1 /* $NetBSD: union_vfsops.c,v 1.61 2010/01/08 11:35:09 pooka Exp $ */ 2 3 /* 4 * Copyright (c) 1994 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software donated to Berkeley by 8 * Jan-Simon Pendry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95 35 */ 36 37 /* 38 * Copyright (c) 1994 Jan-Simon Pendry. 39 * All rights reserved. 40 * 41 * This code is derived from software donated to Berkeley by 42 * Jan-Simon Pendry. 43 * 44 * Redistribution and use in source and binary forms, with or without 45 * modification, are permitted provided that the following conditions 46 * are met: 47 * 1. Redistributions of source code must retain the above copyright 48 * notice, this list of conditions and the following disclaimer. 49 * 2. Redistributions in binary form must reproduce the above copyright 50 * notice, this list of conditions and the following disclaimer in the 51 * documentation and/or other materials provided with the distribution. 52 * 3. All advertising materials mentioning features or use of this software 53 * must display the following acknowledgement: 54 * This product includes software developed by the University of 55 * California, Berkeley and its contributors. 56 * 4. Neither the name of the University nor the names of its contributors 57 * may be used to endorse or promote products derived from this software 58 * without specific prior written permission. 59 * 60 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 61 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 62 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 63 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 64 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 65 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 66 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 67 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 68 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 69 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 70 * SUCH DAMAGE. 71 * 72 * @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95 73 */ 74 75 /* 76 * Union Layer 77 */ 78 79 #include <sys/cdefs.h> 80 __KERNEL_RCSID(0, "$NetBSD: union_vfsops.c,v 1.61 2010/01/08 11:35:09 pooka Exp $"); 81 82 #include <sys/param.h> 83 #include <sys/systm.h> 84 #include <sys/sysctl.h> 85 #include <sys/time.h> 86 #include <sys/proc.h> 87 #include <sys/vnode.h> 88 #include <sys/mount.h> 89 #include <sys/namei.h> 90 #include <sys/malloc.h> 91 #include <sys/filedesc.h> 92 #include <sys/queue.h> 93 #include <sys/stat.h> 94 #include <sys/kauth.h> 95 #include <sys/module.h> 96 97 #include <fs/union/union.h> 98 99 MODULE(MODULE_CLASS_VFS, union, "layerfs"); 100 101 VFS_PROTOS(union); 102 103 static struct sysctllog *union_sysctl_log; 104 105 /* 106 * Mount union filesystem 107 */ 108 int 109 union_mount(struct mount *mp, const char *path, void *data, size_t *data_len) 110 { 111 struct lwp *l = curlwp; 112 int error = 0; 113 struct union_args *args = data; 114 struct vnode *lowerrootvp = NULLVP; 115 struct vnode *upperrootvp = NULLVP; 116 struct union_mount *um = 0; 117 const char *cp; 118 char *xp; 119 int len; 120 size_t size; 121 122 if (*data_len < sizeof *args) 123 return EINVAL; 124 125 #ifdef UNION_DIAGNOSTIC 126 printf("union_mount(mp = %p)\n", mp); 127 #endif 128 129 if (mp->mnt_flag & MNT_GETARGS) { 130 um = MOUNTTOUNIONMOUNT(mp); 131 if (um == NULL) 132 return EIO; 133 args->target = NULL; 134 args->mntflags = um->um_op; 135 *data_len = sizeof *args; 136 return 0; 137 } 138 /* 139 * Update is a no-op 140 */ 141 if (mp->mnt_flag & MNT_UPDATE) { 142 /* 143 * Need to provide. 144 * 1. a way to convert between rdonly and rdwr mounts. 145 * 2. support for nfs exports. 146 */ 147 error = EOPNOTSUPP; 148 goto bad; 149 } 150 151 printf("WARNING: the union file system is experimental\n" 152 "WARNING: it can cause crashes and file system corruption\n"); 153 154 lowerrootvp = mp->mnt_vnodecovered; 155 vref(lowerrootvp); 156 157 /* 158 * Find upper node. 159 */ 160 error = namei_simple_user(args->target, 161 NSM_FOLLOW_NOEMULROOT, &upperrootvp); 162 if (error != 0) 163 goto bad; 164 165 if (upperrootvp->v_type != VDIR) { 166 error = EINVAL; 167 goto bad; 168 } 169 170 um = (struct union_mount *) malloc(sizeof(struct union_mount), 171 M_UFSMNT, M_WAITOK); /* XXX */ 172 173 /* 174 * Keep a held reference to the target vnodes. 175 * They are vrele'd in union_unmount. 176 * 177 * Depending on the _BELOW flag, the filesystems are 178 * viewed in a different order. In effect, this is the 179 * same as providing a mount under option to the mount syscall. 180 */ 181 182 um->um_op = args->mntflags & UNMNT_OPMASK; 183 switch (um->um_op) { 184 case UNMNT_ABOVE: 185 um->um_lowervp = lowerrootvp; 186 um->um_uppervp = upperrootvp; 187 break; 188 189 case UNMNT_BELOW: 190 um->um_lowervp = upperrootvp; 191 um->um_uppervp = lowerrootvp; 192 break; 193 194 case UNMNT_REPLACE: 195 vrele(lowerrootvp); 196 lowerrootvp = NULLVP; 197 um->um_uppervp = upperrootvp; 198 um->um_lowervp = lowerrootvp; 199 break; 200 201 default: 202 error = EINVAL; 203 goto bad; 204 } 205 206 /* 207 * Unless the mount is readonly, ensure that the top layer 208 * supports whiteout operations 209 */ 210 if ((mp->mnt_flag & MNT_RDONLY) == 0) { 211 error = VOP_WHITEOUT(um->um_uppervp, (struct componentname *) 0, LOOKUP); 212 if (error) 213 goto bad; 214 } 215 216 um->um_cred = l->l_cred; 217 kauth_cred_hold(um->um_cred); 218 um->um_cmode = UN_DIRMODE &~ l->l_proc->p_cwdi->cwdi_cmask; 219 220 /* 221 * Depending on what you think the MNT_LOCAL flag might mean, 222 * you may want the && to be || on the conditional below. 223 * At the moment it has been defined that the filesystem is 224 * only local if it is all local, ie the MNT_LOCAL flag implies 225 * that the entire namespace is local. If you think the MNT_LOCAL 226 * flag implies that some of the files might be stored locally 227 * then you will want to change the conditional. 228 */ 229 if (um->um_op == UNMNT_ABOVE) { 230 if (((um->um_lowervp == NULLVP) || 231 (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) && 232 (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL)) 233 mp->mnt_flag |= MNT_LOCAL; 234 } 235 236 /* 237 * Copy in the upper layer's RDONLY flag. This is for the benefit 238 * of lookup() which explicitly checks the flag, rather than asking 239 * the filesystem for it's own opinion. This means, that an update 240 * mount of the underlying filesystem to go from rdonly to rdwr 241 * will leave the unioned view as read-only. 242 */ 243 mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY); 244 245 mp->mnt_data = um; 246 vfs_getnewfsid(mp); 247 248 error = set_statvfs_info( path, UIO_USERSPACE, NULL, UIO_USERSPACE, 249 mp->mnt_op->vfs_name, mp, l); 250 if (error) 251 goto bad; 252 253 switch (um->um_op) { 254 case UNMNT_ABOVE: 255 cp = "<above>:"; 256 break; 257 case UNMNT_BELOW: 258 cp = "<below>:"; 259 break; 260 case UNMNT_REPLACE: 261 cp = ""; 262 break; 263 default: 264 cp = "<invalid>:"; 265 #ifdef DIAGNOSTIC 266 panic("union_mount: bad um_op"); 267 #endif 268 break; 269 } 270 len = strlen(cp); 271 memcpy(mp->mnt_stat.f_mntfromname, cp, len); 272 273 xp = mp->mnt_stat.f_mntfromname + len; 274 len = MNAMELEN - len; 275 276 (void) copyinstr(args->target, xp, len - 1, &size); 277 memset(xp + size, 0, len - size); 278 279 #ifdef UNION_DIAGNOSTIC 280 printf("union_mount: from %s, on %s\n", 281 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 282 #endif 283 284 /* Setup the readdir hook if it's not set already */ 285 if (!vn_union_readdir_hook) 286 vn_union_readdir_hook = union_readdirhook; 287 288 return (0); 289 290 bad: 291 if (um) 292 free(um, M_UFSMNT); 293 if (upperrootvp) 294 vrele(upperrootvp); 295 if (lowerrootvp) 296 vrele(lowerrootvp); 297 return (error); 298 } 299 300 /* 301 * VFS start. Nothing needed here - the start routine 302 * on the underlying filesystem(s) will have been called 303 * when that filesystem was mounted. 304 */ 305 /*ARGSUSED*/ 306 int 307 union_start(struct mount *mp, int flags) 308 { 309 310 return (0); 311 } 312 313 /* 314 * Free reference to union layer 315 */ 316 int 317 union_unmount(struct mount *mp, int mntflags) 318 { 319 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 320 int freeing; 321 int error; 322 323 #ifdef UNION_DIAGNOSTIC 324 printf("union_unmount(mp = %p)\n", mp); 325 #endif 326 327 /* 328 * Keep flushing vnodes from the mount list. 329 * This is needed because of the un_pvp held 330 * reference to the parent vnode. 331 * If more vnodes have been freed on a given pass, 332 * the try again. The loop will iterate at most 333 * (d) times, where (d) is the maximum tree depth 334 * in the filesystem. 335 */ 336 for (freeing = 0; (error = vflush(mp, NULL, 0)) != 0;) { 337 struct vnode *vp; 338 int n; 339 340 /* count #vnodes held on mount list */ 341 n = 0; 342 TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) 343 n++; 344 345 /* if this is unchanged then stop */ 346 if (n == freeing) 347 break; 348 349 /* otherwise try once more time */ 350 freeing = n; 351 } 352 353 /* 354 * Ok, now that we've tried doing it gently, get out the hammer. 355 */ 356 357 if (mntflags & MNT_FORCE) 358 error = vflush(mp, NULL, FORCECLOSE); 359 360 if (error) 361 return error; 362 363 /* 364 * Discard references to upper and lower target vnodes. 365 */ 366 if (um->um_lowervp) 367 vrele(um->um_lowervp); 368 vrele(um->um_uppervp); 369 kauth_cred_free(um->um_cred); 370 /* 371 * Finally, throw away the union_mount structure 372 */ 373 free(mp->mnt_data, M_UFSMNT); /* XXX */ 374 mp->mnt_data = NULL; 375 return (0); 376 } 377 378 int 379 union_root(struct mount *mp, struct vnode **vpp) 380 { 381 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 382 int error; 383 384 /* 385 * Return locked reference to root. 386 */ 387 vref(um->um_uppervp); 388 vn_lock(um->um_uppervp, LK_EXCLUSIVE | LK_RETRY); 389 if (um->um_lowervp) 390 vref(um->um_lowervp); 391 error = union_allocvp(vpp, mp, NULL, NULL, NULL, 392 um->um_uppervp, um->um_lowervp, 1); 393 394 if (error) { 395 vput(um->um_uppervp); 396 if (um->um_lowervp) 397 vrele(um->um_lowervp); 398 } 399 400 return (error); 401 } 402 403 int 404 union_statvfs(struct mount *mp, struct statvfs *sbp) 405 { 406 int error; 407 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 408 struct statvfs *sbuf = malloc(sizeof(*sbuf), M_TEMP, M_WAITOK | M_ZERO); 409 unsigned long lbsize; 410 411 #ifdef UNION_DIAGNOSTIC 412 printf("union_statvfs(mp = %p, lvp = %p, uvp = %p)\n", mp, 413 um->um_lowervp, um->um_uppervp); 414 #endif 415 416 if (um->um_lowervp) { 417 error = VFS_STATVFS(um->um_lowervp->v_mount, sbuf); 418 if (error) 419 goto done; 420 } 421 422 /* now copy across the "interesting" information and fake the rest */ 423 lbsize = sbuf->f_bsize; 424 sbp->f_blocks = sbuf->f_blocks - sbuf->f_bfree; 425 sbp->f_files = sbuf->f_files - sbuf->f_ffree; 426 427 error = VFS_STATVFS(um->um_uppervp->v_mount, sbuf); 428 if (error) 429 goto done; 430 431 sbp->f_flag = sbuf->f_flag; 432 sbp->f_bsize = sbuf->f_bsize; 433 sbp->f_frsize = sbuf->f_frsize; 434 sbp->f_iosize = sbuf->f_iosize; 435 436 /* 437 * The "total" fields count total resources in all layers, 438 * the "free" fields count only those resources which are 439 * free in the upper layer (since only the upper layer 440 * is writable). 441 */ 442 443 if (sbuf->f_bsize != lbsize) 444 sbp->f_blocks = sbp->f_blocks * lbsize / sbuf->f_bsize; 445 sbp->f_blocks += sbuf->f_blocks; 446 sbp->f_bfree = sbuf->f_bfree; 447 sbp->f_bavail = sbuf->f_bavail; 448 sbp->f_bresvd = sbuf->f_bresvd; 449 sbp->f_files += sbuf->f_files; 450 sbp->f_ffree = sbuf->f_ffree; 451 sbp->f_favail = sbuf->f_favail; 452 sbp->f_fresvd = sbuf->f_fresvd; 453 454 copy_statvfs_info(sbp, mp); 455 done: 456 free(sbuf, M_TEMP); 457 return error; 458 } 459 460 /*ARGSUSED*/ 461 int 462 union_sync(struct mount *mp, int waitfor, 463 kauth_cred_t cred) 464 { 465 466 /* 467 * XXX - Assumes no data cached at union layer. 468 */ 469 return (0); 470 } 471 472 /*ARGSUSED*/ 473 int 474 union_vget(struct mount *mp, ino_t ino, 475 struct vnode **vpp) 476 { 477 478 return (EOPNOTSUPP); 479 } 480 481 static int 482 union_renamelock_enter(struct mount *mp) 483 { 484 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 485 486 /* Lock just the upper fs, where the action happens. */ 487 return VFS_RENAMELOCK_ENTER(um->um_uppervp->v_mount); 488 } 489 490 static void 491 union_renamelock_exit(struct mount *mp) 492 { 493 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 494 495 VFS_RENAMELOCK_EXIT(um->um_uppervp->v_mount); 496 } 497 498 extern const struct vnodeopv_desc union_vnodeop_opv_desc; 499 500 const struct vnodeopv_desc * const union_vnodeopv_descs[] = { 501 &union_vnodeop_opv_desc, 502 NULL, 503 }; 504 505 struct vfsops union_vfsops = { 506 MOUNT_UNION, 507 sizeof (struct union_args), 508 union_mount, 509 union_start, 510 union_unmount, 511 union_root, 512 (void *)eopnotsupp, /* vfs_quotactl */ 513 union_statvfs, 514 union_sync, 515 union_vget, 516 (void *)eopnotsupp, /* vfs_fhtovp */ 517 (void *)eopnotsupp, /* vfs_vptofh */ 518 union_init, 519 NULL, /* vfs_reinit */ 520 union_done, 521 NULL, /* vfs_mountroot */ 522 (int (*)(struct mount *, struct vnode *, struct timespec *)) eopnotsupp, 523 vfs_stdextattrctl, 524 (void *)eopnotsupp, /* vfs_suspendctl */ 525 union_renamelock_enter, 526 union_renamelock_exit, 527 (void *)eopnotsupp, 528 union_vnodeopv_descs, 529 0, /* vfs_refcount */ 530 { NULL, NULL }, 531 }; 532 533 static int 534 union_modcmd(modcmd_t cmd, void *arg) 535 { 536 int error; 537 538 switch (cmd) { 539 case MODULE_CMD_INIT: 540 error = vfs_attach(&union_vfsops); 541 if (error != 0) 542 break; 543 sysctl_createv(&union_sysctl_log, 0, NULL, NULL, 544 CTLFLAG_PERMANENT, 545 CTLTYPE_NODE, "vfs", NULL, 546 NULL, 0, NULL, 0, 547 CTL_VFS, CTL_EOL); 548 sysctl_createv(&union_sysctl_log, 0, NULL, NULL, 549 CTLFLAG_PERMANENT, 550 CTLTYPE_NODE, "union", 551 SYSCTL_DESCR("Union file system"), 552 NULL, 0, NULL, 0, 553 CTL_VFS, 15, CTL_EOL); 554 /* 555 * XXX the "15" above could be dynamic, thereby eliminating 556 * one more instance of the "number to vfs" mapping problem, 557 * but "15" is the order as taken from sys/mount.h 558 */ 559 break; 560 case MODULE_CMD_FINI: 561 error = vfs_detach(&union_vfsops); 562 if (error != 0) 563 break; 564 sysctl_teardown(&union_sysctl_log); 565 break; 566 default: 567 error = ENOTTY; 568 break; 569 } 570 571 return (error); 572 } 573