xnu-792.6.61.tar.gz

[apple/xnu.git] / bsd / miscfs / union / union_vnops.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This 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 OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1992, 1993, 1994, 1995 Jan-Simon Pendry.
 * Copyright (c) 1992, 1993, 1994, 1995
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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.
 *
 *	@(#)union_vnops.c	8.32 (Berkeley) 6/23/95
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kauth.h>
#include <sys/file.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/vnode_internal.h>
#include <sys/mount_internal.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/buf_internal.h>
#include <sys/queue.h>
#include <sys/lock.h>
#include <miscfs/union/union.h>
#include <vfs/vfs_support.h>
#include <sys/ubc.h>
#include <sys/uio_internal.h>

#define FIXUP(un, p) { \
	if (((un)->un_flags & UN_ULOCK) == 0) { \
		union_fixup(un, p); \
	} \
}

static void
union_fixup(un, p)
	struct union_node *un;
	struct proc *p;
{

	un->un_flags |= UN_ULOCK;
}

static int
union_lookup1(struct vnode *udvp, struct vnode **dvpp, struct vnode **vpp,
	struct componentname *cnp)
{
	int error;
	vfs_context_t ctx = cnp->cn_context;
	struct vnode *tdvp;
	struct vnode *dvp;
	struct mount *mp;

	dvp = *dvpp;

	/*
	 * If stepping up the directory tree, check for going
	 * back across the mount point, in which case do what
	 * lookup would do by stepping back down the mount
	 * hierarchy.
	 */
	if (cnp->cn_flags & ISDOTDOT) {
		while ((dvp != udvp) && (dvp->v_flag & VROOT)) {
			/*
			 * Don't do the NOCROSSMOUNT check
			 * at this level.  By definition,
			 * union fs deals with namespaces, not
			 * filesystems.
			 */
			tdvp = dvp;
			*dvpp = dvp = dvp->v_mount->mnt_vnodecovered;
			vnode_put(tdvp);
			vnode_get(dvp);
		}
	}

	error = VNOP_LOOKUP(dvp, &tdvp, cnp, ctx);
	if (error)
		return (error);

	dvp = tdvp;
	/*
	 * Lastly check if the current node is a mount point in
	 * which case walk up the mount hierarchy making sure not to
	 * bump into the root of the mount tree (ie. dvp != udvp).
	 */
	while (dvp != udvp && (dvp->v_type == VDIR) &&
	       (mp = dvp->v_mountedhere)) {
		if (vfs_busy(mp, LK_NOWAIT)) {
			vnode_put(dvp);
			return(ENOENT);
		}
		error = VFS_ROOT(mp, &tdvp, ctx);
		vfs_unbusy(mp);
		if (error) {
			vnode_put(dvp);
			return (error);
		}

		vnode_put(dvp);
		dvp = tdvp;
	}

	*vpp = dvp;
	return (0);
}

int
union_lookup(
	struct vnop_lookup_args /* {
		struct vnodeop_desc *a_desc;
		struct vnode *a_dvp;
		struct vnode **a_vpp;
		struct componentname *a_cnp;
		vfs_context_t a_context;
	} */ *ap)
{
	int error;
	int uerror, lerror;
	struct vnode *uppervp, *lowervp;
	struct vnode *upperdvp, *lowerdvp;
	struct vnode *dvp = ap->a_dvp;
	struct union_node *dun = VTOUNION(dvp);
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);
	int lockparent = cnp->cn_flags & LOCKPARENT;
	struct union_mount *um = MOUNTTOUNIONMOUNT(dvp->v_mount);
	kauth_cred_t saved_cred;
	int iswhiteout;
	struct vnode_attr va;

#ifdef notyet
	if (cnp->cn_namelen == 3 &&
			cnp->cn_nameptr[2] == '.' &&
			cnp->cn_nameptr[1] == '.' &&
			cnp->cn_nameptr[0] == '.') {
		dvp = *ap->a_vpp = LOWERVP(ap->a_dvp);
		if (dvp == NULLVP)
			return (ENOENT);
		vnode_get(dvp);

		return (0);
	}
#endif

	cnp->cn_flags |= LOCKPARENT;

	upperdvp = dun->un_uppervp;
	lowerdvp = dun->un_lowervp;
	uppervp = NULLVP;
	lowervp = NULLVP;
	iswhiteout = 0;

	/*
	 * do the lookup in the upper level.
	 * if that level comsumes additional pathnames,
	 * then assume that something special is going
	 * on and just return that vnode.
	 */
	if (upperdvp != NULLVP) {
		FIXUP(dun, p);
		uerror = union_lookup1(um->um_uppervp, &upperdvp,
					&uppervp, cnp);
		/*if (uppervp == upperdvp)
			dun->un_flags |= UN_KLOCK;*/

		if (cnp->cn_consume != 0) {
			*ap->a_vpp = uppervp;
			if (!lockparent)
				cnp->cn_flags &= ~LOCKPARENT;
			return (uerror);
		}
		if (uerror == ENOENT || uerror == EJUSTRETURN) {
			if (cnp->cn_flags & ISWHITEOUT) {
				iswhiteout = 1;
			} else if (lowerdvp != NULLVP) {
				VATTR_INIT(&va);
				VATTR_WANTED(&va, va_flags);
				lerror = vnode_getattr(upperdvp, &va, ap->a_context);
				if (lerror == 0 && (va.va_flags & OPAQUE))
					iswhiteout = 1;
			}
		}
	} else {
		uerror = ENOENT;
	}

	/*
	 * in a similar way to the upper layer, do the lookup
	 * in the lower layer.   this time, if there is some
	 * component magic going on, then vnode_put whatever we got
	 * back from the upper layer and return the lower vnode
	 * instead.
	 */
	if (lowerdvp != NULLVP && !iswhiteout) {
		int nameiop;

		/*
		 * Only do a LOOKUP on the bottom node, since
		 * we won't be making changes to it anyway.
		 */
		nameiop = cnp->cn_nameiop;
		cnp->cn_nameiop = LOOKUP;
		if (um->um_op == UNMNT_BELOW) {
			/* XXX BOGUS */
			saved_cred = cnp->cn_context->vc_ucred;
			cnp->cn_context->vc_ucred = um->um_cred;
			lerror = union_lookup1(um->um_lowervp, &lowerdvp,
					&lowervp, cnp);
			cnp->cn_context->vc_ucred = saved_cred;
		} else {
			lerror = union_lookup1(um->um_lowervp, &lowerdvp,
					&lowervp, cnp);
		}
		cnp->cn_nameiop = nameiop;

		if (cnp->cn_consume != 0) {
			if (uppervp != NULLVP) {
			        vnode_put(uppervp);
				uppervp = NULLVP;
			}
			*ap->a_vpp = lowervp;
			if (!lockparent)
				cnp->cn_flags &= ~LOCKPARENT;
			return (lerror);
		}
	} else {
		lerror = ENOENT;
		if ((cnp->cn_flags & ISDOTDOT) && dun->un_pvp != NULLVP) {
			lowervp = LOWERVP(dun->un_pvp);
			if (lowervp != NULLVP) {
				vnode_get(lowervp);
				lerror = 0;
			}
		}
	}

	if (!lockparent)
		cnp->cn_flags &= ~LOCKPARENT;

	/*
	 * at this point, we have uerror and lerror indicating
	 * possible errors with the lookups in the upper and lower
	 * layers.  additionally, uppervp and lowervp are (locked)
	 * references to existing vnodes in the upper and lower layers.
	 *
	 * there are now three cases to consider.
	 * 1. if both layers returned an error, then return whatever
	 *    error the upper layer generated.
	 *
	 * 2. if the top layer failed and the bottom layer succeeded
	 *    then two subcases occur.
	 *    a.  the bottom vnode is not a directory, in which
	 *	  case just return a new union vnode referencing
	 *	  an empty top layer and the existing bottom layer.
	 *    b.  the bottom vnode is a directory, in which case
	 *	  create a new directory in the top-level and
	 *	  continue as in case 3.
	 *
	 * 3. if the top layer succeeded then return a new union
	 *    vnode referencing whatever the new top layer and
	 *    whatever the bottom layer returned.
	 */

	*ap->a_vpp = NULLVP;

	/* case 1. */
	if ((uerror != 0) && (lerror != 0)) {
		return (uerror);
	}

	/* case 2. */
	if (uerror != 0 /* && (lerror == 0) */ ) {
		if (lowervp->v_type == VDIR) { /* case 2b. */
			dun->un_flags &= ~UN_ULOCK;
			uerror = union_mkshadow(um, upperdvp, cnp, &uppervp);
			dun->un_flags |= UN_ULOCK;

			if (uerror) {
				if (lowervp != NULLVP) {
					vnode_put(lowervp);
					lowervp = NULLVP;
				}
				return (uerror);
			}
		}
	}
	error = union_allocvp(ap->a_vpp, dvp->v_mount, dvp, upperdvp, cnp,
			      uppervp, lowervp, 1);

	if (error) {
		if (uppervp != NULLVP)
			vnode_put(uppervp);
		if (lowervp != NULLVP)
			vnode_put(lowervp);
	}

	return (error);
}

int
union_create(
	struct vnop_create_args /* {
		struct vnode *a_dvp;
		struct vnode **a_vpp;
		struct componentname *a_cnp;
		struct vnode_attr *a_vap;
		vfs_context_t a_context;
	} */ *ap)
{
	struct union_node *un = VTOUNION(ap->a_dvp);
	struct vnode *dvp = un->un_uppervp;
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);

	if (dvp != NULLVP) {
		int error;
		struct vnode *vp;
		struct mount *mp;

		FIXUP(un, p);

		un->un_flags |= UN_KLOCK;
		mp = ap->a_dvp->v_mount;

		/* note that this is a direct passthrough to the filesystem */
		error = VNOP_CREATE(dvp, &vp, cnp, ap->a_vap, ap->a_context);
		if (error)
			return (error);

		error = union_allocvp(ap->a_vpp, mp, NULLVP, NULLVP, cnp, vp,
				NULLVP, 1);
		if (error)
			vnode_put(vp);
		return (error);
	}
	return (EROFS);
}

int
union_whiteout(
	struct vnop_whiteout_args /* {
		struct vnode *a_dvp;
		struct componentname *a_cnp;
		int a_flags;
		vfs_context_t a_context;
	} */ *ap)
{
	struct union_node *un = VTOUNION(ap->a_dvp);
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);

	if (un->un_uppervp == NULLVP)
		return (ENOTSUP);

	FIXUP(un, p);
	return (VNOP_WHITEOUT(un->un_uppervp, cnp, ap->a_flags, ap->a_context));
}

int
union_mknod(
	struct vnop_mknod_args /* {
		struct vnode *a_dvp;
		struct vnode **a_vpp;
		struct componentname *a_cnp;
		struct vnode_attr *a_vap;
		vfs_context_t a_context;
	} */ *ap)
{
	struct union_node *un = VTOUNION(ap->a_dvp);
	struct vnode *dvp = un->un_uppervp;
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);

	if (dvp != NULLVP) {
		int error;
		struct vnode *vp;
		struct mount *mp;

		FIXUP(un, p);

		un->un_flags |= UN_KLOCK;
		mp = ap->a_dvp->v_mount;

		/* note that this is a direct passthrough to the filesystem */
		error = VNOP_MKNOD(dvp, &vp, cnp, ap->a_vap, ap->a_context);
		if (error)
			return (error);

		if (vp != NULLVP) {
			error = union_allocvp(ap->a_vpp, mp, NULLVP, NULLVP,
					cnp, vp, NULLVP, 1);
			if (error)
				vnode_put(vp);
		}
		return (error);
	}
	return (EROFS);
}

int
union_open(
	struct vnop_open_args /* {
		struct vnodeop_desc *a_desc;
		struct vnode *a_vp;
		int a_mode;
		vfs_context_t a_context;
	} */ *ap)
{
	struct union_node *un = VTOUNION(ap->a_vp);
	struct vnode *tvp;
	int mode = ap->a_mode;
	kauth_cred_t cred = vfs_context_ucred(ap->a_context);
	struct proc *p = vfs_context_proc(ap->a_context);
	int error;

	/*
	 * If there is an existing upper vp then simply open that.
	 */
	tvp = un->un_uppervp;
	if (tvp == NULLVP) {
		/*
		 * If the lower vnode is being opened for writing, then
		 * copy the file contents to the upper vnode and open that,
		 * otherwise can simply open the lower vnode.
		 */
		tvp = un->un_lowervp;
		if ((ap->a_mode & FWRITE) && (tvp->v_type == VREG)) {
			error = union_copyup(un, (mode&O_TRUNC) == 0, cred, p);
			if (error == 0)
				error = VNOP_OPEN(un->un_uppervp, mode, ap->a_context);
			return (error);
		}

		/*
		 * Just open the lower vnode
		 */
		un->un_openl++;

		error = VNOP_OPEN(tvp, mode, ap->a_context);

		return (error);
	}

	FIXUP(un, p);

	error = VNOP_OPEN(tvp, mode, ap->a_context);

	return (error);
}

int
union_close(ap)
	struct vnop_close_args /* {
		struct vnode *a_vp;
		int  a_fflag;
		vfs_context_t a_context;
	} */ *ap;
{
	struct union_node *un = VTOUNION(ap->a_vp);
	struct vnode *vp;

	if ((vp = un->un_uppervp) == NULLVP) {
#ifdef UNION_DIAGNOSTIC
		if (un->un_openl <= 0)
			panic("union: un_openl cnt");
#endif
		--un->un_openl;
		vp = un->un_lowervp;
	}

	ap->a_vp = vp;
	return (VCALL(vp, VOFFSET(vnop_close), ap));
}

/*
 * Check access permission on the union vnode.
 * The access check being enforced is to check
 * against both the underlying vnode, and any
 * copied vnode.  This ensures that no additional
 * file permissions are given away simply because
 * the user caused an implicit file copy.
 */
int
union_access(
	struct vnop_access_args /* {
		struct vnodeop_desc *a_desc;
		struct vnode *a_vp;
		int a_action;
		vfs_context_t a_context;
	} */ *ap)
{
	struct union_node *un = VTOUNION(ap->a_vp);
	struct proc *p = vfs_context_proc(ap->a_context);
	int error = EACCES;
	struct vnode *vp;

	if ((vp = un->un_uppervp) != NULLVP) {
		FIXUP(un, p);
		ap->a_vp = vp;
		return (VCALL(vp, VOFFSET(vnop_access), ap));
	}

	if ((vp = un->un_lowervp) != NULLVP) {
		ap->a_vp = vp;
		error = VCALL(vp, VOFFSET(vnop_access), ap);
		if (error == 0) {
			struct union_mount *um = MOUNTTOUNIONMOUNT(vp->v_mount);

			if (um->um_op == UNMNT_BELOW) {
				/* XXX fix me */
			//	ap->a_cred = um->um_cred;
				error = VCALL(vp, VOFFSET(vnop_access), ap);
			}
		}
		if (error)
			return (error);
	}

	return (error);
}

/*
 * We handle getattr only to change the fsid and
 * track object sizes
 */
int
union_getattr(ap)
	struct vnop_getattr_args /* {
		struct vnode *a_vp;
		struct vnode_attr *a_vap;
		vfs_context_t a_context;
	} */ *ap;
{
	int error;
	struct union_node *un = VTOUNION(ap->a_vp);
	struct vnode *vp = un->un_uppervp;
	struct proc *p = vfs_context_proc(ap->a_context);
	struct vnode_attr *vap;
	struct vnode_attr va;


	/*
	 * Some programs walk the filesystem hierarchy by counting
	 * links to directories to avoid stat'ing all the time.
	 * This means the link count on directories needs to be "correct".
	 * The only way to do that is to call getattr on both layers
	 * and fix up the link count.  The link count will not necessarily
	 * be accurate but will be large enough to defeat the tree walkers.
	 */

	vap = ap->a_vap;

	vp = un->un_uppervp;
	if (vp != NULLVP) {
		/*
		 * It's not clear whether vnop_getattr is to be
		 * called with the vnode locked or not.  stat() calls
		 * it with (vp) locked, and fstat calls it with
		 * (vp) unlocked.
		 * In the mean time, compensate here by checking
		 * the union_node's lock flag.
		 */
		if (un->un_flags & UN_LOCKED)
			FIXUP(un, p);

		error = vnode_getattr(vp, vap, ap->a_context);
		if (error)
			return (error);
		union_newsize(ap->a_vp, vap->va_data_size, VNOVAL);
	}

	if (vp == NULLVP) {
		vp = un->un_lowervp;
	} else if (vp->v_type == VDIR) {
		vp = un->un_lowervp;
		VATTR_INIT(&va);
		/* all we want from the lower node is the link count */
		VATTR_WANTED(&va, va_nlink);
		vap = &va;
	} else {
		vp = NULLVP;
	}

	if (vp != NULLVP) {
		error = vnode_getattr(vp, vap, ap->a_context);
		if (error)
			return (error);
		union_newsize(ap->a_vp, VNOVAL, vap->va_data_size);
	}

	if ((vap != ap->a_vap) && (vap->va_type == VDIR))
		ap->a_vap->va_nlink += vap->va_nlink;

	VATTR_RETURN(ap->a_vap, va_fsid, ap->a_vp->v_mount->mnt_vfsstat.f_fsid.val[0]);
	return (0);
}

int
union_setattr(ap)
	struct vnop_setattr_args /* {
		struct vnode *a_vp;
		struct vnode_attr *a_vap;
		vfs_context_t a_context;
	} */ *ap;
{
	struct union_node *un = VTOUNION(ap->a_vp);
	struct proc *p = vfs_context_proc(ap->a_context);
	kauth_cred_t cred = vfs_context_ucred(ap->a_context);
	int error;

	/*
	 * Handle case of truncating lower object to zero size,
	 * by creating a zero length upper object.  This is to
	 * handle the case of open with O_TRUNC and O_CREAT.
	 */
	if (VATTR_IS_ACTIVE(ap->a_vap, va_data_size) &&
	    (un->un_uppervp == NULLVP) &&
	    /* assert(un->un_lowervp != NULLVP) */
	    (un->un_lowervp->v_type == VREG)) {
		error = union_copyup(un, (ap->a_vap->va_data_size != 0), cred, p);
		if (error)
			return (error);
	}

	/*
	 * Try to set attributes in upper layer,
	 * otherwise return read-only filesystem error.
	 */
	if (un->un_uppervp != NULLVP) {
		FIXUP(un, p);
		error = vnode_setattr(un->un_uppervp, ap->a_vap, ap->a_context);
		if ((error == 0) && VATTR_IS_ACTIVE(ap->a_vap, va_data_size))
			union_newsize(ap->a_vp, ap->a_vap->va_data_size, VNOVAL);
	} else {
		error = EROFS;
	}

	return (error);
}

int
union_read(ap)
	struct vnop_read_args /* {
		struct vnode *a_vp;
		struct uio *a_uio;
		int  a_ioflag;
		vfs_context_t a_context;
	} */ *ap;
{
	int error;
	struct proc *p = vfs_context_proc(ap->a_context);
	struct vnode *vp = OTHERVP(ap->a_vp);
	int dolock = (vp == LOWERVP(ap->a_vp));

	if (!dolock)
		FIXUP(VTOUNION(ap->a_vp), p);
	error = VNOP_READ(vp, ap->a_uio, ap->a_ioflag, ap->a_context);

	/*
	 * XXX
	 * perhaps the size of the underlying object has changed under
	 * our feet.  take advantage of the offset information present
	 * in the uio structure.
	 */
	if (error == 0) {
		struct union_node *un = VTOUNION(ap->a_vp);
		off_t cur = ap->a_uio->uio_offset;

		if (vp == un->un_uppervp) {
			if (cur > un->un_uppersz)
				union_newsize(ap->a_vp, cur, VNOVAL);
		} else {
			if (cur > un->un_lowersz)
				union_newsize(ap->a_vp, VNOVAL, cur);
		}
	}

	return (error);
}

int
union_write(ap)
	struct vnop_read_args /* {
		struct vnode *a_vp;
		struct uio *a_uio;
		int  a_ioflag;
		vfs_context_t a_context;
	} */ *ap;
{
	int error;
	struct vnode *vp;
	struct union_node *un = VTOUNION(ap->a_vp);
	struct proc *p = vfs_context_proc(ap->a_context);

	vp = UPPERVP(ap->a_vp);
	if (vp == NULLVP)
		panic("union: missing upper layer in write");

	FIXUP(un, p);
	error = VNOP_WRITE(vp, ap->a_uio, ap->a_ioflag, ap->a_context);

	/*
	 * the size of the underlying object may be changed by the
	 * write.
	 */
	if (error == 0) {
		off_t cur = ap->a_uio->uio_offset;

		if (cur > un->un_uppersz)
			union_newsize(ap->a_vp, cur, VNOVAL);
	}

	return (error);
}


int
union_ioctl(ap)
	struct vnop_ioctl_args /* {
		struct vnode *a_vp;
		int  a_command;
		caddr_t  a_data;
		int  a_fflag;
		vfs_context_t a_context;
	} */ *ap;
{
	register struct vnode *ovp = OTHERVP(ap->a_vp);

	ap->a_vp = ovp;
	return (VCALL(ovp, VOFFSET(vnop_ioctl), ap));
}

int
union_select(ap)
	struct vnop_select_args /* {
		struct vnode *a_vp;
		int  a_which;
		int  a_fflags;
		void * a_wql;
		vfs_context_t a_context;
	} */ *ap;
{
	register struct vnode *ovp = OTHERVP(ap->a_vp);

	ap->a_vp = ovp;
	return (VCALL(ovp, VOFFSET(vnop_select), ap));
}

int
union_revoke(ap)
	struct vnop_revoke_args /* {
		struct vnode *a_vp;
		int a_flags;
		vfs_context_t a_context;
	} */ *ap;
{
	struct vnode *vp = ap->a_vp;

	if (UPPERVP(vp))
		VNOP_REVOKE(UPPERVP(vp), ap->a_flags, ap->a_context);
	if (LOWERVP(vp))
		VNOP_REVOKE(LOWERVP(vp), ap->a_flags, ap->a_context);
	vnode_reclaim(vp);
}

int
union_mmap(ap)
	struct vnop_mmap_args /* {
		struct vnode *a_vp;
		int  a_fflags;
		kauth_cred_t a_cred;
		struct proc *a_p;
	} */ *ap;
{
	register struct vnode *ovp = OTHERVP(ap->a_vp);

	ap->a_vp = ovp;
	return (VCALL(ovp, VOFFSET(vnop_mmap), ap));
}

int
union_fsync(
	struct vnop_fsync_args /* {
		struct vnode *a_vp;
		int  a_waitfor;
		vfs_context_t a_context;
	} */ *ap)
{
	int error = 0;
	struct proc *p = vfs_context_proc(ap->a_context);
	struct vnode *targetvp = OTHERVP(ap->a_vp);

	if (targetvp != NULLVP) {
		int dolock = (targetvp == LOWERVP(ap->a_vp));

		if (!dolock)
			FIXUP(VTOUNION(ap->a_vp), p);
		error = VNOP_FSYNC(targetvp, ap->a_waitfor, ap->a_context);
	}

	return (error);
}

int
union_remove(
	struct vnop_remove_args /* {
		struct vnode *a_dvp;
		struct vnode *a_vp;
		struct componentname *a_cnp;
		vfs_context_t a_context;
	} */ *ap)
{
	int error;
	struct union_node *dun = VTOUNION(ap->a_dvp);
	struct union_node *un = VTOUNION(ap->a_vp);
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);

	if (dun->un_uppervp == NULLVP)
		panic("union remove: null upper vnode");

	if (un->un_uppervp != NULLVP) {
		struct vnode *dvp = dun->un_uppervp;
		struct vnode *vp = un->un_uppervp;

		FIXUP(dun, p);
		dun->un_flags |= UN_KLOCK;
		FIXUP(un, p);
		un->un_flags |= UN_KLOCK;

		if (union_dowhiteout(un, cnp->cn_context))
			cnp->cn_flags |= DOWHITEOUT;
		error = VNOP_REMOVE(dvp, vp, cnp, 0, ap->a_context);
		if (!error)
			union_removed_upper(un);
	} else {
		FIXUP(dun, p);
		error = union_mkwhiteout(
			MOUNTTOUNIONMOUNT(UNIONTOV(dun)->v_mount),
			dun->un_uppervp, ap->a_cnp, un->un_path);
	}

	return (error);
}

int
union_link(
	struct vnop_link_args /* {
		struct vnode *a_vp;
		struct vnode *a_tdvp;
		struct componentname *a_cnp;
		vfs_context_t a_context;
	} */ *ap)
{
	int error = 0;
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);
	struct union_node *un;
	struct vnode *vp;
	struct vnode *tdvp;

	un = VTOUNION(ap->a_tdvp);

	if (ap->a_tdvp->v_op != ap->a_vp->v_op) {
		vp = ap->a_vp;
	} else {
		struct union_node *tun = VTOUNION(ap->a_vp);
		if (tun->un_uppervp == NULLVP) {
			if (un->un_uppervp == tun->un_dirvp) {
				un->un_flags &= ~UN_ULOCK;
			}
			error = union_copyup(tun, 1, vfs_context_ucred(ctx), p);
			if (un->un_uppervp == tun->un_dirvp) {
				un->un_flags |= UN_ULOCK;
			}
		}
		vp = tun->un_uppervp;
	}
	tdvp = un->un_uppervp;
	if (tdvp == NULLVP)
		error = EROFS;

	if (error) {
		return (error);
	}

	FIXUP(un, p);
	vnode_get(tdvp);
	un->un_flags |= UN_KLOCK;

	return (VNOP_LINK(vp, tdvp, cnp, ap->a_context));
}

int
union_rename(ap)
	struct vnop_rename_args  /* {
		struct vnode *a_fdvp;
		struct vnode *a_fvp;
		struct componentname *a_fcnp;
		struct vnode *a_tdvp;
		struct vnode *a_tvp;
		struct componentname *a_tcnp;
		vfs_context_t a_context;
	} */ *ap;
{
	int error;

	struct vnode *fdvp = ap->a_fdvp;
	struct vnode *fvp = ap->a_fvp;
	struct vnode *tdvp = ap->a_tdvp;
	struct vnode *tvp = ap->a_tvp;

	if (fdvp->v_op == union_vnodeop_p) {	/* always true */
		struct union_node *un = VTOUNION(fdvp);
		if (un->un_uppervp == NULLVP) {
			/*
			 * this should never happen in normal
			 * operation but might if there was
			 * a problem creating the top-level shadow
			 * directory.
			 */
			error = EXDEV;
			goto bad;
		}

		fdvp = un->un_uppervp;
		vnode_get(fdvp);
	}

	if (fvp->v_op == union_vnodeop_p) {	/* always true */
		struct union_node *un = VTOUNION(fvp);
		if (un->un_uppervp == NULLVP) {
			/* XXX: should do a copyup */
			error = EXDEV;
			goto bad;
		}

		if (un->un_lowervp != NULLVP)
			ap->a_fcnp->cn_flags |= DOWHITEOUT;

		fvp = un->un_uppervp;
		vnode_get(fvp);
	}

	if (tdvp->v_op == union_vnodeop_p) {
		struct union_node *un = VTOUNION(tdvp);
		if (un->un_uppervp == NULLVP) {
			/*
			 * this should never happen in normal
			 * operation but might if there was
			 * a problem creating the top-level shadow
			 * directory.
			 */
			error = EXDEV;
			goto bad;
		}

		tdvp = un->un_uppervp;
		vnode_get(tdvp);
		un->un_flags |= UN_KLOCK;
	}

	if (tvp != NULLVP && tvp->v_op == union_vnodeop_p) {
		struct union_node *un = VTOUNION(tvp);

		tvp = un->un_uppervp;
		if (tvp != NULLVP) {
			vnode_get(tvp);
			un->un_flags |= UN_KLOCK;
		}
	}

	return (VNOP_RENAME(fdvp, fvp, ap->a_fcnp, tdvp, tvp, ap->a_tcnp, ap->a_context));

bad:
	return (error);
}

int
union_mkdir(
	struct vnop_mkdir_args /* {
		struct vnode *a_dvp;
		struct vnode **a_vpp;
		struct componentname *a_cnp;
		struct vnode_attr *a_vap;
		vfs_context_t a_context;
	} */ *ap)
{
	struct union_node *un = VTOUNION(ap->a_dvp);
	struct vnode *dvp = un->un_uppervp;
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);

	if (dvp != NULLVP) {
		int error;
		struct vnode *vp;

		FIXUP(un, p);
		un->un_flags |= UN_KLOCK;

		/* note that this is a direct fallthrough to the filesystem */
		error = VNOP_MKDIR(dvp, &vp, cnp, ap->a_vap, ap->a_context);
		if (error)
			return (error);

		error = union_allocvp(ap->a_vpp, ap->a_dvp->v_mount, ap->a_dvp,
				NULLVP, cnp, vp, NULLVP, 1);
		if (error)
			vnode_put(vp);
		return (error);
	}
	return (EROFS);
}

int
union_rmdir(
	struct vnop_rmdir_args /* {
		struct vnode *a_dvp;
		struct vnode *a_vp;
		struct componentname *a_cnp;
		vfs_context_t a_context;
	} */ *ap)
{
	int error;
	struct union_node *dun = VTOUNION(ap->a_dvp);
	struct union_node *un = VTOUNION(ap->a_vp);
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);

	if (dun->un_uppervp == NULLVP)
		panic("union rmdir: null upper vnode");

	if (un->un_uppervp != NULLVP) {
		struct vnode *dvp = dun->un_uppervp;
		struct vnode *vp = un->un_uppervp;

		FIXUP(dun, p);
		vnode_get(dvp);
		dun->un_flags |= UN_KLOCK;
		FIXUP(un, p);
		vnode_get(vp);
		un->un_flags |= UN_KLOCK;

		if (union_dowhiteout(un, cnp->cn_context))
			cnp->cn_flags |= DOWHITEOUT;
		error = VNOP_RMDIR(dvp, vp, ap->a_cnp, ap->a_context);
		if (!error)
			union_removed_upper(un);
	} else {
		FIXUP(dun, p);
		error = union_mkwhiteout(
			MOUNTTOUNIONMOUNT(UNIONTOV(dun)->v_mount),
			dun->un_uppervp, ap->a_cnp, un->un_path);
	}
	return (error);
}

int
union_symlink(
	struct vnop_symlink_args /* {
		struct vnode *a_dvp;
		struct vnode **a_vpp;
		struct componentname *a_cnp;
		struct vnode_attr *a_vap;
		char *a_target;
		vfs_context_t a_context;
	} */ *ap)
{
	struct union_node *un = VTOUNION(ap->a_dvp);
	struct vnode *dvp = un->un_uppervp;
	struct componentname *cnp = ap->a_cnp;
	vfs_context_t ctx = cnp->cn_context;
	struct proc *p = vfs_context_proc(ctx);

	if (dvp != NULLVP) {
		int error;
		struct vnode *vp;

		FIXUP(un, p);
		un->un_flags |= UN_KLOCK;

		error = VNOP_SYMLINK(dvp, &vp, cnp, ap->a_vap, ap->a_target, ap->a_context);
		*ap->a_vpp = NULLVP;
		return (error);
	}
	return (EROFS);
}

/*
 * union_readdir works in concert with getdirentries and
 * readdir(3) to provide a list of entries in the unioned
 * directories.  getdirentries is responsible for walking
 * down the union stack.  readdir(3) is responsible for
 * eliminating duplicate names from the returned data stream.
 */
int
union_readdir(ap)
	struct vnop_readdir_args /* {
		struct vnodeop_desc *a_desc;
		struct vnode *a_vp;
		struct uio *a_uio;
		int a_flags;
		int *a_eofflag;
		int *a_numdirent;
		vfs_context_t a_context;
	} */ *ap;
{
	struct union_node *un = VTOUNION(ap->a_vp);
	struct vnode *uvp = un->un_uppervp;
	struct proc *p = vfs_context_proc(ap->a_context);

	if (ap->a_flags & (VNODE_READDIR_EXTENDED | VNODE_READDIR_REQSEEKOFF))
		return (EINVAL);

	if (uvp == NULLVP)
		return (0);

	FIXUP(un, p);
	ap->a_vp = uvp;
	return (VCALL(uvp, VOFFSET(vnop_readdir), ap));
}

int
union_readlink(ap)
	struct vnop_readlink_args /* {
		struct vnode *a_vp;
		struct uio *a_uio;
		vfs_context_t a_context;
	} */ *ap;
{
	int error;
	struct uio *uio = ap->a_uio;
	struct proc *p = vfs_context_proc(ap->a_context);
	struct vnode *vp = OTHERVP(ap->a_vp);
	int dolock = (vp == LOWERVP(ap->a_vp));

	if (!dolock)
	        FIXUP(VTOUNION(ap->a_vp), p);
	ap->a_vp = vp;
	error = VCALL(vp, VOFFSET(vnop_readlink), ap);

	return (error);
}

int
union_inactive(
	struct vnop_inactive_args /* {
		struct vnode *a_vp;
		vfs_context_t a_context;
	} */ *ap)
{
	struct vnode *vp = ap->a_vp;
	struct union_node *un = VTOUNION(vp);
	struct vnode **vpp;

	/*
	 * Do nothing (and _don't_ bypass).
	 * Wait to vnode_put lowervp until reclaim,
	 * so that until then our union_node is in the
	 * cache and reusable.
	 *
	 * NEEDSWORK: Someday, consider inactive'ing
	 * the lowervp and then trying to reactivate it
	 * with capabilities (v_id)
	 * like they do in the name lookup cache code.
	 * That's too much work for now.
	 */

	if (un->un_dircache != 0) {
		for (vpp = un->un_dircache; *vpp != NULLVP; vpp++)
			vnode_put(*vpp);
		_FREE(un->un_dircache, M_TEMP);
		un->un_dircache = 0;
	}

	if ((un->un_flags & UN_CACHED) == 0)
		vnode_recycle(vp);

	return (0);
}

int
union_reclaim(ap)
	struct vnop_reclaim_args /* {
		struct vnode *a_vp;
		vfs_context_t a_context;
	} */ *ap;
{

	union_freevp(ap->a_vp);

	return (0);
}

int
union_blockmap(ap)
	struct vnop_blockmap_args /* {
		struct vnode *a_vp;
		off_t a_offset;    
		size_t a_size;
		daddr64_t *a_bpn;
		size_t *a_run;
		void *a_poff;
		int a_flags;
	} */ *ap;
{
	int error;
	struct proc *p = current_proc();		/* XXX */
	struct vnode *vp = OTHERVP(ap->a_vp);
	int dolock = (vp == LOWERVP(ap->a_vp));

	if (!dolock)
	        FIXUP(VTOUNION(ap->a_vp), p);
	ap->a_vp = vp;
	error = VCALL(vp, VOFFSET(vnop_blockmap), ap);

	return (error);
}

int
union_pathconf(ap)
	struct vnop_pathconf_args /* {
		struct vnode *a_vp;
		int a_name;
		int *a_retval;
		vfs_context_t a_context;
	} */ *ap;
{
	int error;
	struct proc *p = current_proc();		/* XXX */
	struct vnode *vp = OTHERVP(ap->a_vp);
	int dolock = (vp == LOWERVP(ap->a_vp));

	if (!dolock)
	        FIXUP(VTOUNION(ap->a_vp), p);
	ap->a_vp = vp;
	error = VCALL(vp, VOFFSET(vnop_pathconf), ap);

	return (error);
}

int
union_advlock(ap)
	struct vnop_advlock_args /* {
		struct vnode *a_vp;
		caddr_t  a_id;
		int  a_op;
		struct flock *a_fl;
		int  a_flags;
		vfs_context_t a_context;
	} */ *ap;
{
	register struct vnode *ovp = OTHERVP(ap->a_vp);

	ap->a_vp = ovp;
	return (VCALL(ovp, VOFFSET(vnop_advlock), ap));
}


/*
 * XXX - vnop_strategy must be hand coded because it has no
 * vnode in its arguments.
 * This goes away with a merged VM/buffer cache.
 */
int
union_strategy(ap)
	struct vnop_strategy_args /* {
		struct buf *a_bp;
	} */ *ap;
{
	struct buf *bp = ap->a_bp;
	int error;
	struct vnode *savedvp;

	savedvp = buf_vnode(bp);
	buf_setvnode(bp, OTHERVP(savedvp));

#if DIAGNOSTIC
	if (buf_vnode(bp) == NULLVP)
		panic("union_strategy: nil vp");
	if (((buf_flags(bp) & B_READ) == 0) &&
	    (buf_vnode(bp) == LOWERVP(savedvp)))
		panic("union_strategy: writing to lowervp");
#endif

	error = VNOP_STRATEGY(bp);
	buf_setvnode(bp, savedvp);

	return (error);
}

/* Pagein */
int
union_pagein(ap)
	struct vnop_pagein_args /* {
	   	struct vnode 	*a_vp,
	   	upl_t		a_pl,
		vm_offset_t	a_pl_offset,
		off_t		a_f_offset,
		size_t		a_size,
		int		a_flags
		vfs_context_t	a_context;
	} */ *ap;
{
	int error;
	struct vnode *vp = OTHERVP(ap->a_vp);

	error = VNOP_PAGEIN(vp, ap->a_pl, ap->a_pl_offset, ap->a_f_offset,
	                    ap->a_size, ap->a_flags, ap->a_context);

	/*
	 * XXX
	 * perhaps the size of the underlying object has changed under
	 * our feet.  take advantage of the offset information present
	 * in the uio structure.
	 */
	if (error == 0) {
		struct union_node *un = VTOUNION(ap->a_vp);
		off_t cur = ap->a_f_offset + (off_t)ap->a_pl_offset;

		if (vp == un->un_uppervp) {
			if (cur > un->un_uppersz)
				union_newsize(ap->a_vp, cur, VNOVAL);
		} else {
			if (cur > un->un_lowersz)
				union_newsize(ap->a_vp, VNOVAL, cur);
		}
	}

	return (error);
}

/* Pageout  */
int
union_pageout(ap)
	struct vnop_pageout_args /* {
	   	struct vnode 	*a_vp,
	   	upl_t		a_pl,
		vm_offset_t	a_pl_offset,
		off_t		a_f_offset,
		size_t		a_size,
		int		a_flags
		vfs_context_t	a_context;
	} */ *ap;
{
	int error;
	struct vnode *vp;
	struct union_node *un = VTOUNION(ap->a_vp);

	vp = UPPERVP(ap->a_vp);
	if (vp == NULLVP)
		panic("union: missing upper layer in pageout");

	error = VNOP_PAGEOUT(vp, ap->a_pl, ap->a_pl_offset, ap->a_f_offset,
	                     ap->a_size, ap->a_flags, ap->a_context);

	/*
	 * the size of the underlying object may be changed by the
	 * write.
	 */
	if (error == 0) {
		off_t cur = ap->a_f_offset + (off_t)ap->a_pl_offset;

		if (cur > un->un_uppersz)
			union_newsize(ap->a_vp, cur, VNOVAL);
	}

	return (error);
}

/* Blktooff derives file offset for the given logical block number */
int
union_blktooff(ap)
	struct vnop_blktooff_args /* {
		struct vnode *a_vp;
		daddr64_t a_lblkno;
		off_t *a_offset;    
	} */ *ap;
{
	int error;
	struct vnode *vp = OTHERVP(ap->a_vp);

	error = VNOP_BLKTOOFF(vp, ap->a_lblkno, ap->a_offset);

	return(error);
}

/* offtoblk derives file offset for the given logical block number */
int
union_offtoblk(ap)
	struct vnop_offtoblk_args /* {
		struct vnode *a_vp;
		off_t a_offset;    
		daddr64_t *a_lblkno;
	} */ *ap;
{
	int error;
	struct vnode *vp = OTHERVP(ap->a_vp);

	error = VNOP_OFFTOBLK(vp, ap->a_offset, ap->a_lblkno);

	return(error);
}

#define VOPFUNC int (*)(void *)

/*
 * Global vfs data structures
 */
int (**union_vnodeop_p)(void *);
struct vnodeopv_entry_desc union_vnodeop_entries[] = {
	{ &vnop_default_desc, (VOPFUNC)vn_default_error },
	{ &vnop_lookup_desc, (VOPFUNC)union_lookup },		/* lookup */
	{ &vnop_create_desc, (VOPFUNC)union_create },		/* create */
	{ &vnop_whiteout_desc, (VOPFUNC)union_whiteout },	/* whiteout */
	{ &vnop_mknod_desc, (VOPFUNC)union_mknod },		/* mknod */
	{ &vnop_open_desc, (VOPFUNC)union_open },		/* open */
	{ &vnop_close_desc, (VOPFUNC)union_close },		/* close */
	{ &vnop_access_desc, (VOPFUNC)union_access },		/* access */
	{ &vnop_getattr_desc, (VOPFUNC)union_getattr },		/* getattr */
	{ &vnop_setattr_desc, (VOPFUNC)union_setattr },		/* setattr */
	{ &vnop_read_desc, (VOPFUNC)union_read },		/* read */
	{ &vnop_write_desc, (VOPFUNC)union_write },		/* write */
	{ &vnop_ioctl_desc, (VOPFUNC)union_ioctl },		/* ioctl */
	{ &vnop_select_desc, (VOPFUNC)union_select },		/* select */
	{ &vnop_revoke_desc, (VOPFUNC)union_revoke },		/* revoke */
	{ &vnop_mmap_desc, (VOPFUNC)union_mmap },		/* mmap */
	{ &vnop_fsync_desc, (VOPFUNC)union_fsync },		/* fsync */
	{ &vnop_remove_desc, (VOPFUNC)union_remove },		/* remove */
	{ &vnop_link_desc, (VOPFUNC)union_link },		/* link */
	{ &vnop_rename_desc, (VOPFUNC)union_rename },		/* rename */
	{ &vnop_mkdir_desc, (VOPFUNC)union_mkdir },		/* mkdir */
	{ &vnop_rmdir_desc, (VOPFUNC)union_rmdir },		/* rmdir */
	{ &vnop_symlink_desc, (VOPFUNC)union_symlink },		/* symlink */
	{ &vnop_readdir_desc, (VOPFUNC)union_readdir },		/* readdir */
	{ &vnop_readlink_desc, (VOPFUNC)union_readlink },	/* readlink */
	{ &vnop_inactive_desc, (VOPFUNC)union_inactive },	/* inactive */
	{ &vnop_reclaim_desc, (VOPFUNC)union_reclaim },		/* reclaim */
	{ &vnop_strategy_desc, (VOPFUNC)union_strategy },	/* strategy */
	{ &vnop_pathconf_desc, (VOPFUNC)union_pathconf },	/* pathconf */
	{ &vnop_advlock_desc, (VOPFUNC)union_advlock },		/* advlock */
#ifdef notdef
	{ &vnop_bwrite_desc, (VOPFUNC)union_bwrite },		/* bwrite */
#endif
	{ &vnop_pagein_desc, (VOPFUNC)union_pagein },		/* Pagein */
	{ &vnop_pageout_desc, (VOPFUNC)union_pageout },		/* Pageout */
        { &vnop_copyfile_desc, (VOPFUNC)err_copyfile },		/* Copyfile */
	{ &vnop_blktooff_desc, (VOPFUNC)union_blktooff },	/* blktooff */
	{ &vnop_offtoblk_desc, (VOPFUNC)union_offtoblk },	/* offtoblk */
	{ &vnop_blockmap_desc, (VOPFUNC)union_blockmap },	/* blockmap */
	{ (struct vnodeop_desc*)NULL, (int(*)())NULL }
};
struct vnodeopv_desc union_vnodeop_opv_desc =
	{ &union_vnodeop_p, union_vnodeop_entries };