1 /* $NetBSD: union_vfsops.c,v 1.78 2017/04/01 19:35:56 riastradh 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 1.78 2017/04/01 19:35:56 riastradh 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 <miscfs/genfs/genfs.h> 98 #include <fs/union/union.h> 99 100 MODULE(MODULE_CLASS_VFS, union, NULL); 101 102 static struct sysctllog *union_sysctl_log; 103 104 /* 105 * Mount union filesystem 106 */ 107 int 108 union_mount(struct mount *mp, const char *path, void *data, size_t *data_len) 109 { 110 struct lwp *l = curlwp; 111 int error = 0; 112 struct union_args *args = data; 113 struct vnode *lowerrootvp = NULLVP; 114 struct vnode *upperrootvp = NULLVP; 115 struct union_mount *um = 0; 116 const char *cp; 117 char *xp; 118 int len; 119 size_t size; 120 121 if (args == NULL) 122 return EINVAL; 123 if (*data_len < sizeof *args) 124 return EINVAL; 125 126 #ifdef UNION_DIAGNOSTIC 127 printf("union_mount(mp = %p)\n", mp); 128 #endif 129 130 if (mp->mnt_flag & MNT_GETARGS) { 131 um = MOUNTTOUNIONMOUNT(mp); 132 if (um == NULL) 133 return EIO; 134 args->target = NULL; 135 args->mntflags = um->um_op; 136 *data_len = sizeof *args; 137 return 0; 138 } 139 /* 140 * Update is a no-op 141 */ 142 if (mp->mnt_flag & MNT_UPDATE) { 143 /* 144 * Need to provide. 145 * 1. a way to convert between rdonly and rdwr mounts. 146 * 2. support for nfs exports. 147 */ 148 error = EOPNOTSUPP; 149 goto bad; 150 } 151 152 lowerrootvp = mp->mnt_vnodecovered; 153 vref(lowerrootvp); 154 155 /* 156 * Find upper node. 157 */ 158 error = namei_simple_user(args->target, 159 NSM_FOLLOW_NOEMULROOT, &upperrootvp); 160 if (error != 0) 161 goto bad; 162 163 if (upperrootvp->v_type != VDIR) { 164 error = EINVAL; 165 goto bad; 166 } 167 168 um = kmem_zalloc(sizeof(struct union_mount), KM_SLEEP); 169 170 /* 171 * Keep a held reference to the target vnodes. 172 * They are vrele'd in union_unmount. 173 * 174 * Depending on the _BELOW flag, the filesystems are 175 * viewed in a different order. In effect, this is the 176 * same as providing a mount under option to the mount syscall. 177 */ 178 179 um->um_op = args->mntflags & UNMNT_OPMASK; 180 switch (um->um_op) { 181 case UNMNT_ABOVE: 182 um->um_lowervp = lowerrootvp; 183 um->um_uppervp = upperrootvp; 184 break; 185 186 case UNMNT_BELOW: 187 um->um_lowervp = upperrootvp; 188 um->um_uppervp = lowerrootvp; 189 break; 190 191 case UNMNT_REPLACE: 192 vrele(lowerrootvp); 193 lowerrootvp = NULLVP; 194 um->um_uppervp = upperrootvp; 195 um->um_lowervp = lowerrootvp; 196 break; 197 198 default: 199 error = EINVAL; 200 goto bad; 201 } 202 203 mp->mnt_iflag |= IMNT_MPSAFE; 204 205 /* 206 * Unless the mount is readonly, ensure that the top layer 207 * supports whiteout operations 208 */ 209 if ((mp->mnt_flag & MNT_RDONLY) == 0) { 210 vn_lock(um->um_uppervp, LK_EXCLUSIVE | LK_RETRY); 211 error = VOP_WHITEOUT(um->um_uppervp, 212 (struct componentname *) 0, LOOKUP); 213 VOP_UNLOCK(um->um_uppervp); 214 if (error) 215 goto bad; 216 } 217 218 um->um_cred = l->l_cred; 219 kauth_cred_hold(um->um_cred); 220 um->um_cmode = UN_DIRMODE &~ l->l_proc->p_cwdi->cwdi_cmask; 221 222 /* 223 * Depending on what you think the MNT_LOCAL flag might mean, 224 * you may want the && to be || on the conditional below. 225 * At the moment it has been defined that the filesystem is 226 * only local if it is all local, ie the MNT_LOCAL flag implies 227 * that the entire namespace is local. If you think the MNT_LOCAL 228 * flag implies that some of the files might be stored locally 229 * then you will want to change the conditional. 230 */ 231 if (um->um_op == UNMNT_ABOVE) { 232 if (((um->um_lowervp == NULLVP) || 233 (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) && 234 (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL)) 235 mp->mnt_flag |= MNT_LOCAL; 236 } 237 238 /* 239 * Copy in the upper layer's RDONLY flag. This is for the benefit 240 * of lookup() which explicitly checks the flag, rather than asking 241 * the filesystem for its own opinion. This means, that an update 242 * mount of the underlying filesystem to go from rdonly to rdwr 243 * will leave the unioned view as read-only. 244 */ 245 mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY); 246 247 mp->mnt_data = um; 248 vfs_getnewfsid(mp); 249 250 error = set_statvfs_info( path, UIO_USERSPACE, NULL, UIO_USERSPACE, 251 mp->mnt_op->vfs_name, mp, l); 252 if (error) 253 goto bad; 254 255 mp->mnt_lower = um->um_uppervp->v_mount; 256 257 switch (um->um_op) { 258 case UNMNT_ABOVE: 259 cp = "<above>:"; 260 break; 261 case UNMNT_BELOW: 262 cp = "<below>:"; 263 break; 264 case UNMNT_REPLACE: 265 cp = ""; 266 break; 267 default: 268 cp = "<invalid>:"; 269 #ifdef DIAGNOSTIC 270 panic("union_mount: bad um_op"); 271 #endif 272 break; 273 } 274 len = strlen(cp); 275 memcpy(mp->mnt_stat.f_mntfromname, cp, len); 276 277 xp = mp->mnt_stat.f_mntfromname + len; 278 len = MNAMELEN - len; 279 280 (void) copyinstr(args->target, xp, len - 1, &size); 281 memset(xp + size, 0, len - size); 282 283 #ifdef UNION_DIAGNOSTIC 284 printf("union_mount: from %s, on %s\n", 285 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 286 #endif 287 288 /* Setup the readdir hook if it's not set already */ 289 if (!vn_union_readdir_hook) 290 vn_union_readdir_hook = union_readdirhook; 291 292 return (0); 293 294 bad: 295 if (um) 296 kmem_free(um, sizeof(struct union_mount)); 297 if (upperrootvp) 298 vrele(upperrootvp); 299 if (lowerrootvp) 300 vrele(lowerrootvp); 301 return (error); 302 } 303 304 /* 305 * VFS start. Nothing needed here - the start routine 306 * on the underlying filesystem(s) will have been called 307 * when that filesystem was mounted. 308 */ 309 /*ARGSUSED*/ 310 int 311 union_start(struct mount *mp, int flags) 312 { 313 314 return (0); 315 } 316 317 /* 318 * Free reference to union layer 319 */ 320 static bool 321 union_unmount_selector(void *cl, struct vnode *vp) 322 { 323 int *count = cl; 324 325 KASSERT(mutex_owned(vp->v_interlock)); 326 327 *count += 1; 328 return false; 329 } 330 331 int 332 union_unmount(struct mount *mp, int mntflags) 333 { 334 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 335 int freeing; 336 int error; 337 338 #ifdef UNION_DIAGNOSTIC 339 printf("union_unmount(mp = %p)\n", mp); 340 #endif 341 342 /* 343 * Keep flushing vnodes from the mount list. 344 * This is needed because of the un_pvp held 345 * reference to the parent vnode. 346 * If more vnodes have been freed on a given pass, 347 * the try again. The loop will iterate at most 348 * (d) times, where (d) is the maximum tree depth 349 * in the filesystem. 350 */ 351 for (freeing = 0; (error = vflush(mp, NULL, 0)) != 0;) { 352 struct vnode_iterator *marker; 353 int n; 354 355 /* count #vnodes held on mount list */ 356 n = 0; 357 vfs_vnode_iterator_init(mp, &marker); 358 vfs_vnode_iterator_next(marker, union_unmount_selector, &n); 359 vfs_vnode_iterator_destroy(marker); 360 361 /* if this is unchanged then stop */ 362 if (n == freeing) 363 break; 364 365 /* otherwise try once more time */ 366 freeing = n; 367 } 368 369 /* 370 * Ok, now that we've tried doing it gently, get out the hammer. 371 */ 372 373 if (mntflags & MNT_FORCE) 374 error = vflush(mp, NULL, FORCECLOSE); 375 376 if (error) 377 return error; 378 379 /* 380 * Discard references to upper and lower target vnodes. 381 */ 382 if (um->um_lowervp) 383 vrele(um->um_lowervp); 384 vrele(um->um_uppervp); 385 kauth_cred_free(um->um_cred); 386 /* 387 * Finally, throw away the union_mount structure 388 */ 389 kmem_free(um, sizeof(struct union_mount)); 390 mp->mnt_data = NULL; 391 return 0; 392 } 393 394 int 395 union_root(struct mount *mp, struct vnode **vpp) 396 { 397 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 398 int error; 399 400 /* 401 * Return locked reference to root. 402 */ 403 vref(um->um_uppervp); 404 if (um->um_lowervp) 405 vref(um->um_lowervp); 406 error = union_allocvp(vpp, mp, NULL, NULL, NULL, 407 um->um_uppervp, um->um_lowervp, 1); 408 409 if (error) { 410 vrele(um->um_uppervp); 411 if (um->um_lowervp) 412 vrele(um->um_lowervp); 413 return error; 414 } 415 416 vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY); 417 418 return 0; 419 } 420 421 int 422 union_statvfs(struct mount *mp, struct statvfs *sbp) 423 { 424 int error; 425 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 426 struct statvfs *sbuf = malloc(sizeof(*sbuf), M_TEMP, M_WAITOK | M_ZERO); 427 unsigned long lbsize; 428 429 #ifdef UNION_DIAGNOSTIC 430 printf("union_statvfs(mp = %p, lvp = %p, uvp = %p)\n", mp, 431 um->um_lowervp, um->um_uppervp); 432 #endif 433 434 if (um->um_lowervp) { 435 error = VFS_STATVFS(um->um_lowervp->v_mount, sbuf); 436 if (error) 437 goto done; 438 } 439 440 /* now copy across the "interesting" information and fake the rest */ 441 lbsize = sbuf->f_bsize; 442 sbp->f_blocks = sbuf->f_blocks - sbuf->f_bfree; 443 sbp->f_files = sbuf->f_files - sbuf->f_ffree; 444 445 error = VFS_STATVFS(um->um_uppervp->v_mount, sbuf); 446 if (error) 447 goto done; 448 449 sbp->f_flag = sbuf->f_flag; 450 sbp->f_bsize = sbuf->f_bsize; 451 sbp->f_frsize = sbuf->f_frsize; 452 sbp->f_iosize = sbuf->f_iosize; 453 454 /* 455 * The "total" fields count total resources in all layers, 456 * the "free" fields count only those resources which are 457 * free in the upper layer (since only the upper layer 458 * is writable). 459 */ 460 461 if (sbuf->f_bsize != lbsize) 462 sbp->f_blocks = sbp->f_blocks * lbsize / sbuf->f_bsize; 463 sbp->f_blocks += sbuf->f_blocks; 464 sbp->f_bfree = sbuf->f_bfree; 465 sbp->f_bavail = sbuf->f_bavail; 466 sbp->f_bresvd = sbuf->f_bresvd; 467 sbp->f_files += sbuf->f_files; 468 sbp->f_ffree = sbuf->f_ffree; 469 sbp->f_favail = sbuf->f_favail; 470 sbp->f_fresvd = sbuf->f_fresvd; 471 472 copy_statvfs_info(sbp, mp); 473 done: 474 free(sbuf, M_TEMP); 475 return error; 476 } 477 478 /*ARGSUSED*/ 479 int 480 union_sync(struct mount *mp, int waitfor, 481 kauth_cred_t cred) 482 { 483 484 /* 485 * XXX - Assumes no data cached at union layer. 486 */ 487 return (0); 488 } 489 490 /*ARGSUSED*/ 491 int 492 union_vget(struct mount *mp, ino_t ino, 493 struct vnode **vpp) 494 { 495 496 return (EOPNOTSUPP); 497 } 498 499 static int 500 union_renamelock_enter(struct mount *mp) 501 { 502 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 503 504 /* Lock just the upper fs, where the action happens. */ 505 return VFS_RENAMELOCK_ENTER(um->um_uppervp->v_mount); 506 } 507 508 static void 509 union_renamelock_exit(struct mount *mp) 510 { 511 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 512 513 VFS_RENAMELOCK_EXIT(um->um_uppervp->v_mount); 514 } 515 516 extern const struct vnodeopv_desc union_vnodeop_opv_desc; 517 518 const struct vnodeopv_desc * const union_vnodeopv_descs[] = { 519 &union_vnodeop_opv_desc, 520 NULL, 521 }; 522 523 struct vfsops union_vfsops = { 524 .vfs_name = MOUNT_UNION, 525 .vfs_min_mount_data = sizeof (struct union_args), 526 .vfs_mount = union_mount, 527 .vfs_start = union_start, 528 .vfs_unmount = union_unmount, 529 .vfs_root = union_root, 530 .vfs_quotactl = (void *)eopnotsupp, 531 .vfs_statvfs = union_statvfs, 532 .vfs_sync = union_sync, 533 .vfs_vget = union_vget, 534 .vfs_loadvnode = union_loadvnode, 535 .vfs_fhtovp = (void *)eopnotsupp, 536 .vfs_vptofh = (void *)eopnotsupp, 537 .vfs_init = union_init, 538 .vfs_reinit = union_reinit, 539 .vfs_done = union_done, 540 .vfs_snapshot = (void *)eopnotsupp, 541 .vfs_extattrctl = vfs_stdextattrctl, 542 .vfs_suspendctl = genfs_suspendctl, 543 .vfs_renamelock_enter = union_renamelock_enter, 544 .vfs_renamelock_exit = union_renamelock_exit, 545 .vfs_fsync = (void *)eopnotsupp, 546 .vfs_opv_descs = union_vnodeopv_descs 547 }; 548 549 static int 550 union_modcmd(modcmd_t cmd, void *arg) 551 { 552 int error; 553 554 switch (cmd) { 555 case MODULE_CMD_INIT: 556 error = vfs_attach(&union_vfsops); 557 if (error != 0) 558 break; 559 sysctl_createv(&union_sysctl_log, 0, NULL, NULL, 560 CTLFLAG_PERMANENT, 561 CTLTYPE_NODE, "union", 562 SYSCTL_DESCR("Union file system"), 563 NULL, 0, NULL, 0, 564 CTL_VFS, 15, CTL_EOL); 565 /* 566 * XXX the "15" above could be dynamic, thereby eliminating 567 * one more instance of the "number to vfs" mapping problem, 568 * but "15" is the order as taken from sys/mount.h 569 */ 570 break; 571 case MODULE_CMD_FINI: 572 error = vfs_detach(&union_vfsops); 573 if (error != 0) 574 break; 575 sysctl_teardown(&union_sysctl_log); 576 break; 577 default: 578 error = ENOTTY; 579 break; 580 } 581 582 return (error); 583 } 584