xnu-1504.15.3.tar.gz

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

/*
 * Copyright (c) 2000-2009 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, 1991, 1993, 1995
 *      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_socket.c        8.5 (Berkeley) 3/30/95
 * FreeBSD-Id: nfs_socket.c,v 1.30 1997/10/28 15:59:07 bde Exp $
 */

/*
 * Socket operations for use by nfs
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kauth.h>
#include <sys/mount_internal.h>
#include <sys/kernel.h>
#include <sys/kpi_mbuf.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/tprintf.h>
#include <libkern/OSAtomic.h>

#include <sys/time.h>
#include <kern/clock.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <kern/thread_call.h>
#include <sys/user.h>

#include <netinet/in.h>
#include <netinet/tcp.h>

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

/* XXX */
boolean_t       current_thread_aborted(void);
kern_return_t   thread_terminate(thread_t);


#if NFSSERVER
int nfsrv_sock_max_rec_queue_length = 128; /* max # RPC records queued on (UDP) socket */

int nfsrv_getstream(struct nfsrv_sock *,int);
int nfsrv_getreq(struct nfsrv_descript *);
extern int nfsv3_procid[NFS_NPROCS];
#endif /* NFSSERVER */

#if NFSCLIENT

int     nfs_reconnect(struct nfsmount *);
int     nfs_connect_setup(struct nfsmount *);
void    nfs_mount_sock_thread(void *, wait_result_t);
void    nfs_udp_rcv(socket_t, void*, int);
void    nfs_tcp_rcv(socket_t, void*, int);
void    nfs_sock_poke(struct nfsmount *);
void    nfs_request_match_reply(struct nfsmount *, mbuf_t);
void    nfs_reqdequeue(struct nfsreq *);
void    nfs_reqbusy(struct nfsreq *);
struct nfsreq *nfs_reqnext(struct nfsreq *);
int     nfs_wait_reply(struct nfsreq *);
void    nfs_softterm(struct nfsreq *);

#ifdef NFS_SOCKET_DEBUGGING
#define NFS_SOCK_DBG(X) printf X
#else
#define NFS_SOCK_DBG(X)
#endif

/*
 * Estimate rto for an nfs rpc sent via. an unreliable datagram.
 * Use the mean and mean deviation of rtt for the appropriate type of rpc
 * for the frequent rpcs and a default for the others.
 * The justification for doing "other" this way is that these rpcs
 * happen so infrequently that timer est. would probably be stale.
 * Also, since many of these rpcs are
 * non-idempotent, a conservative timeout is desired.
 * getattr, lookup - A+2D
 * read, write     - A+4D
 * other           - nm_timeo
 */
#define NFS_RTO(n, t) \
        ((t) == 0 ? (n)->nm_timeo : \
         ((t) < 3 ? \
          (((((n)->nm_srtt[t-1] + 3) >> 2) + (n)->nm_sdrtt[t-1] + 1) >> 1) : \
          ((((n)->nm_srtt[t-1] + 7) >> 3) + (n)->nm_sdrtt[t-1] + 1)))
#define NFS_SRTT(r)     (r)->r_nmp->nm_srtt[proct[(r)->r_procnum] - 1]
#define NFS_SDRTT(r)    (r)->r_nmp->nm_sdrtt[proct[(r)->r_procnum] - 1]

/*
 * Defines which timer to use for the procnum.
 * 0 - default
 * 1 - getattr
 * 2 - lookup
 * 3 - read
 * 4 - write
 */
static int proct[NFS_NPROCS] = {
        0, 1, 0, 2, 1, 3, 3, 4, 0, 0, 0, 0, 0, 0, 0, 0, 3, 3, 0, 0, 0, 0, 0
};

/*
 * There is a congestion window for outstanding rpcs maintained per mount
 * point. The cwnd size is adjusted in roughly the way that:
 * Van Jacobson, Congestion avoidance and Control, In "Proceedings of
 * SIGCOMM '88". ACM, August 1988.
 * describes for TCP. The cwnd size is chopped in half on a retransmit timeout
 * and incremented by 1/cwnd when each rpc reply is received and a full cwnd
 * of rpcs is in progress.
 * (The sent count and cwnd are scaled for integer arith.)
 * Variants of "slow start" were tried and were found to be too much of a
 * performance hit (ave. rtt 3 times larger),
 * I suspect due to the large rtt that nfs rpcs have.
 */
#define NFS_CWNDSCALE   256
#define NFS_MAXCWND     (NFS_CWNDSCALE * 32)
static int nfs_backoff[8] = { 2, 4, 8, 16, 32, 64, 128, 256, };

/*
 * Initialize socket state and perform setup for a new NFS connection.
 */
int
nfs_connect(struct nfsmount *nmp, int verbose)
{
        socket_t so;
        int error, on = 1, proto;
        sock_upcall upcall;
        struct sockaddr *saddr;
        struct sockaddr_in sin;
        struct timeval timeo;

        lck_mtx_lock(&nmp->nm_lock);
        nmp->nm_sockflags |= NMSOCK_CONNECTING;
        saddr = mbuf_data(nmp->nm_nam);
        upcall = (nmp->nm_sotype == SOCK_STREAM) ? nfs_tcp_rcv : nfs_udp_rcv;
        lck_mtx_unlock(&nmp->nm_lock);
        error = sock_socket(saddr->sa_family, nmp->nm_sotype,
                            nmp->nm_soproto, upcall, nmp, &nmp->nm_so);
        if (error)
                goto bad;
        lck_mtx_lock(&nmp->nm_lock);
        so = nmp->nm_so;

        /*
         * Some servers require that the client port be a reserved port number.
         */
        if (saddr->sa_family == AF_INET && (nmp->nm_flag & NFSMNT_RESVPORT)) {
                int portrange = IP_PORTRANGE_LOW;
                error = sock_setsockopt(so, IPPROTO_IP, IP_PORTRANGE, &portrange, sizeof(portrange));
                if (!error) {   /* bind now to check for failure */
                        sin.sin_len = sizeof (struct sockaddr_in);
                        sin.sin_family = AF_INET;
                        sin.sin_addr.s_addr = INADDR_ANY;
                        sin.sin_port = 0;
                        error = sock_bind(so, (struct sockaddr *) &sin);
                }
                if (error) {
                        lck_mtx_unlock(&nmp->nm_lock);
                        goto bad;
                }
        }

        /*
         * Protocols that do not require connections may be optionally left
         * unconnected for servers that reply from a different address/port.
         */
        if (nmp->nm_flag & NFSMNT_NOCONN) {
                if (nmp->nm_sotype == SOCK_STREAM) {
                        error = ENOTCONN;
                        lck_mtx_unlock(&nmp->nm_lock);
                        goto bad;
                }
        } else {
                int tocnt = 0, optlen = sizeof(error);
                struct timespec ts = { 1, 0 };

                lck_mtx_unlock(&nmp->nm_lock);
                error = sock_connect(so, mbuf_data(nmp->nm_nam), MSG_DONTWAIT);
                if (error && (error != EINPROGRESS))
                        goto bad;
                lck_mtx_lock(&nmp->nm_lock);
                while (!sock_isconnected(so)) {
                        nfs_mount_check_dead_timeout(nmp);
                        if ((tocnt++ == 30) && verbose) /* log a warning if connect is taking a while */
                                log(LOG_INFO, "nfs_connect: socket connect taking a while for %s\n",
                                        vfs_statfs(nmp->nm_mountp)->f_mntfromname);
                        /* check for error on socket */
                        sock_getsockopt(so, SOL_SOCKET, SO_ERROR, &error, &optlen);
                        if (error) {
                                if (verbose)
                                        log(LOG_INFO, "nfs_connect: socket error %d for %s\n",
                                                error, vfs_statfs(nmp->nm_mountp)->f_mntfromname);
                                break;
                        }
                        /* abort if this is taking too long or we're unmounting */
                        if ((tocnt > 120) || (nmp->nm_sockflags & NMSOCK_UNMOUNT)) {
                                error = ENOTCONN;
                                break;
                        }
                        if ((error = nfs_sigintr(nmp, NULL, current_thread(), 1)))
                                break;
                        msleep(&nmp->nm_so, &nmp->nm_lock, PSOCK, "nfs_socket_connect", &ts);
                }
                if ((tocnt > 30) && verbose)
                        log(LOG_INFO, "nfs_connect: socket connect %s for %s\n",
                                error ? "aborted" : "completed",
                                vfs_statfs(nmp->nm_mountp)->f_mntfromname);
                if (error) {
                        lck_mtx_unlock(&nmp->nm_lock);
                        goto bad;
                }
        }

        /*
         * Set socket send/receive timeouts
         * - Receive timeout shouldn't matter because all receives are performed
         *   in the socket upcall non-blocking.
         * - Send timeout should allow us to react to a blocked socket.
         *   Soft mounts will want to abort sooner.
         */
        timeo.tv_usec = 0;
        timeo.tv_sec = (nmp->nm_flag & NFSMNT_SOFT) ? 10 : 60;
        error |= sock_setsockopt(so, SOL_SOCKET, SO_RCVTIMEO, &timeo, sizeof(timeo));
        error |= sock_setsockopt(so, SOL_SOCKET, SO_SNDTIMEO, &timeo, sizeof(timeo));
        if (error) {
                log(LOG_INFO, "nfs_connect: socket timeout setting errors for %s\n",
                        vfs_statfs(nmp->nm_mountp)->f_mntfromname);
                error = 0;
        }

        if (nmp->nm_sotype == SOCK_STREAM) {
                /* Assume that SOCK_STREAM always requires a connection */
                sock_setsockopt(so, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on));
                /* set nodelay for TCP */
                sock_gettype(so, NULL, NULL, &proto);
                if (proto == IPPROTO_TCP)
                        sock_setsockopt(so, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
        }

        if (nmp->nm_sotype == SOCK_DGRAM) { /* set socket buffer sizes for UDP */
                int reserve = NFS_UDPSOCKBUF;
                error |= sock_setsockopt(so, SOL_SOCKET, SO_SNDBUF, &reserve, sizeof(reserve));
                error |= sock_setsockopt(so, SOL_SOCKET, SO_RCVBUF, &reserve, sizeof(reserve));
                if (error) {
                        log(LOG_INFO, "nfs_connect: socket buffer setting errors for %s\n",
                                vfs_statfs(nmp->nm_mountp)->f_mntfromname);
                        error = 0;
                }
        }

        /* set SO_NOADDRERR to detect network changes ASAP */
        error = sock_setsockopt(so, SOL_SOCKET, SO_NOADDRERR, &on, sizeof(on));
        if (error) {
                lck_mtx_unlock(&nmp->nm_lock);
                goto bad;
        }
        /* just playin' it safe */
        sock_setsockopt(so, SOL_SOCKET, SO_UPCALLCLOSEWAIT, &on, sizeof(on));

        if (!(nmp->nm_flag & NFSMNT_INT))
                sock_nointerrupt(so, 1);

        /* Initialize socket state variables */
        nmp->nm_srtt[0] = nmp->nm_srtt[1] = nmp->nm_srtt[2] =
                nmp->nm_srtt[3] = (NFS_TIMEO << 3);
        nmp->nm_sdrtt[0] = nmp->nm_sdrtt[1] = nmp->nm_sdrtt[2] =
                nmp->nm_sdrtt[3] = 0;
        if (nmp->nm_sotype == SOCK_DGRAM) {
                /* XXX do we really want to reset this on each reconnect? */
                nmp->nm_cwnd = NFS_MAXCWND / 2;     /* Initial send window */
                nmp->nm_sent = 0;
        } else if (nmp->nm_sotype == SOCK_STREAM) {
                nmp->nm_markerleft = sizeof(nmp->nm_fragleft);
                nmp->nm_fragleft = nmp->nm_reclen = 0;
                nmp->nm_timeouts = 0;
        }
        nmp->nm_sockflags &= ~NMSOCK_CONNECTING;
        nmp->nm_sockflags |= NMSOCK_SETUP;
        FSDBG(529, nmp, nmp->nm_state, nmp->nm_flag, nmp->nm_cwnd);
        lck_mtx_unlock(&nmp->nm_lock);
        error = nfs_connect_setup(nmp);
bad:
        lck_mtx_lock(&nmp->nm_lock);
        nmp->nm_sockflags &= ~(NMSOCK_CONNECTING|NMSOCK_SETUP);
        if (!error) {
                nmp->nm_sockflags |= NMSOCK_READY;
                wakeup(&nmp->nm_sockflags);
        }
        lck_mtx_unlock(&nmp->nm_lock);
        return (error);
}

/* setup & confirm socket connection is functional */
int
nfs_connect_setup(struct nfsmount *nmp)
{
        struct nfsm_chain nmreq, nmrep;
        int error = 0, status;
        u_int64_t xid;

        if (nmp->nm_vers >= NFS_VER4) {
                error = nfs4_setclientid(nmp);
                if (error)
                        return (error);
                error = nfs4_renew(nmp, R_SETUP);
                if ((error == NFSERR_ADMIN_REVOKED) ||
                    (error == NFSERR_EXPIRED) ||
                    (error == NFSERR_LEASE_MOVED) ||
                    (error == NFSERR_STALE_CLIENTID)) {
                        lck_mtx_lock(&nmp->nm_lock);
                        nmp->nm_state |= NFSSTA_RECOVER;
                        lck_mtx_unlock(&nmp->nm_lock);
                }
        } else {
                /* verify connection's OK by sending a NULL request */
                nfsm_chain_null(&nmreq);
                nfsm_chain_null(&nmrep);
                nfsm_chain_build_alloc_init(error, &nmreq, 0);
                nfsm_chain_build_done(error, &nmreq);
                nfsmout_if(error);
                error = nfs_request2(NULL, nmp->nm_mountp, &nmreq, NFSPROC_NULL,
                                current_thread(), NULL, R_SETUP, &nmrep, &xid, &status);
                if (!error)
                        error = status;
nfsmout:
                nfsm_chain_cleanup(&nmreq);
                nfsm_chain_cleanup(&nmrep);
        }
        return (error);
}

/*
 * NFS socket reconnect routine:
 * Called when a connection is broken.
 * - disconnect the old socket
 * - nfs_connect() again
 * - set R_MUSTRESEND for all outstanding requests on mount point
 * If this fails the mount point is DEAD!
 */
int
nfs_reconnect(struct nfsmount *nmp)
{
        struct nfsreq *rq;
        struct timeval now;
        thread_t thd = current_thread();
        int error, wentdown = 0, verbose = 1;
        time_t lastmsg;

        microuptime(&now);
        lastmsg = now.tv_sec - (nmp->nm_tprintf_delay - nmp->nm_tprintf_initial_delay);

        nfs_disconnect(nmp);

        while ((error = nfs_connect(nmp, verbose))) {
                verbose = 0;
                nfs_disconnect(nmp);
                if (error == EINTR || error == ERESTART)
                        return (EINTR);
                if (error == EIO)
                        return (EIO);
                microuptime(&now);
                if ((lastmsg + nmp->nm_tprintf_delay) < now.tv_sec) {
                        lastmsg = now.tv_sec;
                        nfs_down(nmp, thd, error, NFSSTA_TIMEO, "can not connect");
                        wentdown = 1;
                }
                lck_mtx_lock(&nmp->nm_lock);
                if (!(nmp->nm_state & NFSSTA_MOUNTED)) {
                        /* we're not yet completely mounted and */
                        /* we can't reconnect, so we fail */
                        lck_mtx_unlock(&nmp->nm_lock);
                        return (error);
                }
                nfs_mount_check_dead_timeout(nmp);
                if ((error = nfs_sigintr(nmp, NULL, thd, 1))) {
                        lck_mtx_unlock(&nmp->nm_lock);
                        return (error);
                }
                lck_mtx_unlock(&nmp->nm_lock);
                tsleep(&lbolt, PSOCK, "nfs_reconnect_delay", 0);
                if ((error = nfs_sigintr(nmp, NULL, thd, 0)))
                        return (error);
        }

        if (wentdown)
                nfs_up(nmp, thd, NFSSTA_TIMEO, "connected");

        /*
         * Loop through outstanding request list and mark all requests
         * as needing a resend.  (Though nfs_need_reconnect() probably
         * marked them all already.)
         */
        lck_mtx_lock(nfs_request_mutex);
        TAILQ_FOREACH(rq, &nfs_reqq, r_chain) {
                if (rq->r_nmp == nmp) {
                        lck_mtx_lock(&rq->r_mtx);
                        if (!rq->r_error && !rq->r_nmrep.nmc_mhead && !(rq->r_flags & R_MUSTRESEND)) {
                                rq->r_flags |= R_MUSTRESEND;
                                rq->r_rtt = -1;
                                wakeup(rq);
                                if ((rq->r_flags & (R_ASYNC|R_ASYNCWAIT|R_SENDING)) == R_ASYNC)
                                        nfs_asyncio_resend(rq);
                        }
                        lck_mtx_unlock(&rq->r_mtx);
                }
        }
        lck_mtx_unlock(nfs_request_mutex);
        return (0);
}

/*
 * NFS disconnect. Clean up and unlink.
 */
void
nfs_disconnect(struct nfsmount *nmp)
{
        socket_t so;

        lck_mtx_lock(&nmp->nm_lock);
        if ((nmp->nm_sotype == SOCK_STREAM) && nmp->nm_m) {
                mbuf_freem(nmp->nm_m);
                nmp->nm_m = nmp->nm_mlast = NULL;
        }
        if (nmp->nm_so) {
                so = nmp->nm_so;
                nmp->nm_so = NULL;
                lck_mtx_unlock(&nmp->nm_lock);
                sock_shutdown(so, SHUT_RDWR);
                sock_close(so);
        } else {
                lck_mtx_unlock(&nmp->nm_lock);
        }
}

/*
 * mark an NFS mount as needing a reconnect/resends.
 */
void
nfs_need_reconnect(struct nfsmount *nmp)
{
        struct nfsreq *rq;

        lck_mtx_lock(&nmp->nm_lock);
        nmp->nm_sockflags &= ~(NMSOCK_READY|NMSOCK_SETUP);
        lck_mtx_unlock(&nmp->nm_lock);

        /*
         * Loop through outstanding request list and
         * mark all requests as needing a resend.
         */
        lck_mtx_lock(nfs_request_mutex);
        TAILQ_FOREACH(rq, &nfs_reqq, r_chain) {
                if (rq->r_nmp == nmp) {
                        lck_mtx_lock(&rq->r_mtx);
                        if (!rq->r_error && !rq->r_nmrep.nmc_mhead && !(rq->r_flags & R_MUSTRESEND)) {
                                rq->r_flags |= R_MUSTRESEND;
                                rq->r_rtt = -1;
                                wakeup(rq);
                                if ((rq->r_flags & (R_ASYNC|R_ASYNCWAIT|R_SENDING)) == R_ASYNC)
                                        nfs_asyncio_resend(rq);
                        }
                        lck_mtx_unlock(&rq->r_mtx);
                }
        }
        lck_mtx_unlock(nfs_request_mutex);
}

/*
 * thread to handle miscellaneous async NFS socket work (reconnects/resends)
 */
void
nfs_mount_sock_thread(void *arg, __unused wait_result_t wr)
{
        struct nfsmount *nmp = arg;
        struct timespec ts = { 30, 0 };
        thread_t thd = current_thread();
        struct nfsreq *req;
        struct timeval now;
        int error, dofinish, force;
        nfsnode_t np;
        fhandle_t fh;
        nfs_stateid dstateid;

        lck_mtx_lock(&nmp->nm_lock);

        while (!(nmp->nm_sockflags & NMSOCK_READY) ||
               !TAILQ_EMPTY(&nmp->nm_resendq) ||
               nmp->nm_deadto_start ||
               ((nmp->nm_vers >= NFS_VER4) &&
                        ((nmp->nm_state & NFSSTA_RECOVER) || !TAILQ_EMPTY(&nmp->nm_recallq))))
        {
                if (nmp->nm_sockflags & NMSOCK_UNMOUNT)
                        break;
                force = (nmp->nm_state & NFSSTA_FORCE);
                /* do reconnect, if necessary */
                if (!(nmp->nm_sockflags & NMSOCK_READY) && !force) {
                        if (nmp->nm_reconnect_start <= 0) {
                                microuptime(&now);
                                nmp->nm_reconnect_start = now.tv_sec;
                        }
                        lck_mtx_unlock(&nmp->nm_lock);
                        NFS_SOCK_DBG(("nfs reconnect %s\n", vfs_statfs(nmp->nm_mountp)->f_mntfromname));
                        if (nfs_reconnect(nmp) == 0)
                                nmp->nm_reconnect_start = 0;
                        lck_mtx_lock(&nmp->nm_lock);
                }
                if ((nmp->nm_sockflags & NMSOCK_READY) &&
                    (nmp->nm_state & NFSSTA_RECOVER) &&
                    !(nmp->nm_sockflags & NMSOCK_UNMOUNT) && !force) {
                        /* perform state recovery */
                        lck_mtx_unlock(&nmp->nm_lock);
                        nfs4_recover(nmp);
                        lck_mtx_lock(&nmp->nm_lock);
                }
                /* handle NFSv4 delegation recalls */
                while ((nmp->nm_vers >= NFS_VER4) && !force &&
                       (nmp->nm_sockflags & NMSOCK_READY) && !(nmp->nm_state & NFSSTA_RECOVER) &&
                       ((np = TAILQ_FIRST(&nmp->nm_recallq)))) {
                        TAILQ_REMOVE(&nmp->nm_recallq, np, n_dlink);
                        np->n_dlink.tqe_next = NFSNOLIST;
                        lck_mtx_unlock(&nmp->nm_lock);
                        lck_mtx_lock(&np->n_openlock);
                        dstateid = np->n_dstateid;
                        if (np->n_openflags & N_DELEG_MASK) {
                                fh.fh_len = np->n_fhsize;
                                bcopy(np->n_fhp, &fh.fh_data, fh.fh_len);
                                np->n_openflags &= ~N_DELEG_MASK;
                                lck_mtx_unlock(&np->n_openlock);
                                nfs4_delegreturn_rpc(nmp, fh.fh_data, fh.fh_len, &dstateid, thd, nmp->nm_mcred);
                        } else {
                                lck_mtx_unlock(&np->n_openlock);
                        }
                        lck_mtx_lock(&nmp->nm_lock);
                }
                /* do resends, if necessary/possible */
                while ((((nmp->nm_sockflags & NMSOCK_READY) && !(nmp->nm_state & NFSSTA_RECOVER)) || force) &&
                       ((req = TAILQ_FIRST(&nmp->nm_resendq)))) {
                        if (req->r_resendtime)
                                microuptime(&now);
                        while (req && !force && req->r_resendtime && (now.tv_sec < req->r_resendtime))
                                req = TAILQ_NEXT(req, r_rchain);
                        if (!req)
                                break;
                        TAILQ_REMOVE(&nmp->nm_resendq, req, r_rchain);
                        req->r_rchain.tqe_next = NFSREQNOLIST;
                        lck_mtx_unlock(&nmp->nm_lock);
                        lck_mtx_lock(&req->r_mtx);
                        if (req->r_error || req->r_nmrep.nmc_mhead) {
                                dofinish = req->r_callback.rcb_func && !(req->r_flags & R_WAITSENT);
                                req->r_flags &= ~R_RESENDQ;
                                wakeup(req);
                                lck_mtx_unlock(&req->r_mtx);
                                if (dofinish)
                                        nfs_asyncio_finish(req);
                                lck_mtx_lock(&nmp->nm_lock);
                                continue;
                        }
                        if ((req->r_flags & R_RESTART) || req->r_gss_ctx) {
                                req->r_flags &= ~R_RESTART;
                                req->r_resendtime = 0;
                                lck_mtx_unlock(&req->r_mtx);
                                /* async RPCs on GSS mounts need to be rebuilt and resent. */
                                nfs_reqdequeue(req);
                                if (req->r_gss_ctx) {
                                        nfs_gss_clnt_rpcdone(req);
                                        error = nfs_gss_clnt_args_restore(req);
                                        if (error == ENEEDAUTH)
                                                req->r_xid = 0;
                                }
                                NFS_SOCK_DBG(("nfs async%s restart: p %d x 0x%llx f 0x%x rtt %d\n",
                                        req->r_gss_ctx ? " gss" : "", req->r_procnum, req->r_xid,
                                        req->r_flags, req->r_rtt));
                                error = !req->r_nmp ? ENXIO : 0;        /* unmounted? */
                                if (!error)
                                        error = nfs_sigintr(nmp, req, req->r_thread, 0);
                                if (!error)
                                        error = nfs_request_add_header(req);
                                if (!error)
                                        error = nfs_request_send(req, 0);
                                lck_mtx_lock(&req->r_mtx);
                                if (req->r_flags & R_RESENDQ)
                                        req->r_flags &= ~R_RESENDQ;
                                if (error)
                                        req->r_error = error;
                                wakeup(req);
                                dofinish = error && req->r_callback.rcb_func && !(req->r_flags & R_WAITSENT);
                                lck_mtx_unlock(&req->r_mtx);
                                if (dofinish)
                                        nfs_asyncio_finish(req);
                                lck_mtx_lock(&nmp->nm_lock);
                                error = 0;
                                continue;
                        }
                        NFS_SOCK_DBG(("nfs async resend: p %d x 0x%llx f 0x%x rtt %d\n",
                                req->r_procnum, req->r_xid, req->r_flags, req->r_rtt));
                        error = !req->r_nmp ? ENXIO : 0;        /* unmounted? */
                        if (!error)
                                error = nfs_sigintr(nmp, req, req->r_thread, 0);
                        if (!error) {
                                req->r_flags |= R_SENDING;
                                lck_mtx_unlock(&req->r_mtx);
                                error = nfs_send(req, 0);
                                lck_mtx_lock(&req->r_mtx);
                                if (!error) {
                                        if (req->r_flags & R_RESENDQ)
                                                req->r_flags &= ~R_RESENDQ;
                                        wakeup(req);
                                        lck_mtx_unlock(&req->r_mtx);
                                        lck_mtx_lock(&nmp->nm_lock);
                                        continue;
                                }
                        }
                        req->r_error = error;
                        if (req->r_flags & R_RESENDQ)
                                req->r_flags &= ~R_RESENDQ;
                        wakeup(req);
                        dofinish = req->r_callback.rcb_func && !(req->r_flags & R_WAITSENT);
                        lck_mtx_unlock(&req->r_mtx);
                        if (dofinish)
                                nfs_asyncio_finish(req);
                        lck_mtx_lock(&nmp->nm_lock);
                }
                if (nmp->nm_deadto_start)
                        nfs_mount_check_dead_timeout(nmp);
                if (force || (nmp->nm_state & NFSSTA_DEAD))
                        break;
                if ((nmp->nm_sockflags & NMSOCK_READY) || (nmp->nm_state & NFSSTA_RECOVER)) {
                        if (nmp->nm_deadto_start || !TAILQ_EMPTY(&nmp->nm_resendq) ||
                            (nmp->nm_state & NFSSTA_RECOVER))
                                ts.tv_sec = 1;
                        else
                                ts.tv_sec = 30;
                        msleep(&nmp->nm_sockthd, &nmp->nm_lock, PSOCK, "nfssockthread", &ts);
                }
        }

        /* If we're unmounting, send the unmount RPC, if requested/appropriate. */
        if ((nmp->nm_sockflags & NMSOCK_UNMOUNT) && (nmp->nm_flag & NFSMNT_CALLUMNT) &&
            (nmp->nm_vers < NFS_VER4) && !(nmp->nm_state & (NFSSTA_FORCE|NFSSTA_DEAD))) {
                lck_mtx_unlock(&nmp->nm_lock);
                nfs3_umount_rpc(nmp, vfs_context_kernel(),
                        (nmp->nm_sockflags & NMSOCK_READY) ? 6 : 2);
                lck_mtx_lock(&nmp->nm_lock);
        }

        if (nmp->nm_sockthd == thd)
                nmp->nm_sockthd = NULL;
        lck_mtx_unlock(&nmp->nm_lock);
        wakeup(&nmp->nm_sockthd);
        thread_terminate(thd);
}

/* start or wake a mount's socket thread */
void
nfs_mount_sock_thread_wake(struct nfsmount *nmp)
{
        if (nmp->nm_sockthd)
                wakeup(&nmp->nm_sockthd);
        else if (kernel_thread_start(nfs_mount_sock_thread, nmp, &nmp->nm_sockthd) == KERN_SUCCESS)
                thread_deallocate(nmp->nm_sockthd);
}

/*
 * Check if we should mark the mount dead because the
 * unresponsive mount has reached the dead timeout.
 * (must be called with nmp locked)
 */
void
nfs_mount_check_dead_timeout(struct nfsmount *nmp)
{
        struct timeval now;

        if (!(nmp->nm_flag & NFSMNT_DEADTIMEOUT))
                return;
        if (nmp->nm_deadto_start == 0)
                return;
        if (nmp->nm_state & NFSSTA_DEAD)
                return;
        microuptime(&now);
        if ((now.tv_sec - nmp->nm_deadto_start) < nmp->nm_deadtimeout)
                return;
        printf("nfs server %s: dead\n", vfs_statfs(nmp->nm_mountp)->f_mntfromname);
        nmp->nm_state |= NFSSTA_DEAD;
        vfs_event_signal(&vfs_statfs(nmp->nm_mountp)->f_fsid, VQ_DEAD, 0);
}

/*
 * RPC record marker parsing state
 */
struct nfs_rpc_record_state
{
        uint16_t        nrrs_lastfrag;          /* last fragment of record */
        uint16_t        nrrs_markerleft;        /* marker bytes remaining */
        uint32_t        nrrs_fragleft;          /* fragment bytes remaining */
        uint32_t        nrrs_reclen;            /* length of RPC record */
        mbuf_t          nrrs_m;                 /* mbufs for current record */
        mbuf_t          nrrs_mlast;
};
int nfs_rpc_record_read(socket_t, struct nfs_rpc_record_state *, int *, mbuf_t *);

/*
 * NFS callback channel socket state
 */
struct nfs_callback_socket
{
        TAILQ_ENTRY(nfs_callback_socket) ncbs_link;
        socket_t                        ncbs_so;        /* the socket */
        struct sockaddr_in              ncbs_sin;       /* socket address */
        struct nfs_rpc_record_state     ncbs_rrs;       /* RPC record parsing state */
        time_t                          ncbs_stamp;     /* last accessed at */
        uint32_t                        ncbs_flags;     /* see below */
};
#define NCBSOCK_UPCALL          0x0001
#define NCBSOCK_UPCALLWANT      0x0002
#define NCBSOCK_DEAD            0x0004

/*
 * NFS callback channel state
 *
 * One listening socket for accepting socket connections from servers and
 * a list of connected sockets to handle callback requests on.
 * Mounts registered with the callback channel are assigned IDs and
 * put on a list so that the callback request handling code can match
 * the requests up with mounts.
 */
socket_t nfs4_cb_so = NULL;
in_port_t nfs4_cb_port = 0;
uint32_t nfs4_cb_id = 0;
uint32_t nfs4_cb_so_usecount = 0;
TAILQ_HEAD(nfs4_cb_sock_list,nfs_callback_socket) nfs4_cb_socks;
TAILQ_HEAD(nfs4_cb_mount_list,nfsmount) nfs4_cb_mounts;

int nfs4_cb_handler(struct nfs_callback_socket *, mbuf_t);

/*
 * Set up the callback channel for the NFS mount.
 *
 * Initializes the callback channel socket state and
 * assigns a callback ID to the mount.
 */
void
nfs4_mount_callback_setup(struct nfsmount *nmp)
{
        struct sockaddr_in sin;
        socket_t so = NULL;
        struct timeval timeo;
        int error, on = 1;

        lck_mtx_lock(nfs_global_mutex);
        if (nfs4_cb_id == 0) {
                TAILQ_INIT(&nfs4_cb_mounts);
                TAILQ_INIT(&nfs4_cb_socks);
                nfs4_cb_id++;
        }
        nmp->nm_cbid = nfs4_cb_id++;
        if (nmp->nm_cbid == 0)
                nmp->nm_cbid = nfs4_cb_id++;
        nfs4_cb_so_usecount++;
        TAILQ_INSERT_HEAD(&nfs4_cb_mounts, nmp, nm_cblink);

        if (nfs4_cb_so) {
                lck_mtx_unlock(nfs_global_mutex);
                return;
        }

        error = sock_socket(AF_INET, SOCK_STREAM, IPPROTO_TCP, nfs4_cb_accept, NULL, &nfs4_cb_so);
        if (error) {
                log(LOG_INFO, "nfs callback setup: error %d creating listening socket\n", error);
                goto fail;
        }
        so = nfs4_cb_so;

        sin.sin_len = sizeof(struct sockaddr_in);
        sin.sin_family = AF_INET;
        sin.sin_addr.s_addr = htonl(INADDR_ANY);
        sin.sin_port = 0;
        error = sock_bind(so, (struct sockaddr *)&sin);
        if (error) {
                log(LOG_INFO, "nfs callback setup: error %d binding listening socket\n", error);
                goto fail;
        }
        error = sock_getsockname(so, (struct sockaddr *)&sin, sin.sin_len);
        if (error) {
                log(LOG_INFO, "nfs callback setup: error %d getting listening socket port\n", error);
                goto fail;
        }
        nfs4_cb_port = ntohs(sin.sin_port);

        error = sock_listen(so, 32);
        if (error) {
                log(LOG_INFO, "nfs callback setup: error %d on listen\n", error);
                goto fail;
        }

        /* receive timeout shouldn't matter.  If timeout on send, we'll want to drop the socket */
        timeo.tv_usec = 0;
        timeo.tv_sec = 60;
        error = sock_setsockopt(so, SOL_SOCKET, SO_RCVTIMEO, &timeo, sizeof(timeo));
        if (error)
                log(LOG_INFO, "nfs callback setup: error %d setting socket rx timeout\n", error);
        error = sock_setsockopt(so, SOL_SOCKET, SO_SNDTIMEO, &timeo, sizeof(timeo));
        if (error)
                log(LOG_INFO, "nfs callback setup: error %d setting socket tx timeout\n", error);
        sock_setsockopt(so, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
        sock_setsockopt(so, SOL_SOCKET, SO_NOADDRERR, &on, sizeof(on));
        sock_setsockopt(so, SOL_SOCKET, SO_UPCALLCLOSEWAIT, &on, sizeof(on));
        error = 0;

fail:
        if (error) {
                nfs4_cb_so = NULL;
                lck_mtx_unlock(nfs_global_mutex);
                if (so) {
                        sock_shutdown(so, SHUT_RDWR);
                        sock_close(so);
                }
        } else {
                lck_mtx_unlock(nfs_global_mutex);
        }
}

/*
 * Shut down the callback channel for the NFS mount.
 *
 * Clears the mount's callback ID and releases the mounts
 * reference on the callback socket.  Last reference dropped
 * will also shut down the callback socket(s).
 */
void
nfs4_mount_callback_shutdown(struct nfsmount *nmp)
{
        struct nfs_callback_socket *ncbsp;
        socket_t so;
        struct nfs4_cb_sock_list cb_socks;
        struct timespec ts = {1,0};

        lck_mtx_lock(nfs_global_mutex);
        TAILQ_REMOVE(&nfs4_cb_mounts, nmp, nm_cblink);
        /* wait for any callbacks in progress to complete */
        while (nmp->nm_cbrefs)
                msleep(&nmp->nm_cbrefs, nfs_global_mutex, PSOCK, "cbshutwait", &ts);
        if (--nfs4_cb_so_usecount) {
                lck_mtx_unlock(nfs_global_mutex);
                return;
        }
        so = nfs4_cb_so;
        nfs4_cb_so = NULL;
        TAILQ_INIT(&cb_socks);
        TAILQ_CONCAT(&cb_socks, &nfs4_cb_socks, ncbs_link);
        lck_mtx_unlock(nfs_global_mutex);
        if (so) {
                sock_shutdown(so, SHUT_RDWR);
                sock_close(so);
        }
        while ((ncbsp = TAILQ_FIRST(&cb_socks))) {
                TAILQ_REMOVE(&cb_socks, ncbsp, ncbs_link);
                sock_shutdown(ncbsp->ncbs_so, SHUT_RDWR);
                sock_close(ncbsp->ncbs_so);
                FREE(ncbsp, M_TEMP);
        }
}

/*
 * Check periodically for stale/unused nfs callback sockets
 */
#define NFS4_CB_TIMER_PERIOD    30
#define NFS4_CB_IDLE_MAX        300
void
nfs4_callback_timer(__unused void *param0, __unused void *param1)
{
        struct nfs_callback_socket *ncbsp, *nextncbsp;
        struct timeval now;

loop:
        lck_mtx_lock(nfs_global_mutex);
        if (TAILQ_EMPTY(&nfs4_cb_socks)) {
                nfs4_callback_timer_on = 0;
                lck_mtx_unlock(nfs_global_mutex);
                return;
        }
        microuptime(&now);
        TAILQ_FOREACH_SAFE(ncbsp, &nfs4_cb_socks, ncbs_link, nextncbsp) {
                if (!(ncbsp->ncbs_flags & NCBSOCK_DEAD) &&
                     (now.tv_sec < (ncbsp->ncbs_stamp + NFS4_CB_IDLE_MAX)))
                        continue;
                TAILQ_REMOVE(&nfs4_cb_socks, ncbsp, ncbs_link);
                lck_mtx_unlock(nfs_global_mutex);
                sock_shutdown(ncbsp->ncbs_so, SHUT_RDWR);
                sock_close(ncbsp->ncbs_so);
                FREE(ncbsp, M_TEMP);
                goto loop;
        }
        nfs4_callback_timer_on = 1;
        nfs_interval_timer_start(nfs4_callback_timer_call,
                NFS4_CB_TIMER_PERIOD * 1000);
        lck_mtx_unlock(nfs_global_mutex);
}

/*
 * Accept a new callback socket.
 */
void
nfs4_cb_accept(socket_t so, __unused void *arg, __unused int waitflag)
{
        socket_t newso = NULL;
        struct nfs_callback_socket *ncbsp;
        struct nfsmount *nmp;
        struct timeval timeo, now;
        struct sockaddr_in *saddr;
        int error, on = 1;

        if (so != nfs4_cb_so)
                return;

        /* allocate/initialize a new nfs_callback_socket */
        MALLOC(ncbsp, struct nfs_callback_socket *, sizeof(struct nfs_callback_socket), M_TEMP, M_WAITOK);
        if (!ncbsp) {
                log(LOG_ERR, "nfs callback accept: no memory for new socket\n");
                return;
        }
        bzero(ncbsp, sizeof(*ncbsp));
        ncbsp->ncbs_sin.sin_len = sizeof(struct sockaddr_in);
        ncbsp->ncbs_rrs.nrrs_markerleft = sizeof(ncbsp->ncbs_rrs.nrrs_fragleft);

        /* accept a new socket */
        error = sock_accept(so, (struct sockaddr*)&ncbsp->ncbs_sin,
                        ncbsp->ncbs_sin.sin_len, MSG_DONTWAIT,
                        nfs4_cb_rcv, ncbsp, &newso);
        if (error) {
                log(LOG_INFO, "nfs callback accept: error %d accepting socket\n", error);
                FREE(ncbsp, M_TEMP);
                return;
        }

        /* set up the new socket */
        /* receive timeout shouldn't matter.  If timeout on send, we'll want to drop the socket */
        timeo.tv_usec = 0;
        timeo.tv_sec = 60;
        error = sock_setsockopt(newso, SOL_SOCKET, SO_RCVTIMEO, &timeo, sizeof(timeo));
        if (error)
                log(LOG_INFO, "nfs callback socket: error %d setting socket rx timeout\n", error);
        error = sock_setsockopt(newso, SOL_SOCKET, SO_SNDTIMEO, &timeo, sizeof(timeo));
        if (error)
                log(LOG_INFO, "nfs callback socket: error %d setting socket tx timeout\n", error);
        sock_setsockopt(newso, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
        sock_setsockopt(newso, SOL_SOCKET, SO_NOADDRERR, &on, sizeof(on));
        sock_setsockopt(newso, SOL_SOCKET, SO_UPCALLCLOSEWAIT, &on, sizeof(on));

        ncbsp->ncbs_so = newso;
        microuptime(&now);
        ncbsp->ncbs_stamp = now.tv_sec;

        lck_mtx_lock(nfs_global_mutex);

        /* add it to the list */
        TAILQ_INSERT_HEAD(&nfs4_cb_socks, ncbsp, ncbs_link);

        /* verify it's from a host we have mounted */
        TAILQ_FOREACH(nmp, &nfs4_cb_mounts, nm_cblink) {
                /* check socket's source address matches this mount's server address */
                saddr = mbuf_data(nmp->nm_nam);
                if ((ncbsp->ncbs_sin.sin_len == saddr->sin_len) &&
                    (ncbsp->ncbs_sin.sin_family == saddr->sin_family) &&
                    (ncbsp->ncbs_sin.sin_addr.s_addr == saddr->sin_addr.s_addr))
                        break;
        }
        if (!nmp) /* we don't want this socket, mark it dead */
                ncbsp->ncbs_flags |= NCBSOCK_DEAD;

        /* make sure the callback socket cleanup timer is running */
        /* (shorten the timer if we've got a socket we don't want) */
        if (!nfs4_callback_timer_on) {
                nfs4_callback_timer_on = 1;
                nfs_interval_timer_start(nfs4_callback_timer_call,
                        !nmp ? 500 : (NFS4_CB_TIMER_PERIOD * 1000));
        } else if (!nmp && (nfs4_callback_timer_on < 2)) {
                nfs4_callback_timer_on = 2;
                thread_call_cancel(nfs4_callback_timer_call);
                nfs_interval_timer_start(nfs4_callback_timer_call, 500);
        }

        lck_mtx_unlock(nfs_global_mutex);
}

/*
 * Receive mbufs from callback sockets into RPC records and process each record.
 * Detect connection has been closed and shut down.
 */
void
nfs4_cb_rcv(socket_t so, void *arg, __unused int waitflag)
{
        struct nfs_callback_socket *ncbsp = arg;
        struct timespec ts = {1,0};
        struct timeval now;
        mbuf_t m;
        int error = 0, recv = 1;

        lck_mtx_lock(nfs_global_mutex);
        while (ncbsp->ncbs_flags & NCBSOCK_UPCALL) {
                /* wait if upcall is already in progress */
                ncbsp->ncbs_flags |= NCBSOCK_UPCALLWANT;
                msleep(ncbsp, nfs_global_mutex, PSOCK, "cbupcall", &ts);
        }
        ncbsp->ncbs_flags |= NCBSOCK_UPCALL;
        lck_mtx_unlock(nfs_global_mutex);

        /* loop while we make error-free progress */
        while (!error && recv) {
                error = nfs_rpc_record_read(so, &ncbsp->ncbs_rrs, &recv, &m);
                if (m) /* handle the request */
                        error = nfs4_cb_handler(ncbsp, m);
        }

        /* note: no error and no data indicates server closed its end */
        if ((error != EWOULDBLOCK) && (error || !recv)) {
                /*
                 * Socket is either being closed or should be.
                 * We can't close the socket in the context of the upcall.
                 * So we mark it as dead and leave it for the cleanup timer to reap.
                 */
                ncbsp->ncbs_stamp = 0;
                ncbsp->ncbs_flags |= NCBSOCK_DEAD;
        } else {
                microuptime(&now);
                ncbsp->ncbs_stamp = now.tv_sec;
        }

        lck_mtx_lock(nfs_global_mutex);
        ncbsp->ncbs_flags &= ~NCBSOCK_UPCALL;
        lck_mtx_unlock(nfs_global_mutex);
        wakeup(ncbsp);
}

/*
 * Handle an NFS callback channel request.
 */
int
nfs4_cb_handler(struct nfs_callback_socket *ncbsp, mbuf_t mreq)
{
        socket_t so = ncbsp->ncbs_so;
        struct nfsm_chain nmreq, nmrep;
        mbuf_t mhead = NULL, mrest = NULL, m;
        struct sockaddr_in *saddr;
        struct msghdr msg;
        struct nfsmount *nmp;
        fhandle_t fh;
        nfsnode_t np;
        nfs_stateid stateid;
        uint32_t bitmap[NFS_ATTR_BITMAP_LEN], rbitmap[NFS_ATTR_BITMAP_LEN], bmlen, truncate, attrbytes;
        uint32_t val, xid, procnum, taglen, cbid, numops, op, status;
        uint32_t auth_type, auth_len;
        uint32_t numres, *pnumres;
        int error = 0, replen, len;
        size_t sentlen = 0;

        xid = numops = op = status = procnum = taglen = cbid = 0;

        nfsm_chain_dissect_init(error, &nmreq, mreq);
        nfsm_chain_get_32(error, &nmreq, xid);          // RPC XID
        nfsm_chain_get_32(error, &nmreq, val);          // RPC Call
        nfsm_assert(error, (val == RPC_CALL), EBADRPC);
        nfsm_chain_get_32(error, &nmreq, val);          // RPC Version
        nfsm_assert(error, (val == RPC_VER2), ERPCMISMATCH);
        nfsm_chain_get_32(error, &nmreq, val);          // RPC Program Number
        nfsm_assert(error, (val == NFS4_CALLBACK_PROG), EPROGUNAVAIL);
        nfsm_chain_get_32(error, &nmreq, val);          // NFS Callback Program Version Number
        nfsm_assert(error, (val == NFS4_CALLBACK_PROG_VERSION), EPROGMISMATCH);
        nfsm_chain_get_32(error, &nmreq, procnum);      // NFS Callback Procedure Number
        nfsm_assert(error, (procnum <= NFSPROC4_CB_COMPOUND), EPROCUNAVAIL);

        /* Handle authentication */
        /* XXX just ignore auth for now - handling kerberos may be tricky */
        nfsm_chain_get_32(error, &nmreq, auth_type);    // RPC Auth Flavor
        nfsm_chain_get_32(error, &nmreq, auth_len);     // RPC Auth Length
        nfsm_assert(error, (auth_len <= RPCAUTH_MAXSIZ), EBADRPC);
        if (!error && (auth_len > 0))
                nfsm_chain_adv(error, &nmreq, nfsm_rndup(auth_len));
        nfsm_chain_adv(error, &nmreq, NFSX_UNSIGNED);   // verifier flavor (should be AUTH_NONE)
        nfsm_chain_get_32(error, &nmreq, auth_len);     // verifier length
        nfsm_assert(error, (auth_len <= RPCAUTH_MAXSIZ), EBADRPC);
        if (!error && (auth_len > 0))
                nfsm_chain_adv(error, &nmreq, nfsm_rndup(auth_len));
        if (error) {
                status = error;
                error = 0;
                goto nfsmout;
        }

        switch (procnum) {
        case NFSPROC4_CB_NULL:
                status = NFSERR_RETVOID;
                break;
        case NFSPROC4_CB_COMPOUND:
                /* tag, minorversion, cb ident, numops, op array */
                nfsm_chain_get_32(error, &nmreq, taglen);       /* tag length */
                nfsm_assert(error, (val <= NFS4_OPAQUE_LIMIT), EBADRPC);

                /* start building the body of the response */
                nfsm_mbuf_get(error, &mrest, nfsm_rndup(taglen) + 5*NFSX_UNSIGNED);
                nfsm_chain_init(&nmrep, mrest);

                /* copy tag from request to response */
                nfsm_chain_add_32(error, &nmrep, taglen);       /* tag length */
                for (len = (int)taglen; !error && (len > 0); len -= NFSX_UNSIGNED) {
                        nfsm_chain_get_32(error, &nmreq, val);
                        nfsm_chain_add_32(error, &nmrep, val);
                }

                /* insert number of results placeholder */
                numres = 0;
                nfsm_chain_add_32(error, &nmrep, numres);
                pnumres = (uint32_t*)(nmrep.nmc_ptr - NFSX_UNSIGNED);

                nfsm_chain_get_32(error, &nmreq, val);          /* minorversion */
                nfsm_assert(error, (val == 0), NFSERR_MINOR_VERS_MISMATCH);
                nfsm_chain_get_32(error, &nmreq, cbid);         /* callback ID */
                nfsm_chain_get_32(error, &nmreq, numops);       /* number of operations */
                if (error) {
                        if ((error == EBADRPC) || (error == NFSERR_MINOR_VERS_MISMATCH))
                                status = error;
                        else if ((error == ENOBUFS) || (error == ENOMEM))
                                status = NFSERR_RESOURCE;
                        else 
                                status = NFSERR_SERVERFAULT;
                        error = 0;
                        nfsm_chain_null(&nmrep);
                        goto nfsmout;
                }
                /* match the callback ID to a registered mount */
                lck_mtx_lock(nfs_global_mutex);
                TAILQ_FOREACH(nmp, &nfs4_cb_mounts, nm_cblink) {
                        if (nmp->nm_cbid != cbid)
                                continue;
                        /* verify socket's source address matches this mount's server address */
                        saddr = mbuf_data(nmp->nm_nam);
                        if ((ncbsp->ncbs_sin.sin_len != saddr->sin_len) ||
                            (ncbsp->ncbs_sin.sin_family != saddr->sin_family) ||
                            (ncbsp->ncbs_sin.sin_addr.s_addr != saddr->sin_addr.s_addr))
                                continue;
                        break;
                }
                /* mark the NFS mount as busy */
                if (nmp)
                        nmp->nm_cbrefs++;
                lck_mtx_unlock(nfs_global_mutex);
                if (!nmp) {
                        /* if no mount match, just drop socket. */
                        error = EPERM;
                        nfsm_chain_null(&nmrep);
                        goto out;
                }

                /* process ops, adding results to mrest */
                while (numops > 0) {
                        numops--;
                        nfsm_chain_get_32(error, &nmreq, op);
                        if (error)
                                break;
                        switch (op) {
                        case NFS_OP_CB_GETATTR:
                                // (FH, BITMAP) -> (STATUS, BITMAP, ATTRS)
                                np = NULL;
                                nfsm_chain_get_fh(error, &nmreq, NFS_VER4, &fh);
                                bmlen = NFS_ATTR_BITMAP_LEN;
                                nfsm_chain_get_bitmap(error, &nmreq, bitmap, bmlen);
                                if (error) {
                                        status = error;
                                        error = 0;
                                        numops = 0; /* don't process any more ops */
                                } else {
                                        /* find the node for the file handle */
                                        error = nfs_nget(nmp->nm_mountp, NULL, NULL, fh.fh_data, fh.fh_len, NULL, NULL, NG_NOCREATE, &np);
                                        if (error || !np) {
                                                status = NFSERR_BADHANDLE;
                                                error = 0;
                                                np = NULL;
                                                numops = 0; /* don't process any more ops */
                                        }
                                }
                                nfsm_chain_add_32(error, &nmrep, op);
                                nfsm_chain_add_32(error, &nmrep, status);
                                if (!error && (status == EBADRPC))
                                        error = status;
                                if (np) {
                                        /* only allow returning size, change, and mtime attrs */
                                        NFS_CLEAR_ATTRIBUTES(&rbitmap);
                                        attrbytes = 0;
                                        if (NFS_BITMAP_ISSET(&bitmap, NFS_FATTR_CHANGE)) {
                                                NFS_BITMAP_SET(&rbitmap, NFS_FATTR_CHANGE);
                                                attrbytes += 2 * NFSX_UNSIGNED;
                                        }
                                        if (NFS_BITMAP_ISSET(&bitmap, NFS_FATTR_SIZE)) {
                                                NFS_BITMAP_SET(&rbitmap, NFS_FATTR_SIZE);
                                                attrbytes += 2 * NFSX_UNSIGNED;
                                        }
                                        if (NFS_BITMAP_ISSET(&bitmap, NFS_FATTR_TIME_MODIFY)) {
                                                NFS_BITMAP_SET(&rbitmap, NFS_FATTR_TIME_MODIFY);
                                                attrbytes += 3 * NFSX_UNSIGNED;
                                        }
                                        nfsm_chain_add_bitmap(error, &nmrep, rbitmap, NFS_ATTR_BITMAP_LEN);
                                        nfsm_chain_add_32(error, &nmrep, attrbytes);
                                        if (NFS_BITMAP_ISSET(&bitmap, NFS_FATTR_CHANGE))
                                                nfsm_chain_add_64(error, &nmrep,
                                                        np->n_vattr.nva_change + ((np->n_flag & NMODIFIED) ? 1 : 0));
                                        if (NFS_BITMAP_ISSET(&bitmap, NFS_FATTR_SIZE))
                                                nfsm_chain_add_64(error, &nmrep, np->n_size);
                                        if (NFS_BITMAP_ISSET(&bitmap, NFS_FATTR_TIME_MODIFY)) {
                                                nfsm_chain_add_64(error, &nmrep, np->n_vattr.nva_timesec[NFSTIME_MODIFY]);
                                                nfsm_chain_add_32(error, &nmrep, np->n_vattr.nva_timensec[NFSTIME_MODIFY]);
                                        }
                                        nfs_node_unlock(np);
                                        vnode_put(NFSTOV(np));
                                        np = NULL;
                                }
                                /*
                                 * If we hit an error building the reply, we can't easily back up.
                                 * So we'll just update the status and hope the server ignores the
                                 * extra garbage.
                                 */
                                break;
                        case NFS_OP_CB_RECALL:
                                // (STATEID, TRUNCATE, FH) -> (STATUS)
                                np = NULL;
                                nfsm_chain_get_stateid(error, &nmreq, &stateid);
                                nfsm_chain_get_32(error, &nmreq, truncate);
                                nfsm_chain_get_fh(error, &nmreq, NFS_VER4, &fh);
                                if (error) {
                                        status = error;
                                        error = 0;
                                        numops = 0; /* don't process any more ops */
                                } else {
                                        /* find the node for the file handle */
                                        error = nfs_nget(nmp->nm_mountp, NULL, NULL, fh.fh_data, fh.fh_len, NULL, NULL, NG_NOCREATE, &np);
                                        if (error || !np) {
                                                status = NFSERR_BADHANDLE;
                                                error = 0;
                                                np = NULL;
                                                numops = 0; /* don't process any more ops */
                                        } else if (!(np->n_openflags & N_DELEG_MASK) ||
                                                    bcmp(&np->n_dstateid, &stateid, sizeof(stateid))) {
                                                /* delegation stateid state doesn't match */
                                                status = NFSERR_BAD_STATEID;
                                                numops = 0; /* don't process any more ops */
                                        }
                                        if (!status) {
                                                /* add node to recall queue, and wake socket thread */
                                                lck_mtx_lock(&nmp->nm_lock);
                                                if (np->n_dlink.tqe_next == NFSNOLIST)
                                                        TAILQ_INSERT_TAIL(&nmp->nm_recallq, np, n_dlink);
                                                nfs_mount_sock_thread_wake(nmp);
                                                lck_mtx_unlock(&nmp->nm_lock);
                                        }
                                        if (np) {
                                                nfs_node_unlock(np);
                                                vnode_put(NFSTOV(np));
                                        }
                                }
                                nfsm_chain_add_32(error, &nmrep, op);
                                nfsm_chain_add_32(error, &nmrep, status);
                                if (!error && (status == EBADRPC))
                                        error = status;
                                break;
                        case NFS_OP_CB_ILLEGAL:
                        default:
                                nfsm_chain_add_32(error, &nmrep, NFS_OP_CB_ILLEGAL);
                                status = NFSERR_OP_ILLEGAL;
                                nfsm_chain_add_32(error, &nmrep, status);
                                numops = 0; /* don't process any more ops */
                                break;
                        }
                        numres++;
                }

                if (!status && error) {
                        if (error == EBADRPC)
                                status = error;
                        else if ((error == ENOBUFS) || (error == ENOMEM))
                                status = NFSERR_RESOURCE;
                        else 
                                status = NFSERR_SERVERFAULT;
                        error = 0;
                }

                /* Now, set the numres field */
                *pnumres = txdr_unsigned(numres);
                nfsm_chain_build_done(error, &nmrep);
                nfsm_chain_null(&nmrep);

                /* drop the callback reference on the mount */
                lck_mtx_lock(nfs_global_mutex);
                nmp->nm_cbrefs--;
                if (!nmp->nm_cbid)
                        wakeup(&nmp->nm_cbrefs);
                lck_mtx_unlock(nfs_global_mutex);
                break;
        }

nfsmout:
        if (status == EBADRPC)
                OSAddAtomic(1, &nfsstats.rpcinvalid);

        /* build reply header */
        error = mbuf_gethdr(MBUF_WAITOK, MBUF_TYPE_DATA, &mhead);
        nfsm_chain_init(&nmrep, mhead);
        nfsm_chain_add_32(error, &nmrep, 0); /* insert space for an RPC record mark */
        nfsm_chain_add_32(error, &nmrep, xid);
        nfsm_chain_add_32(error, &nmrep, RPC_REPLY);
        if ((status == ERPCMISMATCH) || (status & NFSERR_AUTHERR)) {
                nfsm_chain_add_32(error, &nmrep, RPC_MSGDENIED);
                if (status & NFSERR_AUTHERR) {
                        nfsm_chain_add_32(error, &nmrep, RPC_AUTHERR);
                        nfsm_chain_add_32(error, &nmrep, (status & ~NFSERR_AUTHERR));
                } else {
                        nfsm_chain_add_32(error, &nmrep, RPC_MISMATCH);
                        nfsm_chain_add_32(error, &nmrep, RPC_VER2);
                        nfsm_chain_add_32(error, &nmrep, RPC_VER2);
                }
        } else {
                /* reply status */
                nfsm_chain_add_32(error, &nmrep, RPC_MSGACCEPTED);
                /* XXX RPCAUTH_NULL verifier */
                nfsm_chain_add_32(error, &nmrep, RPCAUTH_NULL);
                nfsm_chain_add_32(error, &nmrep, 0);
                /* accepted status */
                switch (status) {
                case EPROGUNAVAIL:
                        nfsm_chain_add_32(error, &nmrep, RPC_PROGUNAVAIL);
                        break;
                case EPROGMISMATCH:
                        nfsm_chain_add_32(error, &nmrep, RPC_PROGMISMATCH);
                        nfsm_chain_add_32(error, &nmrep, NFS4_CALLBACK_PROG_VERSION);
                        nfsm_chain_add_32(error, &nmrep, NFS4_CALLBACK_PROG_VERSION);
                        break;
                case EPROCUNAVAIL:
                        nfsm_chain_add_32(error, &nmrep, RPC_PROCUNAVAIL);
                        break;
                case EBADRPC:
                        nfsm_chain_add_32(error, &nmrep, RPC_GARBAGE);
                        break;
                default:
                        nfsm_chain_add_32(error, &nmrep, RPC_SUCCESS);
                        if (status != NFSERR_RETVOID)
                                nfsm_chain_add_32(error, &nmrep, status);
                        break;
                }
        }
        nfsm_chain_build_done(error, &nmrep);
        if (error) {
                nfsm_chain_null(&nmrep);
                goto out;
        }
        error = mbuf_setnext(nmrep.nmc_mcur, mrest);
        if (error) {
                printf("nfs cb: mbuf_setnext failed %d\n", error);
                goto out;
        }
        mrest = NULL;
        /* Calculate the size of the reply */
        replen = 0;
        for (m = nmrep.nmc_mhead; m; m = mbuf_next(m))
                replen += mbuf_len(m);
        mbuf_pkthdr_setlen(mhead, replen);
        error = mbuf_pkthdr_setrcvif(mhead, NULL);
        nfsm_chain_set_recmark(error, &nmrep, (replen - NFSX_UNSIGNED) | 0x80000000);
        nfsm_chain_null(&nmrep);

        /* send the reply */
        bzero(&msg, sizeof(msg));
        error = sock_sendmbuf(so, &msg, mhead, 0, &sentlen);
        mhead = NULL;
        if (!error && ((int)sentlen != replen))
                error = EWOULDBLOCK;
        if (error == EWOULDBLOCK) /* inability to send response is considered fatal */
                error = ETIMEDOUT;
out:
        if (error)
                nfsm_chain_cleanup(&nmrep);
        if (mhead)
                mbuf_freem(mhead);
        if (mrest)
                mbuf_freem(mrest);
        if (mreq)
                mbuf_freem(mreq);
        return (error);
}


/*
 * Read the next (marked) RPC record from the socket.
 *
 * *recvp returns if any data was received.
 * *mp returns the next complete RPC record
 */
int
nfs_rpc_record_read(socket_t so, struct nfs_rpc_record_state *nrrsp, int *recvp, mbuf_t *mp)
{
        struct iovec aio;
        struct msghdr msg;
        size_t rcvlen;
        int error = 0;
        mbuf_t m;

        *recvp = 0;
        *mp = NULL;

        /* read the TCP RPC record marker */
        while (!error && nrrsp->nrrs_markerleft) {
                aio.iov_base = ((char*)&nrrsp->nrrs_fragleft +
                                sizeof(nrrsp->nrrs_fragleft) - nrrsp->nrrs_markerleft);
                aio.iov_len = nrrsp->nrrs_markerleft;
                bzero(&msg, sizeof(msg));
                msg.msg_iov = &aio;
                msg.msg_iovlen = 1;
                error = sock_receive(so, &msg, MSG_DONTWAIT, &rcvlen);
                if (error || !rcvlen)
                        break;
                *recvp = 1;
                nrrsp->nrrs_markerleft -= rcvlen;
                if (nrrsp->nrrs_markerleft)
                        continue;
                /* record marker complete */
                nrrsp->nrrs_fragleft = ntohl(nrrsp->nrrs_fragleft);
                if (nrrsp->nrrs_fragleft & 0x80000000) {
                        nrrsp->nrrs_lastfrag = 1;
                        nrrsp->nrrs_fragleft &= ~0x80000000;
                }
                nrrsp->nrrs_reclen += nrrsp->nrrs_fragleft;
                if (nrrsp->nrrs_reclen > NFS_MAXPACKET) {
                        /*
                         * This is SERIOUS! We are out of sync with the sender
                         * and forcing a disconnect/reconnect is all I can do.
                         */
                        log(LOG_ERR, "impossible RPC record length (%d) on callback", nrrsp->nrrs_reclen);
                        error = EFBIG;
                }
        }

        /* read the TCP RPC record fragment */
        while (!error && !nrrsp->nrrs_markerleft && nrrsp->nrrs_fragleft) {
                m = NULL;
                rcvlen = nrrsp->nrrs_fragleft;
                error = sock_receivembuf(so, NULL, &m, MSG_DONTWAIT, &rcvlen);
                if (error || !rcvlen || !m)
                        break;
                *recvp = 1;
                /* append mbufs to list */
                nrrsp->nrrs_fragleft -= rcvlen;
                if (!nrrsp->nrrs_m) {
                        nrrsp->nrrs_m = m;
                } else {
                        error = mbuf_setnext(nrrsp->nrrs_mlast, m);
                        if (error) {
                                printf("nfs tcp rcv: mbuf_setnext failed %d\n", error);
                                mbuf_freem(m);
                                break;
                        }
                }
                while (mbuf_next(m))
                        m = mbuf_next(m);
                nrrsp->nrrs_mlast = m;
        }

        /* done reading fragment? */
        if (!error && !nrrsp->nrrs_markerleft && !nrrsp->nrrs_fragleft) {
                /* reset socket fragment parsing state */
                nrrsp->nrrs_markerleft = sizeof(nrrsp->nrrs_fragleft);
                if (nrrsp->nrrs_lastfrag) {
                        /* RPC record complete */
                        *mp = nrrsp->nrrs_m;
                        /* reset socket record parsing state */
                        nrrsp->nrrs_reclen = 0;
                        nrrsp->nrrs_m = nrrsp->nrrs_mlast = NULL;
                        nrrsp->nrrs_lastfrag = 0;
                }
        }

        return (error);
}



/*
 * The NFS client send routine.
 *
 * Send the given NFS request out the mount's socket.
 * Holds nfs_sndlock() for the duration of this call.
 *
 * - check for request termination (sigintr)
 * - wait for reconnect, if necessary
 * - UDP: check the congestion window
 * - make a copy of the request to send
 * - UDP: update the congestion window
 * - send the request
 *
 * If sent successfully, R_MUSTRESEND and R_RESENDERR are cleared.
 * rexmit count is also updated if this isn't the first send.
 *
 * If the send is not successful, make sure R_MUSTRESEND is set.
 * If this wasn't the first transmit, set R_RESENDERR.
 * Also, undo any UDP congestion window changes made.
 *
 * If the error appears to indicate that the socket should
 * be reconnected, mark the socket for reconnection.
 *
 * Only return errors when the request should be aborted.
 */
int
nfs_send(struct nfsreq *req, int wait)
{
        struct nfsmount *nmp;
        socket_t so;
        int error, error2, sotype, rexmit, slpflag = 0, needrecon;
        struct msghdr msg;
        struct sockaddr *sendnam;
        mbuf_t mreqcopy;
        size_t sentlen = 0;
        struct timespec ts = { 2, 0 };

again:
        error = nfs_sndlock(req);
        if (error) {
                lck_mtx_lock(&req->r_mtx);
                req->r_error = error;
                req->r_flags &= ~R_SENDING;
                lck_mtx_unlock(&req->r_mtx);
                return (error);
        }

        error = nfs_sigintr(req->r_nmp, req, req->r_thread, 0);
        if (error) {
                nfs_sndunlock(req);
                lck_mtx_lock(&req->r_mtx);
                req->r_error = error;
                req->r_flags &= ~R_SENDING;
                lck_mtx_unlock(&req->r_mtx);
                return (error);
        }
        nmp = req->r_nmp;
        sotype = nmp->nm_sotype;

        /*
         * If it's a setup RPC but we're not in SETUP... must need reconnect.
         * If it's a recovery RPC but the socket's not ready... must need reconnect.
         */
        if (((req->r_flags & R_SETUP) && !(nmp->nm_sockflags & NMSOCK_SETUP)) ||
            ((req->r_flags & R_RECOVER) && !(nmp->nm_sockflags & NMSOCK_READY))) {
                error = ETIMEDOUT;
                nfs_sndunlock(req);
                lck_mtx_lock(&req->r_mtx);
                req->r_error = error;
                req->r_flags &= ~R_SENDING;
                lck_mtx_unlock(&req->r_mtx);
                return (error);
        }

        /* If the socket needs reconnection, do that now. */
        /* wait until socket is ready - unless this request is part of setup */
        lck_mtx_lock(&nmp->nm_lock);
        if (!(nmp->nm_sockflags & NMSOCK_READY) &&
            !((nmp->nm_sockflags & NMSOCK_SETUP) && (req->r_flags & R_SETUP))) {
                if (nmp->nm_flag & NFSMNT_INT)
                        slpflag |= PCATCH;
                lck_mtx_unlock(&nmp->nm_lock);
                nfs_sndunlock(req);
                if (!wait) {
                        lck_mtx_lock(&req->r_mtx);
                        req->r_flags &= ~R_SENDING;
                        req->r_flags |= R_MUSTRESEND;
                        req->r_rtt = 0;
                        lck_mtx_unlock(&req->r_mtx);
                        return (0);
                }
                NFS_SOCK_DBG(("nfs_send: 0x%llx wait reconnect\n", req->r_xid));
                lck_mtx_lock(&req->r_mtx);
                req->r_flags &= ~R_MUSTRESEND;
                req->r_rtt = 0;
                lck_mtx_unlock(&req->r_mtx);
                lck_mtx_lock(&nmp->nm_lock);
                while (!(nmp->nm_sockflags & NMSOCK_READY)) {
                        /* don't bother waiting if the socket thread won't be reconnecting it */
                        if (nmp->nm_state & NFSSTA_FORCE) {
                                error = EIO;
                                break;
                        }
                        if ((nmp->nm_flag & NFSMNT_SOFT) && (nmp->nm_reconnect_start > 0)) {
                                struct timeval now;
                                microuptime(&now);
                                if ((now.tv_sec - nmp->nm_reconnect_start) >= 8) {
                                        /* soft mount in reconnect for a while... terminate ASAP */
                                        OSAddAtomic(1, &nfsstats.rpctimeouts);
                                        req->r_flags |= R_SOFTTERM;
                                        req->r_error = error = ETIMEDOUT;
                                        break;
                                }
                        }
                        /* make sure socket thread is running, then wait */
                        nfs_mount_sock_thread_wake(nmp);
                        if ((error = nfs_sigintr(req->r_nmp, req, req->r_thread, 1)))
                                break;
                        msleep(req, &nmp->nm_lock, slpflag|PSOCK, "nfsconnectwait", &ts);
                        slpflag = 0;
                }
                lck_mtx_unlock(&nmp->nm_lock);
                if (error) {
                        lck_mtx_lock(&req->r_mtx);
                        req->r_error = error;
                        req->r_flags &= ~R_SENDING;
                        lck_mtx_unlock(&req->r_mtx);
                        return (error);
                }
                goto again;
        }
        so = nmp->nm_so;
        lck_mtx_unlock(&nmp->nm_lock);
        if (!so) {
                nfs_sndunlock(req);
                lck_mtx_lock(&req->r_mtx);
                req->r_flags &= ~R_SENDING;
                req->r_flags |= R_MUSTRESEND;
                req->r_rtt = 0;
                lck_mtx_unlock(&req->r_mtx);
                return (0);
        }

        lck_mtx_lock(&req->r_mtx);
        rexmit = (req->r_flags & R_SENT);

        if (sotype == SOCK_DGRAM) {
                lck_mtx_lock(&nmp->nm_lock);
                if (!(req->r_flags & R_CWND) && (nmp->nm_sent >= nmp->nm_cwnd)) {
                        /* if we can't send this out yet, wait on the cwnd queue */
                        slpflag = ((nmp->nm_flag & NFSMNT_INT) && req->r_thread) ? PCATCH : 0;
                        lck_mtx_unlock(&nmp->nm_lock);
                        nfs_sndunlock(req);
                        req->r_flags &= ~R_SENDING;
                        req->r_flags |= R_MUSTRESEND;
                        lck_mtx_unlock(&req->r_mtx);
                        if (!wait) {
                                req->r_rtt = 0;
                                return (0);
                        }
                        lck_mtx_lock(&nmp->nm_lock);
                        while (nmp->nm_sent >= nmp->nm_cwnd) {
                                if ((error = nfs_sigintr(req->r_nmp, req, req->r_thread, 1)))
                                        break;
                                TAILQ_INSERT_TAIL(&nmp->nm_cwndq, req, r_cchain);
                                msleep(req, &nmp->nm_lock, slpflag | (PZERO - 1), "nfswaitcwnd", &ts);
                                slpflag = 0;
                                if ((req->r_cchain.tqe_next != NFSREQNOLIST)) {
                                        TAILQ_REMOVE(&nmp->nm_cwndq, req, r_cchain);
                                        req->r_cchain.tqe_next = NFSREQNOLIST;
                                }
                        }
                        lck_mtx_unlock(&nmp->nm_lock);
                        goto again;
                }
                /*
                 * We update these *before* the send to avoid racing
                 * against others who may be looking to send requests.
                 */
                if (!rexmit) {
                        /* first transmit */
                        req->r_flags |= R_CWND;
                        nmp->nm_sent += NFS_CWNDSCALE;
                } else {
                        /*
                         * When retransmitting, turn timing off
                         * and divide congestion window by 2. 
                         */
                        req->r_flags &= ~R_TIMING;
                        nmp->nm_cwnd >>= 1;
                        if (nmp->nm_cwnd < NFS_CWNDSCALE)
                                nmp->nm_cwnd = NFS_CWNDSCALE;
                }
                lck_mtx_unlock(&nmp->nm_lock);
        }

        req->r_flags &= ~R_MUSTRESEND;
        lck_mtx_unlock(&req->r_mtx);

        error = mbuf_copym(req->r_mhead, 0, MBUF_COPYALL,
                        wait ? MBUF_WAITOK : MBUF_DONTWAIT, &mreqcopy);
        if (error) {
                if (wait)
                        log(LOG_INFO, "nfs_send: mbuf copy failed %d\n", error);
                nfs_sndunlock(req);
                lck_mtx_lock(&req->r_mtx);
                req->r_flags &= ~R_SENDING;
                req->r_flags |= R_MUSTRESEND;
                req->r_rtt = 0;
                lck_mtx_unlock(&req->r_mtx);
                return (0);
        }

        bzero(&msg, sizeof(msg));
        if (nmp->nm_nam && (sotype != SOCK_STREAM) && !sock_isconnected(so)) {
                if ((sendnam = mbuf_data(nmp->nm_nam))) {
                        msg.msg_name = (caddr_t)sendnam;
                        msg.msg_namelen = sendnam->sa_len;
                }
        }
        error = sock_sendmbuf(so, &msg, mreqcopy, 0, &sentlen);
#ifdef NFS_SOCKET_DEBUGGING
        if (error || (sentlen != req->r_mreqlen))
                NFS_SOCK_DBG(("nfs_send: 0x%llx sent %d/%d error %d\n",
                        req->r_xid, (int)sentlen, (int)req->r_mreqlen, error));
#endif
        if (!error && (sentlen != req->r_mreqlen))
                error = EWOULDBLOCK;
        needrecon = ((sotype == SOCK_STREAM) && sentlen && (sentlen != req->r_mreqlen));

        lck_mtx_lock(&req->r_mtx);
        req->r_flags &= ~R_SENDING;
        req->r_rtt = 0;
        if (rexmit && (++req->r_rexmit > NFS_MAXREXMIT))
                req->r_rexmit = NFS_MAXREXMIT;

        if (!error) {
                /* SUCCESS */
                req->r_flags &= ~R_RESENDERR;
                if (rexmit)
                        OSAddAtomic(1, &nfsstats.rpcretries);
                req->r_flags |= R_SENT;
                if (req->r_flags & R_WAITSENT) {
                        req->r_flags &= ~R_WAITSENT;
                        wakeup(req);
                }
                nfs_sndunlock(req);
                lck_mtx_unlock(&req->r_mtx);
                return (0);
        }

        /* send failed */
        req->r_flags |= R_MUSTRESEND;
        if (rexmit)
                req->r_flags |= R_RESENDERR;
        if ((error == EINTR) || (error == ERESTART))
                req->r_error = error;
        lck_mtx_unlock(&req->r_mtx);

        if (sotype == SOCK_DGRAM) {
                /*
                 * Note: even though a first send may fail, we consider
                 * the request sent for congestion window purposes.
                 * So we don't need to undo any of the changes made above.
                 */
                /*
                 * Socket errors ignored for connectionless sockets??
                 * For now, ignore them all
                 */
                if ((error != EINTR) && (error != ERESTART) &&
                    (error != EWOULDBLOCK) && (error != EIO)) {
                        int clearerror = 0, optlen = sizeof(clearerror);
                        sock_getsockopt(so, SOL_SOCKET, SO_ERROR, &clearerror, &optlen);
#ifdef NFS_SOCKET_DEBUGGING
                        if (clearerror)
                                NFS_SOCK_DBG(("nfs_send: ignoring UDP socket error %d so %d\n",
                                        error, clearerror));
#endif
                }
        }

        /* check if it appears we should reconnect the socket */
        switch (error) {
        case EWOULDBLOCK:
                /* if send timed out, reconnect if on TCP */
                if (sotype != SOCK_STREAM)
                        break;
        case EPIPE:
        case EADDRNOTAVAIL:
        case ENETDOWN:
        case ENETUNREACH:
        case ENETRESET:
        case ECONNABORTED:
        case ECONNRESET:
        case ENOTCONN:
        case ESHUTDOWN:
        case ECONNREFUSED:
        case EHOSTDOWN:
        case EHOSTUNREACH:
                needrecon = 1;
                break;
        }
        if (needrecon) { /* mark socket as needing reconnect */
                NFS_SOCK_DBG(("nfs_send: 0x%llx need reconnect %d\n", req->r_xid, error));
                nfs_need_reconnect(nmp);
        }

        nfs_sndunlock(req);

        /*
         * Don't log some errors:
         * EPIPE errors may be common with servers that drop idle connections.
         * EADDRNOTAVAIL may occur on network transitions.
         * ENOTCONN may occur under some network conditions.
         */
        if ((error == EPIPE) || (error == EADDRNOTAVAIL) || (error == ENOTCONN))
                error = 0;
        if (error && (error != EINTR) && (error != ERESTART))
                log(LOG_INFO, "nfs send error %d for server %s\n", error,
                        !req->r_nmp ? "<unmounted>" :
                        vfs_statfs(req->r_nmp->nm_mountp)->f_mntfromname);

        /* prefer request termination error over other errors */
        error2 = nfs_sigintr(req->r_nmp, req, req->r_thread, 0);
        if (error2)
                error = error2;

        /* only allow the following errors to be returned */
        if ((error != EINTR) && (error != ERESTART) && (error != EIO) &&
            (error != ENXIO) && (error != ETIMEDOUT))
                error = 0;
        return (error);
}

/*
 * NFS client socket upcalls
 *
 * Pull RPC replies out of an NFS mount's socket and match them
 * up with the pending request.
 *
 * The datagram code is simple because we always get whole
 * messages out of the socket.
 *
 * The stream code is more involved because we have to parse
 * the RPC records out of the stream.
 */

/* NFS client UDP socket upcall */
void
nfs_udp_rcv(socket_t so, void *arg, __unused int waitflag)
{
        struct nfsmount *nmp = arg;
        size_t rcvlen;
        mbuf_t m;
        int error = 0;

        if (nmp->nm_sockflags & NMSOCK_CONNECTING) {
                wakeup(&nmp->nm_so);
                return;
        }

        /* make sure we're on the current socket */
        if (nmp->nm_so != so)
                return;

        do {
                m = NULL;
                rcvlen = 1000000;
                error = sock_receivembuf(so, NULL, &m, MSG_DONTWAIT, &rcvlen);
                if (m)
                        nfs_request_match_reply(nmp, m);
        } while (m && !error);

        if (error && (error != EWOULDBLOCK)) {
                /* problems with the socket... mark for reconnection */
                NFS_SOCK_DBG(("nfs_udp_rcv: need reconnect %d\n", error));
                nfs_need_reconnect(nmp);
        }
}

/* NFS client TCP socket upcall */
void
nfs_tcp_rcv(socket_t so, void *arg, __unused int waitflag)
{
        struct nfsmount *nmp = arg;
        struct iovec aio;
        struct msghdr msg;
        size_t rcvlen;
        mbuf_t m;
        int error = 0;
        int recv;

        if (nmp->nm_sockflags & NMSOCK_CONNECTING) {
                wakeup(&nmp->nm_so);
                return;
        }

        /* make sure we're on the current socket */
        if (nmp->nm_so != so)
                return;

        lck_mtx_lock(&nmp->nm_lock);
        if (nmp->nm_sockflags & NMSOCK_UPCALL) {
                /* upcall is already receiving data - just return */
                lck_mtx_unlock(&nmp->nm_lock);
                return;
        }
        nmp->nm_sockflags |= NMSOCK_UPCALL;

nextfrag:
        recv = 0;

        /* read the TCP RPC record marker */
        while (!error && nmp->nm_markerleft) {
                aio.iov_base = ((char*)&nmp->nm_fragleft +
                                sizeof(nmp->nm_fragleft) - nmp->nm_markerleft);
                aio.iov_len = nmp->nm_markerleft;
                bzero(&msg, sizeof(msg));
                msg.msg_iov = &aio;
                msg.msg_iovlen = 1;
                lck_mtx_unlock(&nmp->nm_lock);
                error = sock_receive(so, &msg, MSG_DONTWAIT, &rcvlen);
                lck_mtx_lock(&nmp->nm_lock);
                if (error || !rcvlen)
                        break;
                recv = 1;
                nmp->nm_markerleft -= rcvlen;
                if (nmp->nm_markerleft)
                        continue;
                /* record marker complete */
                nmp->nm_fragleft = ntohl(nmp->nm_fragleft);
                if (nmp->nm_fragleft & 0x80000000) {
                        nmp->nm_sockflags |= NMSOCK_LASTFRAG;
                        nmp->nm_fragleft &= ~0x80000000;
                }
                nmp->nm_reclen += nmp->nm_fragleft;
                if (nmp->nm_reclen > NFS_MAXPACKET) {
                        /*
                         * This is SERIOUS! We are out of sync with the sender
                         * and forcing a disconnect/reconnect is all I can do.
                         */
                        log(LOG_ERR, "%s (%d) from nfs server %s\n",
                                "impossible RPC record length", nmp->nm_reclen,
                                vfs_statfs(nmp->nm_mountp)->f_mntfromname);
                        error = EFBIG;
                }
        }

        /* read the TCP RPC record fragment */
        while (!error && !nmp->nm_markerleft && nmp->nm_fragleft) {
                m = NULL;
                rcvlen = nmp->nm_fragleft;
                lck_mtx_unlock(&nmp->nm_lock);
                error = sock_receivembuf(so, NULL, &m, MSG_DONTWAIT, &rcvlen);
                lck_mtx_lock(&nmp->nm_lock);
                if (error || !rcvlen || !m)
                        break;
                recv = 1;
                /* append mbufs to list */
                nmp->nm_fragleft -= rcvlen;
                if (!nmp->nm_m) {
                        nmp->nm_m = m;
                } else {
                        error = mbuf_setnext(nmp->nm_mlast, m);
                        if (error) {
                                printf("nfs_tcp_rcv: mbuf_setnext failed %d\n", error);
                                mbuf_freem(m);
                                break;
                        }
                }
                while (mbuf_next(m))
                        m = mbuf_next(m);
                nmp->nm_mlast = m;
        }

        /* done reading fragment? */
        m = NULL;
        if (!error && !nmp->nm_markerleft && !nmp->nm_fragleft) {
                /* reset socket fragment parsing state */
                nmp->nm_markerleft = sizeof(nmp->nm_fragleft);
                if (nmp->nm_sockflags & NMSOCK_LASTFRAG) {
                        /* RPC record complete */
                        m = nmp->nm_m;
                        /* reset socket record parsing state */
                        nmp->nm_reclen = 0;
                        nmp->nm_m = nmp->nm_mlast = NULL;
                        nmp->nm_sockflags &= ~NMSOCK_LASTFRAG;
                }
        }

        if (m) { /* match completed response with request */
                lck_mtx_unlock(&nmp->nm_lock);
                nfs_request_match_reply(nmp, m);
                lck_mtx_lock(&nmp->nm_lock);
        }

        /* loop if we've been making error-free progress */
        if (!error && recv)
                goto nextfrag;

        nmp->nm_sockflags &= ~NMSOCK_UPCALL;
        lck_mtx_unlock(&nmp->nm_lock);
#ifdef NFS_SOCKET_DEBUGGING
        if (!recv && (error != EWOULDBLOCK))
                NFS_SOCK_DBG(("nfs_tcp_rcv: got nothing, error %d, got FIN?\n", error));
#endif
        /* note: no error and no data indicates server closed its end */
        if ((error != EWOULDBLOCK) && (error || !recv)) {
                /* problems with the socket... mark for reconnection */
                NFS_SOCK_DBG(("nfs_tcp_rcv: need reconnect %d\n", error));
                nfs_need_reconnect(nmp);
        }
}

/*
 * "poke" a socket to try to provoke any pending errors
 */
void
nfs_sock_poke(struct nfsmount *nmp)
{
        struct iovec aio;
        struct msghdr msg;
        size_t len;
        int error = 0;
        int dummy;

        lck_mtx_lock(&nmp->nm_lock);
        if ((nmp->nm_sockflags & NMSOCK_UNMOUNT) || !nmp->nm_so) {
                lck_mtx_unlock(&nmp->nm_lock);
                return;
        }
        lck_mtx_unlock(&nmp->nm_lock);
        aio.iov_base = &dummy;
        aio.iov_len = 0;
        len = 0;
        bzero(&msg, sizeof(msg));
        msg.msg_iov = &aio;
        msg.msg_iovlen = 1;
        error = sock_send(nmp->nm_so, &msg, MSG_DONTWAIT, &len);
        NFS_SOCK_DBG(("nfs_sock_poke: error %d\n", error));
}

/*
 * Match an RPC reply with the corresponding request
 */
void
nfs_request_match_reply(struct nfsmount *nmp, mbuf_t mrep)
{
        struct nfsreq *req;
        struct nfsm_chain nmrep;
        u_int32_t reply = 0, rxid = 0;
        int error = 0, asyncioq, t1;

        /* Get the xid and check that it is an rpc reply */
        nfsm_chain_dissect_init(error, &nmrep, mrep);
        nfsm_chain_get_32(error, &nmrep, rxid);
        nfsm_chain_get_32(error, &nmrep, reply);
        if (error || (reply != RPC_REPLY)) {
                OSAddAtomic(1, &nfsstats.rpcinvalid);
                mbuf_freem(mrep);
                return;
        }

        /*
         * Loop through the request list to match up the reply
         * Iff no match, just drop it.
         */
        lck_mtx_lock(nfs_request_mutex);
        TAILQ_FOREACH(req, &nfs_reqq, r_chain) {
                if (req->r_nmrep.nmc_mhead || (rxid != R_XID32(req->r_xid)))
                        continue;
                /* looks like we have it, grab lock and double check */
                lck_mtx_lock(&req->r_mtx);
                if (req->r_nmrep.nmc_mhead || (rxid != R_XID32(req->r_xid))) {
                        lck_mtx_unlock(&req->r_mtx);
                        continue;
                }
                /* Found it.. */
                req->r_nmrep = nmrep;
                lck_mtx_lock(&nmp->nm_lock);
                if (nmp->nm_sotype == SOCK_DGRAM) {
                        /*
                         * Update congestion window.
                         * Do the additive increase of one rpc/rtt.
                         */
                        FSDBG(530, R_XID32(req->r_xid), req, nmp->nm_sent, nmp->nm_cwnd);
                        if (nmp->nm_cwnd <= nmp->nm_sent) {
                                nmp->nm_cwnd +=
                                   ((NFS_CWNDSCALE * NFS_CWNDSCALE) +
                                    (nmp->nm_cwnd >> 1)) / nmp->nm_cwnd;
                                if (nmp->nm_cwnd > NFS_MAXCWND)
                                        nmp->nm_cwnd = NFS_MAXCWND;
                        }
                        if (req->r_flags & R_CWND) {
                                nmp->nm_sent -= NFS_CWNDSCALE;
                                req->r_flags &= ~R_CWND;
                        }
                        if ((nmp->nm_sent < nmp->nm_cwnd) && !TAILQ_EMPTY(&nmp->nm_cwndq)) {
                                /* congestion window is open, poke the cwnd queue */
                                struct nfsreq *req2 = TAILQ_FIRST(&nmp->nm_cwndq);
                                TAILQ_REMOVE(&nmp->nm_cwndq, req2, r_cchain);
                                req2->r_cchain.tqe_next = NFSREQNOLIST;
                                wakeup(req2);
                        }
                }
                /*
                 * Update rtt using a gain of 0.125 on the mean
                 * and a gain of 0.25 on the deviation.
                 */
                if (req->r_flags & R_TIMING) {
                        /*
                         * Since the timer resolution of
                         * NFS_HZ is so course, it can often
                         * result in r_rtt == 0. Since
                         * r_rtt == N means that the actual
                         * rtt is between N+dt and N+2-dt ticks,
                         * add 1.
                         */
                        if (proct[req->r_procnum] == 0)
                                panic("nfs_request_match_reply: proct[%d] is zero", req->r_procnum);
                        t1 = req->r_rtt + 1;
                        t1 -= (NFS_SRTT(req) >> 3);
                        NFS_SRTT(req) += t1;
                        if (t1 < 0)
                                t1 = -t1;
                        t1 -= (NFS_SDRTT(req) >> 2);
                        NFS_SDRTT(req) += t1;
                }
                nmp->nm_timeouts = 0;
                lck_mtx_unlock(&nmp->nm_lock);
                /* signal anyone waiting on this request */
                wakeup(req);
                asyncioq = (req->r_callback.rcb_func != NULL);
                if (req->r_gss_ctx != NULL)
                        nfs_gss_clnt_rpcdone(req);
                lck_mtx_unlock(&req->r_mtx);
                lck_mtx_unlock(nfs_request_mutex);
                /* if it's an async RPC with a callback, queue it up */
                if (asyncioq)
                        nfs_asyncio_finish(req);
                break;
        }

        if (!req) {
                /* not matched to a request, so drop it. */
                lck_mtx_unlock(nfs_request_mutex);
                OSAddAtomic(1, &nfsstats.rpcunexpected);
                mbuf_freem(mrep);
        }
}

/*
 * Wait for the reply for a given request...
 * ...potentially resending the request if necessary.
 */
int
nfs_wait_reply(struct nfsreq *req)
{
        struct timespec ts = { 2, 0 };
        int error = 0, slpflag;

        if (req->r_nmp && (req->r_nmp->nm_flag & NFSMNT_INT) && req->r_thread)
                slpflag = PCATCH;
        else
                slpflag = 0;

        lck_mtx_lock(&req->r_mtx);
        while (!req->r_nmrep.nmc_mhead) {
                if ((error = nfs_sigintr(req->r_nmp, req, req->r_thread, 0)))
                        break;
                if (((error = req->r_error)) || req->r_nmrep.nmc_mhead)
                        break;
                /* check if we need to resend */
                if (req->r_flags & R_MUSTRESEND) {
                        NFS_SOCK_DBG(("nfs wait resend: p %d x 0x%llx f 0x%x rtt %d\n",
                                req->r_procnum, req->r_xid, req->r_flags, req->r_rtt));
                        req->r_flags |= R_SENDING;
                        lck_mtx_unlock(&req->r_mtx);
                        if (req->r_gss_ctx) {
                                /*
                                 * It's an RPCSEC_GSS mount.
                                 * Can't just resend the original request
                                 * without bumping the cred sequence number.
                                 * Go back and re-build the request.
                                 */
                                lck_mtx_lock(&req->r_mtx);
                                req->r_flags &= ~R_SENDING;
                                lck_mtx_unlock(&req->r_mtx);
                                return (EAGAIN);
                        }
                        error = nfs_send(req, 1);
                        lck_mtx_lock(&req->r_mtx);
                        NFS_SOCK_DBG(("nfs wait resend: p %d x 0x%llx f 0x%x rtt %d err %d\n",
                                req->r_procnum, req->r_xid, req->r_flags, req->r_rtt, error));
                        if (error)
                                break;
                        if (((error = req->r_error)) || req->r_nmrep.nmc_mhead)
                                break;
                }
                /* need to poll if we're P_NOREMOTEHANG */
                if (nfs_noremotehang(req->r_thread))
                        ts.tv_sec = 1;
                msleep(req, &req->r_mtx, slpflag | (PZERO - 1), "nfswaitreply", &ts);
                slpflag = 0;
        }
        lck_mtx_unlock(&req->r_mtx);

        return (error);
}

/*
 * An NFS request goes something like this:
 * (nb: always frees up mreq mbuf list)
 * nfs_request_create()
 *      - allocates a request struct if one is not provided
 *      - initial fill-in of the request struct
 * nfs_request_add_header()
 *      - add the RPC header
 * nfs_request_send()
 *      - link it into list
 *      - call nfs_send() for first transmit
 * nfs_request_wait()
 *      - call nfs_wait_reply() to wait for the reply
 * nfs_request_finish()
 *      - break down rpc header and return with error or nfs reply
 *        pointed to by nmrep.
 * nfs_request_rele()
 * nfs_request_destroy()
 *      - clean up the request struct
 *      - free the request struct if it was allocated by nfs_request_create()
 */

/*
 * Set up an NFS request struct (allocating if no request passed in).
 */
int
nfs_request_create(
        nfsnode_t np,
        mount_t mp,     /* used only if !np */
        struct nfsm_chain *nmrest,
        int procnum,
        thread_t thd,
        kauth_cred_t cred,
        struct nfsreq **reqp)
{
        struct nfsreq *req, *newreq = NULL;
        struct nfsmount *nmp;

        req = *reqp;
        if (!req) {
                /* allocate a new NFS request structure */
                MALLOC_ZONE(newreq, struct nfsreq*, sizeof(*newreq), M_NFSREQ, M_WAITOK);
                if (!newreq) {
                        mbuf_freem(nmrest->nmc_mhead);
                        nmrest->nmc_mhead = NULL;
                        return (ENOMEM);
                }
                req = newreq;
        }

        bzero(req, sizeof(*req));
        if (req == newreq)
                req->r_flags = R_ALLOCATED;

        nmp = VFSTONFS(np ? NFSTOMP(np) : mp);
        if (!nmp) {
                if (newreq)
                        FREE_ZONE(newreq, sizeof(*newreq), M_NFSREQ);
                return (ENXIO);
        }
        lck_mtx_lock(&nmp->nm_lock);
        if ((nmp->nm_state & (NFSSTA_FORCE|NFSSTA_TIMEO)) ==
            (NFSSTA_FORCE|NFSSTA_TIMEO)) {
                lck_mtx_unlock(&nmp->nm_lock);
                mbuf_freem(nmrest->nmc_mhead);
                nmrest->nmc_mhead = NULL;
                if (newreq)
                        FREE_ZONE(newreq, sizeof(*newreq), M_NFSREQ);
                return (ENXIO);
        }

        if ((nmp->nm_vers != NFS_VER4) && (procnum >= 0) && (procnum < NFS_NPROCS))
                OSAddAtomic(1, &nfsstats.rpccnt[procnum]);
        if ((nmp->nm_vers == NFS_VER4) && (procnum != NFSPROC4_COMPOUND) && (procnum != NFSPROC4_NULL))
                panic("nfs_request: invalid NFSv4 RPC request %d\n", procnum);

        lck_mtx_init(&req->r_mtx, nfs_request_grp, LCK_ATTR_NULL);
        req->r_nmp = nmp;
        req->r_np = np;
        req->r_thread = thd;
        if (IS_VALID_CRED(cred)) {
                kauth_cred_ref(cred);
                req->r_cred = cred;
        }
        req->r_procnum = procnum;
        if (proct[procnum] > 0)
                req->r_flags |= R_TIMING;
        req->r_nmrep.nmc_mhead = NULL;
        SLIST_INIT(&req->r_gss_seqlist);
        req->r_achain.tqe_next = NFSREQNOLIST;
        req->r_rchain.tqe_next = NFSREQNOLIST;
        req->r_cchain.tqe_next = NFSREQNOLIST;

        lck_mtx_unlock(&nmp->nm_lock);

        /* move the request mbuf chain to the nfsreq */
        req->r_mrest = nmrest->nmc_mhead;
        nmrest->nmc_mhead = NULL;

        req->r_flags |= R_INITTED;
        req->r_refs = 1;
        if (newreq)
                *reqp = req;
        return (0);
}

/*
 * Clean up and free an NFS request structure.
 */
void
nfs_request_destroy(struct nfsreq *req)
{
        struct nfsmount *nmp = req->r_np ? NFSTONMP(req->r_np) : req->r_nmp;
        struct gss_seq *gsp, *ngsp;
        struct timespec ts = { 1, 0 };
        int clearjbtimeo = 0;

        if (!req || !(req->r_flags & R_INITTED))
                return;
        req->r_flags &= ~R_INITTED;
        if (req->r_lflags & RL_QUEUED)
                nfs_reqdequeue(req);
        if (req->r_achain.tqe_next != NFSREQNOLIST) {
                /* still on an async I/O queue? */
                lck_mtx_lock(nfsiod_mutex);
                if (nmp && (req->r_achain.tqe_next != NFSREQNOLIST)) {
                        TAILQ_REMOVE(&nmp->nm_iodq, req, r_achain);
                        req->r_achain.tqe_next = NFSREQNOLIST;
                }
                lck_mtx_unlock(nfsiod_mutex);
        }
        lck_mtx_lock(&req->r_mtx);
        if (nmp) {
                lck_mtx_lock(&nmp->nm_lock);
                if (req->r_rchain.tqe_next != NFSREQNOLIST) {
                        TAILQ_REMOVE(&nmp->nm_resendq, req, r_rchain);
                        req->r_rchain.tqe_next = NFSREQNOLIST;
                        if (req->r_flags & R_RESENDQ)
                                req->r_flags &= ~R_RESENDQ;
                }
                if (req->r_cchain.tqe_next != NFSREQNOLIST) {
                        TAILQ_REMOVE(&nmp->nm_cwndq, req, r_cchain);
                        req->r_cchain.tqe_next = NFSREQNOLIST;
                }
                if (req->r_flags & R_JBTPRINTFMSG) {
                        req->r_flags &= ~R_JBTPRINTFMSG;
                        nmp->nm_jbreqs--;
                        clearjbtimeo = (nmp->nm_jbreqs == 0) ? NFSSTA_JUKEBOXTIMEO : 0;
                }
                lck_mtx_unlock(&nmp->nm_lock);
        }
        while (req->r_flags & R_RESENDQ)
                msleep(req, &req->r_mtx, (PZERO - 1), "nfsresendqwait", &ts);
        lck_mtx_unlock(&req->r_mtx);
        if (clearjbtimeo)
                nfs_up(nmp, req->r_thread, clearjbtimeo, NULL);
        if (req->r_mhead)
                mbuf_freem(req->r_mhead);
        else if (req->r_mrest)
                mbuf_freem(req->r_mrest);
        if (req->r_nmrep.nmc_mhead)
                mbuf_freem(req->r_nmrep.nmc_mhead);
        if (IS_VALID_CRED(req->r_cred))
                kauth_cred_unref(&req->r_cred);
        if (req->r_gss_ctx)
                nfs_gss_clnt_rpcdone(req);
        SLIST_FOREACH_SAFE(gsp, &req->r_gss_seqlist, gss_seqnext, ngsp)
                FREE(gsp, M_TEMP);
        if (req->r_gss_ctx)
                nfs_gss_clnt_ctx_unref(req);

        lck_mtx_destroy(&req->r_mtx, nfs_request_grp);
        if (req->r_flags & R_ALLOCATED)
                FREE_ZONE(req, sizeof(*req), M_NFSREQ);
}

void
nfs_request_ref(struct nfsreq *req, int locked)
{
        if (!locked)
                lck_mtx_lock(&req->r_mtx);
        if (req->r_refs <= 0)
                panic("nfsreq reference error");
        req->r_refs++;
        if (!locked)
                lck_mtx_unlock(&req->r_mtx);
}

void
nfs_request_rele(struct nfsreq *req)
{
        int destroy;

        lck_mtx_lock(&req->r_mtx);
        if (req->r_refs <= 0)
                panic("nfsreq reference underflow");
        req->r_refs--;
        destroy = (req->r_refs == 0);
        lck_mtx_unlock(&req->r_mtx);
        if (destroy)
                nfs_request_destroy(req);
}


/*
 * Add an (updated) RPC header with authorization to an NFS request.
 */
int
nfs_request_add_header(struct nfsreq *req)
{
        struct nfsmount *nmp;
        int error = 0, auth_len = 0;
        mbuf_t m;

        /* free up any previous header */
        if ((m = req->r_mhead)) {
                while (m && (m != req->r_mrest))
                        m = mbuf_free(m);
                req->r_mhead = NULL;
        }

        nmp = req->r_np ? NFSTONMP(req->r_np) : req->r_nmp;
        if (!nmp)
                return (ENXIO);

        if (!req->r_cred) /* RPCAUTH_NULL */
                auth_len = 0;
        else switch (nmp->nm_auth) {
                case RPCAUTH_UNIX:
                        if (req->r_cred->cr_ngroups < 1)
                                return (EINVAL);
                        auth_len = ((((req->r_cred->cr_ngroups - 1) > nmp->nm_numgrps) ?
                                nmp->nm_numgrps : (req->r_cred->cr_ngroups - 1)) << 2) +
                                5 * NFSX_UNSIGNED;
                        break;
                case RPCAUTH_KRB5:
                case RPCAUTH_KRB5I:
                case RPCAUTH_KRB5P:
                        auth_len = 5 * NFSX_UNSIGNED + 0; // zero context handle for now
                        break;
                }

        error = nfsm_rpchead(req, auth_len, req->r_mrest, &req->r_xid, &req->r_mhead);
        if (error)
                return (error);

        req->r_mreqlen = mbuf_pkthdr_len(req->r_mhead);
        nmp = req->r_np ? NFSTONMP(req->r_np) : req->r_nmp;
        if (!nmp)
                return (ENXIO);
        lck_mtx_lock(&nmp->nm_lock);
        if (nmp->nm_flag & NFSMNT_SOFT)
                req->r_retry = nmp->nm_retry;
        else
                req->r_retry = NFS_MAXREXMIT + 1;       /* past clip limit */
        lck_mtx_unlock(&nmp->nm_lock);

        return (error);
}


/*
 * Queue an NFS request up and send it out.
 */
int
nfs_request_send(struct nfsreq *req, int wait)
{
        struct nfsmount *nmp;
        struct timeval now;

        lck_mtx_lock(&req->r_mtx);
        req->r_flags |= R_SENDING;
        lck_mtx_unlock(&req->r_mtx);

        lck_mtx_lock(nfs_request_mutex);

        nmp = req->r_np ? NFSTONMP(req->r_np) : req->r_nmp;
        if (!nmp) {
                lck_mtx_unlock(nfs_request_mutex);
                return (ENXIO);
        }

        microuptime(&now);
        if (!req->r_start) {
                req->r_start = now.tv_sec;
                req->r_lastmsg = now.tv_sec -
                    ((nmp->nm_tprintf_delay) - (nmp->nm_tprintf_initial_delay));
        }

        OSAddAtomic(1, &nfsstats.rpcrequests);

        /*
         * Chain request into list of outstanding requests. Be sure
         * to put it LAST so timer finds oldest requests first.
         * Make sure that the request queue timer is running
         * to check for possible request timeout.
         */
        TAILQ_INSERT_TAIL(&nfs_reqq, req, r_chain);
        req->r_lflags |= RL_QUEUED;
        if (!nfs_request_timer_on) {
                nfs_request_timer_on = 1;
                nfs_interval_timer_start(nfs_request_timer_call,
                        NFS_REQUESTDELAY);
        }
        lck_mtx_unlock(nfs_request_mutex);

        /* Send the request... */
        return (nfs_send(req, wait));
}

/*
 * Call nfs_wait_reply() to wait for the reply.
 */
void
nfs_request_wait(struct nfsreq *req)
{
        req->r_error = nfs_wait_reply(req);
}

/*
 * Finish up an NFS request by dequeueing it and
 * doing the initial NFS request reply processing.
 */
int
nfs_request_finish(
        struct nfsreq *req,
        struct nfsm_chain *nmrepp,
        int *status)
{
        struct nfsmount *nmp;
        mbuf_t mrep;
        int verf_type = 0;
        uint32_t verf_len = 0;
        uint32_t reply_status = 0;
        uint32_t rejected_status = 0;
        uint32_t auth_status = 0;
        uint32_t accepted_status = 0;
        struct nfsm_chain nmrep;
        int error, auth, clearjbtimeo;

        error = req->r_error;

        if (nmrepp)
                nmrepp->nmc_mhead = NULL;

        /* RPC done, unlink the request. */
        nfs_reqdequeue(req);

        mrep = req->r_nmrep.nmc_mhead;

        nmp = req->r_np ? NFSTONMP(req->r_np) : req->r_nmp;

        /*
         * Decrement the outstanding request count.
         */
        if ((req->r_flags & R_CWND) && nmp) {
                req->r_flags &= ~R_CWND;
                lck_mtx_lock(&nmp->nm_lock);
                FSDBG(273, R_XID32(req->r_xid), req, nmp->nm_sent, nmp->nm_cwnd);
                nmp->nm_sent -= NFS_CWNDSCALE;
                if ((nmp->nm_sent < nmp->nm_cwnd) && !TAILQ_EMPTY(&nmp->nm_cwndq)) {
                        /* congestion window is open, poke the cwnd queue */
                        struct nfsreq *req2 = TAILQ_FIRST(&nmp->nm_cwndq);
                        TAILQ_REMOVE(&nmp->nm_cwndq, req2, r_cchain);
                        req2->r_cchain.tqe_next = NFSREQNOLIST;
                        wakeup(req2);
                }
                lck_mtx_unlock(&nmp->nm_lock);
        }

        if (req->r_gss_ctx) {   // Using gss cred ?
                /*
                 * If the request had an RPCSEC_GSS credential
                 * then reset its sequence number bit in the
                 * request window.
                 */
                nfs_gss_clnt_rpcdone(req);

                /*
                 * If we need to re-send, go back and re-build the
                 * request based on a new sequence number.
                 * Note that we're using the original XID.
                 */
                if (error == EAGAIN) {
                        req->r_error = 0;
                        if (mrep)
                                mbuf_freem(mrep);
                        error = nfs_gss_clnt_args_restore(req); // remove any trailer mbufs
                        req->r_nmrep.nmc_mhead = NULL;
                        req->r_flags |= R_RESTART;
                        if (error == ENEEDAUTH) {
                                req->r_xid = 0;         // get a new XID
                                error = 0;
                        }
                        goto nfsmout;
                }
        }

        /*
         * If there was a successful reply, make sure to mark the mount as up.
         * If a tprintf message was given (or if this is a timed-out soft mount)
         * then post a tprintf message indicating the server is alive again.
         */
        if (!error) {
                if ((req->r_flags & R_TPRINTFMSG) ||
                    (nmp && (nmp->nm_flag & NFSMNT_SOFT) &&
                     ((nmp->nm_state & (NFSSTA_TIMEO|NFSSTA_FORCE)) == NFSSTA_TIMEO)))
                        nfs_up(nmp, req->r_thread, NFSSTA_TIMEO, "is alive again");
                else
                        nfs_up(nmp, req->r_thread, NFSSTA_TIMEO, NULL);
        }
        if (!error && !nmp)
                error = ENXIO;
        nfsmout_if(error);

        /*
         * break down the RPC header and check if ok
         */
        nmrep = req->r_nmrep;
        nfsm_chain_get_32(error, &nmrep, reply_status);
        nfsmout_if(error);
        if (reply_status == RPC_MSGDENIED) {
                nfsm_chain_get_32(error, &nmrep, rejected_status);
                nfsmout_if(error);
                if (rejected_status == RPC_MISMATCH) {
                        error = ENOTSUP;
                        goto nfsmout;
                }
                nfsm_chain_get_32(error, &nmrep, auth_status);
                nfsmout_if(error);
                switch (auth_status) {
                case RPCSEC_GSS_CREDPROBLEM:
                case RPCSEC_GSS_CTXPROBLEM:
                        /*
                         * An RPCSEC_GSS cred or context problem.
                         * We can't use it anymore.
                         * Restore the args, renew the context
                         * and set up for a resend.
                         */
                        error = nfs_gss_clnt_args_restore(req);
                        if (error && error != ENEEDAUTH)
                                break;

                        if (!error) {
                                error = nfs_gss_clnt_ctx_renew(req);
                                if (error)
                                        break;
                        }
                        mbuf_freem(mrep);
                        req->r_nmrep.nmc_mhead = NULL;
                        req->r_xid = 0;         // get a new XID
                        req->r_flags |= R_RESTART;
                        goto nfsmout;
                default:
                        error = EACCES;
                        break;
                }
                goto nfsmout;
        }

        /* Now check the verifier */
        nfsm_chain_get_32(error, &nmrep, verf_type); // verifier flavor
        nfsm_chain_get_32(error, &nmrep, verf_len);  // verifier length
        nfsmout_if(error);

        auth = !req->r_cred ? RPCAUTH_NULL : nmp->nm_auth;
        switch (auth) {
        case RPCAUTH_NULL:
        case RPCAUTH_UNIX:
                /* Any AUTH_UNIX verifier is ignored */
                if (verf_len > 0)
                        nfsm_chain_adv(error, &nmrep, nfsm_rndup(verf_len));
                nfsm_chain_get_32(error, &nmrep, accepted_status);
                break;
        case RPCAUTH_KRB5:
        case RPCAUTH_KRB5I:
        case RPCAUTH_KRB5P:
                error = nfs_gss_clnt_verf_get(req, &nmrep,
                        verf_type, verf_len, &accepted_status);
                break;
        }
        nfsmout_if(error);

        switch (accepted_status) {
        case RPC_SUCCESS:
                if (req->r_procnum == NFSPROC_NULL) {
                        /*
                         * The NFS null procedure is unique,
                         * in not returning an NFS status.
                         */
                        *status = NFS_OK;
                } else {
                        nfsm_chain_get_32(error, &nmrep, *status);
                        nfsmout_if(error);
                }

                if ((nmp->nm_vers != NFS_VER2) && (*status == NFSERR_TRYLATER)) {
                        /*
                         * It's a JUKEBOX error - delay and try again
                         */
                        int delay, slpflag = (nmp->nm_flag & NFSMNT_INT) ? PCATCH : 0;

                        mbuf_freem(mrep);
                        req->r_nmrep.nmc_mhead = NULL;
                        if ((req->r_delay >= 30) && !(nmp->nm_state & NFSSTA_MOUNTED)) {
                                /* we're not yet completely mounted and */
                                /* we can't complete an RPC, so we fail */
                                OSAddAtomic(1, &nfsstats.rpctimeouts);
                                nfs_softterm(req);
                                error = req->r_error;
                                goto nfsmout;
                        }
                        req->r_delay = !req->r_delay ? NFS_TRYLATERDEL : (req->r_delay * 2);
                        if (req->r_delay > 30)
                                req->r_delay = 30;
                        if (nmp->nm_tprintf_initial_delay && (req->r_delay >= nmp->nm_tprintf_initial_delay)) {
                                if (!(req->r_flags & R_JBTPRINTFMSG)) {
                                        req->r_flags |= R_JBTPRINTFMSG;
                                        lck_mtx_lock(&nmp->nm_lock);
                                        nmp->nm_jbreqs++;
                                        lck_mtx_unlock(&nmp->nm_lock);
                                }
                                nfs_down(req->r_nmp, req->r_thread, 0, NFSSTA_JUKEBOXTIMEO,
                                        "resource temporarily unavailable (jukebox)");
                        }
                        if ((nmp->nm_flag & NFSMNT_SOFT) && (req->r_delay == 30)) {
                                /* for soft mounts, just give up after a short while */
                                OSAddAtomic(1, &nfsstats.rpctimeouts);
                                nfs_softterm(req);
                                error = req->r_error;
                                goto nfsmout;
                        }
                        delay = req->r_delay;
                        if (req->r_callback.rcb_func) {
                                struct timeval now;
                                microuptime(&now);
                                req->r_resendtime = now.tv_sec + delay;
                        } else {
                                do {
                                        if ((error = nfs_sigintr(req->r_nmp, req, req->r_thread, 0)))
                                                goto nfsmout;
                                        tsleep(&lbolt, PSOCK|slpflag, "nfs_jukebox_trylater", 0);
                                } while (--delay > 0);
                        }
                        req->r_xid = 0;                 // get a new XID
                        req->r_flags |= R_RESTART;
                        req->r_start = 0;
                        FSDBG(273, R_XID32(req->r_xid), nmp, req, NFSERR_TRYLATER);
                        return (0);
                }

                if (req->r_flags & R_JBTPRINTFMSG) {
                        req->r_flags &= ~R_JBTPRINTFMSG;
                        lck_mtx_lock(&nmp->nm_lock);
                        nmp->nm_jbreqs--;
                        clearjbtimeo = (nmp->nm_jbreqs == 0) ? NFSSTA_JUKEBOXTIMEO : 0;
                        lck_mtx_unlock(&nmp->nm_lock);
                        nfs_up(nmp, req->r_thread, clearjbtimeo, "resource available again");
                }

                if (*status == NFS_OK) {
                        /*
                         * Successful NFS request
                         */
                        *nmrepp = nmrep;
                        req->r_nmrep.nmc_mhead = NULL;
                        break;
                }
                /* Got an NFS error of some kind */

                /*
                 * If the File Handle was stale, invalidate the
                 * lookup cache, just in case.
                 */
                if ((*status == ESTALE) && req->r_np)
                        cache_purge(NFSTOV(req->r_np));
                if (nmp->nm_vers == NFS_VER2)
                        mbuf_freem(mrep);
                else
                        *nmrepp = nmrep;
                req->r_nmrep.nmc_mhead = NULL;
                error = 0;
                break;
        case RPC_PROGUNAVAIL:
                error = EPROGUNAVAIL;
                break;
        case RPC_PROGMISMATCH:
                error = ERPCMISMATCH;
                break;
        case RPC_PROCUNAVAIL:
                error = EPROCUNAVAIL;
                break;
        case RPC_GARBAGE:
                error = EBADRPC;
                break;
        case RPC_SYSTEM_ERR:
        default:
                error = EIO;
                break;
        }
nfsmout:
        if (req->r_flags & R_JBTPRINTFMSG) {
                req->r_flags &= ~R_JBTPRINTFMSG;
                lck_mtx_lock(&nmp->nm_lock);
                nmp->nm_jbreqs--;
                clearjbtimeo = (nmp->nm_jbreqs == 0) ? NFSSTA_JUKEBOXTIMEO : 0;
                lck_mtx_unlock(&nmp->nm_lock);
                if (clearjbtimeo)
                        nfs_up(nmp, req->r_thread, clearjbtimeo, NULL);
        }
        FSDBG(273, R_XID32(req->r_xid), nmp, req,
                (!error && (*status == NFS_OK)) ? 0xf0f0f0f0 : error);
        return (error);
}


/*
 * Perform an NFS request synchronously.
 */

int
nfs_request(
        nfsnode_t np,
        mount_t mp,     /* used only if !np */
        struct nfsm_chain *nmrest,
        int procnum,
        vfs_context_t ctx,
        struct nfsm_chain *nmrepp,
        u_int64_t *xidp,
        int *status)
{
        return nfs_request2(np, mp, nmrest, procnum,
                vfs_context_thread(ctx), vfs_context_ucred(ctx),
                0, nmrepp, xidp, status);
}

int
nfs_request2(
        nfsnode_t np,
        mount_t mp,     /* used only if !np */
        struct nfsm_chain *nmrest,
        int procnum,
        thread_t thd,
        kauth_cred_t cred,
        int flags,
        struct nfsm_chain *nmrepp,
        u_int64_t *xidp,
        int *status)
{
        struct nfsreq rq, *req = &rq;
        int error;

        if ((error = nfs_request_create(np, mp, nmrest, procnum, thd, cred, &req)))
                return (error);
        req->r_flags |= (flags & R_OPTMASK);

        FSDBG_TOP(273, R_XID32(req->r_xid), np, procnum, 0);
        do {
                req->r_error = 0;
                req->r_flags &= ~R_RESTART;
                if ((error = nfs_request_add_header(req)))
                        break;
                if (xidp)
                        *xidp = req->r_xid;
                if ((error = nfs_request_send(req, 1)))
                        break;
                nfs_request_wait(req);
                if ((error = nfs_request_finish(req, nmrepp, status)))
                        break;
        } while (req->r_flags & R_RESTART);

        FSDBG_BOT(273, R_XID32(req->r_xid), np, procnum, error);
        nfs_request_rele(req);
        return (error);
}


/*
 * Set up a new null proc request to exchange GSS context tokens with the
 * server. Associate the context that we are setting up with the request that we
 * are sending.
 */
 
int
nfs_request_gss(
                mount_t mp,
                struct nfsm_chain *nmrest,
                thread_t thd,
                kauth_cred_t cred,
                int flags,
                struct nfs_gss_clnt_ctx *cp,   /* Set to gss context to renew or setup */
                struct nfsm_chain *nmrepp,
                int *status)
{
        struct nfsreq rq, *req = &rq;
        int error;

        if ((error = nfs_request_create(NULL, mp, nmrest, NFSPROC_NULL, thd, cred, &req)))
                return (error);
        req->r_flags |= (flags & R_OPTMASK);
        
        if (cp == NULL) {
                printf("nfs_request_gss request has no context\n");
                nfs_request_rele(req);
                return (NFSERR_EAUTH);
        }
        nfs_gss_clnt_ctx_ref(req, cp);

        FSDBG_TOP(273, R_XID32(req->r_xid), NULL, NFSPROC_NULL, 0);
        do {
                req->r_error = 0;
                req->r_flags &= ~R_RESTART;
                if ((error = nfs_request_add_header(req)))
                        break;

                if ((error = nfs_request_send(req, 1)))
                        break;
                nfs_request_wait(req);
                if ((error = nfs_request_finish(req, nmrepp, status)))
                        break;
        } while (req->r_flags & R_RESTART);

        FSDBG_BOT(273, R_XID32(req->r_xid), NULL, NFSPROC_NULL, error);
        nfs_request_rele(req);
        return (error);
}
        
/*
 * Create and start an asynchronous NFS request.
 */
int
nfs_request_async(
        nfsnode_t np,
        mount_t mp,     /* used only if !np */
        struct nfsm_chain *nmrest,
        int procnum,
        thread_t thd,
        kauth_cred_t cred,
        struct nfsreq_cbinfo *cb,
        struct nfsreq **reqp)
{
        struct nfsreq *req;
        int error, sent;

        error = nfs_request_create(np, mp, nmrest, procnum, thd, cred, reqp);
        req = *reqp;
        FSDBG(274, (req ? R_XID32(req->r_xid) : 0), np, procnum, error);
        if (error)
                return (error);
        req->r_flags |= R_ASYNC;
        if (cb)
                req->r_callback = *cb;
        error = nfs_request_add_header(req);
        if (!error) {
                req->r_flags |= R_WAITSENT;
                if (req->r_callback.rcb_func)
                        nfs_request_ref(req, 0);
                error = nfs_request_send(req, 1);
                lck_mtx_lock(&req->r_mtx);
                if (!error && !(req->r_flags & R_SENT) && req->r_callback.rcb_func) {
                        /* make sure to wait until this async I/O request gets sent */
                        int slpflag = (req->r_nmp && (req->r_nmp->nm_flag & NFSMNT_INT) && req->r_thread) ? PCATCH : 0;
                        struct timespec ts = { 2, 0 };
                        while (!(req->r_flags & R_SENT)) {
                                if ((error = nfs_sigintr(req->r_nmp, req, req->r_thread, 0)))
                                        break;
                                msleep(req, &req->r_mtx, slpflag | (PZERO - 1), "nfswaitsent", &ts);
                                slpflag = 0;
                        }
                }
                sent = req->r_flags & R_SENT;
                lck_mtx_unlock(&req->r_mtx);
                if (error && req->r_callback.rcb_func && !sent)
                        nfs_request_rele(req);
        }
        FSDBG(274, R_XID32(req->r_xid), np, procnum, error);
        if (error || req->r_callback.rcb_func)
                nfs_request_rele(req);
        return (error);
}

/*
 * Wait for and finish an asynchronous NFS request.
 */
int
nfs_request_async_finish(
        struct nfsreq *req,
        struct nfsm_chain *nmrepp,
        u_int64_t *xidp,
        int *status)
{
        int error = 0, asyncio = req->r_callback.rcb_func ? 1 : 0;

        lck_mtx_lock(&req->r_mtx);
        if (!asyncio)
                req->r_flags |= R_ASYNCWAIT;
        while (req->r_flags & R_RESENDQ) {  /* wait until the request is off the resend queue */
                struct timespec ts = { 2, 0 };
                if ((error = nfs_sigintr(req->r_nmp, req, req->r_thread, 0)))
                        break;
                msleep(req, &req->r_mtx, PZERO-1, "nfsresendqwait", &ts);
        }
        lck_mtx_unlock(&req->r_mtx);

        if (!error) {
                nfs_request_wait(req);
                error = nfs_request_finish(req, nmrepp, status);
        }

        while (!error && (req->r_flags & R_RESTART)) {
                if (asyncio && req->r_resendtime) {  /* send later */
                        lck_mtx_lock(&req->r_mtx);
                        nfs_asyncio_resend(req);
                        lck_mtx_unlock(&req->r_mtx);
                        return (EINPROGRESS);
                }
                req->r_error = 0;
                req->r_flags &= ~R_RESTART;
                if ((error = nfs_request_add_header(req)))
                        break;
                if ((error = nfs_request_send(req, !asyncio)))
                        break;
                if (asyncio)
                        return (EINPROGRESS);
                nfs_request_wait(req);
                if ((error = nfs_request_finish(req, nmrepp, status)))
                        break;
        }
        if (xidp)
                *xidp = req->r_xid;

        FSDBG(275, R_XID32(req->r_xid), req->r_np, req->r_procnum, error);
        nfs_request_rele(req);
        return (error);
}

/*
 * Cancel a pending asynchronous NFS request.
 */
void
nfs_request_async_cancel(struct nfsreq *req)
{
        nfs_reqdequeue(req);
        FSDBG(275, R_XID32(req->r_xid), req->r_np, req->r_procnum, 0xD1ED1E);
        nfs_request_rele(req);
}

/*
 * Flag a request as being terminated.
 */
void
nfs_softterm(struct nfsreq *req)
{
        struct nfsmount *nmp = req->r_nmp;
        req->r_flags |= R_SOFTTERM;
        req->r_error = ETIMEDOUT;
        if (!(req->r_flags & R_CWND) || !nmp)
                return;
        /* update congestion window */
        req->r_flags &= ~R_CWND;
        lck_mtx_lock(&nmp->nm_lock);
        FSDBG(532, R_XID32(req->r_xid), req, nmp->nm_sent, nmp->nm_cwnd);
        nmp->nm_sent -= NFS_CWNDSCALE;
        if ((nmp->nm_sent < nmp->nm_cwnd) && !TAILQ_EMPTY(&nmp->nm_cwndq)) {
                /* congestion window is open, poke the cwnd queue */
                struct nfsreq *req2 = TAILQ_FIRST(&nmp->nm_cwndq);
                TAILQ_REMOVE(&nmp->nm_cwndq, req2, r_cchain);
                req2->r_cchain.tqe_next = NFSREQNOLIST;
                wakeup(req2);
        }
        lck_mtx_unlock(&nmp->nm_lock);
}

/*
 * Ensure req isn't in use by the timer, then dequeue it.
 */
void
nfs_reqdequeue(struct nfsreq *req)
{
        lck_mtx_lock(nfs_request_mutex);
        while (req->r_lflags & RL_BUSY) {
                req->r_lflags |= RL_WAITING;
                msleep(&req->r_lflags, nfs_request_mutex, PSOCK, "reqdeq", NULL);
        }
        if (req->r_lflags & RL_QUEUED) {
                TAILQ_REMOVE(&nfs_reqq, req, r_chain);
                req->r_lflags &= ~RL_QUEUED;
        }
        lck_mtx_unlock(nfs_request_mutex);
}

/*
 * Busy (lock) a nfsreq, used by the nfs timer to make sure it's not
 * free()'d out from under it.
 */
void
nfs_reqbusy(struct nfsreq *req)
{
        if (req->r_lflags & RL_BUSY)
                panic("req locked");
        req->r_lflags |= RL_BUSY;
}

/*
 * Unbusy the nfsreq passed in, return the next nfsreq in the chain busied.
 */
struct nfsreq *
nfs_reqnext(struct nfsreq *req)
{
        struct nfsreq * nextreq;

        if (req == NULL)
                return (NULL);
        /*
         * We need to get and busy the next req before signalling the
         * current one, otherwise wakeup() may block us and we'll race to
         * grab the next req.
         */
        nextreq = TAILQ_NEXT(req, r_chain);
        if (nextreq != NULL)
                nfs_reqbusy(nextreq);
        /* unbusy and signal. */
        req->r_lflags &= ~RL_BUSY;
        if (req->r_lflags & RL_WAITING) {
                req->r_lflags &= ~RL_WAITING;
                wakeup(&req->r_lflags);
        }
        return (nextreq);
}

/*
 * NFS request queue timer routine
 *
 * Scan the NFS request queue for any requests that have timed out.
 *
 * Alert the system of unresponsive servers.
 * Mark expired requests on soft mounts as terminated.
 * For UDP, mark/signal requests for retransmission.
 */
void
nfs_request_timer(__unused void *param0, __unused void *param1)
{
        struct nfsreq *req;
        struct nfsmount *nmp;
        int timeo, maxtime, finish_asyncio, error;
        struct timeval now;
        TAILQ_HEAD(nfs_mount_pokeq, nfsmount) nfs_mount_poke_queue;

        lck_mtx_lock(nfs_request_mutex);
        req = TAILQ_FIRST(&nfs_reqq);
        if (req == NULL) {      /* no requests - turn timer off */
                nfs_request_timer_on = 0;
                lck_mtx_unlock(nfs_request_mutex);
                return;
        }

        nfs_reqbusy(req);
        TAILQ_INIT(&nfs_mount_poke_queue);

        microuptime(&now);
        for ( ; req != NULL ; req = nfs_reqnext(req)) {
                nmp = req->r_nmp;
                if (!nmp) /* unmounted */
                        continue;
                if (req->r_error || req->r_nmrep.nmc_mhead)
                        continue;
                if ((error = nfs_sigintr(nmp, req, req->r_thread, 0))) {
                        if (req->r_callback.rcb_func != NULL) {
                                /* async I/O RPC needs to be finished */
                                lck_mtx_lock(&req->r_mtx);
                                req->r_error = error;
                                finish_asyncio = !(req->r_flags & R_WAITSENT);
                                wakeup(req);
                                lck_mtx_unlock(&req->r_mtx);
                                if (finish_asyncio)
                                        nfs_asyncio_finish(req);
                        }
                        continue;
                }

                lck_mtx_lock(&req->r_mtx);

                if (nmp->nm_tprintf_initial_delay &&
                    ((req->r_rexmit > 2) || (req->r_flags & R_RESENDERR)) &&
                    ((req->r_lastmsg + nmp->nm_tprintf_delay) < now.tv_sec)) {
                        req->r_lastmsg = now.tv_sec;
                        nfs_down(req->r_nmp, req->r_thread, 0, NFSSTA_TIMEO,
                                "not responding");
                        req->r_flags |= R_TPRINTFMSG;
                        lck_mtx_lock(&nmp->nm_lock);
                        if (!(nmp->nm_state & NFSSTA_MOUNTED)) {
                                lck_mtx_unlock(&nmp->nm_lock);
                                /* we're not yet completely mounted and */
                                /* we can't complete an RPC, so we fail */
                                OSAddAtomic(1, &nfsstats.rpctimeouts);
                                nfs_softterm(req);
                                finish_asyncio = ((req->r_callback.rcb_func != NULL) && !(req->r_flags & R_WAITSENT));
                                wakeup(req);
                                lck_mtx_unlock(&req->r_mtx);
                                if (finish_asyncio)
                                        nfs_asyncio_finish(req);
                                continue;
                        }
                        lck_mtx_unlock(&nmp->nm_lock);
                }

                /*
                 * Put a reasonable limit on the maximum timeout,
                 * and reduce that limit when soft mounts get timeouts or are in reconnect.
                 */
                if (!(nmp->nm_flag & NFSMNT_SOFT))
                        maxtime = NFS_MAXTIMEO;
                else if ((req->r_flags & (R_SETUP|R_RECOVER)) ||
                         ((nmp->nm_reconnect_start <= 0) || ((now.tv_sec - nmp->nm_reconnect_start) < 8)))
                        maxtime = (NFS_MAXTIMEO / (nmp->nm_timeouts+1))/2;
                else
                        maxtime = NFS_MINTIMEO/4;

                /*
                 * Check for request timeout.
                 */
                if (req->r_rtt >= 0) {
                        req->r_rtt++;
                        lck_mtx_lock(&nmp->nm_lock);
                        if (req->r_flags & R_RESENDERR) {
                                /* with resend errors, retry every few seconds */
                                timeo = 4*hz;
                        } else {
                                if (req->r_procnum == NFSPROC_NULL && req->r_gss_ctx != NULL)
                                        timeo = NFS_MINIDEMTIMEO; // gss context setup
                                else if (nmp->nm_flag & NFSMNT_DUMBTIMR)
                                        timeo = nmp->nm_timeo;
                                else
                                        timeo = NFS_RTO(nmp, proct[req->r_procnum]);

                                /* ensure 62.5 ms floor */
                                while (16 * timeo < hz)
                                        timeo *= 2;
                                if (nmp->nm_timeouts > 0)
                                        timeo *= nfs_backoff[nmp->nm_timeouts - 1];
                        }
                        /* limit timeout to max */
                        if (timeo > maxtime)
                                timeo = maxtime;
                        if (req->r_rtt <= timeo) {
                                lck_mtx_unlock(&nmp->nm_lock);
                                lck_mtx_unlock(&req->r_mtx);
                                continue;
                        }
                        /* The request has timed out */
                        NFS_SOCK_DBG(("nfs timeout: proc %d %d xid %llx rtt %d to %d # %d, t %ld/%d\n",
                                req->r_procnum, proct[req->r_procnum],
                                req->r_xid, req->r_rtt, timeo, nmp->nm_timeouts,
                                (now.tv_sec - req->r_start)*NFS_HZ, maxtime));
                        if (nmp->nm_timeouts < 8)
                                nmp->nm_timeouts++;
                        nfs_mount_check_dead_timeout(nmp);
                        /* if it's been a few seconds, try poking the socket */
                        if ((nmp->nm_sotype == SOCK_STREAM) &&
                            ((now.tv_sec - req->r_start) >= 3) &&
                            !(nmp->nm_sockflags & NMSOCK_POKE)) {
                                nmp->nm_sockflags |= NMSOCK_POKE;
                                TAILQ_INSERT_TAIL(&nfs_mount_poke_queue, nmp, nm_pokeq);
                        }
                        lck_mtx_unlock(&nmp->nm_lock);
                }

                /* For soft mounts (& SETUPs/RECOVERs), check for too many retransmits/timeout. */
                if (((nmp->nm_flag & NFSMNT_SOFT) || (req->r_flags & (R_SETUP|R_RECOVER))) &&
                    ((req->r_rexmit >= req->r_retry) || /* too many */
                     ((now.tv_sec - req->r_start)*NFS_HZ > maxtime))) { /* too long */
                        OSAddAtomic(1, &nfsstats.rpctimeouts);
                        lck_mtx_lock(&nmp->nm_lock);
                        if (!(nmp->nm_state & NFSSTA_TIMEO)) {
                                lck_mtx_unlock(&nmp->nm_lock);
                                /* make sure we note the unresponsive server */
                                /* (maxtime may be less than tprintf delay) */
                                nfs_down(req->r_nmp, req->r_thread, 0, NFSSTA_TIMEO,
                                        "not responding");
                                req->r_lastmsg = now.tv_sec;
                                req->r_flags |= R_TPRINTFMSG;
                        } else {
                                lck_mtx_unlock(&nmp->nm_lock);
                        }
                        NFS_SOCK_DBG(("nfs timer TERMINATE: p %d x 0x%llx f 0x%x rtt %d t %ld\n",
                                req->r_procnum, req->r_xid, req->r_flags, req->r_rtt,
                                now.tv_sec - req->r_start));
                        nfs_softterm(req);
                        finish_asyncio = ((req->r_callback.rcb_func != NULL) && !(req->r_flags & R_WAITSENT));
                        wakeup(req);
                        lck_mtx_unlock(&req->r_mtx);
                        if (finish_asyncio)
                                nfs_asyncio_finish(req);
                        continue;
                }

                /* for TCP, only resend if explicitly requested */
                if ((nmp->nm_sotype == SOCK_STREAM) && !(req->r_flags & R_MUSTRESEND)) {
                        if (++req->r_rexmit > NFS_MAXREXMIT)
                                req->r_rexmit = NFS_MAXREXMIT;
                        req->r_rtt = 0;
                        lck_mtx_unlock(&req->r_mtx);
                        continue;
                }

                /*
                 * The request needs to be (re)sent.  Kick the requester to resend it.
                 * (unless it's already marked as needing a resend)
                 */
                if ((req->r_flags & R_MUSTRESEND) && (req->r_rtt == -1)) {
                        lck_mtx_unlock(&req->r_mtx);
                        continue;
                }
                NFS_SOCK_DBG(("nfs timer mark resend: p %d x 0x%llx f 0x%x rtt %d\n",
                        req->r_procnum, req->r_xid, req->r_flags, req->r_rtt));
                req->r_flags |= R_MUSTRESEND;
                req->r_rtt = -1;
                wakeup(req);
                if ((req->r_flags & (R_ASYNC|R_ASYNCWAIT|R_SENDING)) == R_ASYNC)
                        nfs_asyncio_resend(req);
                lck_mtx_unlock(&req->r_mtx);
        }

        lck_mtx_unlock(nfs_request_mutex);

        /* poke any sockets */
        while ((nmp = TAILQ_FIRST(&nfs_mount_poke_queue))) {
                TAILQ_REMOVE(&nfs_mount_poke_queue, nmp, nm_pokeq);
                nfs_sock_poke(nmp);
                lck_mtx_lock(&nmp->nm_lock);
                nmp->nm_sockflags &= ~NMSOCK_POKE;
                if (!(nmp->nm_state & NFSSTA_MOUNTED))
                        wakeup(&nmp->nm_sockflags);
                lck_mtx_unlock(&nmp->nm_lock);
        }

        nfs_interval_timer_start(nfs_request_timer_call, NFS_REQUESTDELAY);
}

/*
 * check a thread's proc for the "noremotehang" flag.
 */
int
nfs_noremotehang(thread_t thd)
{
        proc_t p = thd ? get_bsdthreadtask_info(thd) : NULL;
        return (p && proc_noremotehang(p));
}

/*
 * Test for a termination condition pending on the process.
 * This is used to determine if we need to bail on a mount.
 * ETIMEDOUT is returned if there has been a soft timeout.
 * EINTR is returned if there is a signal pending that is not being ignored
 * and the mount is interruptable, or if we are a thread that is in the process
 * of cancellation (also SIGKILL posted).
 */
int
nfs_sigintr(struct nfsmount *nmp, struct nfsreq *req, thread_t thd, int nmplocked)
{
        proc_t p;
        int error = 0;

        if (nmp == NULL)
                return (ENXIO);

        if (req && (req->r_flags & R_SOFTTERM))
                return (ETIMEDOUT); /* request has been terminated. */

        /*
         * If we're in the progress of a force unmount and there's
         * been a timeout, we're dead and fail IO.
         */
        if (!nmplocked)
                lck_mtx_lock(&nmp->nm_lock);
        if ((nmp->nm_state & NFSSTA_FORCE) &&
            (nmp->nm_state & (NFSSTA_TIMEO|NFSSTA_JUKEBOXTIMEO|NFSSTA_LOCKTIMEO))) {
                error = EIO;
        } else if (nmp->nm_mountp->mnt_kern_flag & MNTK_FRCUNMOUNT) {
                /* Someone is unmounting us, go soft and mark it. */
                nmp->nm_flag |= NFSMNT_SOFT;
                nmp->nm_state |= NFSSTA_FORCE;
        }

        /* Check if the mount is marked dead. */
        if (!error && (nmp->nm_state & NFSSTA_DEAD))
                error = ENXIO;

        /*
         * If the mount is hung and we've requested not to hang
         * on remote filesystems, then bail now.
         */
        if (!error && (nmp->nm_state & NFSSTA_TIMEO) && nfs_noremotehang(thd))
                error = EIO;

        if (!nmplocked)
                lck_mtx_unlock(&nmp->nm_lock);
        if (error)
                return (error);

        /* may not have a thread for async I/O */
        if (thd == NULL)
                return (0);

        /* If this thread belongs to kernel task; then abort check is not needed */
        if ((current_proc() != kernproc) && current_thread_aborted())
                return (EINTR);

        /* mask off thread and process blocked signals. */
        if ((nmp->nm_flag & NFSMNT_INT) && ((p = get_bsdthreadtask_info(thd))) &&
            proc_pendingsignals(p, NFSINT_SIGMASK))
                return (EINTR);
        return (0);
}

/*
 * Lock a socket against others.
 * Necessary for STREAM sockets to ensure you get an entire rpc request/reply
 * and also to avoid race conditions between the processes with nfs requests
 * in progress when a reconnect is necessary.
 */
int
nfs_sndlock(struct nfsreq *req)
{
        struct nfsmount *nmp = req->r_nmp;
        int *statep;
        int error = 0, slpflag = 0;
        struct timespec ts = { 0, 0 };

        if (nmp == NULL)
                return (ENXIO);

        lck_mtx_lock(&nmp->nm_lock);
        statep = &nmp->nm_state;

        if ((nmp->nm_flag & NFSMNT_INT) && req->r_thread)
                slpflag = PCATCH;
        while (*statep & NFSSTA_SNDLOCK) {
                if ((error = nfs_sigintr(nmp, req, req->r_thread, 1)))
                        break;
                *statep |= NFSSTA_WANTSND;
                if (nfs_noremotehang(req->r_thread))
                        ts.tv_sec = 1;
                msleep(statep, &nmp->nm_lock, slpflag | (PZERO - 1), "nfsndlck", &ts);
                if (slpflag == PCATCH) {
                        slpflag = 0;
                        ts.tv_sec = 2;
                }
        }
        if (!error)
                *statep |= NFSSTA_SNDLOCK;
        lck_mtx_unlock(&nmp->nm_lock);
        return (error);
}

/*
 * Unlock the stream socket for others.
 */
void
nfs_sndunlock(struct nfsreq *req)
{
        struct nfsmount *nmp = req->r_nmp;
        int *statep, wake = 0;

        if (nmp == NULL)
                return;
        lck_mtx_lock(&nmp->nm_lock);
        statep = &nmp->nm_state;
        if ((*statep & NFSSTA_SNDLOCK) == 0)
                panic("nfs sndunlock");
        *statep &= ~NFSSTA_SNDLOCK;
        if (*statep & NFSSTA_WANTSND) {
                *statep &= ~NFSSTA_WANTSND;
                wake = 1;
        }
        lck_mtx_unlock(&nmp->nm_lock);
        if (wake)
                wakeup(statep);
}

int
nfs_aux_request(
        struct nfsmount *nmp,
        thread_t thd,
        struct sockaddr_in *saddr,
        mbuf_t mreq,
        uint32_t xid,
        int bindresv,
        int timeo,
        struct nfsm_chain *nmrep)
{
        int error = 0, on = 1, try, sendat = 2;
        socket_t so = NULL;
        struct sockaddr_in sin;
        struct timeval tv = { 1, 0 };
        mbuf_t m, mrep = NULL;
        struct msghdr msg;
        uint32_t rxid = 0, reply = 0, reply_status, rejected_status;
        uint32_t verf_type, verf_len, accepted_status;
        size_t readlen;

        /* create socket and set options */
        if (((error = sock_socket(saddr->sin_family, SOCK_DGRAM, IPPROTO_UDP, NULL, NULL, &so))) ||
            ((error = sock_setsockopt(so, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)))) ||
            ((error = sock_setsockopt(so, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)))) ||
            ((error = sock_setsockopt(so, SOL_SOCKET, SO_NOADDRERR, &on, sizeof(on)))))
                goto nfsmout;
        if (bindresv) {
                int portrange = IP_PORTRANGE_LOW;
                error = sock_setsockopt(so, IPPROTO_IP, IP_PORTRANGE, &portrange, sizeof(portrange));
                nfsmout_if(error);
                /* bind now to check for failure */
                sin.sin_len = sizeof (struct sockaddr_in);
                sin.sin_family = AF_INET;
                sin.sin_addr.s_addr = INADDR_ANY;
                sin.sin_port = 0;
                error = sock_bind(so, (struct sockaddr *) &sin);
                nfsmout_if(error);
        }

        for (try=0; try < timeo; try++) {
                if ((error = nfs_sigintr(nmp, NULL, thd, 0)))
                        break;
                if (!try || (try == sendat)) {
                        /* send the request (resending periodically) */
                        if ((error = mbuf_copym(mreq, 0, MBUF_COPYALL, MBUF_WAITOK, &m)))
                                goto nfsmout;
                        bzero(&msg, sizeof(msg));
                        msg.msg_name = saddr;
                        msg.msg_namelen = saddr->sin_len;
                        if ((error = sock_sendmbuf(so, &msg, m, 0, NULL)))
                                goto nfsmout;
                        sendat *= 2;
                        if (sendat > 30)
                                sendat = 30;
                }
                /* wait for the response */
                readlen = 1<<18;
                bzero(&msg, sizeof(msg));
                error = sock_receivembuf(so, &msg, &mrep, 0, &readlen);
                if (error == EWOULDBLOCK)
                        continue;
                nfsmout_if(error);
                /* parse the response */
                nfsm_chain_dissect_init(error, nmrep, mrep);
                nfsm_chain_get_32(error, nmrep, rxid);
                nfsm_chain_get_32(error, nmrep, reply);
                nfsmout_if(error);
                if ((rxid != xid) || (reply != RPC_REPLY))
                        error = EBADRPC;
                nfsm_chain_get_32(error, nmrep, reply_status);
                nfsmout_if(error);
                if (reply_status == RPC_MSGDENIED) {
                        nfsm_chain_get_32(error, nmrep, rejected_status);
                        nfsmout_if(error);
                        error = (rejected_status == RPC_MISMATCH) ? ENOTSUP : EACCES;
                        goto nfsmout;
                }
                nfsm_chain_get_32(error, nmrep, verf_type); /* verifier flavor */
                nfsm_chain_get_32(error, nmrep, verf_len); /* verifier length */
                nfsmout_if(error);
                if (verf_len)
                        nfsm_chain_adv(error, nmrep, nfsm_rndup(verf_len));
                nfsm_chain_get_32(error, nmrep, accepted_status);
                nfsm_assert(error, (accepted_status == RPC_SUCCESS), EIO);
                break;
        }
nfsmout:
        if (so) {
                sock_shutdown(so, SHUT_RDWR);
                sock_close(so);
        }
        mbuf_freem(mreq);
        return (error);
}

int
nfs_msg(thread_t thd,
        const char *server,
        const char *msg,
        int error)
{
        proc_t p = thd ? get_bsdthreadtask_info(thd) : NULL;
        tpr_t tpr;

        if (p)
                tpr = tprintf_open(p);
        else
                tpr = NULL;
        if (error)
                tprintf(tpr, "nfs server %s: %s, error %d\n", server, msg, error);
        else
                tprintf(tpr, "nfs server %s: %s\n", server, msg);
        tprintf_close(tpr);
        return (0);
}

void
nfs_down(struct nfsmount *nmp, thread_t thd, int error, int flags, const char *msg)
{
        int timeoutmask, wasunresponsive, unresponsive, softnobrowse;
        uint32_t do_vfs_signal;
        struct timeval now;

        if (nmp == NULL)
                return;

        lck_mtx_lock(&nmp->nm_lock);

        timeoutmask = NFSSTA_TIMEO | NFSSTA_LOCKTIMEO | NFSSTA_JUKEBOXTIMEO;
        if (nmp->nm_flag & NFSMNT_MUTEJUKEBOX) /* jukebox timeouts don't count as unresponsive if muted */
                   timeoutmask &= ~NFSSTA_JUKEBOXTIMEO;
        wasunresponsive = (nmp->nm_state & timeoutmask);

        /* XXX don't allow users to know about/disconnect unresponsive, soft, nobrowse mounts */
        softnobrowse = ((nmp->nm_flag & NFSMNT_SOFT) && (vfs_flags(nmp->nm_mountp) & MNT_DONTBROWSE));

        if ((flags & NFSSTA_TIMEO) && !(nmp->nm_state & NFSSTA_TIMEO))
                nmp->nm_state |= NFSSTA_TIMEO;
        if ((flags & NFSSTA_LOCKTIMEO) && !(nmp->nm_state & NFSSTA_LOCKTIMEO))
                nmp->nm_state |= NFSSTA_LOCKTIMEO;
        if ((flags & NFSSTA_JUKEBOXTIMEO) && !(nmp->nm_state & NFSSTA_JUKEBOXTIMEO))
                nmp->nm_state |= NFSSTA_JUKEBOXTIMEO;

        unresponsive = (nmp->nm_state & timeoutmask);

        if (unresponsive && (nmp->nm_flag & NFSMNT_DEADTIMEOUT)) {
                microuptime(&now);
                if (!wasunresponsive) {
                        nmp->nm_deadto_start = now.tv_sec;
                        nfs_mount_sock_thread_wake(nmp);
                } else if ((now.tv_sec - nmp->nm_deadto_start) > nmp->nm_deadtimeout) {
                        if (!(nmp->nm_state & NFSSTA_DEAD))
                                printf("nfs server %s: dead\n", vfs_statfs(nmp->nm_mountp)->f_mntfromname);
                        nmp->nm_state |= NFSSTA_DEAD;
                }
        }
        lck_mtx_unlock(&nmp->nm_lock);

        if (nmp->nm_state & NFSSTA_DEAD)
                do_vfs_signal = VQ_DEAD;
        else if (softnobrowse || wasunresponsive || !unresponsive)
                do_vfs_signal = 0;
        else
                do_vfs_signal = VQ_NOTRESP;
        if (do_vfs_signal)
                vfs_event_signal(&vfs_statfs(nmp->nm_mountp)->f_fsid, do_vfs_signal, 0);

        nfs_msg(thd, vfs_statfs(nmp->nm_mountp)->f_mntfromname, msg, error);
}

void
nfs_up(struct nfsmount *nmp, thread_t thd, int flags, const char *msg)
{
        int timeoutmask, wasunresponsive, unresponsive, softnobrowse;
        int do_vfs_signal;

        if (nmp == NULL)
                return;

        if (msg)
                nfs_msg(thd, vfs_statfs(nmp->nm_mountp)->f_mntfromname, msg, 0);

        lck_mtx_lock(&nmp->nm_lock);

        timeoutmask = NFSSTA_TIMEO | NFSSTA_LOCKTIMEO | NFSSTA_JUKEBOXTIMEO;
        if (nmp->nm_flag & NFSMNT_MUTEJUKEBOX) /* jukebox timeouts don't count as unresponsive if muted */
                   timeoutmask &= ~NFSSTA_JUKEBOXTIMEO;
        wasunresponsive = (nmp->nm_state & timeoutmask);

        /* XXX don't allow users to know about/disconnect unresponsive, soft, nobrowse mounts */
        softnobrowse = ((nmp->nm_flag & NFSMNT_SOFT) && (vfs_flags(nmp->nm_mountp) & MNT_DONTBROWSE));

        if ((flags & NFSSTA_TIMEO) && (nmp->nm_state & NFSSTA_TIMEO))
                nmp->nm_state &= ~NFSSTA_TIMEO;
        if ((flags & NFSSTA_LOCKTIMEO) && (nmp->nm_state & NFSSTA_LOCKTIMEO))
                nmp->nm_state &= ~NFSSTA_LOCKTIMEO;
        if ((flags & NFSSTA_JUKEBOXTIMEO) && (nmp->nm_state & NFSSTA_JUKEBOXTIMEO))
                nmp->nm_state &= ~NFSSTA_JUKEBOXTIMEO;

        unresponsive = (nmp->nm_state & timeoutmask);

        if (nmp->nm_deadto_start)
                nmp->nm_deadto_start = 0;
        lck_mtx_unlock(&nmp->nm_lock);

        if (softnobrowse)
                do_vfs_signal = 0;
        else
                do_vfs_signal = (wasunresponsive && !unresponsive);
        if (do_vfs_signal)
                vfs_event_signal(&vfs_statfs(nmp->nm_mountp)->f_fsid, VQ_NOTRESP, 1);
}


#endif /* NFSCLIENT */

#if NFSSERVER

/*
 * Generate the rpc reply header
 * siz arg. is used to decide if adding a cluster is worthwhile
 */
int
nfsrv_rephead(
        struct nfsrv_descript *nd,
        __unused struct nfsrv_sock *slp,
        struct nfsm_chain *nmrepp,
        size_t siz)
{
        mbuf_t mrep;
        u_int32_t *tl;
        struct nfsm_chain nmrep;
        int err, error;

        err = nd->nd_repstat;
        if (err && (nd->nd_vers == NFS_VER2))
                siz = 0;

        /*
         * If this is a big reply, use a cluster else
         * try and leave leading space for the lower level headers.
         */
        siz += RPC_REPLYSIZ;
        if (siz >= nfs_mbuf_minclsize) {
                error = mbuf_getpacket(MBUF_WAITOK, &mrep);
        } else {
                error = mbuf_gethdr(MBUF_WAITOK, MBUF_TYPE_DATA, &mrep);
        }
        if (error) {
                /* unable to allocate packet */
                /* XXX should we keep statistics for these errors? */
                return (error);
        }
        if (siz < nfs_mbuf_minclsize) {
                /* leave space for lower level headers */
                tl = mbuf_data(mrep);
                tl += 80/sizeof(*tl);  /* XXX max_hdr? XXX */
                mbuf_setdata(mrep, tl, 6 * NFSX_UNSIGNED);
        }
        nfsm_chain_init(&nmrep, mrep);
        nfsm_chain_add_32(error, &nmrep, nd->nd_retxid);
        nfsm_chain_add_32(error, &nmrep, RPC_REPLY);
        if (err == ERPCMISMATCH || (err & NFSERR_AUTHERR)) {
                nfsm_chain_add_32(error, &nmrep, RPC_MSGDENIED);
                if (err & NFSERR_AUTHERR) {
                        nfsm_chain_add_32(error, &nmrep, RPC_AUTHERR);
                        nfsm_chain_add_32(error, &nmrep, (err & ~NFSERR_AUTHERR));
                } else {
                        nfsm_chain_add_32(error, &nmrep, RPC_MISMATCH);
                        nfsm_chain_add_32(error, &nmrep, RPC_VER2);
                        nfsm_chain_add_32(error, &nmrep, RPC_VER2);
                }
        } else {
                /* reply status */
                nfsm_chain_add_32(error, &nmrep, RPC_MSGACCEPTED);
                if (nd->nd_gss_context != NULL) {
                        /* RPCSEC_GSS verifier */
                        error = nfs_gss_svc_verf_put(nd, &nmrep);
                        if (error) {
                                nfsm_chain_add_32(error, &nmrep, RPC_SYSTEM_ERR);
                                goto done;
                        }
                } else {
                        /* RPCAUTH_NULL verifier */
                        nfsm_chain_add_32(error, &nmrep, RPCAUTH_NULL);
                        nfsm_chain_add_32(error, &nmrep, 0);
                }
                /* accepted status */
                switch (err) {
                case EPROGUNAVAIL:
                        nfsm_chain_add_32(error, &nmrep, RPC_PROGUNAVAIL);
                        break;
                case EPROGMISMATCH:
                        nfsm_chain_add_32(error, &nmrep, RPC_PROGMISMATCH);
                        /* XXX hard coded versions? */
                        nfsm_chain_add_32(error, &nmrep, NFS_VER2);
                        nfsm_chain_add_32(error, &nmrep, NFS_VER3);
                        break;
                case EPROCUNAVAIL:
                        nfsm_chain_add_32(error, &nmrep, RPC_PROCUNAVAIL);
                        break;
                case EBADRPC:
                        nfsm_chain_add_32(error, &nmrep, RPC_GARBAGE);
                        break;
                default:
                        nfsm_chain_add_32(error, &nmrep, RPC_SUCCESS);
                        if (nd->nd_gss_context != NULL)
                                error = nfs_gss_svc_prepare_reply(nd, &nmrep);
                        if (err != NFSERR_RETVOID)
                                nfsm_chain_add_32(error, &nmrep,
                                        (err ? nfsrv_errmap(nd, err) : 0));
                        break;
                }
        }

done:
        nfsm_chain_build_done(error, &nmrep);
        if (error) {
                /* error composing reply header */
                /* XXX should we keep statistics for these errors? */
                mbuf_freem(mrep);
                return (error);
        }

        *nmrepp = nmrep;
        if ((err != 0) && (err != NFSERR_RETVOID))
                OSAddAtomic(1, &nfsstats.srvrpc_errs);
        return (0);
}

/*
 * The nfs server send routine.
 *
 * - return EINTR or ERESTART if interrupted by a signal
 * - return EPIPE if a connection is lost for connection based sockets (TCP...)
 * - do any cleanup required by recoverable socket errors (???)
 */
int
nfsrv_send(struct nfsrv_sock *slp, mbuf_t nam, mbuf_t top)
{
        int error;
        socket_t so = slp->ns_so;
        struct sockaddr *sendnam;
        struct msghdr msg;

        bzero(&msg, sizeof(msg));
        if (nam && !sock_isconnected(so) && (slp->ns_sotype != SOCK_STREAM)) {
                if ((sendnam = mbuf_data(nam))) {
                        msg.msg_name = (caddr_t)sendnam;
                        msg.msg_namelen = sendnam->sa_len;
                }
        }
        error = sock_sendmbuf(so, &msg, top, 0, NULL);
        if (!error)
                return (0);
        log(LOG_INFO, "nfsd send error %d\n", error);

        if ((error == EWOULDBLOCK) && (slp->ns_sotype == SOCK_STREAM))
                error = EPIPE;  /* zap TCP sockets if they time out on send */

        /* Handle any recoverable (soft) socket errors here. (???) */
        if (error != EINTR && error != ERESTART && error != EIO &&
                error != EWOULDBLOCK && error != EPIPE)
                error = 0;

        return (error);
}

/*
 * Socket upcall routine for the nfsd sockets.
 * The caddr_t arg is a pointer to the "struct nfsrv_sock".
 * Essentially do as much as possible non-blocking, else punt and it will
 * be called with MBUF_WAITOK from an nfsd.
 */
void
nfsrv_rcv(socket_t so, caddr_t arg, int waitflag)
{
        struct nfsrv_sock *slp = (struct nfsrv_sock *)arg;

        if (!nfsd_thread_count || !(slp->ns_flag & SLP_VALID))
                return;

        lck_rw_lock_exclusive(&slp->ns_rwlock);
        nfsrv_rcv_locked(so, slp, waitflag);
        /* Note: ns_rwlock gets dropped when called with MBUF_DONTWAIT */
}
void
nfsrv_rcv_locked(socket_t so, struct nfsrv_sock *slp, int waitflag)
{
        mbuf_t m, mp, mhck, m2;
        int ns_flag=0, error;
        struct msghdr   msg;
        size_t bytes_read;

        if ((slp->ns_flag & SLP_VALID) == 0) {
                if (waitflag == MBUF_DONTWAIT)
                        lck_rw_done(&slp->ns_rwlock);
                return;
        }

#ifdef notdef
        /*
         * Define this to test for nfsds handling this under heavy load.
         */
        if (waitflag == MBUF_DONTWAIT) {
                ns_flag = SLP_NEEDQ;
                goto dorecs;
        }
#endif
        if (slp->ns_sotype == SOCK_STREAM) {
                /*
                 * If there are already records on the queue, defer soreceive()
                 * to an(other) nfsd so that there is feedback to the TCP layer that
                 * the nfs servers are heavily loaded.
                 */
                if (slp->ns_rec) {
                        ns_flag = SLP_NEEDQ;
                        goto dorecs;
                }

                /*
                 * Do soreceive().
                 */
                bytes_read = 1000000000;
                error = sock_receivembuf(so, NULL, &mp, MSG_DONTWAIT, &bytes_read);
                if (error || mp == NULL) {
                        if (error == EWOULDBLOCK)
                                ns_flag = (waitflag == MBUF_DONTWAIT) ? SLP_NEEDQ : 0;
                        else
                                ns_flag = SLP_DISCONN;
                        goto dorecs;
                }
                m = mp;
                if (slp->ns_rawend) {
                        if ((error = mbuf_setnext(slp->ns_rawend, m)))
                                panic("nfsrv_rcv: mbuf_setnext failed %d\n", error);
                        slp->ns_cc += bytes_read;
                } else {
                        slp->ns_raw = m;
                        slp->ns_cc = bytes_read;
                }
                while ((m2 = mbuf_next(m)))
                        m = m2;
                slp->ns_rawend = m;

                /*
                 * Now try and parse record(s) out of the raw stream data.
                 */
                error = nfsrv_getstream(slp, waitflag);
                if (error) {
                        if (error == EPERM)
                                ns_flag = SLP_DISCONN;
                        else
                                ns_flag = SLP_NEEDQ;
                }
        } else {
                struct sockaddr_storage nam;

                if (slp->ns_reccnt >= nfsrv_sock_max_rec_queue_length) {
                        /* already have max # RPC records queued on this socket */
                        ns_flag = SLP_NEEDQ;
                        goto dorecs;
                }
                
                bzero(&msg, sizeof(msg));
                msg.msg_name = (caddr_t)&nam;
                msg.msg_namelen = sizeof(nam);
                
                do {
                        bytes_read = 1000000000;
                        error = sock_receivembuf(so, &msg, &mp, MSG_DONTWAIT | MSG_NEEDSA, &bytes_read);
                        if (mp) {
                                if (msg.msg_name && (mbuf_get(MBUF_WAITOK, MBUF_TYPE_SONAME, &mhck) == 0)) {
                                        mbuf_setlen(mhck, nam.ss_len);
                                        bcopy(&nam, mbuf_data(mhck), nam.ss_len);
                                        m = mhck;
                                        if (mbuf_setnext(m, mp)) {
                                                /* trouble... just drop it */
                                                printf("nfsrv_rcv: mbuf_setnext failed\n");
                                                mbuf_free(mhck);
                                                m = mp;
                                        }
                                } else {
                                        m = mp;
                                }
                                if (slp->ns_recend)
                                        mbuf_setnextpkt(slp->ns_recend, m);
                                else {
                                        slp->ns_rec = m;
                                        slp->ns_flag |= SLP_DOREC;
                                }
                                slp->ns_recend = m;
                                mbuf_setnextpkt(m, NULL);
                                slp->ns_reccnt++;
                        }
                } while (mp);
        }

        /*
         * Now try and process the request records, non-blocking.
         */
dorecs:
        if (ns_flag)
                slp->ns_flag |= ns_flag;
        if (waitflag == MBUF_DONTWAIT) {
                int wake = (slp->ns_flag & SLP_WORKTODO);
                lck_rw_done(&slp->ns_rwlock);
                if (wake && nfsd_thread_count) {
                        lck_mtx_lock(nfsd_mutex);
                        nfsrv_wakenfsd(slp);
                        lck_mtx_unlock(nfsd_mutex);
                }
        }
}

/*
 * Try and extract an RPC request from the mbuf data list received on a
 * stream socket. The "waitflag" argument indicates whether or not it
 * can sleep.
 */
int
nfsrv_getstream(struct nfsrv_sock *slp, int waitflag)
{
        mbuf_t m;
        char *cp1, *cp2, *mdata;
        int len, mlen, error;
        mbuf_t om, m2, recm;
        u_int32_t recmark;

        if (slp->ns_flag & SLP_GETSTREAM)
                panic("nfs getstream");
        slp->ns_flag |= SLP_GETSTREAM;
        for (;;) {
            if (slp->ns_reclen == 0) {
                if (slp->ns_cc < NFSX_UNSIGNED) {
                        slp->ns_flag &= ~SLP_GETSTREAM;
                        return (0);
                }
                m = slp->ns_raw;
                mdata = mbuf_data(m);
                mlen = mbuf_len(m);
                if (mlen >= NFSX_UNSIGNED) {
                        bcopy(mdata, (caddr_t)&recmark, NFSX_UNSIGNED);
                        mdata += NFSX_UNSIGNED;
                        mlen -= NFSX_UNSIGNED;
                        mbuf_setdata(m, mdata, mlen);
                } else {
                        cp1 = (caddr_t)&recmark;
                        cp2 = mdata;
                        while (cp1 < ((caddr_t)&recmark) + NFSX_UNSIGNED) {
                                while (mlen == 0) {
                                        m = mbuf_next(m);
                                        cp2 = mbuf_data(m);
                                        mlen = mbuf_len(m);
                                }
                                *cp1++ = *cp2++;
                                mlen--;
                                mbuf_setdata(m, cp2, mlen);
                        }
                }
                slp->ns_cc -= NFSX_UNSIGNED;
                recmark = ntohl(recmark);
                slp->ns_reclen = recmark & ~0x80000000;
                if (recmark & 0x80000000)
                        slp->ns_flag |= SLP_LASTFRAG;
                else
                        slp->ns_flag &= ~SLP_LASTFRAG;
                if (slp->ns_reclen <= 0 || slp->ns_reclen > NFS_MAXPACKET) {
                        slp->ns_flag &= ~SLP_GETSTREAM;
                        return (EPERM);
                }
            }

            /*
             * Now get the record part.
             *
             * Note that slp->ns_reclen may be 0.  Linux sometimes
             * generates 0-length RPCs
             */
            recm = NULL;
            if (slp->ns_cc == slp->ns_reclen) {
                recm = slp->ns_raw;
                slp->ns_raw = slp->ns_rawend = NULL;
                slp->ns_cc = slp->ns_reclen = 0;
            } else if (slp->ns_cc > slp->ns_reclen) {
                len = 0;
                m = slp->ns_raw;
                mlen = mbuf_len(m);
                mdata = mbuf_data(m);
                om = NULL;
                while (len < slp->ns_reclen) {
                        if ((len + mlen) > slp->ns_reclen) {
                                if (mbuf_copym(m, 0, slp->ns_reclen - len, waitflag, &m2)) {
                                        slp->ns_flag &= ~SLP_GETSTREAM;
                                        return (EWOULDBLOCK);
                                }
                                if (om) {
                                        if (mbuf_setnext(om, m2)) {
                                                /* trouble... just drop it */
                                                printf("nfsrv_getstream: mbuf_setnext failed\n");
                                                mbuf_freem(m2);
                                                slp->ns_flag &= ~SLP_GETSTREAM;
                                                return (EWOULDBLOCK);
                                        }
                                        recm = slp->ns_raw;
                                } else {
                                        recm = m2;
                                }
                                mdata += slp->ns_reclen - len;
                                mlen -= slp->ns_reclen - len;
                                mbuf_setdata(m, mdata, mlen);
                                len = slp->ns_reclen;
                        } else if ((len + mlen) == slp->ns_reclen) {
                                om = m;
                                len += mlen;
                                m = mbuf_next(m);
                                recm = slp->ns_raw;
                                if (mbuf_setnext(om, NULL)) {
                                        printf("nfsrv_getstream: mbuf_setnext failed 2\n");
                                        slp->ns_flag &= ~SLP_GETSTREAM;
                                        return (EWOULDBLOCK);
                                }
                                mlen = mbuf_len(m);
                                mdata = mbuf_data(m);
                        } else {
                                om = m;
                                len += mlen;
                                m = mbuf_next(m);
                                mlen = mbuf_len(m);
                                mdata = mbuf_data(m);
                        }
                }
                slp->ns_raw = m;
                slp->ns_cc -= len;
                slp->ns_reclen = 0;
            } else {
                slp->ns_flag &= ~SLP_GETSTREAM;
                return (0);
            }

            /*
             * Accumulate the fragments into a record.
             */
            if (slp->ns_frag == NULL) {
                slp->ns_frag = recm;
            } else {
                m = slp->ns_frag;
                while ((m2 = mbuf_next(m)))
                    m = m2;
                if ((error = mbuf_setnext(m, recm)))
                    panic("nfsrv_getstream: mbuf_setnext failed 3, %d\n", error);
            }
            if (slp->ns_flag & SLP_LASTFRAG) {
                if (slp->ns_recend)
                    mbuf_setnextpkt(slp->ns_recend, slp->ns_frag);
                else {
                    slp->ns_rec = slp->ns_frag;
                    slp->ns_flag |= SLP_DOREC;
                }
                slp->ns_recend = slp->ns_frag;
                slp->ns_frag = NULL;
            }
        }
}

/*
 * Parse an RPC header.
 */
int
nfsrv_dorec(
        struct nfsrv_sock *slp,
        struct nfsd *nfsd,
        struct nfsrv_descript **ndp)
{
        mbuf_t m;
        mbuf_t nam;
        struct nfsrv_descript *nd;
        int error = 0;

        *ndp = NULL;
        if (!(slp->ns_flag & (SLP_VALID|SLP_DOREC)) || (slp->ns_rec == NULL))
                return (ENOBUFS);
        MALLOC_ZONE(nd, struct nfsrv_descript *,
                        sizeof (struct nfsrv_descript), M_NFSRVDESC, M_WAITOK);
        if (!nd)
                return (ENOMEM);
        m = slp->ns_rec;
        slp->ns_rec = mbuf_nextpkt(m);
        if (slp->ns_rec)
                mbuf_setnextpkt(m, NULL);
        else {
                slp->ns_flag &= ~SLP_DOREC;
                slp->ns_recend = NULL;
        }
        slp->ns_reccnt--;
        if (mbuf_type(m) == MBUF_TYPE_SONAME) {
                nam = m;
                m = mbuf_next(m);
                if ((error = mbuf_setnext(nam, NULL)))
                        panic("nfsrv_dorec: mbuf_setnext failed %d\n", error);
        } else
                nam = NULL;
        nd->nd_nam2 = nam;
        nfsm_chain_dissect_init(error, &nd->nd_nmreq, m);
        if (!error)
                error = nfsrv_getreq(nd);
        if (error) {
                if (nam)
                        mbuf_freem(nam);
                FREE_ZONE(nd, sizeof(*nd), M_NFSRVDESC);
                return (error);
        }
        nd->nd_mrep = NULL;
        *ndp = nd;
        nfsd->nfsd_nd = nd;
        return (0);
}

/*
 * Parse an RPC request
 * - verify it
 * - fill in the cred struct.
 */
int
nfsrv_getreq(struct nfsrv_descript *nd)
{
        struct nfsm_chain *nmreq;
        int len, i;
        u_int32_t nfsvers, auth_type;
        int error = 0;
        uid_t user_id;
        gid_t group_id;
        int ngroups;
        struct ucred temp_cred;
        uint32_t val;

        nd->nd_cr = NULL;
        nd->nd_gss_context = NULL;
        nd->nd_gss_seqnum = 0;
        nd->nd_gss_mb = NULL;

        user_id = group_id = -2;
        val = auth_type = len = 0;

        nmreq = &nd->nd_nmreq;
        nfsm_chain_get_32(error, nmreq, nd->nd_retxid); // XID
        nfsm_chain_get_32(error, nmreq, val);           // RPC Call
        if (!error && (val != RPC_CALL))
                error = EBADRPC;
        nfsmout_if(error);
        nd->nd_repstat = 0;
        nfsm_chain_get_32(error, nmreq, val);   // RPC Version
        nfsmout_if(error);
        if (val != RPC_VER2) {
                nd->nd_repstat = ERPCMISMATCH;
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        nfsm_chain_get_32(error, nmreq, val);   // RPC Program Number
        nfsmout_if(error);
        if (val != NFS_PROG) {
                nd->nd_repstat = EPROGUNAVAIL;
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        nfsm_chain_get_32(error, nmreq, nfsvers);// NFS Version Number
        nfsmout_if(error);
        if ((nfsvers < NFS_VER2) || (nfsvers > NFS_VER3)) {
                nd->nd_repstat = EPROGMISMATCH;
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        nd->nd_vers = nfsvers;
        nfsm_chain_get_32(error, nmreq, nd->nd_procnum);// NFS Procedure Number
        nfsmout_if(error);
        if ((nd->nd_procnum >= NFS_NPROCS) ||
                ((nd->nd_vers == NFS_VER2) && (nd->nd_procnum > NFSV2PROC_STATFS))) {
                nd->nd_repstat = EPROCUNAVAIL;
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        if (nfsvers != NFS_VER3)
                nd->nd_procnum = nfsv3_procid[nd->nd_procnum];
        nfsm_chain_get_32(error, nmreq, auth_type);     // Auth Flavor
        nfsm_chain_get_32(error, nmreq, len);           // Auth Length
        if (!error && (len < 0 || len > RPCAUTH_MAXSIZ))
                error = EBADRPC;
        nfsmout_if(error);

        /* Handle authentication */
        if (auth_type == RPCAUTH_UNIX) {
                if (nd->nd_procnum == NFSPROC_NULL)
                        return (0);
                nd->nd_sec = RPCAUTH_UNIX;
                nfsm_chain_adv(error, nmreq, NFSX_UNSIGNED);    // skip stamp
                nfsm_chain_get_32(error, nmreq, len);           // hostname length
                if (len < 0 || len > NFS_MAXNAMLEN)
                        error = EBADRPC;
                nfsm_chain_adv(error, nmreq, nfsm_rndup(len));  // skip hostname
                nfsmout_if(error);

                /* create a temporary credential using the bits from the wire */
                bzero(&temp_cred, sizeof(temp_cred));
                nfsm_chain_get_32(error, nmreq, user_id);
                nfsm_chain_get_32(error, nmreq, group_id);
                temp_cred.cr_groups[0] = group_id;
                nfsm_chain_get_32(error, nmreq, len);           // extra GID count
                if ((len < 0) || (len > RPCAUTH_UNIXGIDS))
                        error = EBADRPC;
                nfsmout_if(error);
                for (i = 1; i <= len; i++)
                        if (i < NGROUPS)
                                nfsm_chain_get_32(error, nmreq, temp_cred.cr_groups[i]);
                        else
                                nfsm_chain_adv(error, nmreq, NFSX_UNSIGNED);
                nfsmout_if(error);
                ngroups = (len >= NGROUPS) ? NGROUPS : (len + 1);
                if (ngroups > 1)
                        nfsrv_group_sort(&temp_cred.cr_groups[0], ngroups);
                nfsm_chain_adv(error, nmreq, NFSX_UNSIGNED);    // verifier flavor (should be AUTH_NONE)
                nfsm_chain_get_32(error, nmreq, len);           // verifier length
                if (len < 0 || len > RPCAUTH_MAXSIZ)
                        error = EBADRPC;
                if (len > 0)
                        nfsm_chain_adv(error, nmreq, nfsm_rndup(len));

                /* request creation of a real credential */
                temp_cred.cr_uid = user_id;
                temp_cred.cr_ngroups = ngroups;
                nd->nd_cr = kauth_cred_create(&temp_cred);
                if (nd->nd_cr == NULL) {
                        nd->nd_repstat = ENOMEM;
                        nd->nd_procnum = NFSPROC_NOOP;
                        return (0);
                }
        } else if (auth_type == RPCSEC_GSS) {
                error = nfs_gss_svc_cred_get(nd, nmreq);
                if (error) {
                        if (error == EINVAL)
                                goto nfsmout;   // drop the request
                        nd->nd_repstat = error;
                        nd->nd_procnum = NFSPROC_NOOP;
                        return (0);
                }
        } else {
                if (nd->nd_procnum == NFSPROC_NULL)     // assume it's AUTH_NONE
                        return (0);
                nd->nd_repstat = (NFSERR_AUTHERR | AUTH_REJECTCRED);
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        return (0);
nfsmout:
        if (IS_VALID_CRED(nd->nd_cr))
                kauth_cred_unref(&nd->nd_cr);
        nfsm_chain_cleanup(nmreq);
        return (error);
}

/*
 * Search for a sleeping nfsd and wake it up.
 * SIDE EFFECT: If none found, make sure the socket is queued up so that one
 * of the running nfsds will go look for the work in the nfsrv_sockwait list.
 * Note: Must be called with nfsd_mutex held.
 */
void
nfsrv_wakenfsd(struct nfsrv_sock *slp)
{
        struct nfsd *nd;

        if ((slp->ns_flag & SLP_VALID) == 0)
                return;

        lck_rw_lock_exclusive(&slp->ns_rwlock);
        /* if there's work to do on this socket, make sure it's queued up */
        if ((slp->ns_flag & SLP_WORKTODO) && !(slp->ns_flag & SLP_QUEUED)) {
                TAILQ_INSERT_TAIL(&nfsrv_sockwait, slp, ns_svcq);
                slp->ns_flag |= SLP_WAITQ;
        }
        lck_rw_done(&slp->ns_rwlock);

        /* wake up a waiting nfsd, if possible */
        nd = TAILQ_FIRST(&nfsd_queue);
        if (!nd)
                return;

        TAILQ_REMOVE(&nfsd_queue, nd, nfsd_queue);
        nd->nfsd_flag &= ~NFSD_WAITING;
        wakeup(nd);
}

#endif /* NFSSERVER */