1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or https://opensource.org/licenses/CDDL-1.0. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * 23 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. 24 * Copyright (C) 2011 Lawrence Livermore National Security, LLC. 25 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). 26 * LLNL-CODE-403049. 27 * Rewritten for Linux by: 28 * Rohan Puri <rohan.puri15@gmail.com> 29 * Brian Behlendorf <behlendorf1@llnl.gov> 30 * Copyright (c) 2013 by Delphix. All rights reserved. 31 * Copyright 2015, OmniTI Computer Consulting, Inc. All rights reserved. 32 * Copyright (c) 2018 George Melikov. All Rights Reserved. 33 * Copyright (c) 2019 Datto, Inc. All rights reserved. 34 * Copyright (c) 2020 The MathWorks, Inc. All rights reserved. 35 */ 36 37 /* 38 * ZFS control directory (a.k.a. ".zfs") 39 * 40 * This directory provides a common location for all ZFS meta-objects. 41 * Currently, this is only the 'snapshot' and 'shares' directory, but this may 42 * expand in the future. The elements are built dynamically, as the hierarchy 43 * does not actually exist on disk. 44 * 45 * For 'snapshot', we don't want to have all snapshots always mounted, because 46 * this would take up a huge amount of space in /etc/mnttab. We have three 47 * types of objects: 48 * 49 * ctldir ------> snapshotdir -------> snapshot 50 * | 51 * | 52 * V 53 * mounted fs 54 * 55 * The 'snapshot' node contains just enough information to lookup '..' and act 56 * as a mountpoint for the snapshot. Whenever we lookup a specific snapshot, we 57 * perform an automount of the underlying filesystem and return the 58 * corresponding inode. 59 * 60 * All mounts are handled automatically by an user mode helper which invokes 61 * the mount procedure. Unmounts are handled by allowing the mount 62 * point to expire so the kernel may automatically unmount it. 63 * 64 * The '.zfs', '.zfs/snapshot', and all directories created under 65 * '.zfs/snapshot' (ie: '.zfs/snapshot/<snapname>') all share the same 66 * zfsvfs_t as the head filesystem (what '.zfs' lives under). 67 * 68 * File systems mounted on top of the '.zfs/snapshot/<snapname>' paths 69 * (ie: snapshots) are complete ZFS filesystems and have their own unique 70 * zfsvfs_t. However, the fsid reported by these mounts will be the same 71 * as that used by the parent zfsvfs_t to make NFS happy. 72 */ 73 74 #include <sys/types.h> 75 #include <sys/param.h> 76 #include <sys/time.h> 77 #include <sys/sysmacros.h> 78 #include <sys/pathname.h> 79 #include <sys/vfs.h> 80 #include <sys/zfs_ctldir.h> 81 #include <sys/zfs_ioctl.h> 82 #include <sys/zfs_vfsops.h> 83 #include <sys/zfs_vnops.h> 84 #include <sys/stat.h> 85 #include <sys/dmu.h> 86 #include <sys/dmu_objset.h> 87 #include <sys/dsl_destroy.h> 88 #include <sys/dsl_deleg.h> 89 #include <sys/zpl.h> 90 #include <sys/mntent.h> 91 #include "zfs_namecheck.h" 92 93 /* 94 * Two AVL trees are maintained which contain all currently automounted 95 * snapshots. Every automounted snapshots maps to a single zfs_snapentry_t 96 * entry which MUST: 97 * 98 * - be attached to both trees, and 99 * - be unique, no duplicate entries are allowed. 100 * 101 * The zfs_snapshots_by_name tree is indexed by the full dataset name 102 * while the zfs_snapshots_by_objsetid tree is indexed by the unique 103 * objsetid. This allows for fast lookups either by name or objsetid. 104 */ 105 static avl_tree_t zfs_snapshots_by_name; 106 static avl_tree_t zfs_snapshots_by_objsetid; 107 static krwlock_t zfs_snapshot_lock; 108 109 /* 110 * Control Directory Tunables (.zfs) 111 */ 112 int zfs_expire_snapshot = ZFSCTL_EXPIRE_SNAPSHOT; 113 static int zfs_admin_snapshot = 0; 114 115 typedef struct { 116 char *se_name; /* full snapshot name */ 117 char *se_path; /* full mount path */ 118 spa_t *se_spa; /* pool spa */ 119 uint64_t se_objsetid; /* snapshot objset id */ 120 struct dentry *se_root_dentry; /* snapshot root dentry */ 121 krwlock_t se_taskqid_lock; /* scheduled unmount taskqid lock */ 122 taskqid_t se_taskqid; /* scheduled unmount taskqid */ 123 avl_node_t se_node_name; /* zfs_snapshots_by_name link */ 124 avl_node_t se_node_objsetid; /* zfs_snapshots_by_objsetid link */ 125 zfs_refcount_t se_refcount; /* reference count */ 126 } zfs_snapentry_t; 127 128 static void zfsctl_snapshot_unmount_delay_impl(zfs_snapentry_t *se, int delay); 129 130 /* 131 * Allocate a new zfs_snapentry_t being careful to make a copy of the 132 * the snapshot name and provided mount point. No reference is taken. 133 */ 134 static zfs_snapentry_t * 135 zfsctl_snapshot_alloc(const char *full_name, const char *full_path, spa_t *spa, 136 uint64_t objsetid, struct dentry *root_dentry) 137 { 138 zfs_snapentry_t *se; 139 140 se = kmem_zalloc(sizeof (zfs_snapentry_t), KM_SLEEP); 141 142 se->se_name = kmem_strdup(full_name); 143 se->se_path = kmem_strdup(full_path); 144 se->se_spa = spa; 145 se->se_objsetid = objsetid; 146 se->se_root_dentry = root_dentry; 147 se->se_taskqid = TASKQID_INVALID; 148 rw_init(&se->se_taskqid_lock, NULL, RW_DEFAULT, NULL); 149 150 zfs_refcount_create(&se->se_refcount); 151 152 return (se); 153 } 154 155 /* 156 * Free a zfs_snapentry_t the caller must ensure there are no active 157 * references. 158 */ 159 static void 160 zfsctl_snapshot_free(zfs_snapentry_t *se) 161 { 162 zfs_refcount_destroy(&se->se_refcount); 163 kmem_strfree(se->se_name); 164 kmem_strfree(se->se_path); 165 rw_destroy(&se->se_taskqid_lock); 166 167 kmem_free(se, sizeof (zfs_snapentry_t)); 168 } 169 170 /* 171 * Hold a reference on the zfs_snapentry_t. 172 */ 173 static void 174 zfsctl_snapshot_hold(zfs_snapentry_t *se) 175 { 176 zfs_refcount_add(&se->se_refcount, NULL); 177 } 178 179 /* 180 * Release a reference on the zfs_snapentry_t. When the number of 181 * references drops to zero the structure will be freed. 182 */ 183 static void 184 zfsctl_snapshot_rele(zfs_snapentry_t *se) 185 { 186 if (zfs_refcount_remove(&se->se_refcount, NULL) == 0) 187 zfsctl_snapshot_free(se); 188 } 189 190 /* 191 * Add a zfs_snapentry_t to both the zfs_snapshots_by_name and 192 * zfs_snapshots_by_objsetid trees. While the zfs_snapentry_t is part 193 * of the trees a reference is held. 194 */ 195 static void 196 zfsctl_snapshot_add(zfs_snapentry_t *se) 197 { 198 ASSERT(RW_WRITE_HELD(&zfs_snapshot_lock)); 199 zfsctl_snapshot_hold(se); 200 avl_add(&zfs_snapshots_by_name, se); 201 avl_add(&zfs_snapshots_by_objsetid, se); 202 } 203 204 /* 205 * Remove a zfs_snapentry_t from both the zfs_snapshots_by_name and 206 * zfs_snapshots_by_objsetid trees. Upon removal a reference is dropped, 207 * this can result in the structure being freed if that was the last 208 * remaining reference. 209 */ 210 static void 211 zfsctl_snapshot_remove(zfs_snapentry_t *se) 212 { 213 ASSERT(RW_WRITE_HELD(&zfs_snapshot_lock)); 214 avl_remove(&zfs_snapshots_by_name, se); 215 avl_remove(&zfs_snapshots_by_objsetid, se); 216 zfsctl_snapshot_rele(se); 217 } 218 219 /* 220 * Snapshot name comparison function for the zfs_snapshots_by_name. 221 */ 222 static int 223 snapentry_compare_by_name(const void *a, const void *b) 224 { 225 const zfs_snapentry_t *se_a = a; 226 const zfs_snapentry_t *se_b = b; 227 int ret; 228 229 ret = strcmp(se_a->se_name, se_b->se_name); 230 231 if (ret < 0) 232 return (-1); 233 else if (ret > 0) 234 return (1); 235 else 236 return (0); 237 } 238 239 /* 240 * Snapshot name comparison function for the zfs_snapshots_by_objsetid. 241 */ 242 static int 243 snapentry_compare_by_objsetid(const void *a, const void *b) 244 { 245 const zfs_snapentry_t *se_a = a; 246 const zfs_snapentry_t *se_b = b; 247 248 if (se_a->se_spa != se_b->se_spa) 249 return ((ulong_t)se_a->se_spa < (ulong_t)se_b->se_spa ? -1 : 1); 250 251 if (se_a->se_objsetid < se_b->se_objsetid) 252 return (-1); 253 else if (se_a->se_objsetid > se_b->se_objsetid) 254 return (1); 255 else 256 return (0); 257 } 258 259 /* 260 * Find a zfs_snapentry_t in zfs_snapshots_by_name. If the snapname 261 * is found a pointer to the zfs_snapentry_t is returned and a reference 262 * taken on the structure. The caller is responsible for dropping the 263 * reference with zfsctl_snapshot_rele(). If the snapname is not found 264 * NULL will be returned. 265 */ 266 static zfs_snapentry_t * 267 zfsctl_snapshot_find_by_name(const char *snapname) 268 { 269 zfs_snapentry_t *se, search; 270 271 ASSERT(RW_LOCK_HELD(&zfs_snapshot_lock)); 272 273 search.se_name = (char *)snapname; 274 se = avl_find(&zfs_snapshots_by_name, &search, NULL); 275 if (se) 276 zfsctl_snapshot_hold(se); 277 278 return (se); 279 } 280 281 /* 282 * Find a zfs_snapentry_t in zfs_snapshots_by_objsetid given the objset id 283 * rather than the snapname. In all other respects it behaves the same 284 * as zfsctl_snapshot_find_by_name(). 285 */ 286 static zfs_snapentry_t * 287 zfsctl_snapshot_find_by_objsetid(spa_t *spa, uint64_t objsetid) 288 { 289 zfs_snapentry_t *se, search; 290 291 ASSERT(RW_LOCK_HELD(&zfs_snapshot_lock)); 292 293 search.se_spa = spa; 294 search.se_objsetid = objsetid; 295 se = avl_find(&zfs_snapshots_by_objsetid, &search, NULL); 296 if (se) 297 zfsctl_snapshot_hold(se); 298 299 return (se); 300 } 301 302 /* 303 * Rename a zfs_snapentry_t in the zfs_snapshots_by_name. The structure is 304 * removed, renamed, and added back to the new correct location in the tree. 305 */ 306 static int 307 zfsctl_snapshot_rename(const char *old_snapname, const char *new_snapname) 308 { 309 zfs_snapentry_t *se; 310 311 ASSERT(RW_WRITE_HELD(&zfs_snapshot_lock)); 312 313 se = zfsctl_snapshot_find_by_name(old_snapname); 314 if (se == NULL) 315 return (SET_ERROR(ENOENT)); 316 317 zfsctl_snapshot_remove(se); 318 kmem_strfree(se->se_name); 319 se->se_name = kmem_strdup(new_snapname); 320 zfsctl_snapshot_add(se); 321 zfsctl_snapshot_rele(se); 322 323 return (0); 324 } 325 326 /* 327 * Delayed task responsible for unmounting an expired automounted snapshot. 328 */ 329 static void 330 snapentry_expire(void *data) 331 { 332 zfs_snapentry_t *se = (zfs_snapentry_t *)data; 333 spa_t *spa = se->se_spa; 334 uint64_t objsetid = se->se_objsetid; 335 336 if (zfs_expire_snapshot <= 0) { 337 zfsctl_snapshot_rele(se); 338 return; 339 } 340 341 rw_enter(&se->se_taskqid_lock, RW_WRITER); 342 se->se_taskqid = TASKQID_INVALID; 343 rw_exit(&se->se_taskqid_lock); 344 (void) zfsctl_snapshot_unmount(se->se_name, MNT_EXPIRE); 345 zfsctl_snapshot_rele(se); 346 347 /* 348 * Reschedule the unmount if the zfs_snapentry_t wasn't removed. 349 * This can occur when the snapshot is busy. 350 */ 351 rw_enter(&zfs_snapshot_lock, RW_READER); 352 if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) { 353 zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot); 354 zfsctl_snapshot_rele(se); 355 } 356 rw_exit(&zfs_snapshot_lock); 357 } 358 359 /* 360 * Cancel an automatic unmount of a snapname. This callback is responsible 361 * for dropping the reference on the zfs_snapentry_t which was taken when 362 * during dispatch. 363 */ 364 static void 365 zfsctl_snapshot_unmount_cancel(zfs_snapentry_t *se) 366 { 367 int err = 0; 368 rw_enter(&se->se_taskqid_lock, RW_WRITER); 369 err = taskq_cancel_id(system_delay_taskq, se->se_taskqid); 370 /* 371 * if we get ENOENT, the taskq couldn't be found to be 372 * canceled, so we can just mark it as invalid because 373 * it's already gone. If we got EBUSY, then we already 374 * blocked until it was gone _anyway_, so we don't care. 375 */ 376 se->se_taskqid = TASKQID_INVALID; 377 rw_exit(&se->se_taskqid_lock); 378 if (err == 0) { 379 zfsctl_snapshot_rele(se); 380 } 381 } 382 383 /* 384 * Dispatch the unmount task for delayed handling with a hold protecting it. 385 */ 386 static void 387 zfsctl_snapshot_unmount_delay_impl(zfs_snapentry_t *se, int delay) 388 { 389 390 if (delay <= 0) 391 return; 392 393 zfsctl_snapshot_hold(se); 394 rw_enter(&se->se_taskqid_lock, RW_WRITER); 395 /* 396 * If this condition happens, we managed to: 397 * - dispatch once 398 * - want to dispatch _again_ before it returned 399 * 400 * So let's just return - if that task fails at unmounting, 401 * we'll eventually dispatch again, and if it succeeds, 402 * no problem. 403 */ 404 if (se->se_taskqid != TASKQID_INVALID) { 405 rw_exit(&se->se_taskqid_lock); 406 zfsctl_snapshot_rele(se); 407 return; 408 } 409 se->se_taskqid = taskq_dispatch_delay(system_delay_taskq, 410 snapentry_expire, se, TQ_SLEEP, ddi_get_lbolt() + delay * HZ); 411 rw_exit(&se->se_taskqid_lock); 412 } 413 414 /* 415 * Schedule an automatic unmount of objset id to occur in delay seconds from 416 * now. Any previous delayed unmount will be cancelled in favor of the 417 * updated deadline. A reference is taken by zfsctl_snapshot_find_by_name() 418 * and held until the outstanding task is handled or cancelled. 419 */ 420 int 421 zfsctl_snapshot_unmount_delay(spa_t *spa, uint64_t objsetid, int delay) 422 { 423 zfs_snapentry_t *se; 424 int error = ENOENT; 425 426 rw_enter(&zfs_snapshot_lock, RW_READER); 427 if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) { 428 zfsctl_snapshot_unmount_cancel(se); 429 zfsctl_snapshot_unmount_delay_impl(se, delay); 430 zfsctl_snapshot_rele(se); 431 error = 0; 432 } 433 rw_exit(&zfs_snapshot_lock); 434 435 return (error); 436 } 437 438 /* 439 * Check if snapname is currently mounted. Returned non-zero when mounted 440 * and zero when unmounted. 441 */ 442 static boolean_t 443 zfsctl_snapshot_ismounted(const char *snapname) 444 { 445 zfs_snapentry_t *se; 446 boolean_t ismounted = B_FALSE; 447 448 rw_enter(&zfs_snapshot_lock, RW_READER); 449 if ((se = zfsctl_snapshot_find_by_name(snapname)) != NULL) { 450 zfsctl_snapshot_rele(se); 451 ismounted = B_TRUE; 452 } 453 rw_exit(&zfs_snapshot_lock); 454 455 return (ismounted); 456 } 457 458 /* 459 * Check if the given inode is a part of the virtual .zfs directory. 460 */ 461 boolean_t 462 zfsctl_is_node(struct inode *ip) 463 { 464 return (ITOZ(ip)->z_is_ctldir); 465 } 466 467 /* 468 * Check if the given inode is a .zfs/snapshots/snapname directory. 469 */ 470 boolean_t 471 zfsctl_is_snapdir(struct inode *ip) 472 { 473 return (zfsctl_is_node(ip) && (ip->i_ino <= ZFSCTL_INO_SNAPDIRS)); 474 } 475 476 /* 477 * Allocate a new inode with the passed id and ops. 478 */ 479 static struct inode * 480 zfsctl_inode_alloc(zfsvfs_t *zfsvfs, uint64_t id, 481 const struct file_operations *fops, const struct inode_operations *ops) 482 { 483 inode_timespec_t now; 484 struct inode *ip; 485 znode_t *zp; 486 487 ip = new_inode(zfsvfs->z_sb); 488 if (ip == NULL) 489 return (NULL); 490 491 now = current_time(ip); 492 zp = ITOZ(ip); 493 ASSERT3P(zp->z_dirlocks, ==, NULL); 494 ASSERT3P(zp->z_acl_cached, ==, NULL); 495 ASSERT3P(zp->z_xattr_cached, ==, NULL); 496 zp->z_id = id; 497 zp->z_unlinked = B_FALSE; 498 zp->z_atime_dirty = B_FALSE; 499 zp->z_zn_prefetch = B_FALSE; 500 zp->z_is_sa = B_FALSE; 501 #if !defined(HAVE_FILEMAP_RANGE_HAS_PAGE) 502 zp->z_is_mapped = B_FALSE; 503 #endif 504 zp->z_is_ctldir = B_TRUE; 505 zp->z_sa_hdl = NULL; 506 zp->z_blksz = 0; 507 zp->z_seq = 0; 508 zp->z_mapcnt = 0; 509 zp->z_size = 0; 510 zp->z_pflags = 0; 511 zp->z_mode = 0; 512 zp->z_sync_cnt = 0; 513 zp->z_sync_writes_cnt = 0; 514 zp->z_async_writes_cnt = 0; 515 ip->i_generation = 0; 516 ip->i_ino = id; 517 ip->i_mode = (S_IFDIR | S_IRWXUGO); 518 ip->i_uid = SUID_TO_KUID(0); 519 ip->i_gid = SGID_TO_KGID(0); 520 ip->i_blkbits = SPA_MINBLOCKSHIFT; 521 ip->i_atime = now; 522 ip->i_mtime = now; 523 ip->i_ctime = now; 524 ip->i_fop = fops; 525 ip->i_op = ops; 526 #if defined(IOP_XATTR) 527 ip->i_opflags &= ~IOP_XATTR; 528 #endif 529 530 if (insert_inode_locked(ip)) { 531 unlock_new_inode(ip); 532 iput(ip); 533 return (NULL); 534 } 535 536 mutex_enter(&zfsvfs->z_znodes_lock); 537 list_insert_tail(&zfsvfs->z_all_znodes, zp); 538 zfsvfs->z_nr_znodes++; 539 membar_producer(); 540 mutex_exit(&zfsvfs->z_znodes_lock); 541 542 unlock_new_inode(ip); 543 544 return (ip); 545 } 546 547 /* 548 * Lookup the inode with given id, it will be allocated if needed. 549 */ 550 static struct inode * 551 zfsctl_inode_lookup(zfsvfs_t *zfsvfs, uint64_t id, 552 const struct file_operations *fops, const struct inode_operations *ops) 553 { 554 struct inode *ip = NULL; 555 556 while (ip == NULL) { 557 ip = ilookup(zfsvfs->z_sb, (unsigned long)id); 558 if (ip) 559 break; 560 561 /* May fail due to concurrent zfsctl_inode_alloc() */ 562 ip = zfsctl_inode_alloc(zfsvfs, id, fops, ops); 563 } 564 565 return (ip); 566 } 567 568 /* 569 * Create the '.zfs' directory. This directory is cached as part of the VFS 570 * structure. This results in a hold on the zfsvfs_t. The code in zfs_umount() 571 * therefore checks against a vfs_count of 2 instead of 1. This reference 572 * is removed when the ctldir is destroyed in the unmount. All other entities 573 * under the '.zfs' directory are created dynamically as needed. 574 * 575 * Because the dynamically created '.zfs' directory entries assume the use 576 * of 64-bit inode numbers this support must be disabled on 32-bit systems. 577 */ 578 int 579 zfsctl_create(zfsvfs_t *zfsvfs) 580 { 581 ASSERT(zfsvfs->z_ctldir == NULL); 582 583 zfsvfs->z_ctldir = zfsctl_inode_alloc(zfsvfs, ZFSCTL_INO_ROOT, 584 &zpl_fops_root, &zpl_ops_root); 585 if (zfsvfs->z_ctldir == NULL) 586 return (SET_ERROR(ENOENT)); 587 588 return (0); 589 } 590 591 /* 592 * Destroy the '.zfs' directory or remove a snapshot from zfs_snapshots_by_name. 593 * Only called when the filesystem is unmounted. 594 */ 595 void 596 zfsctl_destroy(zfsvfs_t *zfsvfs) 597 { 598 if (zfsvfs->z_issnap) { 599 zfs_snapentry_t *se; 600 spa_t *spa = zfsvfs->z_os->os_spa; 601 uint64_t objsetid = dmu_objset_id(zfsvfs->z_os); 602 603 rw_enter(&zfs_snapshot_lock, RW_WRITER); 604 se = zfsctl_snapshot_find_by_objsetid(spa, objsetid); 605 if (se != NULL) 606 zfsctl_snapshot_remove(se); 607 rw_exit(&zfs_snapshot_lock); 608 if (se != NULL) { 609 zfsctl_snapshot_unmount_cancel(se); 610 zfsctl_snapshot_rele(se); 611 } 612 } else if (zfsvfs->z_ctldir) { 613 iput(zfsvfs->z_ctldir); 614 zfsvfs->z_ctldir = NULL; 615 } 616 } 617 618 /* 619 * Given a root znode, retrieve the associated .zfs directory. 620 * Add a hold to the vnode and return it. 621 */ 622 struct inode * 623 zfsctl_root(znode_t *zp) 624 { 625 ASSERT(zfs_has_ctldir(zp)); 626 /* Must have an existing ref, so igrab() cannot return NULL */ 627 VERIFY3P(igrab(ZTOZSB(zp)->z_ctldir), !=, NULL); 628 return (ZTOZSB(zp)->z_ctldir); 629 } 630 631 /* 632 * Generate a long fid to indicate a snapdir. We encode whether snapdir is 633 * already mounted in gen field. We do this because nfsd lookup will not 634 * trigger automount. Next time the nfsd does fh_to_dentry, we will notice 635 * this and do automount and return ESTALE to force nfsd revalidate and follow 636 * mount. 637 */ 638 static int 639 zfsctl_snapdir_fid(struct inode *ip, fid_t *fidp) 640 { 641 zfid_short_t *zfid = (zfid_short_t *)fidp; 642 zfid_long_t *zlfid = (zfid_long_t *)fidp; 643 uint32_t gen = 0; 644 uint64_t object; 645 uint64_t objsetid; 646 int i; 647 struct dentry *dentry; 648 649 if (fidp->fid_len < LONG_FID_LEN) { 650 fidp->fid_len = LONG_FID_LEN; 651 return (SET_ERROR(ENOSPC)); 652 } 653 654 object = ip->i_ino; 655 objsetid = ZFSCTL_INO_SNAPDIRS - ip->i_ino; 656 zfid->zf_len = LONG_FID_LEN; 657 658 dentry = d_obtain_alias(igrab(ip)); 659 if (!IS_ERR(dentry)) { 660 gen = !!d_mountpoint(dentry); 661 dput(dentry); 662 } 663 664 for (i = 0; i < sizeof (zfid->zf_object); i++) 665 zfid->zf_object[i] = (uint8_t)(object >> (8 * i)); 666 667 for (i = 0; i < sizeof (zfid->zf_gen); i++) 668 zfid->zf_gen[i] = (uint8_t)(gen >> (8 * i)); 669 670 for (i = 0; i < sizeof (zlfid->zf_setid); i++) 671 zlfid->zf_setid[i] = (uint8_t)(objsetid >> (8 * i)); 672 673 for (i = 0; i < sizeof (zlfid->zf_setgen); i++) 674 zlfid->zf_setgen[i] = 0; 675 676 return (0); 677 } 678 679 /* 680 * Generate an appropriate fid for an entry in the .zfs directory. 681 */ 682 int 683 zfsctl_fid(struct inode *ip, fid_t *fidp) 684 { 685 znode_t *zp = ITOZ(ip); 686 zfsvfs_t *zfsvfs = ITOZSB(ip); 687 uint64_t object = zp->z_id; 688 zfid_short_t *zfid; 689 int i; 690 int error; 691 692 if ((error = zfs_enter(zfsvfs, FTAG)) != 0) 693 return (error); 694 695 if (zfsctl_is_snapdir(ip)) { 696 zfs_exit(zfsvfs, FTAG); 697 return (zfsctl_snapdir_fid(ip, fidp)); 698 } 699 700 if (fidp->fid_len < SHORT_FID_LEN) { 701 fidp->fid_len = SHORT_FID_LEN; 702 zfs_exit(zfsvfs, FTAG); 703 return (SET_ERROR(ENOSPC)); 704 } 705 706 zfid = (zfid_short_t *)fidp; 707 708 zfid->zf_len = SHORT_FID_LEN; 709 710 for (i = 0; i < sizeof (zfid->zf_object); i++) 711 zfid->zf_object[i] = (uint8_t)(object >> (8 * i)); 712 713 /* .zfs znodes always have a generation number of 0 */ 714 for (i = 0; i < sizeof (zfid->zf_gen); i++) 715 zfid->zf_gen[i] = 0; 716 717 zfs_exit(zfsvfs, FTAG); 718 return (0); 719 } 720 721 /* 722 * Construct a full dataset name in full_name: "pool/dataset@snap_name" 723 */ 724 static int 725 zfsctl_snapshot_name(zfsvfs_t *zfsvfs, const char *snap_name, int len, 726 char *full_name) 727 { 728 objset_t *os = zfsvfs->z_os; 729 730 if (zfs_component_namecheck(snap_name, NULL, NULL) != 0) 731 return (SET_ERROR(EILSEQ)); 732 733 dmu_objset_name(os, full_name); 734 if ((strlen(full_name) + 1 + strlen(snap_name)) >= len) 735 return (SET_ERROR(ENAMETOOLONG)); 736 737 (void) strcat(full_name, "@"); 738 (void) strcat(full_name, snap_name); 739 740 return (0); 741 } 742 743 /* 744 * Returns full path in full_path: "/pool/dataset/.zfs/snapshot/snap_name/" 745 */ 746 static int 747 zfsctl_snapshot_path_objset(zfsvfs_t *zfsvfs, uint64_t objsetid, 748 int path_len, char *full_path) 749 { 750 objset_t *os = zfsvfs->z_os; 751 fstrans_cookie_t cookie; 752 char *snapname; 753 boolean_t case_conflict; 754 uint64_t id, pos = 0; 755 int error = 0; 756 757 if (zfsvfs->z_vfs->vfs_mntpoint == NULL) 758 return (SET_ERROR(ENOENT)); 759 760 cookie = spl_fstrans_mark(); 761 snapname = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 762 763 while (error == 0) { 764 dsl_pool_config_enter(dmu_objset_pool(os), FTAG); 765 error = dmu_snapshot_list_next(zfsvfs->z_os, 766 ZFS_MAX_DATASET_NAME_LEN, snapname, &id, &pos, 767 &case_conflict); 768 dsl_pool_config_exit(dmu_objset_pool(os), FTAG); 769 if (error) 770 goto out; 771 772 if (id == objsetid) 773 break; 774 } 775 776 snprintf(full_path, path_len, "%s/.zfs/snapshot/%s", 777 zfsvfs->z_vfs->vfs_mntpoint, snapname); 778 out: 779 kmem_free(snapname, ZFS_MAX_DATASET_NAME_LEN); 780 spl_fstrans_unmark(cookie); 781 782 return (error); 783 } 784 785 /* 786 * Special case the handling of "..". 787 */ 788 int 789 zfsctl_root_lookup(struct inode *dip, const char *name, struct inode **ipp, 790 int flags, cred_t *cr, int *direntflags, pathname_t *realpnp) 791 { 792 zfsvfs_t *zfsvfs = ITOZSB(dip); 793 int error = 0; 794 795 if ((error = zfs_enter(zfsvfs, FTAG)) != 0) 796 return (error); 797 798 if (strcmp(name, "..") == 0) { 799 *ipp = dip->i_sb->s_root->d_inode; 800 } else if (strcmp(name, ZFS_SNAPDIR_NAME) == 0) { 801 *ipp = zfsctl_inode_lookup(zfsvfs, ZFSCTL_INO_SNAPDIR, 802 &zpl_fops_snapdir, &zpl_ops_snapdir); 803 } else if (strcmp(name, ZFS_SHAREDIR_NAME) == 0) { 804 *ipp = zfsctl_inode_lookup(zfsvfs, ZFSCTL_INO_SHARES, 805 &zpl_fops_shares, &zpl_ops_shares); 806 } else { 807 *ipp = NULL; 808 } 809 810 if (*ipp == NULL) 811 error = SET_ERROR(ENOENT); 812 813 zfs_exit(zfsvfs, FTAG); 814 815 return (error); 816 } 817 818 /* 819 * Lookup entry point for the 'snapshot' directory. Try to open the 820 * snapshot if it exist, creating the pseudo filesystem inode as necessary. 821 */ 822 int 823 zfsctl_snapdir_lookup(struct inode *dip, const char *name, struct inode **ipp, 824 int flags, cred_t *cr, int *direntflags, pathname_t *realpnp) 825 { 826 zfsvfs_t *zfsvfs = ITOZSB(dip); 827 uint64_t id; 828 int error; 829 830 if ((error = zfs_enter(zfsvfs, FTAG)) != 0) 831 return (error); 832 833 error = dmu_snapshot_lookup(zfsvfs->z_os, name, &id); 834 if (error) { 835 zfs_exit(zfsvfs, FTAG); 836 return (error); 837 } 838 839 *ipp = zfsctl_inode_lookup(zfsvfs, ZFSCTL_INO_SNAPDIRS - id, 840 &simple_dir_operations, &simple_dir_inode_operations); 841 if (*ipp == NULL) 842 error = SET_ERROR(ENOENT); 843 844 zfs_exit(zfsvfs, FTAG); 845 846 return (error); 847 } 848 849 /* 850 * Renaming a directory under '.zfs/snapshot' will automatically trigger 851 * a rename of the snapshot to the new given name. The rename is confined 852 * to the '.zfs/snapshot' directory snapshots cannot be moved elsewhere. 853 */ 854 int 855 zfsctl_snapdir_rename(struct inode *sdip, const char *snm, 856 struct inode *tdip, const char *tnm, cred_t *cr, int flags) 857 { 858 zfsvfs_t *zfsvfs = ITOZSB(sdip); 859 char *to, *from, *real, *fsname; 860 int error; 861 862 if (!zfs_admin_snapshot) 863 return (SET_ERROR(EACCES)); 864 865 if ((error = zfs_enter(zfsvfs, FTAG)) != 0) 866 return (error); 867 868 to = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 869 from = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 870 real = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 871 fsname = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 872 873 if (zfsvfs->z_case == ZFS_CASE_INSENSITIVE) { 874 error = dmu_snapshot_realname(zfsvfs->z_os, snm, real, 875 ZFS_MAX_DATASET_NAME_LEN, NULL); 876 if (error == 0) { 877 snm = real; 878 } else if (error != ENOTSUP) { 879 goto out; 880 } 881 } 882 883 dmu_objset_name(zfsvfs->z_os, fsname); 884 885 error = zfsctl_snapshot_name(ITOZSB(sdip), snm, 886 ZFS_MAX_DATASET_NAME_LEN, from); 887 if (error == 0) 888 error = zfsctl_snapshot_name(ITOZSB(tdip), tnm, 889 ZFS_MAX_DATASET_NAME_LEN, to); 890 if (error == 0) 891 error = zfs_secpolicy_rename_perms(from, to, cr); 892 if (error != 0) 893 goto out; 894 895 /* 896 * Cannot move snapshots out of the snapdir. 897 */ 898 if (sdip != tdip) { 899 error = SET_ERROR(EINVAL); 900 goto out; 901 } 902 903 /* 904 * No-op when names are identical. 905 */ 906 if (strcmp(snm, tnm) == 0) { 907 error = 0; 908 goto out; 909 } 910 911 rw_enter(&zfs_snapshot_lock, RW_WRITER); 912 913 error = dsl_dataset_rename_snapshot(fsname, snm, tnm, B_FALSE); 914 if (error == 0) 915 (void) zfsctl_snapshot_rename(snm, tnm); 916 917 rw_exit(&zfs_snapshot_lock); 918 out: 919 kmem_free(from, ZFS_MAX_DATASET_NAME_LEN); 920 kmem_free(to, ZFS_MAX_DATASET_NAME_LEN); 921 kmem_free(real, ZFS_MAX_DATASET_NAME_LEN); 922 kmem_free(fsname, ZFS_MAX_DATASET_NAME_LEN); 923 924 zfs_exit(zfsvfs, FTAG); 925 926 return (error); 927 } 928 929 /* 930 * Removing a directory under '.zfs/snapshot' will automatically trigger 931 * the removal of the snapshot with the given name. 932 */ 933 int 934 zfsctl_snapdir_remove(struct inode *dip, const char *name, cred_t *cr, 935 int flags) 936 { 937 zfsvfs_t *zfsvfs = ITOZSB(dip); 938 char *snapname, *real; 939 int error; 940 941 if (!zfs_admin_snapshot) 942 return (SET_ERROR(EACCES)); 943 944 if ((error = zfs_enter(zfsvfs, FTAG)) != 0) 945 return (error); 946 947 snapname = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 948 real = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 949 950 if (zfsvfs->z_case == ZFS_CASE_INSENSITIVE) { 951 error = dmu_snapshot_realname(zfsvfs->z_os, name, real, 952 ZFS_MAX_DATASET_NAME_LEN, NULL); 953 if (error == 0) { 954 name = real; 955 } else if (error != ENOTSUP) { 956 goto out; 957 } 958 } 959 960 error = zfsctl_snapshot_name(ITOZSB(dip), name, 961 ZFS_MAX_DATASET_NAME_LEN, snapname); 962 if (error == 0) 963 error = zfs_secpolicy_destroy_perms(snapname, cr); 964 if (error != 0) 965 goto out; 966 967 error = zfsctl_snapshot_unmount(snapname, MNT_FORCE); 968 if ((error == 0) || (error == ENOENT)) 969 error = dsl_destroy_snapshot(snapname, B_FALSE); 970 out: 971 kmem_free(snapname, ZFS_MAX_DATASET_NAME_LEN); 972 kmem_free(real, ZFS_MAX_DATASET_NAME_LEN); 973 974 zfs_exit(zfsvfs, FTAG); 975 976 return (error); 977 } 978 979 /* 980 * Creating a directory under '.zfs/snapshot' will automatically trigger 981 * the creation of a new snapshot with the given name. 982 */ 983 int 984 zfsctl_snapdir_mkdir(struct inode *dip, const char *dirname, vattr_t *vap, 985 struct inode **ipp, cred_t *cr, int flags) 986 { 987 zfsvfs_t *zfsvfs = ITOZSB(dip); 988 char *dsname; 989 int error; 990 991 if (!zfs_admin_snapshot) 992 return (SET_ERROR(EACCES)); 993 994 dsname = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 995 996 if (zfs_component_namecheck(dirname, NULL, NULL) != 0) { 997 error = SET_ERROR(EILSEQ); 998 goto out; 999 } 1000 1001 dmu_objset_name(zfsvfs->z_os, dsname); 1002 1003 error = zfs_secpolicy_snapshot_perms(dsname, cr); 1004 if (error != 0) 1005 goto out; 1006 1007 if (error == 0) { 1008 error = dmu_objset_snapshot_one(dsname, dirname); 1009 if (error != 0) 1010 goto out; 1011 1012 error = zfsctl_snapdir_lookup(dip, dirname, ipp, 1013 0, cr, NULL, NULL); 1014 } 1015 out: 1016 kmem_free(dsname, ZFS_MAX_DATASET_NAME_LEN); 1017 1018 return (error); 1019 } 1020 1021 /* 1022 * Flush everything out of the kernel's export table and such. 1023 * This is needed as once the snapshot is used over NFS, its 1024 * entries in svc_export and svc_expkey caches hold reference 1025 * to the snapshot mount point. There is no known way of flushing 1026 * only the entries related to the snapshot. 1027 */ 1028 static void 1029 exportfs_flush(void) 1030 { 1031 char *argv[] = { "/usr/sbin/exportfs", "-f", NULL }; 1032 char *envp[] = { NULL }; 1033 1034 (void) call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC); 1035 } 1036 1037 /* 1038 * Attempt to unmount a snapshot by making a call to user space. 1039 * There is no assurance that this can or will succeed, is just a 1040 * best effort. In the case where it does fail, perhaps because 1041 * it's in use, the unmount will fail harmlessly. 1042 */ 1043 int 1044 zfsctl_snapshot_unmount(const char *snapname, int flags) 1045 { 1046 char *argv[] = { "/usr/bin/env", "umount", "-t", "zfs", "-n", NULL, 1047 NULL }; 1048 char *envp[] = { NULL }; 1049 zfs_snapentry_t *se; 1050 int error; 1051 1052 rw_enter(&zfs_snapshot_lock, RW_READER); 1053 if ((se = zfsctl_snapshot_find_by_name(snapname)) == NULL) { 1054 rw_exit(&zfs_snapshot_lock); 1055 return (SET_ERROR(ENOENT)); 1056 } 1057 rw_exit(&zfs_snapshot_lock); 1058 1059 exportfs_flush(); 1060 1061 if (flags & MNT_FORCE) 1062 argv[4] = "-fn"; 1063 argv[5] = se->se_path; 1064 dprintf("unmount; path=%s\n", se->se_path); 1065 error = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC); 1066 zfsctl_snapshot_rele(se); 1067 1068 1069 /* 1070 * The umount system utility will return 256 on error. We must 1071 * assume this error is because the file system is busy so it is 1072 * converted to the more sensible EBUSY. 1073 */ 1074 if (error) 1075 error = SET_ERROR(EBUSY); 1076 1077 return (error); 1078 } 1079 1080 int 1081 zfsctl_snapshot_mount(struct path *path, int flags) 1082 { 1083 struct dentry *dentry = path->dentry; 1084 struct inode *ip = dentry->d_inode; 1085 zfsvfs_t *zfsvfs; 1086 zfsvfs_t *snap_zfsvfs; 1087 zfs_snapentry_t *se; 1088 char *full_name, *full_path; 1089 char *argv[] = { "/usr/bin/env", "mount", "-t", "zfs", "-n", NULL, NULL, 1090 NULL }; 1091 char *envp[] = { NULL }; 1092 int error; 1093 struct path spath; 1094 1095 if (ip == NULL) 1096 return (SET_ERROR(EISDIR)); 1097 1098 zfsvfs = ITOZSB(ip); 1099 if ((error = zfs_enter(zfsvfs, FTAG)) != 0) 1100 return (error); 1101 1102 full_name = kmem_zalloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP); 1103 full_path = kmem_zalloc(MAXPATHLEN, KM_SLEEP); 1104 1105 error = zfsctl_snapshot_name(zfsvfs, dname(dentry), 1106 ZFS_MAX_DATASET_NAME_LEN, full_name); 1107 if (error) 1108 goto error; 1109 1110 /* 1111 * Construct a mount point path from sb of the ctldir inode and dirent 1112 * name, instead of from d_path(), so that chroot'd process doesn't fail 1113 * on mount.zfs(8). 1114 */ 1115 snprintf(full_path, MAXPATHLEN, "%s/.zfs/snapshot/%s", 1116 zfsvfs->z_vfs->vfs_mntpoint ? zfsvfs->z_vfs->vfs_mntpoint : "", 1117 dname(dentry)); 1118 1119 /* 1120 * Multiple concurrent automounts of a snapshot are never allowed. 1121 * The snapshot may be manually mounted as many times as desired. 1122 */ 1123 if (zfsctl_snapshot_ismounted(full_name)) { 1124 error = 0; 1125 goto error; 1126 } 1127 1128 /* 1129 * Attempt to mount the snapshot from user space. Normally this 1130 * would be done using the vfs_kern_mount() function, however that 1131 * function is marked GPL-only and cannot be used. On error we 1132 * careful to log the real error to the console and return EISDIR 1133 * to safely abort the automount. This should be very rare. 1134 * 1135 * If the user mode helper happens to return EBUSY, a concurrent 1136 * mount is already in progress in which case the error is ignored. 1137 * Take note that if the program was executed successfully the return 1138 * value from call_usermodehelper() will be (exitcode << 8 + signal). 1139 */ 1140 dprintf("mount; name=%s path=%s\n", full_name, full_path); 1141 argv[5] = full_name; 1142 argv[6] = full_path; 1143 error = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC); 1144 if (error) { 1145 if (!(error & MOUNT_BUSY << 8)) { 1146 zfs_dbgmsg("Unable to automount %s error=%d", 1147 full_path, error); 1148 error = SET_ERROR(EISDIR); 1149 } else { 1150 /* 1151 * EBUSY, this could mean a concurrent mount, or the 1152 * snapshot has already been mounted at completely 1153 * different place. We return 0 so VFS will retry. For 1154 * the latter case the VFS will retry several times 1155 * and return ELOOP, which is probably not a very good 1156 * behavior. 1157 */ 1158 error = 0; 1159 } 1160 goto error; 1161 } 1162 1163 /* 1164 * Follow down in to the mounted snapshot and set MNT_SHRINKABLE 1165 * to identify this as an automounted filesystem. 1166 */ 1167 spath = *path; 1168 path_get(&spath); 1169 if (follow_down_one(&spath)) { 1170 snap_zfsvfs = ITOZSB(spath.dentry->d_inode); 1171 snap_zfsvfs->z_parent = zfsvfs; 1172 dentry = spath.dentry; 1173 spath.mnt->mnt_flags |= MNT_SHRINKABLE; 1174 1175 rw_enter(&zfs_snapshot_lock, RW_WRITER); 1176 se = zfsctl_snapshot_alloc(full_name, full_path, 1177 snap_zfsvfs->z_os->os_spa, dmu_objset_id(snap_zfsvfs->z_os), 1178 dentry); 1179 zfsctl_snapshot_add(se); 1180 zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot); 1181 rw_exit(&zfs_snapshot_lock); 1182 } 1183 path_put(&spath); 1184 error: 1185 kmem_free(full_name, ZFS_MAX_DATASET_NAME_LEN); 1186 kmem_free(full_path, MAXPATHLEN); 1187 1188 zfs_exit(zfsvfs, FTAG); 1189 1190 return (error); 1191 } 1192 1193 /* 1194 * Get the snapdir inode from fid 1195 */ 1196 int 1197 zfsctl_snapdir_vget(struct super_block *sb, uint64_t objsetid, int gen, 1198 struct inode **ipp) 1199 { 1200 int error; 1201 struct path path; 1202 char *mnt; 1203 struct dentry *dentry; 1204 1205 mnt = kmem_alloc(MAXPATHLEN, KM_SLEEP); 1206 1207 error = zfsctl_snapshot_path_objset(sb->s_fs_info, objsetid, 1208 MAXPATHLEN, mnt); 1209 if (error) 1210 goto out; 1211 1212 /* Trigger automount */ 1213 error = -kern_path(mnt, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &path); 1214 if (error) 1215 goto out; 1216 1217 path_put(&path); 1218 /* 1219 * Get the snapdir inode. Note, we don't want to use the above 1220 * path because it contains the root of the snapshot rather 1221 * than the snapdir. 1222 */ 1223 *ipp = ilookup(sb, ZFSCTL_INO_SNAPDIRS - objsetid); 1224 if (*ipp == NULL) { 1225 error = SET_ERROR(ENOENT); 1226 goto out; 1227 } 1228 1229 /* check gen, see zfsctl_snapdir_fid */ 1230 dentry = d_obtain_alias(igrab(*ipp)); 1231 if (gen != (!IS_ERR(dentry) && d_mountpoint(dentry))) { 1232 iput(*ipp); 1233 *ipp = NULL; 1234 error = SET_ERROR(ENOENT); 1235 } 1236 if (!IS_ERR(dentry)) 1237 dput(dentry); 1238 out: 1239 kmem_free(mnt, MAXPATHLEN); 1240 return (error); 1241 } 1242 1243 int 1244 zfsctl_shares_lookup(struct inode *dip, char *name, struct inode **ipp, 1245 int flags, cred_t *cr, int *direntflags, pathname_t *realpnp) 1246 { 1247 zfsvfs_t *zfsvfs = ITOZSB(dip); 1248 znode_t *zp; 1249 znode_t *dzp; 1250 int error; 1251 1252 if ((error = zfs_enter(zfsvfs, FTAG)) != 0) 1253 return (error); 1254 1255 if (zfsvfs->z_shares_dir == 0) { 1256 zfs_exit(zfsvfs, FTAG); 1257 return (SET_ERROR(ENOTSUP)); 1258 } 1259 1260 if ((error = zfs_zget(zfsvfs, zfsvfs->z_shares_dir, &dzp)) == 0) { 1261 error = zfs_lookup(dzp, name, &zp, 0, cr, NULL, NULL); 1262 zrele(dzp); 1263 } 1264 1265 zfs_exit(zfsvfs, FTAG); 1266 1267 return (error); 1268 } 1269 1270 /* 1271 * Initialize the various pieces we'll need to create and manipulate .zfs 1272 * directories. Currently this is unused but available. 1273 */ 1274 void 1275 zfsctl_init(void) 1276 { 1277 avl_create(&zfs_snapshots_by_name, snapentry_compare_by_name, 1278 sizeof (zfs_snapentry_t), offsetof(zfs_snapentry_t, 1279 se_node_name)); 1280 avl_create(&zfs_snapshots_by_objsetid, snapentry_compare_by_objsetid, 1281 sizeof (zfs_snapentry_t), offsetof(zfs_snapentry_t, 1282 se_node_objsetid)); 1283 rw_init(&zfs_snapshot_lock, NULL, RW_DEFAULT, NULL); 1284 } 1285 1286 /* 1287 * Cleanup the various pieces we needed for .zfs directories. In particular 1288 * ensure the expiry timer is canceled safely. 1289 */ 1290 void 1291 zfsctl_fini(void) 1292 { 1293 avl_destroy(&zfs_snapshots_by_name); 1294 avl_destroy(&zfs_snapshots_by_objsetid); 1295 rw_destroy(&zfs_snapshot_lock); 1296 } 1297 1298 module_param(zfs_admin_snapshot, int, 0644); 1299 MODULE_PARM_DESC(zfs_admin_snapshot, "Enable mkdir/rmdir/mv in .zfs/snapshot"); 1300 1301 module_param(zfs_expire_snapshot, int, 0644); 1302 MODULE_PARM_DESC(zfs_expire_snapshot, "Seconds to expire .zfs/snapshot"); 1303