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>
33 * ZFS control directory (a.k.a. ".zfs")
35 * This directory provides a common location for all ZFS meta-objects.
36 * Currently, this is only the 'snapshot' and 'shares' directory, but this may
37 * expand in the future. The elements are built dynamically, as the hierarchy
38 * does not actually exist on disk.
40 * For 'snapshot', we don't want to have all snapshots always mounted, because
41 * this would take up a huge amount of space in /etc/mnttab. We have three
44 * ctldir ------> snapshotdir -------> snapshot
50 * The 'snapshot' node contains just enough information to lookup '..' and act
51 * as a mountpoint for the snapshot. Whenever we lookup a specific snapshot, we
52 * perform an automount of the underlying filesystem and return the
53 * corresponding inode.
55 * All mounts are handled automatically by an user mode helper which invokes
56 * the mount mount procedure. Unmounts are handled by allowing the mount
57 * point to expire so the kernel may automatically unmount it.
59 * The '.zfs', '.zfs/snapshot', and all directories created under
60 * '.zfs/snapshot' (ie: '.zfs/snapshot/<snapname>') all share the same
61 * share the same zfs_sb_t as the head filesystem (what '.zfs' lives under).
63 * File systems mounted on top of the '.zfs/snapshot/<snapname>' paths
64 * (ie: snapshots) are complete ZFS filesystems and have their own unique
65 * zfs_sb_t. However, the fsid reported by these mounts will be the same
66 * as that used by the parent zfs_sb_t to make NFS happy.
69 #include <sys/types.h>
70 #include <sys/param.h>
72 #include <sys/systm.h>
73 #include <sys/sysmacros.h>
74 #include <sys/pathname.h>
76 #include <sys/vfs_opreg.h>
77 #include <sys/zfs_ctldir.h>
78 #include <sys/zfs_ioctl.h>
79 #include <sys/zfs_vfsops.h>
80 #include <sys/zfs_vnops.h>
83 #include <sys/dsl_deleg.h>
84 #include <sys/mount.h>
86 #include "zfs_namecheck.h"
89 * Control Directory Tunables (.zfs)
91 int zfs_expire_snapshot
= ZFSCTL_EXPIRE_SNAPSHOT
;
93 static zfs_snapentry_t
*
94 zfsctl_sep_alloc(void)
96 return kmem_zalloc(sizeof (zfs_snapentry_t
), KM_SLEEP
);
100 zfsctl_sep_free(zfs_snapentry_t
*sep
)
102 kmem_free(sep
->se_name
, MAXNAMELEN
);
103 kmem_free(sep
->se_path
, PATH_MAX
);
104 kmem_free(sep
, sizeof (zfs_snapentry_t
));
108 * Attempt to expire an automounted snapshot, unmounts are attempted every
109 * 'zfs_expire_snapshot' seconds until they succeed. The work request is
110 * responsible for rescheduling itself and freeing the zfs_expire_snapshot_t.
113 zfsctl_expire_snapshot(void *data
)
115 zfs_snapentry_t
*sep
;
119 sep
= spl_get_work_data(data
, zfs_snapentry_t
, se_work
.work
);
120 zsb
= ITOZSB(sep
->se_inode
);
122 error
= zfsctl_unmount_snapshot(zsb
, sep
->se_name
, MNT_EXPIRE
);
124 schedule_delayed_work(&sep
->se_work
, zfs_expire_snapshot
* HZ
);
128 snapentry_compare(const void *a
, const void *b
)
130 const zfs_snapentry_t
*sa
= a
;
131 const zfs_snapentry_t
*sb
= b
;
132 int ret
= strcmp(sa
->se_name
, sb
->se_name
);
143 zfsctl_is_node(struct inode
*ip
)
145 return (ITOZ(ip
)->z_is_ctldir
);
149 zfsctl_is_snapdir(struct inode
*ip
)
151 return (zfsctl_is_node(ip
) && (ip
->i_ino
<= ZFSCTL_INO_SNAPDIRS
));
155 * Allocate a new inode with the passed id and ops.
157 static struct inode
*
158 zfsctl_inode_alloc(zfs_sb_t
*zsb
, uint64_t id
,
159 const struct file_operations
*fops
, const struct inode_operations
*ops
)
161 struct timespec now
= current_fs_time(zsb
->z_sb
);
165 ip
= new_inode(zsb
->z_sb
);
170 ASSERT3P(zp
->z_dirlocks
, ==, NULL
);
171 ASSERT3P(zp
->z_acl_cached
, ==, NULL
);
172 ASSERT3P(zp
->z_xattr_cached
, ==, NULL
);
175 zp
->z_atime_dirty
= 0;
176 zp
->z_zn_prefetch
= 0;
192 zp
->z_is_zvol
= B_FALSE
;
193 zp
->z_is_mapped
= B_FALSE
;
194 zp
->z_is_ctldir
= B_TRUE
;
195 zp
->z_is_sa
= B_FALSE
;
197 ip
->i_mode
= (S_IFDIR
| S_IRUGO
| S_IXUGO
);
200 ip
->i_blkbits
= SPA_MINBLOCKSHIFT
;
207 if (insert_inode_locked(ip
)) {
208 unlock_new_inode(ip
);
213 mutex_enter(&zsb
->z_znodes_lock
);
214 list_insert_tail(&zsb
->z_all_znodes
, zp
);
217 mutex_exit(&zsb
->z_znodes_lock
);
219 unlock_new_inode(ip
);
225 * Lookup the inode with given id, it will be allocated if needed.
227 static struct inode
*
228 zfsctl_inode_lookup(zfs_sb_t
*zsb
, uint64_t id
,
229 const struct file_operations
*fops
, const struct inode_operations
*ops
)
231 struct inode
*ip
= NULL
;
234 ip
= ilookup(zsb
->z_sb
, (unsigned long)id
);
238 /* May fail due to concurrent zfsctl_inode_alloc() */
239 ip
= zfsctl_inode_alloc(zsb
, id
, fops
, ops
);
246 * Free zfsctl inode specific structures, currently there are none.
249 zfsctl_inode_destroy(struct inode
*ip
)
255 * An inode is being evicted from the cache.
258 zfsctl_inode_inactive(struct inode
*ip
)
260 if (zfsctl_is_snapdir(ip
))
261 zfsctl_snapdir_inactive(ip
);
265 * Create the '.zfs' directory. This directory is cached as part of the VFS
266 * structure. This results in a hold on the zfs_sb_t. The code in zfs_umount()
267 * therefore checks against a vfs_count of 2 instead of 1. This reference
268 * is removed when the ctldir is destroyed in the unmount. All other entities
269 * under the '.zfs' directory are created dynamically as needed.
271 * Because the dynamically created '.zfs' directory entries assume the use
272 * of 64-bit inode numbers this support must be disabled on 32-bit systems.
275 zfsctl_create(zfs_sb_t
*zsb
)
277 #if defined(CONFIG_64BIT)
278 ASSERT(zsb
->z_ctldir
== NULL
);
280 zsb
->z_ctldir
= zfsctl_inode_alloc(zsb
, ZFSCTL_INO_ROOT
,
281 &zpl_fops_root
, &zpl_ops_root
);
282 if (zsb
->z_ctldir
== NULL
)
288 #endif /* CONFIG_64BIT */
292 * Destroy the '.zfs' directory. Only called when the filesystem is unmounted.
295 zfsctl_destroy(zfs_sb_t
*zsb
)
298 zsb
->z_ctldir
= NULL
;
302 * Given a root znode, retrieve the associated .zfs directory.
303 * Add a hold to the vnode and return it.
306 zfsctl_root(znode_t
*zp
)
308 ASSERT(zfs_has_ctldir(zp
));
309 igrab(ZTOZSB(zp
)->z_ctldir
);
310 return (ZTOZSB(zp
)->z_ctldir
);
315 zfsctl_fid(struct inode
*ip
, fid_t
*fidp
)
317 znode_t
*zp
= ITOZ(ip
);
318 zfs_sb_t
*zsb
= ITOZSB(ip
);
319 uint64_t object
= zp
->z_id
;
325 if (fidp
->fid_len
< SHORT_FID_LEN
) {
326 fidp
->fid_len
= SHORT_FID_LEN
;
331 zfid
= (zfid_short_t
*)fidp
;
333 zfid
->zf_len
= SHORT_FID_LEN
;
335 for (i
= 0; i
< sizeof (zfid
->zf_object
); i
++)
336 zfid
->zf_object
[i
] = (uint8_t)(object
>> (8 * i
));
338 /* .zfs znodes always have a generation number of 0 */
339 for (i
= 0; i
< sizeof (zfid
->zf_gen
); i
++)
347 zfsctl_snapshot_zname(struct inode
*ip
, const char *name
, int len
, char *zname
)
349 objset_t
*os
= ITOZSB(ip
)->z_os
;
351 if (snapshot_namecheck(name
, NULL
, NULL
) != 0)
354 dmu_objset_name(os
, zname
);
355 if ((strlen(zname
) + 1 + strlen(name
)) >= len
)
356 return (ENAMETOOLONG
);
358 (void) strcat(zname
, "@");
359 (void) strcat(zname
, name
);
365 zfsctl_snapshot_zpath(struct path
*path
, int len
, char *zpath
)
367 char *path_buffer
, *path_ptr
;
368 int path_len
, error
= 0;
370 path_buffer
= kmem_alloc(len
, KM_SLEEP
);
372 path_ptr
= d_path(path
, path_buffer
, len
);
373 if (IS_ERR(path_ptr
)) {
374 error
= -PTR_ERR(path_ptr
);
378 path_len
= path_buffer
+ len
- 1 - path_ptr
;
379 if (path_len
> len
) {
384 memcpy(zpath
, path_ptr
, path_len
);
385 zpath
[path_len
] = '\0';
387 kmem_free(path_buffer
, len
);
393 * Special case the handling of "..".
397 zfsctl_root_lookup(struct inode
*dip
, char *name
, struct inode
**ipp
,
398 int flags
, cred_t
*cr
, int *direntflags
, pathname_t
*realpnp
)
400 zfs_sb_t
*zsb
= ITOZSB(dip
);
405 if (strcmp(name
, "..") == 0) {
406 *ipp
= dip
->i_sb
->s_root
->d_inode
;
407 } else if (strcmp(name
, ZFS_SNAPDIR_NAME
) == 0) {
408 *ipp
= zfsctl_inode_lookup(zsb
, ZFSCTL_INO_SNAPDIR
,
409 &zpl_fops_snapdir
, &zpl_ops_snapdir
);
410 } else if (strcmp(name
, ZFS_SHAREDIR_NAME
) == 0) {
411 *ipp
= zfsctl_inode_lookup(zsb
, ZFSCTL_INO_SHARES
,
412 &zpl_fops_shares
, &zpl_ops_shares
);
426 * Lookup entry point for the 'snapshot' directory. Try to open the
427 * snapshot if it exist, creating the pseudo filesystem inode as necessary.
428 * Perform a mount of the associated dataset on top of the inode.
432 zfsctl_snapdir_lookup(struct inode
*dip
, char *name
, struct inode
**ipp
,
433 int flags
, cred_t
*cr
, int *direntflags
, pathname_t
*realpnp
)
435 zfs_sb_t
*zsb
= ITOZSB(dip
);
441 error
= dmu_snapshot_id(zsb
->z_os
, name
, &id
);
447 *ipp
= zfsctl_inode_lookup(zsb
, ZFSCTL_INO_SNAPDIRS
- id
,
448 &simple_dir_operations
, &simple_dir_inode_operations
);
450 #ifdef HAVE_AUTOMOUNT
451 (*ipp
)->i_flags
|= S_AUTOMOUNT
;
452 #endif /* HAVE_AUTOMOUNT */
463 zfsctl_rename_snap(zfs_sb_t
*zsb
, zfs_snapentry_t
*sep
, const char *name
)
467 ASSERT(MUTEX_HELD(&zsb
->z_ctldir_lock
));
471 * Change the name in the AVL tree.
473 avl_remove(&zsb
->z_ctldir_snaps
, sep
);
474 (void) strcpy(sep
->se_name
, name
);
475 VERIFY(avl_find(&zsb
->z_ctldir_snaps
, sep
, &where
) == NULL
);
476 avl_insert(&zsb
->z_ctldir_snaps
, sep
, where
);
480 * Renaming a directory under '.zfs/snapshot' will automatically trigger
481 * a rename of the snapshot to the new given name. The rename is confined
482 * to the '.zfs/snapshot' directory snapshots cannot be moved elsewhere.
486 zfsctl_snapdir_rename(struct inode
*sdip
, char *sname
,
487 struct inode
*tdip
, char *tname
, cred_t
*cr
, int flags
)
489 zfs_sb_t
*zsb
= ITOZSB(sdip
);
490 zfs_snapentry_t search
, *sep
;
492 char *to
, *from
, *real
;
497 to
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
498 from
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
499 real
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
501 if (zsb
->z_case
== ZFS_CASE_INSENSITIVE
) {
502 error
= dmu_snapshot_realname(zsb
->z_os
, sname
, real
,
506 } else if (error
!= ENOTSUP
) {
511 error
= zfsctl_snapshot_zname(sdip
, sname
, MAXNAMELEN
, from
);
513 error
= zfsctl_snapshot_zname(tdip
, tname
, MAXNAMELEN
, to
);
515 error
= zfs_secpolicy_rename_perms(from
, to
, cr
);
520 * Cannot move snapshots out of the snapdir.
528 * No-op when names are identical.
530 if (strcmp(sname
, tname
) == 0) {
535 mutex_enter(&zsb
->z_ctldir_lock
);
537 error
= dmu_objset_rename(from
, to
, B_FALSE
);
541 search
.se_name
= (char *)sname
;
542 sep
= avl_find(&zsb
->z_ctldir_snaps
, &search
, &where
);
544 zfsctl_rename_snap(zsb
, sep
, tname
);
547 mutex_exit(&zsb
->z_ctldir_lock
);
549 kmem_free(from
, MAXNAMELEN
);
550 kmem_free(to
, MAXNAMELEN
);
551 kmem_free(real
, MAXNAMELEN
);
559 * Removing a directory under '.zfs/snapshot' will automatically trigger
560 * the removal of the snapshot with the given name.
564 zfsctl_snapdir_remove(struct inode
*dip
, char *name
, cred_t
*cr
, int flags
)
566 zfs_sb_t
*zsb
= ITOZSB(dip
);
567 char *snapname
, *real
;
572 snapname
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
573 real
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
575 if (zsb
->z_case
== ZFS_CASE_INSENSITIVE
) {
576 error
= dmu_snapshot_realname(zsb
->z_os
, name
, real
,
580 } else if (error
!= ENOTSUP
) {
585 error
= zfsctl_snapshot_zname(dip
, name
, MAXNAMELEN
, snapname
);
587 error
= zfs_secpolicy_destroy_perms(snapname
, cr
);
591 error
= zfsctl_unmount_snapshot(zsb
, name
, MNT_FORCE
);
592 if ((error
== 0) || (error
== ENOENT
))
593 error
= dmu_objset_destroy(snapname
, B_FALSE
);
595 kmem_free(snapname
, MAXNAMELEN
);
596 kmem_free(real
, MAXNAMELEN
);
604 * Creating a directory under '.zfs/snapshot' will automatically trigger
605 * the creation of a new snapshot with the given name.
609 zfsctl_snapdir_mkdir(struct inode
*dip
, char *dirname
, vattr_t
*vap
,
610 struct inode
**ipp
, cred_t
*cr
, int flags
)
612 zfs_sb_t
*zsb
= ITOZSB(dip
);
616 dsname
= kmem_alloc(MAXNAMELEN
, KM_SLEEP
);
618 if (snapshot_namecheck(dirname
, NULL
, NULL
) != 0) {
623 dmu_objset_name(zsb
->z_os
, dsname
);
625 error
= zfs_secpolicy_snapshot_perms(dsname
, cr
);
630 error
= dmu_objset_snapshot(dsname
, dirname
,
631 NULL
, NULL
, B_FALSE
, B_FALSE
, -1);
635 error
= zfsctl_snapdir_lookup(dip
, dirname
, ipp
,
639 kmem_free(dsname
, MAXNAMELEN
);
645 * When a .zfs/snapshot/<snapshot> inode is evicted they must be removed
646 * from the snapshot list. This will normally happen as part of the auto
647 * unmount, however in the case of a manual snapshot unmount this will be
648 * the only notification we receive.
651 zfsctl_snapdir_inactive(struct inode
*ip
)
653 zfs_sb_t
*zsb
= ITOZSB(ip
);
654 zfs_snapentry_t
*sep
, *next
;
656 mutex_enter(&zsb
->z_ctldir_lock
);
658 sep
= avl_first(&zsb
->z_ctldir_snaps
);
659 while (sep
!= NULL
) {
660 next
= AVL_NEXT(&zsb
->z_ctldir_snaps
, sep
);
662 if (sep
->se_inode
== ip
) {
663 avl_remove(&zsb
->z_ctldir_snaps
, sep
);
664 cancel_delayed_work_sync(&sep
->se_work
);
665 zfsctl_sep_free(sep
);
671 mutex_exit(&zsb
->z_ctldir_lock
);
675 * Attempt to unmount a snapshot by making a call to user space.
676 * There is no assurance that this can or will succeed, is just a
677 * best effort. In the case where it does fail, perhaps because
678 * it's in use, the unmount will fail harmlessly.
680 #define SET_UNMOUNT_CMD \
681 "exec 0</dev/null " \
684 "umount -t zfs -n %s%s"
687 __zfsctl_unmount_snapshot(zfs_snapentry_t
*sep
, int flags
)
689 char *argv
[] = { "/bin/sh", "-c", NULL
, NULL
};
690 char *envp
[] = { NULL
};
693 argv
[2] = kmem_asprintf(SET_UNMOUNT_CMD
,
694 flags
& MNT_FORCE
? "-f " : "", sep
->se_path
);
695 error
= call_usermodehelper(argv
[0], argv
, envp
, 1);
699 * The umount system utility will return 256 on error. We must
700 * assume this error is because the file system is busy so it is
701 * converted to the more sensible EBUSY.
707 * This was the result of a manual unmount, cancel the delayed work
708 * to prevent zfsctl_expire_snapshot() from attempting a unmount.
710 if ((error
== 0) && !(flags
& MNT_EXPIRE
))
711 cancel_delayed_work(&sep
->se_work
);
717 zfsctl_unmount_snapshot(zfs_sb_t
*zsb
, char *name
, int flags
)
719 zfs_snapentry_t search
;
720 zfs_snapentry_t
*sep
;
723 mutex_enter(&zsb
->z_ctldir_lock
);
725 search
.se_name
= name
;
726 sep
= avl_find(&zsb
->z_ctldir_snaps
, &search
, NULL
);
728 avl_remove(&zsb
->z_ctldir_snaps
, sep
);
729 error
= __zfsctl_unmount_snapshot(sep
, flags
);
731 avl_add(&zsb
->z_ctldir_snaps
, sep
);
733 zfsctl_sep_free(sep
);
738 mutex_exit(&zsb
->z_ctldir_lock
);
739 ASSERT3S(error
, >=, 0);
745 * Traverse all mounted snapshots and attempt to unmount them. This
746 * is best effort, on failure EEXIST is returned and count will be set
747 * to the number of file snapshots which could not be unmounted.
750 zfsctl_unmount_snapshots(zfs_sb_t
*zsb
, int flags
, int *count
)
752 zfs_snapentry_t
*sep
, *next
;
757 ASSERT(zsb
->z_ctldir
!= NULL
);
758 mutex_enter(&zsb
->z_ctldir_lock
);
760 sep
= avl_first(&zsb
->z_ctldir_snaps
);
761 while (sep
!= NULL
) {
762 next
= AVL_NEXT(&zsb
->z_ctldir_snaps
, sep
);
763 avl_remove(&zsb
->z_ctldir_snaps
, sep
);
764 error
= __zfsctl_unmount_snapshot(sep
, flags
);
765 if (error
== EBUSY
) {
766 avl_add(&zsb
->z_ctldir_snaps
, sep
);
769 zfsctl_sep_free(sep
);
775 mutex_exit(&zsb
->z_ctldir_lock
);
777 return ((*count
> 0) ? EEXIST
: 0);
780 #define SET_MOUNT_CMD \
781 "exec 0</dev/null " \
784 "mount -t zfs -n %s %s"
787 zfsctl_mount_snapshot(struct path
*path
, int flags
)
789 struct dentry
*dentry
= path
->dentry
;
790 struct inode
*ip
= dentry
->d_inode
;
791 zfs_sb_t
*zsb
= ITOZSB(ip
);
792 char *full_name
, *full_path
;
793 zfs_snapentry_t
*sep
;
794 zfs_snapentry_t search
;
795 char *argv
[] = { "/bin/sh", "-c", NULL
, NULL
};
796 char *envp
[] = { NULL
};
801 full_name
= kmem_zalloc(MAXNAMELEN
, KM_SLEEP
);
802 full_path
= kmem_zalloc(PATH_MAX
, KM_SLEEP
);
804 error
= zfsctl_snapshot_zname(ip
, dname(dentry
), MAXNAMELEN
, full_name
);
808 error
= zfsctl_snapshot_zpath(path
, PATH_MAX
, full_path
);
813 * Attempt to mount the snapshot from user space. Normally this
814 * would be done using the vfs_kern_mount() function, however that
815 * function is marked GPL-only and cannot be used. On error we
816 * careful to log the real error to the console and return EISDIR
817 * to safely abort the automount. This should be very rare.
819 argv
[2] = kmem_asprintf(SET_MOUNT_CMD
, full_name
, full_path
);
820 error
= call_usermodehelper(argv
[0], argv
, envp
, 1);
823 printk("ZFS: Unable to automount %s at %s: %d\n",
824 full_name
, full_path
, error
);
829 mutex_enter(&zsb
->z_ctldir_lock
);
832 * Ensure a previous entry does not exist, if it does safely remove
833 * it any cancel the outstanding expiration. This can occur when a
834 * snapshot is manually unmounted and then an automount is triggered.
836 search
.se_name
= full_name
;
837 sep
= avl_find(&zsb
->z_ctldir_snaps
, &search
, NULL
);
839 avl_remove(&zsb
->z_ctldir_snaps
, sep
);
840 cancel_delayed_work_sync(&sep
->se_work
);
841 zfsctl_sep_free(sep
);
844 sep
= zfsctl_sep_alloc();
845 sep
->se_name
= full_name
;
846 sep
->se_path
= full_path
;
848 avl_add(&zsb
->z_ctldir_snaps
, sep
);
850 spl_init_delayed_work(&sep
->se_work
, zfsctl_expire_snapshot
, sep
);
851 schedule_delayed_work(&sep
->se_work
, zfs_expire_snapshot
* HZ
);
853 mutex_exit(&zsb
->z_ctldir_lock
);
856 kmem_free(full_name
, MAXNAMELEN
);
857 kmem_free(full_path
, PATH_MAX
);
866 * Check if this super block has a matching objset id.
869 zfsctl_test_super(struct super_block
*sb
, void *objsetidp
)
871 zfs_sb_t
*zsb
= sb
->s_fs_info
;
872 uint64_t objsetid
= *(uint64_t *)objsetidp
;
874 return (dmu_objset_id(zsb
->z_os
) == objsetid
);
878 * Prevent a new super block from being allocated if an existing one
879 * could not be located. We only want to preform a lookup operation.
882 zfsctl_set_super(struct super_block
*sb
, void *objsetidp
)
888 zfsctl_lookup_objset(struct super_block
*sb
, uint64_t objsetid
, zfs_sb_t
**zsbp
)
890 zfs_sb_t
*zsb
= sb
->s_fs_info
;
891 struct super_block
*sbp
;
892 zfs_snapentry_t
*sep
;
896 ASSERT(zsb
->z_ctldir
!= NULL
);
898 mutex_enter(&zsb
->z_ctldir_lock
);
901 * Verify that the snapshot is mounted.
903 sep
= avl_first(&zsb
->z_ctldir_snaps
);
904 while (sep
!= NULL
) {
905 error
= dmu_snapshot_id(zsb
->z_os
, sep
->se_name
, &id
);
912 sep
= AVL_NEXT(&zsb
->z_ctldir_snaps
, sep
);
917 * Lookup the mounted root rather than the covered mount
918 * point. This may fail if the snapshot has just been
919 * unmounted by an unrelated user space process. This
920 * race cannot occur to an expired mount point because
921 * we hold the zsb->z_ctldir_lock to prevent the race.
923 sbp
= sget(&zpl_fs_type
, zfsctl_test_super
,
924 zfsctl_set_super
, &id
);
926 error
= -PTR_ERR(sbp
);
928 *zsbp
= sbp
->s_fs_info
;
929 deactivate_super(sbp
);
935 mutex_exit(&zsb
->z_ctldir_lock
);
936 ASSERT3S(error
, >=, 0);
943 zfsctl_shares_lookup(struct inode
*dip
, char *name
, struct inode
**ipp
,
944 int flags
, cred_t
*cr
, int *direntflags
, pathname_t
*realpnp
)
946 zfs_sb_t
*zsb
= ITOZSB(dip
);
953 if (zsb
->z_shares_dir
== 0) {
958 error
= zfs_zget(zsb
, zsb
->z_shares_dir
, &dzp
);
964 error
= zfs_lookup(ZTOI(dzp
), name
, &ip
, 0, cr
, NULL
, NULL
);
974 * Initialize the various pieces we'll need to create and manipulate .zfs
975 * directories. Currently this is unused but available.
983 * Cleanup the various pieces we needed for .zfs directories. In particular
984 * ensure the expiry timer is canceled safely.
991 module_param(zfs_expire_snapshot
, int, 0644);
992 MODULE_PARM_DESC(zfs_expire_snapshot
, "Seconds to expire .zfs/snapshot");