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unionfs_vfsops.c revision 1.6 
      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 componentname fakecn;
     82 	struct nameidata nd, *ndp;
     83 	struct vattr	va;
     84 	struct union_args *args = data;
     85 	kauth_cred_t	cred;
     86 	size_t		size;
     87 	size_t		len;
     88 	const char	*cp;
     89 	char		*xp;
     90 
     91 	if (*data_len < sizeof *args)
     92 		return EINVAL;
     93 
     94 	UNIONFSDEBUG("unionfs_mount(mp = %p)\n", (void *)mp);
     95 
     96 	error = 0;
     97 	below = 0;
     98 	uid = 0;
     99 	gid = 0;
    100 	udir = 0;
    101 	ufile = 0;
    102 	copymode = UNIONFS_TRANSPARENT;	/* default */
    103 	whitemode = UNIONFS_WHITE_ALWAYS;
    104 	ndp = &nd;
    105 	cred = kauth_cred_get();
    106 
    107 	if (mp->mnt_flag & MNT_ROOTFS) {
    108 		printf("union_mount: cannot union mount root filesystem\n");
    109 		return (EOPNOTSUPP);
    110 	}
    111 
    112 	if (mp->mnt_flag & MNT_GETARGS) {
    113 		ump = MOUNTTOUNIONFSMOUNT(mp);
    114 		if (ump == NULL)
    115 			return EIO;
    116 		args->target = NULL;
    117 		args->mntflags = ump->um_op;
    118 		*data_len = sizeof *args;
    119 		return 0;
    120 	}
    121 
    122 	/*
    123 	 * Update is a no operation.
    124 	 */
    125 	if (mp->mnt_flag & MNT_UPDATE) {
    126 		printf("union_mount: cannot update union mount\n");
    127 		return (EOPNOTSUPP);
    128 	}
    129 
    130 	vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
    131 	error = VOP_GETATTR(mp->mnt_vnodecovered, &va, cred);
    132 	if (!error) {
    133 		if (udir == 0)
    134 			udir = va.va_mode;
    135 		if (ufile == 0)
    136 			ufile = va.va_mode;
    137 		uid = va.va_uid;
    138 		gid = va.va_gid;
    139 	}
    140 	VOP_UNLOCK(mp->mnt_vnodecovered, 0);
    141 	if (error)
    142 		return (error);
    143 
    144 	switch (args->mntflags & UNMNT_OPMASK) {
    145 	case UNMNT_ABOVE:
    146 		below = 0;
    147 		break;
    148 
    149 	case UNMNT_BELOW:
    150 		below = 1;
    151 		break;
    152 
    153 	case UNMNT_REPLACE:
    154 	default:
    155 		return EINVAL;
    156 	}
    157 
    158 	/* If copymode is UNIONFS_TRADITIONAL, uid/gid is mounted user. */
    159 	if (copymode == UNIONFS_TRADITIONAL) {
    160 		uid = kauth_cred_getuid(cred);
    161 		gid = kauth_cred_getgid(cred);
    162 	}
    163 
    164 	UNIONFSDEBUG("unionfs_mount: uid=%d, gid=%d\n", uid, gid);
    165 	UNIONFSDEBUG("unionfs_mount: udir=0%03o, ufile=0%03o\n", udir, ufile);
    166 	UNIONFSDEBUG("unionfs_mount: copymode=%d\n", copymode);
    167 
    168 	/*
    169 	 * Find upper node
    170 	 */
    171 	NDINIT(ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE, args->target);
    172 	if ((error = namei(ndp)))
    173 		return (error);
    174 
    175 	/* get root vnodes */
    176 	lowerrootvp = mp->mnt_vnodecovered;
    177 	upperrootvp = ndp->ni_vp;
    178 
    179 	vrele(ndp->ni_dvp);
    180 	ndp->ni_dvp = NULLVP;
    181 
    182 	/* create unionfs_mount */
    183 	ump = (struct unionfs_mount *)malloc(sizeof(struct unionfs_mount),
    184 	    M_UNIONFSMNT, M_WAITOK | M_ZERO);
    185 
    186 	/*
    187 	 * Save reference
    188 	 */
    189 	if (below) {
    190 		VOP_UNLOCK(upperrootvp, 0);
    191 		vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY);
    192 		ump->um_lowervp = upperrootvp;
    193 		ump->um_uppervp = lowerrootvp;
    194 	} else {
    195 		ump->um_lowervp = lowerrootvp;
    196 		ump->um_uppervp = upperrootvp;
    197 	}
    198 	ump->um_rootvp = NULLVP;
    199 	ump->um_uid = uid;
    200 	ump->um_gid = gid;
    201 	ump->um_udir = udir;
    202 	ump->um_ufile = ufile;
    203 	ump->um_copymode = copymode;
    204 	ump->um_whitemode = whitemode;
    205 
    206 	if ((lowerrootvp->v_mount->mnt_iflag & IMNT_MPSAFE) &&
    207 	    (upperrootvp->v_mount->mnt_flag & IMNT_MPSAFE))
    208 		mp->mnt_iflag |= IMNT_MPSAFE;
    209 	mp->mnt_data = ump;
    210 
    211 	/*
    212 	 * Copy upper layer's RDONLY flag.
    213 	 */
    214 	mp->mnt_flag |= ump->um_uppervp->v_mount->mnt_flag & MNT_RDONLY;
    215 
    216 	/*
    217 	 * Check whiteout
    218 	 */
    219 	if ((mp->mnt_flag & MNT_RDONLY) == 0) {
    220 		memset(&fakecn, 0, sizeof(fakecn));
    221 		fakecn.cn_nameiop = LOOKUP;
    222 		error = VOP_WHITEOUT(ump->um_uppervp, &fakecn, LOOKUP);
    223 		if (error) {
    224 			if (below) {
    225 				VOP_UNLOCK(ump->um_uppervp, 0);
    226 				vrele(upperrootvp);
    227 			} else
    228 				vput(ump->um_uppervp);
    229 			free(ump, M_UNIONFSMNT);
    230 			mp->mnt_data = NULL;
    231 			return (error);
    232 		}
    233 	}
    234 
    235 	/*
    236 	 * Unlock the node
    237 	 */
    238 	VOP_UNLOCK(ump->um_uppervp, 0);
    239 
    240 	ump->um_op = args->mntflags & UNMNT_OPMASK;
    241 
    242 	/*
    243 	 * Get the unionfs root vnode.
    244 	 */
    245 	error = unionfs_nodeget(mp, ump->um_uppervp, ump->um_lowervp,
    246 	    NULLVP, &(ump->um_rootvp), NULL);
    247 	vrele(upperrootvp);
    248 	if (error) {
    249 		free(ump, M_UNIONFSMNT);
    250 		mp->mnt_data = NULL;
    251 		return (error);
    252 	}
    253 
    254 	/*
    255 	 * Check mnt_flag
    256 	 */
    257 	if ((ump->um_lowervp->v_mount->mnt_flag & MNT_LOCAL) &&
    258 	    (ump->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
    259 		mp->mnt_flag |= MNT_LOCAL;
    260 
    261 	/*
    262 	 * Get new fsid
    263 	 */
    264 	vfs_getnewfsid(mp);
    265 
    266 	error = set_statvfs_info(path, UIO_USERSPACE, NULL, UIO_USERSPACE,
    267 	    mp->mnt_op->vfs_name, mp, curlwp);
    268 	if (error) {
    269 		unionfs_noderem(ump->um_rootvp);
    270 		free(ump, M_UNIONFSMNT);
    271 		mp->mnt_data = NULL;
    272 		return (error);
    273 	}
    274 
    275 	switch (ump->um_op) {
    276 	case UNMNT_ABOVE:
    277 		cp = "<above>:";
    278 		break;
    279 	case UNMNT_BELOW:
    280 		cp = "<below>:";
    281 		break;
    282 	default:
    283 		panic("union_mount: bad um_op");
    284 		break;
    285 	}
    286 	len = strlen(cp);
    287 	memcpy(mp->mnt_stat.f_mntfromname, cp, len);
    288 	xp = mp->mnt_stat.f_mntfromname + len;
    289 	len = MNAMELEN - len;
    290 	(void) copyinstr(args->target, xp, len - 1, &size);
    291 	memset(xp + size, 0, len - size);
    292 
    293 	UNIONFSDEBUG("unionfs_mount: from %s, on %s\n",
    294 	    mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
    295 
    296 	return (0);
    297 }
    298 
    299 /*
    300  * Free reference to unionfs layer
    301  */
    302 int
    303 unionfs_unmount(struct mount *mp, int mntflags)
    304 {
    305 	struct unionfs_mount *ump;
    306 	int		error;
    307 	int		freeing;
    308 	int		flags;
    309 
    310 	UNIONFSDEBUG("unionfs_unmount: mp = %p\n", (void *)mp);
    311 
    312 	ump = MOUNTTOUNIONFSMOUNT(mp);
    313 	flags = 0;
    314 
    315 	if (mntflags & MNT_FORCE)
    316 		flags |= FORCECLOSE;
    317 
    318 	/* vflush (no need to call vrele) */
    319 	for (freeing = 0; (error = vflush(mp, NULL, flags)) != 0;) {
    320 		struct vnode *vp;
    321 		int n;
    322 
    323 		/* count #vnodes held on mount list */
    324 		n = 0;
    325 		TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes)
    326 			n++;
    327 
    328 		/* if this is unchanged then stop */
    329 		if (n == freeing)
    330 			break;
    331 
    332 		/* otherwise try once more time */
    333 		freeing = n;
    334 	}
    335 
    336 	if (error)
    337 		return (error);
    338 
    339 	free(ump, M_UNIONFSMNT);
    340 	mp->mnt_data = NULL;
    341 
    342 	return (0);
    343 }
    344 
    345 int
    346 unionfs_root(struct mount *mp, struct vnode **vpp)
    347 {
    348 	struct unionfs_mount *ump;
    349 	struct vnode   *vp;
    350 
    351 	ump = MOUNTTOUNIONFSMOUNT(mp);
    352 	vp = ump->um_rootvp;
    353 
    354 	UNIONFSDEBUG("unionfs_root: rootvp=%p locked=%x\n",
    355 	    vp, VOP_ISLOCKED(vp));
    356 
    357 	vref(vp);
    358 	vn_lock(vp, LK_EXCLUSIVE);
    359 
    360 	*vpp = vp;
    361 
    362 	return (0);
    363 }
    364 
    365 int
    366 unionfs_quotactl(struct mount *mp, int cmd, uid_t uid, void *arg)
    367 {
    368 	struct unionfs_mount *ump;
    369 
    370 	ump = MOUNTTOUNIONFSMOUNT(mp);
    371 
    372 	/*
    373 	 * Writing is always performed to upper vnode.
    374 	 */
    375 	return (VFS_QUOTACTL(ump->um_uppervp->v_mount, cmd, uid, arg));
    376 }
    377 
    378 int
    379 unionfs_statvfs(struct mount *mp, struct statvfs *sbp)
    380 {
    381 	struct unionfs_mount *ump;
    382 	int		error;
    383 	uint64_t	lbsize;
    384 	struct statvfs *sbuf = malloc(sizeof(*sbuf), M_TEMP, M_WAITOK | M_ZERO);
    385 
    386 	ump = MOUNTTOUNIONFSMOUNT(mp);
    387 
    388 	UNIONFSDEBUG("unionfs_statvfs(mp = %p, lvp = %p, uvp = %p)\n",
    389 	    (void *)mp, (void *)ump->um_lowervp, (void *)ump->um_uppervp);
    390 
    391 	error = VFS_STATVFS(ump->um_lowervp->v_mount, sbuf);
    392 	if (error)
    393 		goto done;
    394 
    395 	/* now copy across the "interesting" information and fake the rest */
    396 	sbp->f_blocks = sbuf->f_blocks;
    397 	sbp->f_files = sbuf->f_files;
    398 
    399 	lbsize = sbuf->f_bsize;
    400 
    401 	error = VFS_STATVFS(ump->um_uppervp->v_mount, sbuf);
    402 	if (error)
    403 		goto done;
    404 
    405 	/*
    406 	 * The FS type etc is copy from upper vfs.
    407 	 * (write able vfs have priority)
    408 	 */
    409 	sbp->f_flag = sbuf->f_flag;
    410 	sbp->f_bsize = sbuf->f_bsize;
    411 	sbp->f_iosize = sbuf->f_iosize;
    412 
    413 	if (sbuf->f_bsize != lbsize)
    414 		sbp->f_blocks = ((off_t)sbp->f_blocks * lbsize) / sbuf->f_bsize;
    415 
    416 	sbp->f_blocks += sbuf->f_blocks;
    417 	sbp->f_bfree = sbuf->f_bfree;
    418 	sbp->f_bavail = sbuf->f_bavail;
    419 	sbp->f_files += sbuf->f_files;
    420 	sbp->f_ffree = sbuf->f_ffree;
    421 
    422  done:
    423 	free(sbuf, M_TEMP);
    424 	return (error);
    425 }
    426 
    427 int
    428 unionfs_sync(struct mount *mp, int waitfor, kauth_cred_t cred)
    429 {
    430 	/* nothing to do */
    431 	return (0);
    432 }
    433 
    434 int
    435 unionfs_vget(struct mount *mp, ino_t ino, struct vnode **vpp)
    436 {
    437 	return (EOPNOTSUPP);
    438 }
    439 
    440 int
    441 unionfs_fhtovp(struct mount *mp, struct fid *fidp, struct vnode **vpp)
    442 {
    443 	return (EOPNOTSUPP);
    444 }
    445 
    446 int
    447 unionfs_extattrctl(struct mount *mp, int cmd, struct vnode *filename_vp,
    448     int namespace, const char *attrname)
    449 {
    450 	struct unionfs_mount *ump;
    451 	struct unionfs_node *unp;
    452 
    453 	ump = MOUNTTOUNIONFSMOUNT(mp);
    454 	unp = VTOUNIONFS(filename_vp);
    455 
    456 	if (unp->un_uppervp != NULLVP) {
    457 		return (VFS_EXTATTRCTL(ump->um_uppervp->v_mount, cmd,
    458 		    unp->un_uppervp, namespace, attrname));
    459 	} else {
    460 		return (VFS_EXTATTRCTL(ump->um_lowervp->v_mount, cmd,
    461 		    unp->un_lowervp, namespace, attrname));
    462 	}
    463 }
    464 
    465 /*
    466  * Initialize
    467  */
    468 void
    469 unionfs_init(void)
    470 {
    471 	UNIONFSDEBUG("unionfs_init\n");	/* printed during system boot */
    472 }
    473 
    474 static int
    475 unionfs_renamelock_enter(struct mount *mp)
    476 {
    477 	struct unionfs_mount *um = MOUNTTOUNIONFSMOUNT(mp);
    478 
    479 	/* Lock just the upper fs, where the action happens. */
    480 	return VFS_RENAMELOCK_ENTER(um->um_uppervp->v_mount);
    481 }
    482 
    483 static void
    484 unionfs_renamelock_exit(struct mount *mp)
    485 {
    486 	struct unionfs_mount *um = MOUNTTOUNIONFSMOUNT(mp);
    487 
    488 	VFS_RENAMELOCK_EXIT(um->um_uppervp->v_mount);
    489 }
    490 
    491 int
    492 unionfs_start(struct mount *mp, int flags)
    493 {
    494 
    495 	return (0);
    496 }
    497 
    498 void
    499 unionfs_done(void)
    500 {
    501 
    502 	/* Make sure to unset the readdir hook. */
    503 	vn_union_readdir_hook = NULL;
    504 }
    505 
    506 extern const struct vnodeopv_desc unionfs_vnodeop_opv_desc;
    507 
    508 const struct vnodeopv_desc * const unionfs_vnodeopv_descs[] = {
    509 	&unionfs_vnodeop_opv_desc,
    510 	NULL,
    511 };
    512 
    513 struct vfsops unionfs_vfsops = {
    514 	MOUNT_UNION,
    515 	sizeof (struct unionfs_args),
    516 	unionfs_mount,
    517 	unionfs_start,
    518 	unionfs_unmount,
    519 	unionfs_root,
    520 	(void *)eopnotsupp,		/* vfs_quotactl */
    521 	unionfs_statvfs,
    522 	unionfs_sync,
    523 	unionfs_vget,
    524 	(void *)eopnotsupp,		/* vfs_fhtovp */
    525 	(void *)eopnotsupp,		/* vfs_vptofh */
    526 	unionfs_init,
    527 	NULL,				/* vfs_reinit */
    528 	unionfs_done,
    529 	NULL,				/* vfs_mountroot */
    530 	(int (*)(struct mount *, struct vnode *, struct timespec *)) eopnotsupp,
    531 	vfs_stdextattrctl,
    532 	(void *)eopnotsupp,		/* vfs_suspendctl */
    533 	unionfs_renamelock_enter,
    534 	unionfs_renamelock_exit,
    535 	(void *)eopnotsupp,
    536 	unionfs_vnodeopv_descs,
    537 	0,				/* vfs_refcount */
    538 	{ NULL, NULL },
    539 };
    540 
    541 static int
    542 unionfs_modcmd(modcmd_t cmd, void *arg)
    543 {
    544 	int error;
    545 
    546 	switch (cmd) {
    547 	case MODULE_CMD_INIT:
    548 		error = vfs_attach(&unionfs_vfsops);
    549 		if (error != 0)
    550 			break;
    551 		sysctl_createv(&unionfs_sysctl_log, 0, NULL, NULL,
    552 			       CTLFLAG_PERMANENT,
    553 			       CTLTYPE_NODE, "vfs", NULL,
    554 			       NULL, 0, NULL, 0,
    555 			       CTL_VFS, CTL_EOL);
    556 		sysctl_createv(&unionfs_sysctl_log, 0, NULL, NULL,
    557 			       CTLFLAG_PERMANENT,
    558 			       CTLTYPE_NODE, "union",
    559 			       SYSCTL_DESCR("Union file system"),
    560 			       NULL, 0, NULL, 0,
    561 			       CTL_VFS, 15, CTL_EOL);
    562 		/*
    563 		 * XXX the "15" above could be dynamic, thereby eliminating
    564 		 * one more instance of the "number to vfs" mapping problem,
    565 		 * but "15" is the order as taken from sys/mount.h
    566 		 */
    567 		break;
    568 	case MODULE_CMD_FINI:
    569 		error = vfs_detach(&unionfs_vfsops);
    570 		if (error != 0)
    571 			break;
    572 		sysctl_teardown(&unionfs_sysctl_log);
    573 		break;
    574 	default:
    575 		error = ENOTTY;
    576 		break;
    577 	}
    578 
    579 	return (error);
    580 }
    581