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unionfs_vfsops.c revision 1.14 
      1 /*-
      2  * Copyright (c) 1994, 1995 The Regents of the University of California.
      3  * Copyright (c) 1994, 1995 Jan-Simon Pendry.
      4  * Copyright (c) 2005, 2006 Masanori Ozawa <ozawa (at) ongs.co.jp>, ONGS Inc.
      5  * Copyright (c) 2006 Daichi Goto <daichi (at) freebsd.org>
      6  * All rights reserved.
      7  *
      8  * This code is derived from software donated to Berkeley by
      9  * Jan-Simon Pendry.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  *
     35  *	@(#)union_vfsops.c	8.20 (Berkeley) 5/20/95
     36  * $FreeBSD: src/sys/fs/unionfs/union_vfsops.c,v 1.89 2008/01/13 14:44:06 attilio Exp $
     37  */
     38 
     39 #include <sys/param.h>
     40 #include <sys/systm.h>
     41 #include <sys/kernel.h>
     42 #include <sys/lock.h>
     43 #include <sys/malloc.h>
     44 #include <sys/mount.h>
     45 #include <sys/namei.h>
     46 #include <sys/proc.h>
     47 #include <sys/vnode.h>
     48 #include <sys/stat.h>
     49 #include <sys/sysctl.h>
     50 #include <sys/module.h>
     51 
     52 #include <fs/unionfs/unionfs.h>
     53 
     54 MODULE(MODULE_CLASS_VFS, unionfs, "layerfs");
     55 
     56 MALLOC_DEFINE(M_UNIONFSMNT, "UNIONFS mount", "UNIONFS mount structure");
     57 
     58 struct vfsops unionfs_vfsops;
     59 
     60 VFS_PROTOS(unionfs);
     61 
     62 static struct sysctllog *unionfs_sysctl_log;
     63 
     64 /*
     65  * Mount unionfs layer.
     66  */
     67 int
     68 unionfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
     69 {
     70 	int		error;
     71 	struct vnode   *lowerrootvp;
     72 	struct vnode   *upperrootvp;
     73 	struct unionfs_mount *ump;
     74 	int		below;
     75 	uid_t		uid;
     76 	gid_t		gid;
     77 	u_short		udir;
     78 	u_short		ufile;
     79 	unionfs_copymode copymode;
     80 	unionfs_whitemode whitemode;
     81 	struct pathbuf *pb;
     82 	struct componentname fakecn;
     83 	struct nameidata nd, *ndp;
     84 	struct vattr	va;
     85 	struct union_args *args = data;
     86 	kauth_cred_t	cred;
     87 	size_t		size;
     88 	size_t		len;
     89 	const char	*cp;
     90 	char		*xp;
     91 
     92 	if (args == NULL)
     93 		return EINVAL;
     94 	if (*data_len < sizeof *args)
     95 		return EINVAL;
     96 
     97 	UNIONFSDEBUG("unionfs_mount(mp = %p)\n", (void *)mp);
     98 
     99 	error = 0;
    100 	below = 0;
    101 	uid = 0;
    102 	gid = 0;
    103 	udir = 0;
    104 	ufile = 0;
    105 	copymode = UNIONFS_TRANSPARENT;	/* default */
    106 	whitemode = UNIONFS_WHITE_ALWAYS;
    107 	ndp = &nd;
    108 	cred = kauth_cred_get();
    109 
    110 	if (mp->mnt_flag & MNT_ROOTFS) {
    111 		printf("union_mount: cannot union mount root filesystem\n");
    112 		return (EOPNOTSUPP);
    113 	}
    114 
    115 	if (mp->mnt_flag & MNT_GETARGS) {
    116 		ump = MOUNTTOUNIONFSMOUNT(mp);
    117 		if (ump == NULL)
    118 			return EIO;
    119 		args->target = NULL;
    120 		args->mntflags = ump->um_op;
    121 		*data_len = sizeof *args;
    122 		return 0;
    123 	}
    124 
    125 	/*
    126 	 * Update is a no operation.
    127 	 */
    128 	if (mp->mnt_flag & MNT_UPDATE) {
    129 		printf("union_mount: cannot update union mount\n");
    130 		return (EOPNOTSUPP);
    131 	}
    132 
    133 	vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
    134 	error = VOP_GETATTR(mp->mnt_vnodecovered, &va, cred);
    135 	if (!error) {
    136 		if (udir == 0)
    137 			udir = va.va_mode;
    138 		if (ufile == 0)
    139 			ufile = va.va_mode;
    140 		uid = va.va_uid;
    141 		gid = va.va_gid;
    142 	}
    143 	VOP_UNLOCK(mp->mnt_vnodecovered);
    144 	if (error)
    145 		return (error);
    146 
    147 	switch (args->mntflags & UNMNT_OPMASK) {
    148 	case UNMNT_ABOVE:
    149 		below = 0;
    150 		break;
    151 
    152 	case UNMNT_BELOW:
    153 		below = 1;
    154 		break;
    155 
    156 	case UNMNT_REPLACE:
    157 	default:
    158 		return EINVAL;
    159 	}
    160 
    161 	/* If copymode is UNIONFS_TRADITIONAL, uid/gid is mounted user. */
    162 	if (copymode == UNIONFS_TRADITIONAL) {
    163 		uid = kauth_cred_getuid(cred);
    164 		gid = kauth_cred_getgid(cred);
    165 	}
    166 
    167 	UNIONFSDEBUG("unionfs_mount: uid=%d, gid=%d\n", uid, gid);
    168 	UNIONFSDEBUG("unionfs_mount: udir=0%03o, ufile=0%03o\n", udir, ufile);
    169 	UNIONFSDEBUG("unionfs_mount: copymode=%d\n", copymode);
    170 
    171 	/*
    172 	 * Find upper node
    173 	 */
    174 	error = pathbuf_copyin(args->target, &pb);
    175 	if (error) {
    176 		return error;
    177 	}
    178 	NDINIT(ndp, LOOKUP, FOLLOW | LOCKLEAF, pb);
    179 	if ((error = namei(ndp))) {
    180 		pathbuf_destroy(pb);
    181 		return error;
    182 	}
    183 
    184 	/* get root vnodes */
    185 	lowerrootvp = mp->mnt_vnodecovered;
    186 	upperrootvp = ndp->ni_vp;
    187 
    188 	vrele(ndp->ni_dvp);
    189 	ndp->ni_dvp = NULLVP;
    190 	pathbuf_destroy(pb);
    191 
    192 	/* create unionfs_mount */
    193 	ump = (struct unionfs_mount *)malloc(sizeof(struct unionfs_mount),
    194 	    M_UNIONFSMNT, M_WAITOK | M_ZERO);
    195 
    196 	/*
    197 	 * Save reference
    198 	 */
    199 	if (below) {
    200 		VOP_UNLOCK(upperrootvp);
    201 		vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY);
    202 		ump->um_lowervp = upperrootvp;
    203 		ump->um_uppervp = lowerrootvp;
    204 	} else {
    205 		ump->um_lowervp = lowerrootvp;
    206 		ump->um_uppervp = upperrootvp;
    207 	}
    208 	ump->um_rootvp = NULLVP;
    209 	ump->um_uid = uid;
    210 	ump->um_gid = gid;
    211 	ump->um_udir = udir;
    212 	ump->um_ufile = ufile;
    213 	ump->um_copymode = copymode;
    214 	ump->um_whitemode = whitemode;
    215 
    216 	if ((lowerrootvp->v_mount->mnt_iflag & IMNT_MPSAFE) &&
    217 	    (upperrootvp->v_mount->mnt_flag & IMNT_MPSAFE))
    218 		mp->mnt_iflag |= IMNT_MPSAFE;
    219 	mp->mnt_data = ump;
    220 
    221 	/*
    222 	 * Copy upper layer's RDONLY flag.
    223 	 */
    224 	mp->mnt_flag |= ump->um_uppervp->v_mount->mnt_flag & MNT_RDONLY;
    225 
    226 	/*
    227 	 * Check whiteout
    228 	 */
    229 	if ((mp->mnt_flag & MNT_RDONLY) == 0) {
    230 		memset(&fakecn, 0, sizeof(fakecn));
    231 		fakecn.cn_nameiop = LOOKUP;
    232 		error = VOP_WHITEOUT(ump->um_uppervp, &fakecn, LOOKUP);
    233 		if (error) {
    234 			if (below) {
    235 				VOP_UNLOCK(ump->um_uppervp);
    236 				vrele(upperrootvp);
    237 			} else
    238 				vput(ump->um_uppervp);
    239 			free(ump, M_UNIONFSMNT);
    240 			mp->mnt_data = NULL;
    241 			return (error);
    242 		}
    243 	}
    244 
    245 	/*
    246 	 * Unlock the node
    247 	 */
    248 	VOP_UNLOCK(ump->um_uppervp);
    249 
    250 	ump->um_op = args->mntflags & UNMNT_OPMASK;
    251 
    252 	/*
    253 	 * Get the unionfs root vnode.
    254 	 */
    255 	error = unionfs_nodeget(mp, ump->um_uppervp, ump->um_lowervp,
    256 	    NULLVP, &(ump->um_rootvp), NULL);
    257 	vrele(upperrootvp);
    258 	if (error) {
    259 		free(ump, M_UNIONFSMNT);
    260 		mp->mnt_data = NULL;
    261 		return (error);
    262 	}
    263 
    264 	/*
    265 	 * Check mnt_flag
    266 	 */
    267 	if ((ump->um_lowervp->v_mount->mnt_flag & MNT_LOCAL) &&
    268 	    (ump->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
    269 		mp->mnt_flag |= MNT_LOCAL;
    270 
    271 	/*
    272 	 * Get new fsid
    273 	 */
    274 	vfs_getnewfsid(mp);
    275 
    276 	error = set_statvfs_info(path, UIO_USERSPACE, NULL, UIO_USERSPACE,
    277 	    mp->mnt_op->vfs_name, mp, curlwp);
    278 	if (error) {
    279 		unionfs_noderem(ump->um_rootvp);
    280 		free(ump, M_UNIONFSMNT);
    281 		mp->mnt_data = NULL;
    282 		return (error);
    283 	}
    284 
    285 	switch (ump->um_op) {
    286 	case UNMNT_ABOVE:
    287 		cp = "<above>:";
    288 		break;
    289 	case UNMNT_BELOW:
    290 		cp = "<below>:";
    291 		break;
    292 	default:
    293 		panic("union_mount: bad um_op");
    294 		break;
    295 	}
    296 	len = strlen(cp);
    297 	memcpy(mp->mnt_stat.f_mntfromname, cp, len);
    298 	xp = mp->mnt_stat.f_mntfromname + len;
    299 	len = MNAMELEN - len;
    300 	(void) copyinstr(args->target, xp, len - 1, &size);
    301 	memset(xp + size, 0, len - size);
    302 
    303 	UNIONFSDEBUG("unionfs_mount: from %s, on %s\n",
    304 	    mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
    305 
    306 	return (0);
    307 }
    308 
    309 /*
    310  * Free reference to unionfs layer
    311  */
    312 int
    313 unionfs_unmount(struct mount *mp, int mntflags)
    314 {
    315 	struct unionfs_mount *ump;
    316 	int		error;
    317 	int		freeing;
    318 	int		flags;
    319 
    320 	UNIONFSDEBUG("unionfs_unmount: mp = %p\n", (void *)mp);
    321 
    322 	ump = MOUNTTOUNIONFSMOUNT(mp);
    323 	flags = 0;
    324 
    325 	if (mntflags & MNT_FORCE)
    326 		flags |= FORCECLOSE;
    327 
    328 	/* vflush (no need to call vrele) */
    329 	for (freeing = 0; (error = vflush(mp, NULL, flags)) != 0;) {
    330 		struct vnode *vp;
    331 		int n;
    332 
    333 		/* count #vnodes held on mount list */
    334 		n = 0;
    335 		TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes)
    336 			n++;
    337 
    338 		/* if this is unchanged then stop */
    339 		if (n == freeing)
    340 			break;
    341 
    342 		/* otherwise try once more time */
    343 		freeing = n;
    344 	}
    345 
    346 	if (error)
    347 		return (error);
    348 
    349 	free(ump, M_UNIONFSMNT);
    350 	mp->mnt_data = NULL;
    351 
    352 	return (0);
    353 }
    354 
    355 int
    356 unionfs_root(struct mount *mp, int lktype, struct vnode **vpp)
    357 {
    358 	struct unionfs_mount *ump;
    359 	struct vnode   *vp;
    360 
    361 	ump = MOUNTTOUNIONFSMOUNT(mp);
    362 	vp = ump->um_rootvp;
    363 
    364 	UNIONFSDEBUG("unionfs_root: rootvp=%p locked=%x\n",
    365 	    vp, VOP_ISLOCKED(vp));
    366 
    367 	vref(vp);
    368 	vn_lock(vp, lktype);
    369 
    370 	*vpp = vp;
    371 
    372 	return (0);
    373 }
    374 
    375 int
    376 unionfs_quotactl(struct mount *mp, struct quotactl_args *args)
    377 {
    378 	struct unionfs_mount *ump;
    379 
    380 	ump = MOUNTTOUNIONFSMOUNT(mp);
    381 
    382 	/*
    383 	 * Writing is always performed to upper vnode.
    384 	 */
    385 	return (VFS_QUOTACTL(ump->um_uppervp->v_mount, args));
    386 }
    387 
    388 int
    389 unionfs_statvfs(struct mount *mp, struct statvfs *sbp)
    390 {
    391 	struct unionfs_mount *ump;
    392 	int		error;
    393 	uint64_t	lbsize;
    394 	struct statvfs *sbuf = malloc(sizeof(*sbuf), M_TEMP, M_WAITOK | M_ZERO);
    395 
    396 	ump = MOUNTTOUNIONFSMOUNT(mp);
    397 
    398 	UNIONFSDEBUG("unionfs_statvfs(mp = %p, lvp = %p, uvp = %p)\n",
    399 	    (void *)mp, (void *)ump->um_lowervp, (void *)ump->um_uppervp);
    400 
    401 	error = VFS_STATVFS(ump->um_lowervp->v_mount, sbuf);
    402 	if (error)
    403 		goto done;
    404 
    405 	/* now copy across the "interesting" information and fake the rest */
    406 	sbp->f_blocks = sbuf->f_blocks;
    407 	sbp->f_files = sbuf->f_files;
    408 
    409 	lbsize = sbuf->f_bsize;
    410 
    411 	error = VFS_STATVFS(ump->um_uppervp->v_mount, sbuf);
    412 	if (error)
    413 		goto done;
    414 
    415 	/*
    416 	 * The FS type etc is copy from upper vfs.
    417 	 * (write able vfs have priority)
    418 	 */
    419 	sbp->f_flag = sbuf->f_flag;
    420 	sbp->f_bsize = sbuf->f_bsize;
    421 	sbp->f_iosize = sbuf->f_iosize;
    422 
    423 	if (sbuf->f_bsize != lbsize)
    424 		sbp->f_blocks = ((off_t)sbp->f_blocks * lbsize) / sbuf->f_bsize;
    425 
    426 	sbp->f_blocks += sbuf->f_blocks;
    427 	sbp->f_bfree = sbuf->f_bfree;
    428 	sbp->f_bavail = sbuf->f_bavail;
    429 	sbp->f_files += sbuf->f_files;
    430 	sbp->f_ffree = sbuf->f_ffree;
    431 
    432  done:
    433 	free(sbuf, M_TEMP);
    434 	return (error);
    435 }
    436 
    437 int
    438 unionfs_sync(struct mount *mp, int waitfor, kauth_cred_t cred)
    439 {
    440 	/* nothing to do */
    441 	return (0);
    442 }
    443 
    444 int
    445 unionfs_vget(struct mount *mp, ino_t ino, int lktype, struct vnode **vpp)
    446 {
    447 	return (EOPNOTSUPP);
    448 }
    449 
    450 int
    451 unionfs_fhtovp(struct mount *mp, struct fid *fidp, int lktype, struct vnode **vpp)
    452 {
    453 	return (EOPNOTSUPP);
    454 }
    455 
    456 int
    457 unionfs_extattrctl(struct mount *mp, int cmd, struct vnode *filename_vp,
    458     int namespace, const char *attrname)
    459 {
    460 	struct unionfs_mount *ump;
    461 	struct unionfs_node *unp;
    462 
    463 	ump = MOUNTTOUNIONFSMOUNT(mp);
    464 	unp = VTOUNIONFS(filename_vp);
    465 
    466 	if (unp->un_uppervp != NULLVP) {
    467 		return (VFS_EXTATTRCTL(ump->um_uppervp->v_mount, cmd,
    468 		    unp->un_uppervp, namespace, attrname));
    469 	} else {
    470 		return (VFS_EXTATTRCTL(ump->um_lowervp->v_mount, cmd,
    471 		    unp->un_lowervp, namespace, attrname));
    472 	}
    473 }
    474 
    475 /*
    476  * Initialize
    477  */
    478 void
    479 unionfs_init(void)
    480 {
    481 	UNIONFSDEBUG("unionfs_init\n");	/* printed during system boot */
    482 }
    483 
    484 static int
    485 unionfs_renamelock_enter(struct mount *mp)
    486 {
    487 	struct unionfs_mount *um = MOUNTTOUNIONFSMOUNT(mp);
    488 
    489 	/* Lock just the upper fs, where the action happens. */
    490 	return VFS_RENAMELOCK_ENTER(um->um_uppervp->v_mount);
    491 }
    492 
    493 static void
    494 unionfs_renamelock_exit(struct mount *mp)
    495 {
    496 	struct unionfs_mount *um = MOUNTTOUNIONFSMOUNT(mp);
    497 
    498 	VFS_RENAMELOCK_EXIT(um->um_uppervp->v_mount);
    499 }
    500 
    501 int
    502 unionfs_start(struct mount *mp, int flags)
    503 {
    504 
    505 	return (0);
    506 }
    507 
    508 void
    509 unionfs_done(void)
    510 {
    511 
    512 	/* Make sure to unset the readdir hook. */
    513 	vn_union_readdir_hook = NULL;
    514 }
    515 
    516 extern const struct vnodeopv_desc unionfs_vnodeop_opv_desc;
    517 
    518 const struct vnodeopv_desc * const unionfs_vnodeopv_descs[] = {
    519 	&unionfs_vnodeop_opv_desc,
    520 	NULL,
    521 };
    522 
    523 struct vfsops unionfs_vfsops = {
    524 	.vfs_name = MOUNT_UNION,
    525 	.vfs_min_mount_data = sizeof (struct unionfs_args),
    526 	.vfs_mount = unionfs_mount,
    527 	.vfs_start = unionfs_start,
    528 	.vfs_unmount = unionfs_unmount,
    529 	.vfs_root = unionfs_root,
    530 	.vfs_quotactl = (void *)eopnotsupp,
    531 	.vfs_statvfs = unionfs_statvfs,
    532 	.vfs_sync = unionfs_sync,
    533 	.vfs_vget = unionfs_vget,
    534 	.vfs_fhtovp = (void *)eopnotsupp,
    535 	.vfs_vptofh = (void *)eopnotsupp,
    536 	.vfs_init = unionfs_init,
    537 	.vfs_done = unionfs_done,
    538 	.vfs_snapshot = (void *)eopnotsupp,
    539 	.vfs_extattrctl = vfs_stdextattrctl,
    540 	.vfs_suspendctl = (void *)eopnotsupp,
    541 	.vfs_renamelock_enter = unionfs_renamelock_enter,
    542 	.vfs_renamelock_exit = unionfs_renamelock_exit,
    543 	.vfs_fsync = (void *)eopnotsupp,
    544 	.vfs_opv_descs = unionfs_vnodeopv_descs
    545 };
    546 
    547 static int
    548 unionfs_modcmd(modcmd_t cmd, void *arg)
    549 {
    550 	int error;
    551 
    552 	switch (cmd) {
    553 	case MODULE_CMD_INIT:
    554 		error = vfs_attach(&unionfs_vfsops);
    555 		if (error != 0)
    556 			break;
    557 		sysctl_createv(&unionfs_sysctl_log, 0, NULL, NULL,
    558 			       CTLFLAG_PERMANENT,
    559 			       CTLTYPE_NODE, "union",
    560 			       SYSCTL_DESCR("Union file system"),
    561 			       NULL, 0, NULL, 0,
    562 			       CTL_VFS, 15, CTL_EOL);
    563 		/*
    564 		 * XXX the "15" above could be dynamic, thereby eliminating
    565 		 * one more instance of the "number to vfs" mapping problem,
    566 		 * but "15" is the order as taken from sys/mount.h
    567 		 */
    568 		break;
    569 	case MODULE_CMD_FINI:
    570 		error = vfs_detach(&unionfs_vfsops);
    571 		if (error != 0)
    572 			break;
    573 		sysctl_teardown(&unionfs_sysctl_log);
    574 		break;
    575 	default:
    576 		error = ENOTTY;
    577 		break;
    578 	}
    579 
    580 	return (error);
    581 }
    582