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unionfs_vfsops.c revision 1.8 
      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 (*data_len < sizeof *args)
     93 		return EINVAL;
     94 
     95 	UNIONFSDEBUG("unionfs_mount(mp = %p)\n", (void *)mp);
     96 
     97 	error = 0;
     98 	below = 0;
     99 	uid = 0;
    100 	gid = 0;
    101 	udir = 0;
    102 	ufile = 0;
    103 	copymode = UNIONFS_TRANSPARENT;	/* default */
    104 	whitemode = UNIONFS_WHITE_ALWAYS;
    105 	ndp = &nd;
    106 	cred = kauth_cred_get();
    107 
    108 	if (mp->mnt_flag & MNT_ROOTFS) {
    109 		printf("union_mount: cannot union mount root filesystem\n");
    110 		return (EOPNOTSUPP);
    111 	}
    112 
    113 	if (mp->mnt_flag & MNT_GETARGS) {
    114 		ump = MOUNTTOUNIONFSMOUNT(mp);
    115 		if (ump == NULL)
    116 			return EIO;
    117 		args->target = NULL;
    118 		args->mntflags = ump->um_op;
    119 		*data_len = sizeof *args;
    120 		return 0;
    121 	}
    122 
    123 	/*
    124 	 * Update is a no operation.
    125 	 */
    126 	if (mp->mnt_flag & MNT_UPDATE) {
    127 		printf("union_mount: cannot update union mount\n");
    128 		return (EOPNOTSUPP);
    129 	}
    130 
    131 	vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
    132 	error = VOP_GETATTR(mp->mnt_vnodecovered, &va, cred);
    133 	if (!error) {
    134 		if (udir == 0)
    135 			udir = va.va_mode;
    136 		if (ufile == 0)
    137 			ufile = va.va_mode;
    138 		uid = va.va_uid;
    139 		gid = va.va_gid;
    140 	}
    141 	VOP_UNLOCK(mp->mnt_vnodecovered);
    142 	if (error)
    143 		return (error);
    144 
    145 	switch (args->mntflags & UNMNT_OPMASK) {
    146 	case UNMNT_ABOVE:
    147 		below = 0;
    148 		break;
    149 
    150 	case UNMNT_BELOW:
    151 		below = 1;
    152 		break;
    153 
    154 	case UNMNT_REPLACE:
    155 	default:
    156 		return EINVAL;
    157 	}
    158 
    159 	/* If copymode is UNIONFS_TRADITIONAL, uid/gid is mounted user. */
    160 	if (copymode == UNIONFS_TRADITIONAL) {
    161 		uid = kauth_cred_getuid(cred);
    162 		gid = kauth_cred_getgid(cred);
    163 	}
    164 
    165 	UNIONFSDEBUG("unionfs_mount: uid=%d, gid=%d\n", uid, gid);
    166 	UNIONFSDEBUG("unionfs_mount: udir=0%03o, ufile=0%03o\n", udir, ufile);
    167 	UNIONFSDEBUG("unionfs_mount: copymode=%d\n", copymode);
    168 
    169 	/*
    170 	 * Find upper node
    171 	 */
    172 	error = pathbuf_copyin(args->target, &pb);
    173 	if (error) {
    174 		return error;
    175 	}
    176 	NDINIT(ndp, LOOKUP, FOLLOW | LOCKLEAF, pb);
    177 	if ((error = namei(ndp))) {
    178 		pathbuf_destroy(pb);
    179 		return error;
    180 	}
    181 
    182 	/* get root vnodes */
    183 	lowerrootvp = mp->mnt_vnodecovered;
    184 	upperrootvp = ndp->ni_vp;
    185 
    186 	vrele(ndp->ni_dvp);
    187 	ndp->ni_dvp = NULLVP;
    188 	pathbuf_destroy(pb);
    189 
    190 	/* create unionfs_mount */
    191 	ump = (struct unionfs_mount *)malloc(sizeof(struct unionfs_mount),
    192 	    M_UNIONFSMNT, M_WAITOK | M_ZERO);
    193 
    194 	/*
    195 	 * Save reference
    196 	 */
    197 	if (below) {
    198 		VOP_UNLOCK(upperrootvp);
    199 		vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY);
    200 		ump->um_lowervp = upperrootvp;
    201 		ump->um_uppervp = lowerrootvp;
    202 	} else {
    203 		ump->um_lowervp = lowerrootvp;
    204 		ump->um_uppervp = upperrootvp;
    205 	}
    206 	ump->um_rootvp = NULLVP;
    207 	ump->um_uid = uid;
    208 	ump->um_gid = gid;
    209 	ump->um_udir = udir;
    210 	ump->um_ufile = ufile;
    211 	ump->um_copymode = copymode;
    212 	ump->um_whitemode = whitemode;
    213 
    214 	if ((lowerrootvp->v_mount->mnt_iflag & IMNT_MPSAFE) &&
    215 	    (upperrootvp->v_mount->mnt_flag & IMNT_MPSAFE))
    216 		mp->mnt_iflag |= IMNT_MPSAFE;
    217 	mp->mnt_data = ump;
    218 
    219 	/*
    220 	 * Copy upper layer's RDONLY flag.
    221 	 */
    222 	mp->mnt_flag |= ump->um_uppervp->v_mount->mnt_flag & MNT_RDONLY;
    223 
    224 	/*
    225 	 * Check whiteout
    226 	 */
    227 	if ((mp->mnt_flag & MNT_RDONLY) == 0) {
    228 		memset(&fakecn, 0, sizeof(fakecn));
    229 		fakecn.cn_nameiop = LOOKUP;
    230 		error = VOP_WHITEOUT(ump->um_uppervp, &fakecn, LOOKUP);
    231 		if (error) {
    232 			if (below) {
    233 				VOP_UNLOCK(ump->um_uppervp);
    234 				vrele(upperrootvp);
    235 			} else
    236 				vput(ump->um_uppervp);
    237 			free(ump, M_UNIONFSMNT);
    238 			mp->mnt_data = NULL;
    239 			return (error);
    240 		}
    241 	}
    242 
    243 	/*
    244 	 * Unlock the node
    245 	 */
    246 	VOP_UNLOCK(ump->um_uppervp);
    247 
    248 	ump->um_op = args->mntflags & UNMNT_OPMASK;
    249 
    250 	/*
    251 	 * Get the unionfs root vnode.
    252 	 */
    253 	error = unionfs_nodeget(mp, ump->um_uppervp, ump->um_lowervp,
    254 	    NULLVP, &(ump->um_rootvp), NULL);
    255 	vrele(upperrootvp);
    256 	if (error) {
    257 		free(ump, M_UNIONFSMNT);
    258 		mp->mnt_data = NULL;
    259 		return (error);
    260 	}
    261 
    262 	/*
    263 	 * Check mnt_flag
    264 	 */
    265 	if ((ump->um_lowervp->v_mount->mnt_flag & MNT_LOCAL) &&
    266 	    (ump->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
    267 		mp->mnt_flag |= MNT_LOCAL;
    268 
    269 	/*
    270 	 * Get new fsid
    271 	 */
    272 	vfs_getnewfsid(mp);
    273 
    274 	error = set_statvfs_info(path, UIO_USERSPACE, NULL, UIO_USERSPACE,
    275 	    mp->mnt_op->vfs_name, mp, curlwp);
    276 	if (error) {
    277 		unionfs_noderem(ump->um_rootvp);
    278 		free(ump, M_UNIONFSMNT);
    279 		mp->mnt_data = NULL;
    280 		return (error);
    281 	}
    282 
    283 	switch (ump->um_op) {
    284 	case UNMNT_ABOVE:
    285 		cp = "<above>:";
    286 		break;
    287 	case UNMNT_BELOW:
    288 		cp = "<below>:";
    289 		break;
    290 	default:
    291 		panic("union_mount: bad um_op");
    292 		break;
    293 	}
    294 	len = strlen(cp);
    295 	memcpy(mp->mnt_stat.f_mntfromname, cp, len);
    296 	xp = mp->mnt_stat.f_mntfromname + len;
    297 	len = MNAMELEN - len;
    298 	(void) copyinstr(args->target, xp, len - 1, &size);
    299 	memset(xp + size, 0, len - size);
    300 
    301 	UNIONFSDEBUG("unionfs_mount: from %s, on %s\n",
    302 	    mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
    303 
    304 	return (0);
    305 }
    306 
    307 /*
    308  * Free reference to unionfs layer
    309  */
    310 int
    311 unionfs_unmount(struct mount *mp, int mntflags)
    312 {
    313 	struct unionfs_mount *ump;
    314 	int		error;
    315 	int		freeing;
    316 	int		flags;
    317 
    318 	UNIONFSDEBUG("unionfs_unmount: mp = %p\n", (void *)mp);
    319 
    320 	ump = MOUNTTOUNIONFSMOUNT(mp);
    321 	flags = 0;
    322 
    323 	if (mntflags & MNT_FORCE)
    324 		flags |= FORCECLOSE;
    325 
    326 	/* vflush (no need to call vrele) */
    327 	for (freeing = 0; (error = vflush(mp, NULL, flags)) != 0;) {
    328 		struct vnode *vp;
    329 		int n;
    330 
    331 		/* count #vnodes held on mount list */
    332 		n = 0;
    333 		TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes)
    334 			n++;
    335 
    336 		/* if this is unchanged then stop */
    337 		if (n == freeing)
    338 			break;
    339 
    340 		/* otherwise try once more time */
    341 		freeing = n;
    342 	}
    343 
    344 	if (error)
    345 		return (error);
    346 
    347 	free(ump, M_UNIONFSMNT);
    348 	mp->mnt_data = NULL;
    349 
    350 	return (0);
    351 }
    352 
    353 int
    354 unionfs_root(struct mount *mp, struct vnode **vpp)
    355 {
    356 	struct unionfs_mount *ump;
    357 	struct vnode   *vp;
    358 
    359 	ump = MOUNTTOUNIONFSMOUNT(mp);
    360 	vp = ump->um_rootvp;
    361 
    362 	UNIONFSDEBUG("unionfs_root: rootvp=%p locked=%x\n",
    363 	    vp, VOP_ISLOCKED(vp));
    364 
    365 	vref(vp);
    366 	vn_lock(vp, LK_EXCLUSIVE);
    367 
    368 	*vpp = vp;
    369 
    370 	return (0);
    371 }
    372 
    373 int
    374 unionfs_quotactl(struct mount *mp, int cmd, uid_t uid, void *arg)
    375 {
    376 	struct unionfs_mount *ump;
    377 
    378 	ump = MOUNTTOUNIONFSMOUNT(mp);
    379 
    380 	/*
    381 	 * Writing is always performed to upper vnode.
    382 	 */
    383 	return (VFS_QUOTACTL(ump->um_uppervp->v_mount, cmd, uid, arg));
    384 }
    385 
    386 int
    387 unionfs_statvfs(struct mount *mp, struct statvfs *sbp)
    388 {
    389 	struct unionfs_mount *ump;
    390 	int		error;
    391 	uint64_t	lbsize;
    392 	struct statvfs *sbuf = malloc(sizeof(*sbuf), M_TEMP, M_WAITOK | M_ZERO);
    393 
    394 	ump = MOUNTTOUNIONFSMOUNT(mp);
    395 
    396 	UNIONFSDEBUG("unionfs_statvfs(mp = %p, lvp = %p, uvp = %p)\n",
    397 	    (void *)mp, (void *)ump->um_lowervp, (void *)ump->um_uppervp);
    398 
    399 	error = VFS_STATVFS(ump->um_lowervp->v_mount, sbuf);
    400 	if (error)
    401 		goto done;
    402 
    403 	/* now copy across the "interesting" information and fake the rest */
    404 	sbp->f_blocks = sbuf->f_blocks;
    405 	sbp->f_files = sbuf->f_files;
    406 
    407 	lbsize = sbuf->f_bsize;
    408 
    409 	error = VFS_STATVFS(ump->um_uppervp->v_mount, sbuf);
    410 	if (error)
    411 		goto done;
    412 
    413 	/*
    414 	 * The FS type etc is copy from upper vfs.
    415 	 * (write able vfs have priority)
    416 	 */
    417 	sbp->f_flag = sbuf->f_flag;
    418 	sbp->f_bsize = sbuf->f_bsize;
    419 	sbp->f_iosize = sbuf->f_iosize;
    420 
    421 	if (sbuf->f_bsize != lbsize)
    422 		sbp->f_blocks = ((off_t)sbp->f_blocks * lbsize) / sbuf->f_bsize;
    423 
    424 	sbp->f_blocks += sbuf->f_blocks;
    425 	sbp->f_bfree = sbuf->f_bfree;
    426 	sbp->f_bavail = sbuf->f_bavail;
    427 	sbp->f_files += sbuf->f_files;
    428 	sbp->f_ffree = sbuf->f_ffree;
    429 
    430  done:
    431 	free(sbuf, M_TEMP);
    432 	return (error);
    433 }
    434 
    435 int
    436 unionfs_sync(struct mount *mp, int waitfor, kauth_cred_t cred)
    437 {
    438 	/* nothing to do */
    439 	return (0);
    440 }
    441 
    442 int
    443 unionfs_vget(struct mount *mp, ino_t ino, struct vnode **vpp)
    444 {
    445 	return (EOPNOTSUPP);
    446 }
    447 
    448 int
    449 unionfs_fhtovp(struct mount *mp, struct fid *fidp, struct vnode **vpp)
    450 {
    451 	return (EOPNOTSUPP);
    452 }
    453 
    454 int
    455 unionfs_extattrctl(struct mount *mp, int cmd, struct vnode *filename_vp,
    456     int namespace, const char *attrname)
    457 {
    458 	struct unionfs_mount *ump;
    459 	struct unionfs_node *unp;
    460 
    461 	ump = MOUNTTOUNIONFSMOUNT(mp);
    462 	unp = VTOUNIONFS(filename_vp);
    463 
    464 	if (unp->un_uppervp != NULLVP) {
    465 		return (VFS_EXTATTRCTL(ump->um_uppervp->v_mount, cmd,
    466 		    unp->un_uppervp, namespace, attrname));
    467 	} else {
    468 		return (VFS_EXTATTRCTL(ump->um_lowervp->v_mount, cmd,
    469 		    unp->un_lowervp, namespace, attrname));
    470 	}
    471 }
    472 
    473 /*
    474  * Initialize
    475  */
    476 void
    477 unionfs_init(void)
    478 {
    479 	UNIONFSDEBUG("unionfs_init\n");	/* printed during system boot */
    480 }
    481 
    482 static int
    483 unionfs_renamelock_enter(struct mount *mp)
    484 {
    485 	struct unionfs_mount *um = MOUNTTOUNIONFSMOUNT(mp);
    486 
    487 	/* Lock just the upper fs, where the action happens. */
    488 	return VFS_RENAMELOCK_ENTER(um->um_uppervp->v_mount);
    489 }
    490 
    491 static void
    492 unionfs_renamelock_exit(struct mount *mp)
    493 {
    494 	struct unionfs_mount *um = MOUNTTOUNIONFSMOUNT(mp);
    495 
    496 	VFS_RENAMELOCK_EXIT(um->um_uppervp->v_mount);
    497 }
    498 
    499 int
    500 unionfs_start(struct mount *mp, int flags)
    501 {
    502 
    503 	return (0);
    504 }
    505 
    506 void
    507 unionfs_done(void)
    508 {
    509 
    510 	/* Make sure to unset the readdir hook. */
    511 	vn_union_readdir_hook = NULL;
    512 }
    513 
    514 extern const struct vnodeopv_desc unionfs_vnodeop_opv_desc;
    515 
    516 const struct vnodeopv_desc * const unionfs_vnodeopv_descs[] = {
    517 	&unionfs_vnodeop_opv_desc,
    518 	NULL,
    519 };
    520 
    521 struct vfsops unionfs_vfsops = {
    522 	MOUNT_UNION,
    523 	sizeof (struct unionfs_args),
    524 	unionfs_mount,
    525 	unionfs_start,
    526 	unionfs_unmount,
    527 	unionfs_root,
    528 	(void *)eopnotsupp,		/* vfs_quotactl */
    529 	unionfs_statvfs,
    530 	unionfs_sync,
    531 	unionfs_vget,
    532 	(void *)eopnotsupp,		/* vfs_fhtovp */
    533 	(void *)eopnotsupp,		/* vfs_vptofh */
    534 	unionfs_init,
    535 	NULL,				/* vfs_reinit */
    536 	unionfs_done,
    537 	NULL,				/* vfs_mountroot */
    538 	(int (*)(struct mount *, struct vnode *, struct timespec *)) eopnotsupp,
    539 	vfs_stdextattrctl,
    540 	(void *)eopnotsupp,		/* vfs_suspendctl */
    541 	unionfs_renamelock_enter,
    542 	unionfs_renamelock_exit,
    543 	(void *)eopnotsupp,
    544 	unionfs_vnodeopv_descs,
    545 	0,				/* vfs_refcount */
    546 	{ NULL, NULL },
    547 };
    548 
    549 static int
    550 unionfs_modcmd(modcmd_t cmd, void *arg)
    551 {
    552 	int error;
    553 
    554 	switch (cmd) {
    555 	case MODULE_CMD_INIT:
    556 		error = vfs_attach(&unionfs_vfsops);
    557 		if (error != 0)
    558 			break;
    559 		sysctl_createv(&unionfs_sysctl_log, 0, NULL, NULL,
    560 			       CTLFLAG_PERMANENT,
    561 			       CTLTYPE_NODE, "vfs", NULL,
    562 			       NULL, 0, NULL, 0,
    563 			       CTL_VFS, CTL_EOL);
    564 		sysctl_createv(&unionfs_sysctl_log, 0, NULL, NULL,
    565 			       CTLFLAG_PERMANENT,
    566 			       CTLTYPE_NODE, "union",
    567 			       SYSCTL_DESCR("Union file system"),
    568 			       NULL, 0, NULL, 0,
    569 			       CTL_VFS, 15, CTL_EOL);
    570 		/*
    571 		 * XXX the "15" above could be dynamic, thereby eliminating
    572 		 * one more instance of the "number to vfs" mapping problem,
    573 		 * but "15" is the order as taken from sys/mount.h
    574 		 */
    575 		break;
    576 	case MODULE_CMD_FINI:
    577 		error = vfs_detach(&unionfs_vfsops);
    578 		if (error != 0)
    579 			break;
    580 		sysctl_teardown(&unionfs_sysctl_log);
    581 		break;
    582 	default:
    583 		error = ENOTTY;
    584 		break;
    585 	}
    586 
    587 	return (error);
    588 }
    589