[apple/xnu.git] / bsd / miscfs / union / union_vfsops.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) 1994, 1995 The Regents of the University of California.
 * Copyright (c) 1994, 1995 Jan-Simon Pendry.
 * All rights reserved.
 *
 * This code is derived from software donated 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_vfsops.c	8.20 (Berkeley) 5/20/95
 */

/*
 * Union Layer
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/filedesc.h>
#include <sys/queue.h>
#include <miscfs/union/union.h>

/*
 * Mount union filesystem
 */
int
union_mount(mp, path, data, ndp, p)
	struct mount *mp;
	char *path;
	caddr_t data;
	struct nameidata *ndp;
	struct proc *p;
{
	int error = 0;
	struct union_args args;
	struct vnode *lowerrootvp = NULLVP;
	struct vnode *upperrootvp = NULLVP;
	struct union_mount *um = 0;
	struct ucred *cred = 0;
	struct ucred *scred;
	struct vattr va;
	char *cp;
	int len;
	u_int size;

#ifdef UNION_DIAGNOSTIC
	printf("union_mount(mp = %x)\n", mp);
#endif

	/*
	 * Update is a no-op
	 */
	if (mp->mnt_flag & MNT_UPDATE) {
		/*
		 * Need to provide.
		 * 1. a way to convert between rdonly and rdwr mounts.
		 * 2. support for nfs exports.
		 */
		error = EOPNOTSUPP;
		goto bad;
	}

	/*
	 * Get argument
	 */
	if (error = copyin(data, (caddr_t)&args, sizeof(struct union_args)))
		goto bad;

	lowerrootvp = mp->mnt_vnodecovered;
	VREF(lowerrootvp);

	/*
	 * Find upper node.
	 */
	NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT,
	       UIO_USERSPACE, args.target, p);

	if (error = namei(ndp))
		goto bad;

	upperrootvp = ndp->ni_vp;
	vrele(ndp->ni_dvp);
	ndp->ni_dvp = NULL;

	if (upperrootvp->v_type != VDIR) {
		error = EINVAL;
		goto bad;
	}
	
//	um = (struct union_mount *) malloc(sizeof(struct union_mount),
//				M_UFSMNT, M_WAITOK);	/* XXX */
	MALLOC(um, struct union_mount *, sizeof(struct union_mount),
				M_UFSMNT, M_WAITOK);

	/*
	 * Keep a held reference to the target vnodes.
	 * They are vrele'd in union_unmount.
	 *
	 * Depending on the _BELOW flag, the filesystems are
	 * viewed in a different order.  In effect, this is the
	 * same as providing a mount under option to the mount syscall.
	 */

	um->um_op = args.mntflags & UNMNT_OPMASK;
	switch (um->um_op) {
	case UNMNT_ABOVE:
		um->um_lowervp = lowerrootvp;
		um->um_uppervp = upperrootvp;
		break;

	case UNMNT_BELOW:
		um->um_lowervp = upperrootvp;
		um->um_uppervp = lowerrootvp;
		break;

	case UNMNT_REPLACE:
		vrele(lowerrootvp);
		lowerrootvp = NULLVP;
		um->um_uppervp = upperrootvp;
		um->um_lowervp = lowerrootvp;
		break;

	default:
		error = EINVAL;
		goto bad;
	}

	/*
	 * Unless the mount is readonly, ensure that the top layer
	 * supports whiteout operations
	 */
	if ((mp->mnt_flag & MNT_RDONLY) == 0) {
		error = VOP_WHITEOUT(um->um_uppervp, (struct componentname *) 0, LOOKUP);
		if (error)
			goto bad;
	}

	um->um_cred = p->p_ucred;
	crhold(um->um_cred);
	um->um_cmode = UN_DIRMODE &~ p->p_fd->fd_cmask;

	/*
	 * Depending on what you think the MNT_LOCAL flag might mean,
	 * you may want the && to be || on the conditional below.
	 * At the moment it has been defined that the filesystem is
	 * only local if it is all local, ie the MNT_LOCAL flag implies
	 * that the entire namespace is local.  If you think the MNT_LOCAL
	 * flag implies that some of the files might be stored locally
	 * then you will want to change the conditional.
	 */
	if (um->um_op == UNMNT_ABOVE) {
		if (((um->um_lowervp == NULLVP) ||
		     (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) &&
		    (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
			mp->mnt_flag |= MNT_LOCAL;
	}

	/*
	 * Copy in the upper layer's RDONLY flag.  This is for the benefit
	 * of lookup() which explicitly checks the flag, rather than asking
	 * the filesystem for it's own opinion.  This means, that an update
	 * mount of the underlying filesystem to go from rdonly to rdwr
	 * will leave the unioned view as read-only.
	 */
	mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY);

	mp->mnt_data = (qaddr_t) um;
	vfs_getnewfsid(mp);

	(void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
	bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);

	switch (um->um_op) {
	case UNMNT_ABOVE:
		cp = "<above>:";
		break;
	case UNMNT_BELOW:
		cp = "<below>:";
		break;
	case UNMNT_REPLACE:
		cp = "";
		break;
	}
	len = strlen(cp);
	bcopy(cp, mp->mnt_stat.f_mntfromname, len);

	cp = mp->mnt_stat.f_mntfromname + len;
	len = MNAMELEN - len;

	(void) copyinstr(args.target, cp, len - 1, &size);
	bzero(cp + size, len - size);

#ifdef UNION_DIAGNOSTIC
	printf("union_mount: from %s, on %s\n",
		mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
#endif
	return (0);

bad:
	if (um)
		_FREE(um, M_UFSMNT);
	if (cred != NOCRED)
		crfree(cred);
	if (upperrootvp)
		vrele(upperrootvp);
	if (lowerrootvp)
		vrele(lowerrootvp);
	return (error);
}

/*
 * VFS start.  Nothing needed here - the start routine
 * on the underlying filesystem(s) will have been called
 * when that filesystem was mounted.
 */
int
union_start(mp, flags, p)
	struct mount *mp;
	int flags;
	struct proc *p;
{

	return (0);
}

/*
 * Free reference to union layer
 */
int
union_unmount(mp, mntflags, p)
	struct mount *mp;
	int mntflags;
	struct proc *p;
{
	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
	struct vnode *um_rootvp;
	int error;
	int freeing;
	int flags = 0;
	struct ucred *cred;

#ifdef UNION_DIAGNOSTIC
	printf("union_unmount(mp = %x)\n", mp);
#endif

	if (mntflags & MNT_FORCE)
		flags |= FORCECLOSE;

	if (error = union_root(mp, &um_rootvp))
		return (error);

	/*
	 * Keep flushing vnodes from the mount list.
	 * This is needed because of the un_pvp held
	 * reference to the parent vnode.
	 * If more vnodes have been freed on a given pass,
	 * the try again.  The loop will iterate at most
	 * (d) times, where (d) is the maximum tree depth
	 * in the filesystem.
	 */
	for (freeing = 0; vflush(mp, um_rootvp, flags) != 0;) {
		struct vnode *vp;
		int n;

		/* count #vnodes held on mount list */
		for (n = 0, vp = mp->mnt_vnodelist.lh_first;
				vp != NULLVP;
				vp = vp->v_mntvnodes.le_next)
			n++;

		/* if this is unchanged then stop */
		if (n == freeing)
			break;

		/* otherwise try once more time */
		freeing = n;
	}

	/* At this point the root vnode should have a single reference */
	if (um_rootvp->v_usecount > 1) {
		vput(um_rootvp);
		return (EBUSY);
	}

#ifdef UNION_DIAGNOSTIC
	vprint("union root", um_rootvp);
#endif	 
	/*
	 * Discard references to upper and lower target vnodes.
	 */
	if (um->um_lowervp)
		vrele(um->um_lowervp);
	vrele(um->um_uppervp);
	cred = um->um_cred;
	if (cred != NOCRED) {
		um->um_cred = NOCRED;
		crfree(cred);
	}
	/*
	 * Release reference on underlying root vnode
	 */
	vput(um_rootvp);
	/*
	 * And blow it away for future re-use
	 */
	vgone(um_rootvp);
	/*
	 * Finally, throw away the union_mount structure
	 */
	_FREE(mp->mnt_data, M_UFSMNT);	/* XXX */
	mp->mnt_data = 0;
	return (0);
}

int
union_root(mp, vpp)
	struct mount *mp;
	struct vnode **vpp;
{
	struct proc *p = current_proc();	/* XXX */
	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
	int error;
	int loselock;

	/*
	 * Return locked reference to root.
	 */
	VREF(um->um_uppervp);
	if ((um->um_op == UNMNT_BELOW) &&
	     VOP_ISLOCKED(um->um_uppervp)) {
		loselock = 1;
	} else {
		vn_lock(um->um_uppervp, LK_EXCLUSIVE | LK_RETRY, p);
		loselock = 0;
	}
	if (um->um_lowervp)
		VREF(um->um_lowervp);
	error = union_allocvp(vpp, mp,
			      (struct vnode *) 0,
			      (struct vnode *) 0,
			      (struct componentname *) 0,
			      um->um_uppervp,
			      um->um_lowervp,
			      1);

	if (error) {
		if (loselock)
			vrele(um->um_uppervp);
		else
			vput(um->um_uppervp);
		if (um->um_lowervp)
			vrele(um->um_lowervp);
	} else {
		if (loselock)
			VTOUNION(*vpp)->un_flags &= ~UN_ULOCK;
	}

	return (error);
}

int
union_statfs(mp, sbp, p)
	struct mount *mp;
	struct statfs *sbp;
	struct proc *p;
{
	int error;
	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
	struct statfs mstat;
	int lbsize;

#ifdef UNION_DIAGNOSTIC
	printf("union_statfs(mp = %x, lvp = %x, uvp = %x)\n", mp,
			um->um_lowervp,
	       		um->um_uppervp);
#endif

	bzero(&mstat, sizeof(mstat));

	if (um->um_lowervp) {
		error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, p);
		if (error)
			return (error);
	}

	/* now copy across the "interesting" information and fake the rest */
#if 0
	sbp->f_type = mstat.f_type;
	sbp->f_flags = mstat.f_flags;
	sbp->f_bsize = mstat.f_bsize;
	sbp->f_iosize = mstat.f_iosize;
#endif
	lbsize = mstat.f_bsize;
	sbp->f_blocks = mstat.f_blocks;
	sbp->f_bfree = mstat.f_bfree;
	sbp->f_bavail = mstat.f_bavail;
	sbp->f_files = mstat.f_files;
	sbp->f_ffree = mstat.f_ffree;

	error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, p);
	if (error)
		return (error);

	sbp->f_flags = mstat.f_flags;
	sbp->f_bsize = mstat.f_bsize;
	sbp->f_iosize = mstat.f_iosize;

	/*
	 * if the lower and upper blocksizes differ, then frig the
	 * block counts so that the sizes reported by df make some
	 * kind of sense.  none of this makes sense though.
	 */

	if (mstat.f_bsize != lbsize)
		sbp->f_blocks = sbp->f_blocks * lbsize / mstat.f_bsize;

	/*
	 * The "total" fields count total resources in all layers,
	 * the "free" fields count only those resources which are
	 * free in the upper layer (since only the upper layer
	 * is writeable).
	 */
	sbp->f_blocks += mstat.f_blocks;
	sbp->f_bfree = mstat.f_bfree;
	sbp->f_bavail = mstat.f_bavail;
	sbp->f_files += mstat.f_files;
	sbp->f_ffree = mstat.f_ffree;

	if (sbp != &mp->mnt_stat) {
		sbp->f_type = mp->mnt_vfc->vfc_typenum;
		bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
		bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
	}
	return (0);
}

/*
 * XXX - Assumes no data cached at union layer.
 */
#define union_sync ((int (*) __P((struct mount *, int, struct ucred *, \
	    struct proc *)))nullop)

#define union_fhtovp ((int (*) __P((struct mount *, struct fid *, \
	    struct mbuf *, struct vnode **, int *, struct ucred **)))eopnotsupp)
int union_init __P((struct vfsconf *));
#define union_quotactl ((int (*) __P((struct mount *, int, uid_t, caddr_t, \
	    struct proc *)))eopnotsupp)
#define union_sysctl ((int (*) __P((int *, u_int, void *, size_t *, void *, \
	    size_t, struct proc *)))eopnotsupp)
#define union_vget ((int (*) __P((struct mount *, ino_t, struct vnode **))) \
	    eopnotsupp)
#define union_vptofh ((int (*) __P((struct vnode *, struct fid *)))eopnotsupp)

struct vfsops union_vfsops = {
	union_mount,
	union_start,
	union_unmount,
	union_root,
	union_quotactl,
	union_statfs,
	union_sync,
	union_vget,
	union_fhtovp,
	union_vptofh,
	union_init,
	union_sysctl,
};
Commit	Line	Data
1c79356b A	1	/*
	2	* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
	6	* The contents of this file constitute Original Code as defined in and
	7	* are subject to the Apple Public Source License Version 1.1 (the
	8	* "License"). You may not use this file except in compliance with the
	9	* License. Please obtain a copy of the License at
	10	* http://www.apple.com/publicsource and read it before using this file.
	11	*
	12	* This Original Code and all software distributed under the License are
	13	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	14	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	15	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	16	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	17	* License for the specific language governing rights and limitations
	18	* under the License.
	19	*
	20	* @APPLE_LICENSE_HEADER_END@
	21	*/
	22	/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
	23	/*
	24	* Copyright (c) 1994, 1995 The Regents of the University of California.
	25	* Copyright (c) 1994, 1995 Jan-Simon Pendry.
	26	* All rights reserved.
	27	*
	28	* This code is derived from software donated to Berkeley by
	29	* Jan-Simon Pendry.
	30	*
	31	* Redistribution and use in source and binary forms, with or without
	32	* modification, are permitted provided that the following conditions
	33	* are met:
	34	* 1. Redistributions of source code must retain the above copyright
	35	* notice, this list of conditions and the following disclaimer.
	36	* 2. Redistributions in binary form must reproduce the above copyright
	37	* notice, this list of conditions and the following disclaimer in the
	38	* documentation and/or other materials provided with the distribution.
	39	* 3. All advertising materials mentioning features or use of this software
	40	* must display the following acknowledgement:
	41	* This product includes software developed by the University of
	42	* California, Berkeley and its contributors.
	43	* 4. Neither the name of the University nor the names of its contributors
	44	* may be used to endorse or promote products derived from this software
	45	* without specific prior written permission.
	46	*
	47	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	48	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	49	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	50	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	51	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	52	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	53	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	54	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	55	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	56	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	57	* SUCH DAMAGE.
	58	*
	59	* @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95
	60	*/
	61
	62	/*
	63	* Union Layer
	64	*/
65
66	#include <sys/param.h>
67	#include <sys/systm.h>
68	#include <sys/time.h>
69	#include <sys/types.h>
70	#include <sys/proc.h>
71	#include <sys/vnode.h>
72	#include <sys/mount.h>
73	#include <sys/namei.h>
74	#include <sys/malloc.h>
75	#include <sys/filedesc.h>
76	#include <sys/queue.h>
77	#include <miscfs/union/union.h>
78
79	/*
80	* Mount union filesystem
81	*/
82	int
83	union_mount(mp, path, data, ndp, p)
84	struct mount *mp;
85	char *path;
86	caddr_t data;
87	struct nameidata *ndp;
88	struct proc *p;
89	{
90	int error = 0;
91	struct union_args args;
92	struct vnode *lowerrootvp = NULLVP;
93	struct vnode *upperrootvp = NULLVP;
94	struct union_mount *um = 0;
95	struct ucred *cred = 0;
96	struct ucred *scred;
97	struct vattr va;
98	char *cp;
99	int len;
100	u_int size;
101
102	#ifdef UNION_DIAGNOSTIC
103	printf("union_mount(mp = %x)\n", mp);
104	#endif
105
106	/*
107	* Update is a no-op
108	*/
109	if (mp->mnt_flag & MNT_UPDATE) {
110	/*
111	* Need to provide.
112	* 1. a way to convert between rdonly and rdwr mounts.
113	* 2. support for nfs exports.
114	*/
115	error = EOPNOTSUPP;
116	goto bad;
117	}
118
119	/*
120	* Get argument
121	*/
122	if (error = copyin(data, (caddr_t)&args, sizeof(struct union_args)))
123	goto bad;
124
125	lowerrootvp = mp->mnt_vnodecovered;
126	VREF(lowerrootvp);
127
128	/*
129	* Find upper node.
130	*/
131	NDINIT(ndp, LOOKUP, FOLLOW\|WANTPARENT,
132	UIO_USERSPACE, args.target, p);
133
134	if (error = namei(ndp))
135	goto bad;
136
137	upperrootvp = ndp->ni_vp;
138	vrele(ndp->ni_dvp);
139	ndp->ni_dvp = NULL;
140
141	if (upperrootvp->v_type != VDIR) {
142	error = EINVAL;
143	goto bad;
144	}
145
146	// um = (struct union_mount *) malloc(sizeof(struct union_mount),
147	// M_UFSMNT, M_WAITOK); /* XXX */
148	MALLOC(um, struct union_mount *, sizeof(struct union_mount),
149	M_UFSMNT, M_WAITOK);
150
151	/*
152	* Keep a held reference to the target vnodes.
153	* They are vrele'd in union_unmount.
154	*
155	* Depending on the _BELOW flag, the filesystems are
156	* viewed in a different order. In effect, this is the
157	* same as providing a mount under option to the mount syscall.
158	*/
159
160	um->um_op = args.mntflags & UNMNT_OPMASK;
161	switch (um->um_op) {
162	case UNMNT_ABOVE:
163	um->um_lowervp = lowerrootvp;
164	um->um_uppervp = upperrootvp;
165	break;
166
167	case UNMNT_BELOW:
168	um->um_lowervp = upperrootvp;
169	um->um_uppervp = lowerrootvp;
170	break;
171
172	case UNMNT_REPLACE:
173	vrele(lowerrootvp);
174	lowerrootvp = NULLVP;
175	um->um_uppervp = upperrootvp;
176	um->um_lowervp = lowerrootvp;
177	break;
178
179	default:
180	error = EINVAL;
181	goto bad;
182	}
183
184	/*
185	* Unless the mount is readonly, ensure that the top layer
186	* supports whiteout operations
187	*/
188	if ((mp->mnt_flag & MNT_RDONLY) == 0) {
189	error = VOP_WHITEOUT(um->um_uppervp, (struct componentname *) 0, LOOKUP);
190	if (error)
191	goto bad;
192	}
193
194	um->um_cred = p->p_ucred;
195	crhold(um->um_cred);
196	um->um_cmode = UN_DIRMODE &~ p->p_fd->fd_cmask;
197
198	/*
199	* Depending on what you think the MNT_LOCAL flag might mean,
200	* you may want the && to be \|\| on the conditional below.
201	* At the moment it has been defined that the filesystem is
202	* only local if it is all local, ie the MNT_LOCAL flag implies
203	* that the entire namespace is local. If you think the MNT_LOCAL
204	* flag implies that some of the files might be stored locally
205	* then you will want to change the conditional.
206	*/
207	if (um->um_op == UNMNT_ABOVE) {
208	if (((um->um_lowervp == NULLVP) \|\|
209	(um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) &&
210	(um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
211	mp->mnt_flag \|= MNT_LOCAL;
212	}
213
214	/*
215	* Copy in the upper layer's RDONLY flag. This is for the benefit
216	* of lookup() which explicitly checks the flag, rather than asking
217	* the filesystem for it's own opinion. This means, that an update
218	* mount of the underlying filesystem to go from rdonly to rdwr
219	* will leave the unioned view as read-only.
220	*/
221	mp->mnt_flag \|= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY);
222
223	mp->mnt_data = (qaddr_t) um;
224	vfs_getnewfsid(mp);
225
226	(void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
227	bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
228
229	switch (um->um_op) {
230	case UNMNT_ABOVE:
231	cp = "<above>:";
232	break;
233	case UNMNT_BELOW:
234	cp = "<below>:";
235	break;
236	case UNMNT_REPLACE:
237	cp = "";
238	break;
239	}
240	len = strlen(cp);
241	bcopy(cp, mp->mnt_stat.f_mntfromname, len);
242
243	cp = mp->mnt_stat.f_mntfromname + len;
244	len = MNAMELEN - len;
245
246	(void) copyinstr(args.target, cp, len - 1, &size);
247	bzero(cp + size, len - size);
248
249	#ifdef UNION_DIAGNOSTIC
250	printf("union_mount: from %s, on %s\n",
251	mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
252	#endif
253	return (0);
254
255	bad:
256	if (um)
257	_FREE(um, M_UFSMNT);
258	if (cred != NOCRED)
259	crfree(cred);
260	if (upperrootvp)
261	vrele(upperrootvp);
262	if (lowerrootvp)
263	vrele(lowerrootvp);
264	return (error);
265	}
266
267	/*
268	* VFS start. Nothing needed here - the start routine
269	* on the underlying filesystem(s) will have been called
270	* when that filesystem was mounted.
271	*/
272	int
273	union_start(mp, flags, p)
274	struct mount *mp;
275	int flags;
276	struct proc *p;
277	{
278
279	return (0);
280	}
281
282	/*
283	* Free reference to union layer
284	*/
285	int
286	union_unmount(mp, mntflags, p)
287	struct mount *mp;
288	int mntflags;
289	struct proc *p;
290	{
291	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
292	struct vnode *um_rootvp;
293	int error;
294	int freeing;
295	int flags = 0;
296	struct ucred *cred;
297
298	#ifdef UNION_DIAGNOSTIC
299	printf("union_unmount(mp = %x)\n", mp);
300	#endif
301
302	if (mntflags & MNT_FORCE)
303	flags \|= FORCECLOSE;
304
305	if (error = union_root(mp, &um_rootvp))
306	return (error);
307
308	/*
309	* Keep flushing vnodes from the mount list.
310	* This is needed because of the un_pvp held
311	* reference to the parent vnode.
312	* If more vnodes have been freed on a given pass,
313	* the try again. The loop will iterate at most
314	* (d) times, where (d) is the maximum tree depth
315	* in the filesystem.
316	*/
317	for (freeing = 0; vflush(mp, um_rootvp, flags) != 0;) {
318	struct vnode *vp;
319	int n;
320
321	/* count #vnodes held on mount list */
322	for (n = 0, vp = mp->mnt_vnodelist.lh_first;
323	vp != NULLVP;
324	vp = vp->v_mntvnodes.le_next)
325	n++;
326
327	/* if this is unchanged then stop */
328	if (n == freeing)
329	break;
330
331	/* otherwise try once more time */
332	freeing = n;
333	}
334
335	/* At this point the root vnode should have a single reference */
336	if (um_rootvp->v_usecount > 1) {
337	vput(um_rootvp);
338	return (EBUSY);
339	}
340
341	#ifdef UNION_DIAGNOSTIC
342	vprint("union root", um_rootvp);
343	#endif
344	/*
345	* Discard references to upper and lower target vnodes.
346	*/
347	if (um->um_lowervp)
348	vrele(um->um_lowervp);
349	vrele(um->um_uppervp);
350	cred = um->um_cred;
351	if (cred != NOCRED) {
352	um->um_cred = NOCRED;
353	crfree(cred);
354	}
355	/*
356	* Release reference on underlying root vnode
357	*/
358	vput(um_rootvp);
359	/*
360	* And blow it away for future re-use
361	*/
362	vgone(um_rootvp);
363	/*
364	* Finally, throw away the union_mount structure
365	*/
366	_FREE(mp->mnt_data, M_UFSMNT); /* XXX */
367	mp->mnt_data = 0;
368	return (0);
369	}
370
371	int
372	union_root(mp, vpp)
373	struct mount *mp;
374	struct vnode **vpp;
375	{
376	struct proc p = current_proc(); / XXX */
377	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
378	int error;
379	int loselock;
380
381	/*
382	* Return locked reference to root.
383	*/
384	VREF(um->um_uppervp);
385	if ((um->um_op == UNMNT_BELOW) &&
386	VOP_ISLOCKED(um->um_uppervp)) {
387	loselock = 1;
388	} else {
389	vn_lock(um->um_uppervp, LK_EXCLUSIVE \| LK_RETRY, p);
390	loselock = 0;
391	}
392	if (um->um_lowervp)
393	VREF(um->um_lowervp);
394	error = union_allocvp(vpp, mp,
395	(struct vnode *) 0,
396	(struct vnode *) 0,
397	(struct componentname *) 0,
398	um->um_uppervp,
399	um->um_lowervp,
400	1);
401
402	if (error) {
403	if (loselock)
404	vrele(um->um_uppervp);
405	else
406	vput(um->um_uppervp);
407	if (um->um_lowervp)
408	vrele(um->um_lowervp);
409	} else {
410	if (loselock)
411	VTOUNION(*vpp)->un_flags &= ~UN_ULOCK;
412	}
413
414	return (error);
415	}
416
417	int
418	union_statfs(mp, sbp, p)
419	struct mount *mp;
420	struct statfs *sbp;
421	struct proc *p;
422	{
423	int error;
424	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
425	struct statfs mstat;
426	int lbsize;
427
428	#ifdef UNION_DIAGNOSTIC
429	printf("union_statfs(mp = %x, lvp = %x, uvp = %x)\n", mp,
430	um->um_lowervp,
431	um->um_uppervp);
432	#endif
433
434	bzero(&mstat, sizeof(mstat));
435
436	if (um->um_lowervp) {
437	error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, p);
438	if (error)
439	return (error);
440	}
441
442	/* now copy across the "interesting" information and fake the rest */
443	#if 0
444	sbp->f_type = mstat.f_type;
445	sbp->f_flags = mstat.f_flags;
446	sbp->f_bsize = mstat.f_bsize;
447	sbp->f_iosize = mstat.f_iosize;
448	#endif
449	lbsize = mstat.f_bsize;
450	sbp->f_blocks = mstat.f_blocks;
451	sbp->f_bfree = mstat.f_bfree;
452	sbp->f_bavail = mstat.f_bavail;
453	sbp->f_files = mstat.f_files;
454	sbp->f_ffree = mstat.f_ffree;
455
456	error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, p);
457	if (error)
458	return (error);
459
460	sbp->f_flags = mstat.f_flags;
461	sbp->f_bsize = mstat.f_bsize;
462	sbp->f_iosize = mstat.f_iosize;
463
464	/*
465	* if the lower and upper blocksizes differ, then frig the
466	* block counts so that the sizes reported by df make some
467	* kind of sense. none of this makes sense though.
468	*/
469
470	if (mstat.f_bsize != lbsize)
471	sbp->f_blocks = sbp->f_blocks * lbsize / mstat.f_bsize;
472
473	/*
474	* The "total" fields count total resources in all layers,
475	* the "free" fields count only those resources which are
476	* free in the upper layer (since only the upper layer
477	* is writeable).
478	*/
479	sbp->f_blocks += mstat.f_blocks;
480	sbp->f_bfree = mstat.f_bfree;
481	sbp->f_bavail = mstat.f_bavail;
482	sbp->f_files += mstat.f_files;
483	sbp->f_ffree = mstat.f_ffree;
484
485	if (sbp != &mp->mnt_stat) {
486	sbp->f_type = mp->mnt_vfc->vfc_typenum;
487	bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
488	bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
489	bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
490	}
491	return (0);
492	}
493
494	/*
495	* XXX - Assumes no data cached at union layer.
496	*/
497	#define union_sync ((int () __P((struct mount , int, struct ucred *, \
498	struct proc *)))nullop)
499
500	#define union_fhtovp ((int () __P((struct mount , struct fid *, \
501	struct mbuf , struct vnode , int , struct ucred **)))eopnotsupp)
502	int union_init __P((struct vfsconf *));
503	#define union_quotactl ((int () __P((struct mount , int, uid_t, caddr_t, \
504	struct proc *)))eopnotsupp)
505	#define union_sysctl ((int () __P((int , u_int, void , size_t , void *, \
506	size_t, struct proc *)))eopnotsupp)
507	#define union_vget ((int () __P((struct mount , ino_t, struct vnode **))) \
508	eopnotsupp)
509	#define union_vptofh ((int () __P((struct vnode , struct fid *)))eopnotsupp)
510
511	struct vfsops union_vfsops = {
512	union_mount,
513	union_start,
514	union_unmount,
515	union_root,
516	union_quotactl,
517	union_statfs,
518	union_sync,
519	union_vget,
520	union_fhtovp,
521	union_vptofh,
522	union_init,
523	union_sysctl,
524	};