > 0) && req[nextwait]) {
                        iosize = retsize = MIN(nmrsize, rxsize);
                        uio_reset(uio, uio_offset(uio), UIO_SYSSPACE, UIO_READ);
                        uio_addiov(uio, CAST_USER_ADDR_T(rxaddr), iosize);
                        FSDBG(322, uio_offset(uio), uio_resid(uio), rxaddr, rxsize);
#if UPL_DEBUG
                        upl_ubc_alias_set(pl, (uintptr_t) current_thread(), (uintptr_t) 2);
#endif /* UPL_DEBUG */
                        OSAddAtomic64(1, &nfsstats.pageins);
                        error = nmp->nm_funcs->nf_read_rpc_async_finish(np, req[nextwait], uio, &retsize, NULL);
                        req[nextwait] = NULL;
                        nextwait = (nextwait + 1) % MAXPAGINGREQS;
#if CONFIG_NFS4
                        if ((nmp->nm_vers >= NFS_VER4) && nfs_mount_state_error_should_restart(error)) {
                                lck_mtx_lock(&nmp->nm_lock);
                                if ((error != NFSERR_GRACE) && (stategenid == nmp->nm_stategenid)) {
                                        NP(np, "nfs_vnop_pagein: error %d, initiating recovery", error);
                                        nfs_need_recover(nmp, error);
                                }
                                lck_mtx_unlock(&nmp->nm_lock);
                                restart++;
                                goto cancel;
                        }
#endif
                        if (error) {
                                FSDBG(322, uio_offset(uio), uio_resid(uio), error, -1);
                                break;
                        }
                        if (retsize < iosize) {
                                /* Just zero fill the rest of the valid area. */
                                int zcnt = iosize - retsize;
                                bzero((char *)rxaddr + retsize, zcnt);
                                FSDBG(324, uio_offset(uio), retsize, zcnt, rxaddr);
                                uio_update(uio, zcnt);
                        }
                        rxaddr += iosize;
                        rxsize -= iosize;
                        if (txsize) {
                                break;
                        }
                }
        } while (!error && (txsize || rxsize));

        restart = 0;

        if (error) {
#if CONFIG_NFS4
cancel:
#endif
                /* cancel any outstanding requests */
                while (req[nextwait]) {
                        nfs_request_async_cancel(req[nextwait]);
                        req[nextwait] = NULL;
                        nextwait = (nextwait + 1) % MAXPAGINGREQS;
                }
                if (np->n_flag & NREVOKE) {
                        error = EIO;
                } else if (restart) {
                        if (restart <= nfs_mount_state_max_restarts(nmp)) { /* guard against no progress */
                                if (error == NFSERR_GRACE) {
                                        tsleep(&nmp->nm_state, (PZERO - 1), "nfsgrace", 2 * hz);
                                }
                                if (!(error = nfs_mount_state_wait_for_recovery(nmp))) {
                                        goto tryagain;
                                }
                        } else {
                                NP(np, "nfs_pagein: too many restarts, aborting");
                        }
                }
        }

        ubc_upl_unmap(pl);

        if (!nofreeupl) {
                if (error) {
                        ubc_upl_abort_range(pl, pl_offset, size,
                            UPL_ABORT_ERROR |
                            UPL_ABORT_FREE_ON_EMPTY);
                } else {
                        ubc_upl_commit_range(pl, pl_offset, size,
                            UPL_COMMIT_CLEAR_DIRTY |
                            UPL_COMMIT_FREE_ON_EMPTY);
                }
        }
        return error;
}


/*
 * the following are needed only by nfs_pageout to know how to handle errors
 * see nfs_pageout comments on explanation of actions.
 * the errors here are copied from errno.h and errors returned by servers
 * are expected to match the same numbers here. If not, our actions maybe
 * erroneous.
 */
char nfs_pageouterrorhandler(int);
enum actiontype {NOACTION, DUMP, DUMPANDLOG, RETRY, SEVER};
#define NFS_ELAST 88
static u_char errorcount[NFS_ELAST + 1]; /* better be zeros when initialized */
static const char errortooutcome[NFS_ELAST + 1] = {
        NOACTION,
        DUMP,                   /* EPERM        1       Operation not permitted */
        DUMP,                   /* ENOENT       2       No such file or directory */
        DUMPANDLOG,             /* ESRCH        3       No such process */
        RETRY,                  /* EINTR        4       Interrupted system call */
        DUMP,                   /* EIO          5       Input/output error */
        DUMP,                   /* ENXIO        6       Device not configured */
        DUMPANDLOG,             /* E2BIG        7       Argument list too long */
        DUMPANDLOG,             /* ENOEXEC      8       Exec format error */
        DUMPANDLOG,             /* EBADF        9       Bad file descriptor */
        DUMPANDLOG,             /* ECHILD       10      No child processes */
        DUMPANDLOG,             /* EDEADLK      11      Resource deadlock avoided - was EAGAIN */
        RETRY,                  /* ENOMEM       12      Cannot allocate memory */
        DUMP,                   /* EACCES       13      Permission denied */
        DUMPANDLOG,             /* EFAULT       14      Bad address */
        DUMPANDLOG,             /* ENOTBLK      15      POSIX - Block device required */
        RETRY,                  /* EBUSY        16      Device busy */
        DUMP,                   /* EEXIST       17      File exists */
        DUMP,                   /* EXDEV        18      Cross-device link */
        DUMP,                   /* ENODEV       19      Operation not supported by device */
        DUMP,                   /* ENOTDIR      20      Not a directory */
        DUMP,                   /* EISDIR       21      Is a directory */
        DUMP,                   /* EINVAL       22      Invalid argument */
        DUMPANDLOG,             /* ENFILE       23      Too many open files in system */
        DUMPANDLOG,             /* EMFILE       24      Too many open files */
        DUMPANDLOG,             /* ENOTTY       25      Inappropriate ioctl for device */
        DUMPANDLOG,             /* ETXTBSY      26      Text file busy - POSIX */
        DUMP,                   /* EFBIG        27      File too large */
        DUMP,                   /* ENOSPC       28      No space left on device */
        DUMPANDLOG,             /* ESPIPE       29      Illegal seek */
        DUMP,                   /* EROFS        30      Read-only file system */
        DUMP,                   /* EMLINK       31      Too many links */
        RETRY,                  /* EPIPE        32      Broken pipe */
        /* math software */
        DUMPANDLOG,             /* EDOM                         33      Numerical argument out of domain */
        DUMPANDLOG,             /* ERANGE                       34      Result too large */
        RETRY,                  /* EAGAIN/EWOULDBLOCK   35      Resource temporarily unavailable */
        DUMPANDLOG,             /* EINPROGRESS          36      Operation now in progress */
        DUMPANDLOG,             /* EALREADY                     37      Operation already in progress */
        /* ipc/network software -- argument errors */
        DUMPANDLOG,             /* ENOTSOC                      38      Socket operation on non-socket */
        DUMPANDLOG,             /* EDESTADDRREQ         39      Destination address required */
        DUMPANDLOG,             /* EMSGSIZE                     40      Message too long */
        DUMPANDLOG,             /* EPROTOTYPE           41      Protocol wrong type for socket */
        DUMPANDLOG,             /* ENOPROTOOPT          42      Protocol not available */
        DUMPANDLOG,             /* EPROTONOSUPPORT      43      Protocol not supported */
        DUMPANDLOG,             /* ESOCKTNOSUPPORT      44      Socket type not supported */
        DUMPANDLOG,             /* ENOTSUP                      45      Operation not supported */
        DUMPANDLOG,             /* EPFNOSUPPORT         46      Protocol family not supported */
        DUMPANDLOG,             /* EAFNOSUPPORT         47      Address family not supported by protocol family */
        DUMPANDLOG,             /* EADDRINUSE           48      Address already in use */
        DUMPANDLOG,             /* EADDRNOTAVAIL        49      Can't assign requested address */
        /* ipc/network software -- operational errors */
        RETRY,                  /* ENETDOWN                     50      Network is down */
        RETRY,                  /* ENETUNREACH          51      Network is unreachable */
        RETRY,                  /* ENETRESET            52      Network dropped connection on reset */
        RETRY,                  /* ECONNABORTED         53      Software caused connection abort */
        RETRY,                  /* ECONNRESET           54      Connection reset by peer */
        RETRY,                  /* ENOBUFS                      55      No buffer space available */
        RETRY,                  /* EISCONN                      56      Socket is already connected */
        RETRY,                  /* ENOTCONN                     57      Socket is not connected */
        RETRY,                  /* ESHUTDOWN            58      Can't send after socket shutdown */
        RETRY,                  /* ETOOMANYREFS         59      Too many references: can't splice */
        RETRY,                  /* ETIMEDOUT            60      Operation timed out */
        RETRY,                  /* ECONNREFUSED         61      Connection refused */

        DUMPANDLOG,             /* ELOOP                        62      Too many levels of symbolic links */
        DUMP,                   /* ENAMETOOLONG         63      File name too long */
        RETRY,                  /* EHOSTDOWN            64      Host is down */
        RETRY,                  /* EHOSTUNREACH         65      No route to host */
        DUMP,                   /* ENOTEMPTY            66      Directory not empty */
        /* quotas & mush */
        DUMPANDLOG,             /* PROCLIM                      67      Too many processes */
        DUMPANDLOG,             /* EUSERS                       68      Too many users */
        DUMPANDLOG,             /* EDQUOT                       69      Disc quota exceeded */
        /* Network File System */
        DUMP,                   /* ESTALE                       70      Stale NFS file handle */
        DUMP,                   /* EREMOTE                      71      Too many levels of remote in path */
        DUMPANDLOG,             /* EBADRPC                      72      RPC struct is bad */
        DUMPANDLOG,             /* ERPCMISMATCH         73      RPC version wrong */
        DUMPANDLOG,             /* EPROGUNAVAIL         74      RPC prog. not avail */
        DUMPANDLOG,             /* EPROGMISMATCH        75      Program version wrong */
        DUMPANDLOG,             /* EPROCUNAVAIL         76      Bad procedure for program */

        DUMPANDLOG,             /* ENOLCK                       77      No locks available */
        DUMPANDLOG,             /* ENOSYS                       78      Function not implemented */
        DUMPANDLOG,             /* EFTYPE                       79      Inappropriate file type or format */
        DUMPANDLOG,             /* EAUTH                        80      Authentication error */
        DUMPANDLOG,             /* ENEEDAUTH            81      Need authenticator */
        /* Intelligent device errors */
        DUMPANDLOG,             /* EPWROFF                      82      Device power is off */
        DUMPANDLOG,             /* EDEVERR                      83      Device error, e.g. paper out */
        DUMPANDLOG,             /* EOVERFLOW            84      Value too large to be stored in data type */
        /* Program loading errors */
        DUMPANDLOG,             /* EBADEXEC                     85      Bad executable */
        DUMPANDLOG,             /* EBADARCH                     86      Bad CPU type in executable */
        DUMPANDLOG,             /* ESHLIBVERS           87      Shared library version mismatch */
        DUMPANDLOG,             /* EBADMACHO            88      Malformed Macho file */
};

char
nfs_pageouterrorhandler(int error)
{
        if (error > NFS_ELAST) {
                return DUMP;
        } else {
                return errortooutcome[error];
        }
}


/*
 * vnode OP for pageout using UPL
 *
 * No buffer I/O, just RPCs straight from the mapped pages.
 * File size changes are not permitted in pageout.
 */
int
nfs_vnop_pageout(
        struct vnop_pageout_args /* {
                                  *  struct vnodeop_desc *a_desc;
                                  *  vnode_t a_vp;
                                  *  upl_t a_pl;
                                  *  vm_offset_t a_pl_offset;
                                  *  off_t a_f_offset;
                                  *  size_t a_size;
                                  *  int a_flags;
                                  *  vfs_context_t a_context;
                                  *  } */*ap)
{
        vnode_t vp = ap->a_vp;
        upl_t pl = ap->a_pl;
        size_t size = ap->a_size;
        off_t f_offset = ap->a_f_offset;
        vm_offset_t pl_offset = ap->a_pl_offset;
        int flags = ap->a_flags;
        nfsnode_t np = VTONFS(vp);
        thread_t thd;
        kauth_cred_t cred;
        struct nfsbuf *bp;
        struct nfsmount *nmp = VTONMP(vp);
        daddr64_t lbn;
        int error = 0, iomode;
        off_t off, txoffset, rxoffset;
        vm_offset_t ioaddr, txaddr, rxaddr;
        uio_t auio;
        char uio_buf[UIO_SIZEOF(1)];
        int nofreeupl = flags & UPL_NOCOMMIT;
        size_t nmwsize, biosize, iosize, pgsize, txsize, rxsize, xsize, remsize;
        struct nfsreq *req[MAXPAGINGREQS];
        int nextsend, nextwait, wverfset, commit;
        uint64_t wverf, wverf2;
#if CONFIG_NFS4
        uint32_t stategenid = 0;
#endif
        uint32_t vrestart = 0, restart = 0, vrestarts = 0, restarts = 0;
        kern_return_t kret;

        FSDBG(323, f_offset, size, pl, pl_offset);

        if (pl == (upl_t)NULL) {
                panic("nfs_pageout: no upl");
        }

        if (size <= 0) {
                printf("nfs_pageout: invalid size %ld", size);
                if (!nofreeupl) {
                        ubc_upl_abort_range(pl, pl_offset, size, 0);
                }
                return EINVAL;
        }

        if (!nmp) {
                if (!nofreeupl) {
                        ubc_upl_abort(pl, UPL_ABORT_DUMP_PAGES | UPL_ABORT_FREE_ON_EMPTY);
                }
                return ENXIO;
        }
        biosize = nmp->nm_biosize;
        nmwsize = nmp->nm_wsize;

        nfs_data_lock_noupdate(np, NFS_DATA_LOCK_SHARED);

        /*
         * Check to see whether the buffer is incore.
         * If incore and not busy, invalidate it from the cache.
         */
        for (iosize = 0; iosize < size; iosize += xsize) {
                off = f_offset + iosize;
                /* need make sure we do things on block boundaries */
                xsize = biosize - (off % biosize);
                if (off + xsize > f_offset + size) {
                        xsize = f_offset + size - off;
                }
                lbn = (daddr64_t)(off / biosize);
                lck_mtx_lock(nfs_buf_mutex);
                if ((bp = nfs_buf_incore(np, lbn))) {
                        FSDBG(323, off, bp, bp->nb_lflags, bp->nb_flags);
                        if (nfs_buf_acquire(bp, NBAC_NOWAIT, 0, 0)) {
                                lck_mtx_unlock(nfs_buf_mutex);
                                nfs_data_unlock_noupdate(np);
                                /* no panic. just tell vm we are busy */
                                if (!nofreeupl) {
                                        ubc_upl_abort_range(pl, pl_offset, size, 0);
                                }
                                return EBUSY;
                        }
                        if (bp->nb_dirtyend > 0) {
                                /*
                                 * if there's a dirty range in the buffer, check
                                 * to see if it extends beyond the pageout region
                                 *
                                 * if the dirty region lies completely within the
                                 * pageout region, we just invalidate the buffer
                                 * because it's all being written out now anyway.
                                 *
                                 * if any of the dirty region lies outside the
                                 * pageout region, we'll try to clip the dirty
                                 * region to eliminate the portion that's being
                                 * paged out.  If that's not possible, because
                                 * the dirty region extends before and after the
                                 * pageout region, then we'll just return EBUSY.
                                 */
                                off_t boff, start, end;
                                boff = NBOFF(bp);
                                start = off;
                                end = off + xsize;
                                /* clip end to EOF */
                                if (end > (off_t)np->n_size) {
                                        end = np->n_size;
                                }
                                start -= boff;
                                end -= boff;
                                if ((bp->nb_dirtyoff < start) &&
                                    (bp->nb_dirtyend > end)) {
                                        /*
                                         * not gonna be able to clip the dirty region
                                         *
                                         * But before returning the bad news, move the
                                         * buffer to the start of the delwri list and
                                         * give the list a push to try to flush the
                                         * buffer out.
                                         */
                                        FSDBG(323, np, bp, 0xd00deebc, EBUSY);
                                        nfs_buf_remfree(bp);
                                        TAILQ_INSERT_HEAD(&nfsbufdelwri, bp, nb_free);
                                        nfsbufdelwricnt++;
                                        nfs_buf_drop(bp);
                                        nfs_buf_delwri_push(1);
                                        lck_mtx_unlock(nfs_buf_mutex);
                                        nfs_data_unlock_noupdate(np);
                                        if (!nofreeupl) {
                                                ubc_upl_abort_range(pl, pl_offset, size, 0);
                                        }
                                        return EBUSY;
                                }
                                if ((bp->nb_dirtyoff < start) ||
                                    (bp->nb_dirtyend > end)) {
                                        /* clip dirty region, if necessary */
                                        if (bp->nb_dirtyoff < start) {
                                                bp->nb_dirtyend = min(bp->nb_dirtyend, start);
                                        }
                                        if (bp->nb_dirtyend > end) {
                                                bp->nb_dirtyoff = max(bp->nb_dirtyoff, end);
                                        }
                                        FSDBG(323, bp, bp->nb_dirtyoff, bp->nb_dirtyend, 0xd00dee00);
                                        /* we're leaving this block dirty */
                                        nfs_buf_drop(bp);
                                        lck_mtx_unlock(nfs_buf_mutex);
                                        continue;
                                }
                        }
                        nfs_buf_remfree(bp);
                        lck_mtx_unlock(nfs_buf_mutex);
                        SET(bp->nb_flags, NB_INVAL);
                        nfs_node_lock_force(np);
                        if (ISSET(bp->nb_flags, NB_NEEDCOMMIT)) {
                                CLR(bp->nb_flags, NB_NEEDCOMMIT);
                                np->n_needcommitcnt--;
                                CHECK_NEEDCOMMITCNT(np);
                        }
                        nfs_node_unlock(np);
                        nfs_buf_release(bp, 1);
                } else {
                        lck_mtx_unlock(nfs_buf_mutex);
                }
        }

        thd = vfs_context_thread(ap->a_context);
        cred = ubc_getcred(vp);
        if (!IS_VALID_CRED(cred)) {
                cred = vfs_context_ucred(ap->a_context);
        }

        nfs_node_lock_force(np);
        if (np->n_flag & NWRITEERR) {
                error = np->n_error;
                nfs_node_unlock(np);
                nfs_data_unlock_noupdate(np);
                if (!nofreeupl) {
                        ubc_upl_abort_range(pl, pl_offset, size,
                            UPL_ABORT_FREE_ON_EMPTY);
                }
                return error;
        }
        nfs_node_unlock(np);

        if (f_offset < 0 || f_offset >= (off_t)np->n_size ||
            f_offset & PAGE_MASK_64 || size & PAGE_MASK_64) {
                nfs_data_unlock_noupdate(np);
                if (!nofreeupl) {
                        ubc_upl_abort_range(pl, pl_offset, size,
                            UPL_ABORT_FREE_ON_EMPTY);
                }
                return EINVAL;
        }

        kret = ubc_upl_map(pl, &ioaddr);
        if (kret != KERN_SUCCESS) {
                panic("nfs_vnop_pageout: ubc_upl_map() failed with (%d)", kret);
        }
        ioaddr += pl_offset;

        if ((u_quad_t)f_offset + size > np->n_size) {
                xsize = np->n_size - f_offset;
        } else {
                xsize = size;
        }

        pgsize = round_page_64(xsize);
        if ((size > pgsize) && !nofreeupl) {
                ubc_upl_abort_range(pl, pl_offset + pgsize, size - pgsize,
                    UPL_ABORT_FREE_ON_EMPTY);
        }

        /*
         * check for partial page and clear the
         * contents past end of the file before
         * releasing it in the VM page cache
         */
        if ((u_quad_t)f_offset < np->n_size && (u_quad_t)f_offset + size > np->n_size) {
                size_t io = np->n_size - f_offset;
                bzero((caddr_t)(ioaddr + io), size - io);
                FSDBG(321, np->n_size, f_offset, f_offset + io, size - io);
        }
        nfs_data_unlock_noupdate(np);

        auio = uio_createwithbuffer(1, 0, UIO_SYSSPACE, UIO_WRITE,
            &uio_buf, sizeof(uio_buf));

tryagain:
#if CONFIG_NFS4
        if (nmp->nm_vers >= NFS_VER4) {
                stategenid = nmp->nm_stategenid;
        }
#endif
        wverf = wverf2 = wverfset = 0;
        txsize = rxsize = xsize;
        txoffset = rxoffset = f_offset;
        txaddr = rxaddr = ioaddr;
        commit = NFS_WRITE_FILESYNC;

        bzero(req, sizeof(req));
        nextsend = nextwait = 0;
        do {
                if (np->n_flag & NREVOKE) {
                        error = EIO;
                        break;
                }
                /* send requests while we need to and have available slots */
                while ((txsize > 0) && (req[nextsend] == NULL)) {
                        iosize = MIN(nmwsize, txsize);
                        uio_reset(auio, txoffset, UIO_SYSSPACE, UIO_WRITE);
                        uio_addiov(auio, CAST_USER_ADDR_T(txaddr), iosize);
                        FSDBG(323, uio_offset(auio), iosize, txaddr, txsize);
                        OSAddAtomic64(1, &nfsstats.pageouts);
                        nfs_node_lock_force(np);
                        np->n_numoutput++;
                        nfs_node_unlock(np);
                        vnode_startwrite(vp);
                        iomode = NFS_WRITE_UNSTABLE;
                        if ((error = nmp->nm_funcs->nf_write_rpc_async(np, auio, iosize, thd, cred, iomode, NULL, &req[nextsend]))) {
                                req[nextsend] = NULL;
                                vnode_writedone(vp);
                                nfs_node_lock_force(np);
                                np->n_numoutput--;
                                nfs_node_unlock(np);
                                break;
                        }
                        txaddr += iosize;
                        txoffset += iosize;
                        txsize -= iosize;
                        nextsend = (nextsend + 1) % MAXPAGINGREQS;
                }
                /* wait while we need to and break out if more requests to send */
                while ((rxsize > 0) && req[nextwait]) {
                        iosize = remsize = MIN(nmwsize, rxsize);
                        error = nmp->nm_funcs->nf_write_rpc_async_finish(np, req[nextwait], &iomode, &iosize, &wverf2);
                        req[nextwait] = NULL;
                        nextwait = (nextwait + 1) % MAXPAGINGREQS;
                        vnode_writedone(vp);
                        nfs_node_lock_force(np);
                        np->n_numoutput--;
                        nfs_node_unlock(np);
#if CONFIG_NFS4
                        if ((nmp->nm_vers >= NFS_VER4) && nfs_mount_state_error_should_restart(error)) {
                                lck_mtx_lock(&nmp->nm_lock);
                                if ((error != NFSERR_GRACE) && (stategenid == nmp->nm_stategenid)) {
                                        NP(np, "nfs_vnop_pageout: error %d, initiating recovery", error);
                                        nfs_need_recover(nmp, error);
                                }
                                lck_mtx_unlock(&nmp->nm_lock);
                                restart = 1;
                                goto cancel;
                        }
#endif
                        if (error) {
                                FSDBG(323, rxoffset, rxsize, error, -1);
                                break;
                        }
                        if (!wverfset) {
                                wverf = wverf2;
                                wverfset = 1;
                        } else if (wverf != wverf2) {
                                /* verifier changed, so we need to restart all the writes */
                                vrestart = 1;
                                goto cancel;
                        }
                        /* Retain the lowest commitment level returned. */
                        if (iomode < commit) {
                                commit = iomode;
                        }
                        rxaddr += iosize;
                        rxoffset += iosize;
                        rxsize -= iosize;
                        remsize -= iosize;
                        if (remsize > 0) {
                                /* need to try sending the remainder */
                                iosize = remsize;
                                uio_reset(auio, rxoffset, UIO_SYSSPACE, UIO_WRITE);
                                uio_addiov(auio, CAST_USER_ADDR_T(rxaddr), remsize);
                                iomode = NFS_WRITE_UNSTABLE;
                                error = nfs_write_rpc2(np, auio, thd, cred, &iomode, &wverf2);
#if CONFIG_NFS4
                                if ((nmp->nm_vers >= NFS_VER4) && nfs_mount_state_error_should_restart(error)) {
                                        NP(np, "nfs_vnop_pageout: restart: error %d", error);
                                        lck_mtx_lock(&nmp->nm_lock);
                                        if ((error != NFSERR_GRACE) && (stategenid == nmp->nm_stategenid)) {
                                                NP(np, "nfs_vnop_pageout: error %d, initiating recovery", error);
                                                nfs_need_recover(nmp, error);
                                        }
                                        lck_mtx_unlock(&nmp->nm_lock);
                                        restart = 1;
                                        goto cancel;
                                }
#endif
                                if (error) {
                                        FSDBG(323, rxoffset, rxsize, error, -1);
                                        break;
                                }
                                if (wverf != wverf2) {
                                        /* verifier changed, so we need to restart all the writes */
                                        vrestart = 1;
                                        goto cancel;
                                }
                                if (iomode < commit) {
                                        commit = iomode;
                                }
                                rxaddr += iosize;
                                rxoffset += iosize;
                                rxsize -= iosize;
                        }
                        if (txsize) {
                                break;
                        }
                }
        } while (!error && (txsize || rxsize));

        vrestart = 0;

        if (!error && (commit != NFS_WRITE_FILESYNC)) {
                error = nmp->nm_funcs->nf_commit_rpc(np, f_offset, xsize, cred, wverf);
                if (error == NFSERR_STALEWRITEVERF) {
                        vrestart = 1;
                        error = EIO;
                }
        }

        if (error) {
cancel:
                /* cancel any outstanding requests */
                while (req[nextwait]) {
                        nfs_request_async_cancel(req[nextwait]);
                        req[nextwait] = NULL;
                        nextwait = (nextwait + 1) % MAXPAGINGREQS;
                        vnode_writedone(vp);
                        nfs_node_lock_force(np);
                        np->n_numoutput--;
                        nfs_node_unlock(np);
                }
                if (np->n_flag & NREVOKE) {
                        error = EIO;
                } else {
                        if (vrestart) {
                                if (++vrestarts <= 100) { /* guard against no progress */
                                        goto tryagain;
                                }
                                NP(np, "nfs_pageout: too many restarts, aborting");
                                FSDBG(323, f_offset, xsize, ERESTART, -1);
                        }
                        if (restart) {
                                if (restarts <= nfs_mount_state_max_restarts(nmp)) { /* guard against no progress */
                                        if (error == NFSERR_GRACE) {
                                                tsleep(&nmp->nm_state, (PZERO - 1), "nfsgrace", 2 * hz);
                                        }
                                        if (!(error = nfs_mount_state_wait_for_recovery(nmp))) {
                                                goto tryagain;
                                        }
                                } else {
                                        NP(np, "nfs_pageout: too many restarts, aborting");
                                        FSDBG(323, f_offset, xsize, ERESTART, -1);
                                }
                        }
                }
        }

        ubc_upl_unmap(pl);

        /*
         * We've had several different solutions on what to do when the pageout
         * gets an error. If we don't handle it, and return an error to the
         * caller, vm, it will retry . This can end in endless looping
         * between vm and here doing retries of the same page. Doing a dump
         * back to vm, will get it out of vm's knowledge and we lose whatever
         * data existed. This is risky, but in some cases necessary. For
         * example, the initial fix here was to do that for ESTALE. In that case
         * the server is telling us that the file is no longer the same. We
         * would not want to keep paging out to that. We also saw some 151
         * errors from Auspex server and NFSv3 can return errors higher than
         * ELAST. Those along with NFS known server errors we will "dump" from
         * vm.  Errors we don't expect to occur, we dump and log for further
         * analysis. Errors that could be transient, networking ones,
         * we let vm "retry". Lastly, errors that we retry, but may have potential
         * to storm the network, we "retrywithsleep". "sever" will be used in
         * in the future to dump all pages of object for cases like ESTALE.
         * All this is the basis for the states returned and first guesses on
         * error handling. Tweaking expected as more statistics are gathered.
         * Note, in the long run we may need another more robust solution to
         * have some kind of persistant store when the vm cannot dump nor keep
         * retrying as a solution, but this would be a file architectural change
         */
        if (!nofreeupl) { /* otherwise stacked file system has to handle this */
                if (error) {
                        int abortflags = 0;
                        char action = nfs_pageouterrorhandler(error);

                        switch (action) {
                        case DUMP:
                                abortflags = UPL_ABORT_DUMP_PAGES | UPL_ABORT_FREE_ON_EMPTY;
                                break;
                        case DUMPANDLOG:
                                abortflags = UPL_ABORT_DUMP_PAGES | UPL_ABORT_FREE_ON_EMPTY;
                                if (error <= NFS_ELAST) {
                                        if ((errorcount[error] % 100) == 0) {
                                                NP(np, "nfs_pageout: unexpected error %d. dumping vm page", error);
                                        }
                                        errorcount[error]++;
                                }
                                break;
                        case RETRY:
                                abortflags = UPL_ABORT_FREE_ON_EMPTY;
                                break;
                        case SEVER:         /* not implemented */
                        default:
                                NP(np, "nfs_pageout: action %d not expected", action);
                                break;
                        }

                        ubc_upl_abort_range(pl, pl_offset, pgsize, abortflags);
                        /* return error in all cases above */
                } else {
                        ubc_upl_commit_range(pl, pl_offset, pgsize,
                            UPL_COMMIT_CLEAR_DIRTY |
                            UPL_COMMIT_FREE_ON_EMPTY);
                }
        }
        return error;
}

/* Blktooff derives file offset given a logical block number */
int
nfs_vnop_blktooff(
        struct vnop_blktooff_args /* {
                                   *  struct vnodeop_desc *a_desc;
                                   *  vnode_t a_vp;
                                   *  daddr64_t a_lblkno;
                                   *  off_t *a_offset;
                                   *  } */*ap)
{
        int biosize;
        vnode_t vp = ap->a_vp;
        struct nfsmount *nmp = VTONMP(vp);

        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        biosize = nmp->nm_biosize;

        *ap->a_offset = (off_t)(ap->a_lblkno * biosize);

        return 0;
}

int
nfs_vnop_offtoblk(
        struct vnop_offtoblk_args /* {
                                   *  struct vnodeop_desc *a_desc;
                                   *  vnode_t a_vp;
                                   *  off_t a_offset;
                                   *  daddr64_t *a_lblkno;
                                   *  } */*ap)
{
        int biosize;
        vnode_t vp = ap->a_vp;
        struct nfsmount *nmp = VTONMP(vp);

        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }
        biosize = nmp->nm_biosize;

        *ap->a_lblkno = (daddr64_t)(ap->a_offset / biosize);

        return 0;
}

/*
 * vnode change monitoring
 */
int
nfs_vnop_monitor(
        struct vnop_monitor_args /* {
                                  *  struct vnodeop_desc *a_desc;
                                  *  vnode_t a_vp;
                                  *  uint32_t a_events;
                                  *  uint32_t a_flags;
                                  *  void *a_handle;
                                  *  vfs_context_t a_context;
                                  *  } */*ap)
{
        nfsnode_t np = VTONFS(ap->a_vp);
        struct nfsmount *nmp = VTONMP(ap->a_vp);
        int error = 0;

        if (nfs_mount_gone(nmp)) {
                return ENXIO;
        }

        /* make sure that the vnode's monitoring status is up to date */
        lck_mtx_lock(&nmp->nm_lock);
        if (vnode_ismonitored(ap->a_vp)) {
                /* This vnode is currently being monitored, make sure we're tracking it. */
                if (np->n_monlink.le_next == NFSNOLIST) {
                        LIST_INSERT_HEAD(&nmp->nm_monlist, np, n_monlink);
                        nfs_mount_sock_thread_wake(nmp);
                }
        } else {
                /* This vnode is no longer being monitored, make sure we're not tracking it. */
                /* Wait for any in-progress getattr to complete first. */
                while (np->n_mflag & NMMONSCANINPROG) {
                        struct timespec ts = { .tv_sec = 1, .tv_nsec = 0 };
                        np->n_mflag |= NMMONSCANWANT;
                        msleep(&np->n_mflag, &nmp->nm_lock, PZERO - 1, "nfswaitmonscan", &ts);
                }
                if (np->n_monlink.le_next != NFSNOLIST) {
                        LIST_REMOVE(np, n_monlink);
                        np->n_monlink.le_next = NFSNOLIST;
                }
        }
        lck_mtx_unlock(&nmp->nm_lock);

        return error;
}

/*
 * Send a vnode notification for the given events.
 */
void
nfs_vnode_notify(nfsnode_t np, uint32_t events)
{
        struct nfsmount *nmp = NFSTONMP(np);
        struct nfs_vattr nvattr;
        struct vnode_attr vattr, *vap = NULL;
        struct timeval now;

        microuptime(&now);
        if ((np->n_evtstamp == now.tv_sec) || !nmp) {
                /* delay sending this notify */
                np->n_events |= events;
                return;
        }
        events |= np->n_events;
        np->n_events = 0;
        np->n_evtstamp = now.tv_sec;

        vfs_get_notify_attributes(&vattr);
        if (!nfs_getattrcache(np, &nvattr, 0)) {
                vap = &vattr;
                VATTR_INIT(vap);

                VATTR_RETURN(vap, va_fsid, vfs_statfs(nmp->nm_mountp)->f_fsid.val[0]);
                VATTR_RETURN(vap, va_fileid, nvattr.nva_fileid);
                VATTR_RETURN(vap, va_mode, nvattr.nva_mode);
                VATTR_RETURN(vap, va_uid, nvattr.nva_uid);
                VATTR_RETURN(vap, va_gid, nvattr.nva_gid);
                VATTR_RETURN(vap, va_nlink, nvattr.nva_nlink);
        }
        vnode_notify(NFSTOV(np), events, vap);
}

#endif /* CONFIG_NFS_CLIENT */