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.
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
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]
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).
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.
34 * ZFS control directory (a.k.a. ".zfs")
36 * This directory provides a common location for all ZFS meta-objects.
37 * Currently, this is only the 'snapshot' and 'shares' directory, but this may
38 * expand in the future. The elements are built dynamically, as the hierarchy
39 * does not actually exist on disk.
41 * For 'snapshot', we don't want to have all snapshots always mounted, because
42 * this would take up a huge amount of space in /etc/mnttab. We have three
45 * ctldir ------> snapshotdir -------> snapshot
51 * The 'snapshot' node contains just enough information to lookup '..' and act
52 * as a mountpoint for the snapshot. Whenever we lookup a specific snapshot, we
53 * perform an automount of the underlying filesystem and return the
54 * corresponding inode.
56 * All mounts are handled automatically by an user mode helper which invokes
57 * the mount mount procedure. Unmounts are handled by allowing the mount
58 * point to expire so the kernel may automatically unmount it.
60 * The '.zfs', '.zfs/snapshot', and all directories created under
61 * '.zfs/snapshot' (ie: '.zfs/snapshot/<snapname>') all share the same
62 * share the same zfs_sb_t as the head filesystem (what '.zfs' lives under).
64 * File systems mounted on top of the '.zfs/snapshot/<snapname>' paths
65 * (ie: snapshots) are complete ZFS filesystems and have their own unique
66 * zfs_sb_t. However, the fsid reported by these mounts will be the same
67 * as that used by the parent zfs_sb_t to make NFS happy.
70 #include <sys/types.h>
71 #include <sys/param.h>
73 #include <sys/systm.h>
74 #include <sys/sysmacros.h>
75 #include <sys/pathname.h>
77 #include <sys/vfs_opreg.h>
78 #include <sys/zfs_ctldir.h>
79 #include <sys/zfs_ioctl.h>
80 #include <sys/zfs_vfsops.h>
81 #include <sys/zfs_vnops.h>
84 #include <sys/dmu_objset.h>
85 #include <sys/dsl_destroy.h>
86 #include <sys/dsl_deleg.h>
87 #include <sys/mount.h>
89 #include "zfs_namecheck.h"
92 * Two AVL trees are maintained which contain all currently automounted
93 * snapshots. Every automounted snapshots maps to a single zfs_snapentry_t
96 * - be attached to both trees, and
97 * - be unique, no duplicate entries are allowed.
99 * The zfs_snapshots_by_name tree is indexed by the full dataset name
100 * while the zfs_snapshots_by_objsetid tree is indexed by the unique
101 * objsetid. This allows for fast lookups either by name or objsetid.
103 static avl_tree_t zfs_snapshots_by_name
;
104 static avl_tree_t zfs_snapshots_by_objsetid
;
105 static krwlock_t zfs_snapshot_lock
;
108 * Control Directory Tunables (.zfs)
110 int zfs_expire_snapshot
= ZFSCTL_EXPIRE_SNAPSHOT
;
111 int zfs_admin_snapshot
= 0;
114 * Dedicated task queue for unmounting snapshots.
116 static taskq_t
*zfs_expire_taskq
;
119 char *se_name
; /* full snapshot name */
120 char *se_path
; /* full mount path */
121 spa_t
*se_spa
; /* pool spa */
122 uint64_t se_objsetid
; /* snapshot objset id */
123 struct dentry
*se_root_dentry
; /* snapshot root dentry */
124 taskqid_t se_taskqid
; /* scheduled unmount taskqid */
125 avl_node_t se_node_name
; /* zfs_snapshots_by_name link */
126 avl_node_t se_node_objsetid
; /* zfs_snapshots_by_objsetid link */
127 refcount_t se_refcount
; /* reference count */
130 static void zfsctl_snapshot_unmount_delay_impl(zfs_snapentry_t
*se
, int delay
);
133 * Allocate a new zfs_snapentry_t being careful to make a copy of the
134 * the snapshot name and provided mount point. No reference is taken.
136 static zfs_snapentry_t
*
137 zfsctl_snapshot_alloc(char *full_name
, char *full_path
, spa_t
*spa
,
138 uint64_t objsetid
, struct dentry
*root_dentry
)
142 se
= kmem_zalloc(sizeof (zfs_snapentry_t
), KM_SLEEP
);
144 se
->se_name
= strdup(full_name
);
145 se
->se_path
= strdup(full_path
);
147 se
->se_objsetid
= objsetid
;
148 se
->se_root_dentry
= root_dentry
;
151 refcount_create(&se
->se_refcount
);
157 * Free a zfs_snapentry_t the called must ensure there are no active
161 zfsctl_snapshot_free(zfs_snapentry_t
*se
)
163 refcount_destroy(&se
->se_refcount
);
164 strfree(se
->se_name
);
165 strfree(se
->se_path
);
167 kmem_free(se
, sizeof (zfs_snapentry_t
));
171 * Hold a reference on the zfs_snapentry_t.
174 zfsctl_snapshot_hold(zfs_snapentry_t
*se
)
176 refcount_add(&se
->se_refcount
, NULL
);
180 * Release a reference on the zfs_snapentry_t. When the number of
181 * references drops to zero the structure will be freed.
184 zfsctl_snapshot_rele(zfs_snapentry_t
*se
)
186 if (refcount_remove(&se
->se_refcount
, NULL
) == 0)
187 zfsctl_snapshot_free(se
);
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.
196 zfsctl_snapshot_add(zfs_snapentry_t
*se
)
198 ASSERT(RW_WRITE_HELD(&zfs_snapshot_lock
));
199 refcount_add(&se
->se_refcount
, NULL
);
200 avl_add(&zfs_snapshots_by_name
, se
);
201 avl_add(&zfs_snapshots_by_objsetid
, se
);
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.
211 zfsctl_snapshot_remove(zfs_snapentry_t
*se
)
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
);
220 * Snapshot name comparison function for the zfs_snapshots_by_name.
223 snapentry_compare_by_name(const void *a
, const void *b
)
225 const zfs_snapentry_t
*se_a
= a
;
226 const zfs_snapentry_t
*se_b
= b
;
229 ret
= strcmp(se_a
->se_name
, se_b
->se_name
);
240 * Snapshot name comparison function for the zfs_snapshots_by_objsetid.
243 snapentry_compare_by_objsetid(const void *a
, const void *b
)
245 const zfs_snapentry_t
*se_a
= a
;
246 const zfs_snapentry_t
*se_b
= b
;
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);
251 if (se_a
->se_objsetid
< se_b
->se_objsetid
)
253 else if (se_a
->se_objsetid
> se_b
->se_objsetid
)
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.
266 static zfs_snapentry_t
*
267 zfsctl_snapshot_find_by_name(char *snapname
)
269 zfs_snapentry_t
*se
, search
;
271 ASSERT(RW_LOCK_HELD(&zfs_snapshot_lock
));
273 search
.se_name
= snapname
;
274 se
= avl_find(&zfs_snapshots_by_name
, &search
, NULL
);
276 refcount_add(&se
->se_refcount
, NULL
);
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().
286 static zfs_snapentry_t
*
287 zfsctl_snapshot_find_by_objsetid(spa_t
*spa
, uint64_t objsetid
)
289 zfs_snapentry_t
*se
, search
;
291 ASSERT(RW_LOCK_HELD(&zfs_snapshot_lock
));
294 search
.se_objsetid
= objsetid
;
295 se
= avl_find(&zfs_snapshots_by_objsetid
, &search
, NULL
);
297 refcount_add(&se
->se_refcount
, NULL
);
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.
307 zfsctl_snapshot_rename(char *old_snapname
, char *new_snapname
)
311 ASSERT(RW_WRITE_HELD(&zfs_snapshot_lock
));
313 se
= zfsctl_snapshot_find_by_name(old_snapname
);
317 zfsctl_snapshot_remove(se
);
318 strfree(se
->se_name
);
319 se
->se_name
= strdup(new_snapname
);
320 zfsctl_snapshot_add(se
);
321 zfsctl_snapshot_rele(se
);
327 * Delayed task responsible for unmounting an expired automounted snapshot.
330 snapentry_expire(void *data
)
332 zfs_snapentry_t
*se
= (zfs_snapentry_t
*)data
;
333 spa_t
*spa
= se
->se_spa
;
334 uint64_t objsetid
= se
->se_objsetid
;
336 if (zfs_expire_snapshot
<= 0) {
337 zfsctl_snapshot_rele(se
);
342 (void) zfsctl_snapshot_unmount(se
->se_name
, MNT_EXPIRE
);
343 zfsctl_snapshot_rele(se
);
346 * Reschedule the unmount if the zfs_snapentry_t wasn't removed.
347 * This can occur when the snapshot is busy.
349 rw_enter(&zfs_snapshot_lock
, RW_READER
);
350 if ((se
= zfsctl_snapshot_find_by_objsetid(spa
, objsetid
)) != NULL
) {
351 zfsctl_snapshot_unmount_delay_impl(se
, zfs_expire_snapshot
);
352 zfsctl_snapshot_rele(se
);
354 rw_exit(&zfs_snapshot_lock
);
358 * Cancel an automatic unmount of a snapname. This callback is responsible
359 * for dropping the reference on the zfs_snapentry_t which was taken when
363 zfsctl_snapshot_unmount_cancel(zfs_snapentry_t
*se
)
365 ASSERT(RW_LOCK_HELD(&zfs_snapshot_lock
));
367 if (taskq_cancel_id(zfs_expire_taskq
, se
->se_taskqid
) == 0) {
369 zfsctl_snapshot_rele(se
);
374 * Dispatch the unmount task for delayed handling with a hold protecting it.
377 zfsctl_snapshot_unmount_delay_impl(zfs_snapentry_t
*se
, int delay
)
379 ASSERT3S(se
->se_taskqid
, ==, -1);
384 zfsctl_snapshot_hold(se
);
385 se
->se_taskqid
= taskq_dispatch_delay(zfs_expire_taskq
,
386 snapentry_expire
, se
, TQ_SLEEP
, ddi_get_lbolt() + delay
* HZ
);
390 * Schedule an automatic unmount of objset id to occur in delay seconds from
391 * now. Any previous delayed unmount will be cancelled in favor of the
392 * updated deadline. A reference is taken by zfsctl_snapshot_find_by_name()
393 * and held until the outstanding task is handled or cancelled.
396 zfsctl_snapshot_unmount_delay(spa_t
*spa
, uint64_t objsetid
, int delay
)
401 rw_enter(&zfs_snapshot_lock
, RW_READER
);
402 if ((se
= zfsctl_snapshot_find_by_objsetid(spa
, objsetid
)) != NULL
) {
403 zfsctl_snapshot_unmount_cancel(se
);
404 zfsctl_snapshot_unmount_delay_impl(se
, delay
);
405 zfsctl_snapshot_rele(se
);
408 rw_exit(&zfs_snapshot_lock
);
414 * Check if snapname is currently mounted. Returned non-zero when mounted
415 * and zero when unmounted.
418 zfsctl_snapshot_ismounted(char *snapname
)
421 boolean_t ismounted
= B_FALSE
;
423 rw_enter(&zfs_snapshot_lock
, RW_READER
);
424 if ((se
= zfsctl_snapshot_find_by_name(snapname
)) != NULL
) {
425 zfsctl_snapshot_rele(se
);
428 rw_exit(&zfs_snapshot_lock
);
434 * Check if the given inode is a part of the virtual .zfs directory.
437 zfsctl_is_node(struct inode
*ip
)
439 return (ITOZ(ip
)->z_is_ctldir
);
443 * Check if the given inode is a .zfs/snapshots/snapname directory.
446 zfsctl_is_snapdir(struct inode
*ip
)
448 return (zfsctl_is_node(ip
) && (ip
->i_ino
<= ZFSCTL_INO_SNAPDIRS
));
452 * Allocate a new inode with the passed id and ops.
454 static struct inode
*
455 zfsctl_inode_alloc(zfs_sb_t
*zsb
, uint64_t id
,
456 const struct file_operations
*fops
, const struct inode_operations
*ops
)
462 ip
= new_inode(zsb
->z_sb
);
466 now
= current_time(ip
);
468 ASSERT3P(zp
->z_dirlocks
, ==, NULL
);
469 ASSERT3P(zp
->z_acl_cached
, ==, NULL
);
470 ASSERT3P(zp
->z_xattr_cached
, ==, NULL
);
473 zp
->z_atime_dirty
= 0;
474 zp
->z_zn_prefetch
= 0;
488 zp
->z_is_mapped
= B_FALSE
;
489 zp
->z_is_ctldir
= B_TRUE
;
490 zp
->z_is_sa
= B_FALSE
;
491 zp
->z_is_stale
= B_FALSE
;
493 ip
->i_mode
= (S_IFDIR
| S_IRUGO
| S_IXUGO
);
494 ip
->i_uid
= SUID_TO_KUID(0);
495 ip
->i_gid
= SGID_TO_KGID(0);
496 ip
->i_blkbits
= SPA_MINBLOCKSHIFT
;
503 if (insert_inode_locked(ip
)) {
504 unlock_new_inode(ip
);
509 mutex_enter(&zsb
->z_znodes_lock
);
510 list_insert_tail(&zsb
->z_all_znodes
, zp
);
513 mutex_exit(&zsb
->z_znodes_lock
);
515 unlock_new_inode(ip
);
521 * Lookup the inode with given id, it will be allocated if needed.
523 static struct inode
*
524 zfsctl_inode_lookup(zfs_sb_t
*zsb
, uint64_t id
,
525 const struct file_operations
*fops
, const struct inode_operations
*ops
)
527 struct inode
*ip
= NULL
;
530 ip
= ilookup(zsb
->z_sb
, (unsigned long)id
);
534 /* May fail due to concurrent zfsctl_inode_alloc() */
535 ip
= zfsctl_inode_alloc(zsb
, id
, fops
, ops
);
542 * Create the '.zfs' directory. This directory is cached as part of the VFS
543 * structure. This results in a hold on the zfs_sb_t. The code in zfs_umount()
544 * therefore checks against a vfs_count of 2 instead of 1. This reference
545 * is removed when the ctldir is destroyed in the unmount. All other entities
546 * under the '.zfs' directory are created dynamically as needed.
548 * Because the dynamically created '.zfs' directory entries assume the use
549 * of 64-bit inode numbers this support must be disabled on 32-bit systems.
552 zfsctl_create(zfs_sb_t
*zsb
)
554 #if defined(CONFIG_64BIT)
555 ASSERT(zsb
->z_ctldir
== NULL
);
557 zsb
->z_ctldir
= zfsctl_inode_alloc(zsb
, ZFSCTL_INO_ROOT
,
558 &zpl_fops_root
, &zpl_ops_root
);
559 if (zsb
->z_ctldir
== NULL
)
560 return (SET_ERROR(ENOENT
));
564 return (SET_ERROR(EOPNOTSUPP
));
565 #endif /* CONFIG_64BIT */
569 * Destroy the '.zfs' directory or remove a snapshot from zfs_snapshots_by_name.
570 * Only called when the filesystem is unmounted.
573 zfsctl_destroy(zfs_sb_t
*zsb
)
577 spa_t
*spa
= zsb
->z_os
->os_spa
;
578 uint64_t objsetid
= dmu_objset_id(zsb
->z_os
);
580 rw_enter(&zfs_snapshot_lock
, RW_WRITER
);
581 if ((se
= zfsctl_snapshot_find_by_objsetid(spa
, objsetid
))
583 zfsctl_snapshot_unmount_cancel(se
);
584 zfsctl_snapshot_remove(se
);
585 zfsctl_snapshot_rele(se
);
587 rw_exit(&zfs_snapshot_lock
);
588 } else if (zsb
->z_ctldir
) {
590 zsb
->z_ctldir
= NULL
;
595 * Given a root znode, retrieve the associated .zfs directory.
596 * Add a hold to the vnode and return it.
599 zfsctl_root(znode_t
*zp
)
601 ASSERT(zfs_has_ctldir(zp
));
602 igrab(ZTOZSB(zp
)->z_ctldir
);
603 return (ZTOZSB(zp
)->z_ctldir
);
606 * Generate a long fid which includes the root object and objset of a
607 * snapshot but not the generation number. For the root object the
608 * generation number is ignored when zero to avoid needing to open
609 * the dataset when generating fids for the snapshot names.
612 zfsctl_snapdir_fid(struct inode
*ip
, fid_t
*fidp
)
614 zfs_sb_t
*zsb
= ITOZSB(ip
);
615 zfid_short_t
*zfid
= (zfid_short_t
*)fidp
;
616 zfid_long_t
*zlfid
= (zfid_long_t
*)fidp
;
622 object
= zsb
->z_root
;
623 objsetid
= ZFSCTL_INO_SNAPDIRS
- ip
->i_ino
;
624 zfid
->zf_len
= LONG_FID_LEN
;
626 for (i
= 0; i
< sizeof (zfid
->zf_object
); i
++)
627 zfid
->zf_object
[i
] = (uint8_t)(object
>> (8 * i
));
629 for (i
= 0; i
< sizeof (zfid
->zf_gen
); i
++)
630 zfid
->zf_gen
[i
] = (uint8_t)(gen
>> (8 * i
));
632 for (i
= 0; i
< sizeof (zlfid
->zf_setid
); i
++)
633 zlfid
->zf_setid
[i
] = (uint8_t)(objsetid
>> (8 * i
));
635 for (i
= 0; i
< sizeof (zlfid
->zf_setgen
); i
++)
636 zlfid
->zf_setgen
[i
] = 0;
642 * Generate an appropriate fid for an entry in the .zfs directory.
645 zfsctl_fid(struct inode
*ip
, fid_t
*fidp
)
647 znode_t
*zp
= ITOZ(ip
);
648 zfs_sb_t
*zsb
= ITOZSB(ip
);
649 uint64_t object
= zp
->z_id
;
655 if (fidp
->fid_len
< SHORT_FID_LEN
) {
656 fidp
->fid_len
= SHORT_FID_LEN
;
658 return (SET_ERROR(ENOSPC
));
661 if (zfsctl_is_snapdir(ip
)) {
663 return (zfsctl_snapdir_fid(ip
, fidp
));
666 zfid
= (zfid_short_t
*)fidp
;
668 zfid
->zf_len
= SHORT_FID_LEN
;
670 for (i
= 0; i
< sizeof (zfid
->zf_object
); i
++)
671 zfid
->zf_object
[i
] = (uint8_t)(object
>> (8 * i
));
673 /* .zfs znodes always have a generation number of 0 */
674 for (i
= 0; i
< sizeof (zfid
->zf_gen
); i
++)
682 * Construct a full dataset name in full_name: "pool/dataset@snap_name"
685 zfsctl_snapshot_name(zfs_sb_t
*zsb
, const char *snap_name
, int len
,
688 objset_t
*os
= zsb
->z_os
;
690 if (zfs_component_namecheck(snap_name
, NULL
, NULL
) != 0)
691 return (SET_ERROR(EILSEQ
));
693 dmu_objset_name(os
, full_name
);
694 if ((strlen(full_name
) + 1 + strlen(snap_name
)) >= len
)
695 return (SET_ERROR(ENAMETOOLONG
));
697 (void) strcat(full_name
, "@");
698 (void) strcat(full_name
, snap_name
);
704 * Returns full path in full_path: "/pool/dataset/.zfs/snapshot/snap_name/"
707 zfsctl_snapshot_path(struct path
*path
, int len
, char *full_path
)
709 char *path_buffer
, *path_ptr
;
710 int path_len
, error
= 0;
712 path_buffer
= kmem_alloc(len
, KM_SLEEP
);
714 path_ptr
= d_path(path
, path_buffer
, len
);
715 if (IS_ERR(path_ptr
)) {
716 error
= -PTR_ERR(path_ptr
);
720 path_len
= path_buffer
+ len
- 1 - path_ptr
;
721 if (path_len
> len
) {
722 error
= SET_ERROR(EFAULT
);
726 memcpy(full_path
, path_ptr
, path_len
);
727 full_path
[path_len
] = '\0';
729 kmem_free(path_buffer
, len
);
735 * Returns full path in full_path: "/pool/dataset/.zfs/snapshot/snap_name/"
738 zfsctl_snapshot_path_objset(zfs_sb_t
*zsb
, uint64_t objsetid
,
739 int path_len
, char *full_path
)
741 objset_t
*os
= zsb
->z_os
;
742 fstrans_cookie_t cookie
;
744 boolean_t case_conflict
;
745 uint64_t id
, pos
= 0;
748 if (zsb
->z_mntopts
->z_mntpoint
== NULL
)
751 cookie
= spl_fstrans_mark();
752 snapname
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
755 dsl_pool_config_enter(dmu_objset_pool(os
), FTAG
);
756 error
= dmu_snapshot_list_next(zsb
->z_os
, MAXNAMELEN
,
757 snapname
, &id
, &pos
, &case_conflict
);
758 dsl_pool_config_exit(dmu_objset_pool(os
), FTAG
);
766 memset(full_path
, 0, path_len
);
767 snprintf(full_path
, path_len
- 1, "%s/.zfs/snapshot/%s",
768 zsb
->z_mntopts
->z_mntpoint
, snapname
);
770 kmem_free(snapname
, MAXNAMELEN
);
771 spl_fstrans_unmark(cookie
);
777 * Special case the handling of "..".
780 zfsctl_root_lookup(struct inode
*dip
, char *name
, struct inode
**ipp
,
781 int flags
, cred_t
*cr
, int *direntflags
, pathname_t
*realpnp
)
783 zfs_sb_t
*zsb
= ITOZSB(dip
);
788 if (strcmp(name
, "..") == 0) {
789 *ipp
= dip
->i_sb
->s_root
->d_inode
;
790 } else if (strcmp(name
, ZFS_SNAPDIR_NAME
) == 0) {
791 *ipp
= zfsctl_inode_lookup(zsb
, ZFSCTL_INO_SNAPDIR
,
792 &zpl_fops_snapdir
, &zpl_ops_snapdir
);
793 } else if (strcmp(name
, ZFS_SHAREDIR_NAME
) == 0) {
794 *ipp
= zfsctl_inode_lookup(zsb
, ZFSCTL_INO_SHARES
,
795 &zpl_fops_shares
, &zpl_ops_shares
);
801 error
= SET_ERROR(ENOENT
);
809 * Lookup entry point for the 'snapshot' directory. Try to open the
810 * snapshot if it exist, creating the pseudo filesystem inode as necessary.
811 * Perform a mount of the associated dataset on top of the inode.
814 zfsctl_snapdir_lookup(struct inode
*dip
, char *name
, struct inode
**ipp
,
815 int flags
, cred_t
*cr
, int *direntflags
, pathname_t
*realpnp
)
817 zfs_sb_t
*zsb
= ITOZSB(dip
);
823 error
= dmu_snapshot_lookup(zsb
->z_os
, name
, &id
);
829 *ipp
= zfsctl_inode_lookup(zsb
, ZFSCTL_INO_SNAPDIRS
- id
,
830 &simple_dir_operations
, &simple_dir_inode_operations
);
832 error
= SET_ERROR(ENOENT
);
840 * Renaming a directory under '.zfs/snapshot' will automatically trigger
841 * a rename of the snapshot to the new given name. The rename is confined
842 * to the '.zfs/snapshot' directory snapshots cannot be moved elsewhere.
845 zfsctl_snapdir_rename(struct inode
*sdip
, char *snm
,
846 struct inode
*tdip
, char *tnm
, cred_t
*cr
, int flags
)
848 zfs_sb_t
*zsb
= ITOZSB(sdip
);
849 char *to
, *from
, *real
, *fsname
;
852 if (!zfs_admin_snapshot
)
857 to
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
858 from
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
859 real
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
860 fsname
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
862 if (zsb
->z_case
== ZFS_CASE_INSENSITIVE
) {
863 error
= dmu_snapshot_realname(zsb
->z_os
, snm
, real
,
867 } else if (error
!= ENOTSUP
) {
872 dmu_objset_name(zsb
->z_os
, fsname
);
874 error
= zfsctl_snapshot_name(ITOZSB(sdip
), snm
, MAXNAMELEN
, from
);
876 error
= zfsctl_snapshot_name(ITOZSB(tdip
), tnm
, MAXNAMELEN
, to
);
878 error
= zfs_secpolicy_rename_perms(from
, to
, cr
);
883 * Cannot move snapshots out of the snapdir.
886 error
= SET_ERROR(EINVAL
);
891 * No-op when names are identical.
893 if (strcmp(snm
, tnm
) == 0) {
898 rw_enter(&zfs_snapshot_lock
, RW_WRITER
);
900 error
= dsl_dataset_rename_snapshot(fsname
, snm
, tnm
, B_FALSE
);
902 (void) zfsctl_snapshot_rename(snm
, tnm
);
904 rw_exit(&zfs_snapshot_lock
);
906 kmem_free(from
, MAXNAMELEN
);
907 kmem_free(to
, MAXNAMELEN
);
908 kmem_free(real
, MAXNAMELEN
);
909 kmem_free(fsname
, MAXNAMELEN
);
917 * Removing a directory under '.zfs/snapshot' will automatically trigger
918 * the removal of the snapshot with the given name.
921 zfsctl_snapdir_remove(struct inode
*dip
, char *name
, cred_t
*cr
, int flags
)
923 zfs_sb_t
*zsb
= ITOZSB(dip
);
924 char *snapname
, *real
;
927 if (!zfs_admin_snapshot
)
932 snapname
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
933 real
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
935 if (zsb
->z_case
== ZFS_CASE_INSENSITIVE
) {
936 error
= dmu_snapshot_realname(zsb
->z_os
, name
, real
,
940 } else if (error
!= ENOTSUP
) {
945 error
= zfsctl_snapshot_name(ITOZSB(dip
), name
, MAXNAMELEN
, snapname
);
947 error
= zfs_secpolicy_destroy_perms(snapname
, cr
);
951 error
= zfsctl_snapshot_unmount(snapname
, MNT_FORCE
);
952 if ((error
== 0) || (error
== ENOENT
))
953 error
= dsl_destroy_snapshot(snapname
, B_FALSE
);
955 kmem_free(snapname
, MAXNAMELEN
);
956 kmem_free(real
, MAXNAMELEN
);
964 * Creating a directory under '.zfs/snapshot' will automatically trigger
965 * the creation of a new snapshot with the given name.
968 zfsctl_snapdir_mkdir(struct inode
*dip
, char *dirname
, vattr_t
*vap
,
969 struct inode
**ipp
, cred_t
*cr
, int flags
)
971 zfs_sb_t
*zsb
= ITOZSB(dip
);
975 if (!zfs_admin_snapshot
)
978 dsname
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
980 if (zfs_component_namecheck(dirname
, NULL
, NULL
) != 0) {
981 error
= SET_ERROR(EILSEQ
);
985 dmu_objset_name(zsb
->z_os
, dsname
);
987 error
= zfs_secpolicy_snapshot_perms(dsname
, cr
);
992 error
= dmu_objset_snapshot_one(dsname
, dirname
);
996 error
= zfsctl_snapdir_lookup(dip
, dirname
, ipp
,
1000 kmem_free(dsname
, MAXNAMELEN
);
1006 * Attempt to unmount a snapshot by making a call to user space.
1007 * There is no assurance that this can or will succeed, is just a
1008 * best effort. In the case where it does fail, perhaps because
1009 * it's in use, the unmount will fail harmlessly.
1012 zfsctl_snapshot_unmount(char *snapname
, int flags
)
1014 char *argv
[] = { "/usr/bin/env", "umount", "-t", "zfs", "-n", NULL
,
1016 char *envp
[] = { NULL
};
1017 zfs_snapentry_t
*se
;
1020 rw_enter(&zfs_snapshot_lock
, RW_READER
);
1021 if ((se
= zfsctl_snapshot_find_by_name(snapname
)) == NULL
) {
1022 rw_exit(&zfs_snapshot_lock
);
1025 rw_exit(&zfs_snapshot_lock
);
1027 if (flags
& MNT_FORCE
)
1029 argv
[5] = se
->se_path
;
1030 dprintf("unmount; path=%s\n", se
->se_path
);
1031 error
= call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_PROC
);
1032 zfsctl_snapshot_rele(se
);
1036 * The umount system utility will return 256 on error. We must
1037 * assume this error is because the file system is busy so it is
1038 * converted to the more sensible EBUSY.
1041 error
= SET_ERROR(EBUSY
);
1046 #define MOUNT_BUSY 0x80 /* Mount failed due to EBUSY (from mntent.h) */
1049 zfsctl_snapshot_mount(struct path
*path
, int flags
)
1051 struct dentry
*dentry
= path
->dentry
;
1052 struct inode
*ip
= dentry
->d_inode
;
1055 zfs_snapentry_t
*se
;
1056 char *full_name
, *full_path
;
1057 char *argv
[] = { "/usr/bin/env", "mount", "-t", "zfs", "-n", NULL
, NULL
,
1059 char *envp
[] = { NULL
};
1069 full_name
= kmem_zalloc(MAXNAMELEN
, KM_SLEEP
);
1070 full_path
= kmem_zalloc(MAXPATHLEN
, KM_SLEEP
);
1072 error
= zfsctl_snapshot_name(zsb
, dname(dentry
),
1073 MAXNAMELEN
, full_name
);
1077 error
= zfsctl_snapshot_path(path
, MAXPATHLEN
, full_path
);
1082 * Multiple concurrent automounts of a snapshot are never allowed.
1083 * The snapshot may be manually mounted as many times as desired.
1085 if (zfsctl_snapshot_ismounted(full_name
)) {
1091 * Attempt to mount the snapshot from user space. Normally this
1092 * would be done using the vfs_kern_mount() function, however that
1093 * function is marked GPL-only and cannot be used. On error we
1094 * careful to log the real error to the console and return EISDIR
1095 * to safely abort the automount. This should be very rare.
1097 * If the user mode helper happens to return EBUSY, a concurrent
1098 * mount is already in progress in which case the error is ignored.
1099 * Take note that if the program was executed successfully the return
1100 * value from call_usermodehelper() will be (exitcode << 8 + signal).
1102 dprintf("mount; name=%s path=%s\n", full_name
, full_path
);
1103 argv
[5] = full_name
;
1104 argv
[6] = full_path
;
1105 error
= call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_PROC
);
1107 if (!(error
& MOUNT_BUSY
<< 8)) {
1108 cmn_err(CE_WARN
, "Unable to automount %s/%s: %d",
1109 full_path
, full_name
, error
);
1110 error
= SET_ERROR(EISDIR
);
1113 * EBUSY, this could mean a concurrent mount, or the
1114 * snapshot has already been mounted at completely
1115 * different place. We return 0 so VFS will retry. For
1116 * the latter case the VFS will retry several times
1117 * and return ELOOP, which is probably not a very good
1126 * Follow down in to the mounted snapshot and set MNT_SHRINKABLE
1127 * to identify this as an automounted filesystem.
1131 if (zpl_follow_down_one(&spath
)) {
1132 snap_zsb
= ITOZSB(spath
.dentry
->d_inode
);
1133 snap_zsb
->z_parent
= zsb
;
1134 dentry
= spath
.dentry
;
1135 spath
.mnt
->mnt_flags
|= MNT_SHRINKABLE
;
1137 rw_enter(&zfs_snapshot_lock
, RW_WRITER
);
1138 se
= zfsctl_snapshot_alloc(full_name
, full_path
,
1139 snap_zsb
->z_os
->os_spa
, dmu_objset_id(snap_zsb
->z_os
),
1141 zfsctl_snapshot_add(se
);
1142 zfsctl_snapshot_unmount_delay_impl(se
, zfs_expire_snapshot
);
1143 rw_exit(&zfs_snapshot_lock
);
1147 kmem_free(full_name
, MAXNAMELEN
);
1148 kmem_free(full_path
, MAXPATHLEN
);
1156 * Given the objset id of the snapshot return its zfs_sb_t as zsbp.
1159 zfsctl_lookup_objset(struct super_block
*sb
, uint64_t objsetid
, zfs_sb_t
**zsbp
)
1161 zfs_snapentry_t
*se
;
1163 spa_t
*spa
= ((zfs_sb_t
*)(sb
->s_fs_info
))->z_os
->os_spa
;
1166 * Verify that the snapshot is mounted then lookup the mounted root
1167 * rather than the covered mount point. This may fail if the
1168 * snapshot has just been unmounted by an unrelated user space
1169 * process. This race cannot occur to an expired mount point
1170 * because we hold the zfs_snapshot_lock to prevent the race.
1172 rw_enter(&zfs_snapshot_lock
, RW_READER
);
1173 if ((se
= zfsctl_snapshot_find_by_objsetid(spa
, objsetid
)) != NULL
) {
1176 zsb
= ITOZSB(se
->se_root_dentry
->d_inode
);
1177 ASSERT3U(dmu_objset_id(zsb
->z_os
), ==, objsetid
);
1179 if (time_after(jiffies
, zsb
->z_snap_defer_time
+
1180 MAX(zfs_expire_snapshot
* HZ
/ 2, HZ
))) {
1181 zsb
->z_snap_defer_time
= jiffies
;
1182 zfsctl_snapshot_unmount_cancel(se
);
1183 zfsctl_snapshot_unmount_delay_impl(se
,
1184 zfs_expire_snapshot
);
1188 zfsctl_snapshot_rele(se
);
1189 error
= SET_ERROR(0);
1191 error
= SET_ERROR(ENOENT
);
1193 rw_exit(&zfs_snapshot_lock
);
1196 * Automount the snapshot given the objset id by constructing the
1197 * full mount point and performing a traversal.
1199 if (error
== ENOENT
) {
1203 mnt
= kmem_alloc(MAXPATHLEN
, KM_SLEEP
);
1204 error
= zfsctl_snapshot_path_objset(sb
->s_fs_info
, objsetid
,
1207 kmem_free(mnt
, MAXPATHLEN
);
1208 return (SET_ERROR(error
));
1211 error
= kern_path(mnt
, LOOKUP_FOLLOW
|LOOKUP_DIRECTORY
, &path
);
1213 *zsbp
= ITOZSB(path
.dentry
->d_inode
);
1217 kmem_free(mnt
, MAXPATHLEN
);
1224 zfsctl_shares_lookup(struct inode
*dip
, char *name
, struct inode
**ipp
,
1225 int flags
, cred_t
*cr
, int *direntflags
, pathname_t
*realpnp
)
1227 zfs_sb_t
*zsb
= ITOZSB(dip
);
1234 if (zsb
->z_shares_dir
== 0) {
1236 return (SET_ERROR(ENOTSUP
));
1239 error
= zfs_zget(zsb
, zsb
->z_shares_dir
, &dzp
);
1245 error
= zfs_lookup(ZTOI(dzp
), name
, &ip
, 0, cr
, NULL
, NULL
);
1255 * Initialize the various pieces we'll need to create and manipulate .zfs
1256 * directories. Currently this is unused but available.
1261 avl_create(&zfs_snapshots_by_name
, snapentry_compare_by_name
,
1262 sizeof (zfs_snapentry_t
), offsetof(zfs_snapentry_t
,
1264 avl_create(&zfs_snapshots_by_objsetid
, snapentry_compare_by_objsetid
,
1265 sizeof (zfs_snapentry_t
), offsetof(zfs_snapentry_t
,
1267 rw_init(&zfs_snapshot_lock
, NULL
, RW_DEFAULT
, NULL
);
1269 zfs_expire_taskq
= taskq_create("z_unmount", 1, defclsyspri
,
1270 1, 8, TASKQ_PREPOPULATE
);
1274 * Cleanup the various pieces we needed for .zfs directories. In particular
1275 * ensure the expiry timer is canceled safely.
1280 taskq_destroy(zfs_expire_taskq
);
1282 avl_destroy(&zfs_snapshots_by_name
);
1283 avl_destroy(&zfs_snapshots_by_objsetid
);
1284 rw_destroy(&zfs_snapshot_lock
);
1287 module_param(zfs_admin_snapshot
, int, 0644);
1288 MODULE_PARM_DESC(zfs_admin_snapshot
, "Enable mkdir/rmdir/mv in .zfs/snapshot");
1290 module_param(zfs_expire_snapshot
, int, 0644);
1291 MODULE_PARM_DESC(zfs_expire_snapshot
, "Seconds to expire .zfs/snapshot");