4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * super.c contains code to handle: - mount structures
8 * - filesystem drivers list
10 * - umount system call
13 * GK 2/5/95 - Changed to support mounting the root fs via NFS
15 * Added kerneld support: Jacques Gelinas and Bjorn Ekwall
16 * Added change_root: Werner Almesberger & Hans Lermen, Feb '96
17 * Added options to /proc/mounts:
18 * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
19 * Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998
20 * Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
23 #include <linux/module.h>
24 #include <linux/slab.h>
25 #include <linux/acct.h>
26 #include <linux/blkdev.h>
27 #include <linux/quotaops.h>
28 #include <linux/mount.h>
29 #include <linux/security.h>
30 #include <linux/writeback.h> /* for the emergency remount stuff */
31 #include <linux/idr.h>
32 #include <linux/mutex.h>
33 #include <linux/backing-dev.h>
37 LIST_HEAD(super_blocks
);
38 DEFINE_SPINLOCK(sb_lock
);
41 * alloc_super - create new superblock
42 * @type: filesystem type superblock should belong to
44 * Allocates and initializes a new &struct super_block. alloc_super()
45 * returns a pointer new superblock or %NULL if allocation had failed.
47 static struct super_block
*alloc_super(struct file_system_type
*type
)
49 struct super_block
*s
= kzalloc(sizeof(struct super_block
), GFP_USER
);
50 static const struct super_operations default_op
;
53 if (security_sb_alloc(s
)) {
58 INIT_LIST_HEAD(&s
->s_files
);
59 INIT_LIST_HEAD(&s
->s_instances
);
60 INIT_HLIST_HEAD(&s
->s_anon
);
61 INIT_LIST_HEAD(&s
->s_inodes
);
62 INIT_LIST_HEAD(&s
->s_dentry_lru
);
63 init_rwsem(&s
->s_umount
);
64 mutex_init(&s
->s_lock
);
65 lockdep_set_class(&s
->s_umount
, &type
->s_umount_key
);
67 * The locking rules for s_lock are up to the
68 * filesystem. For example ext3fs has different
69 * lock ordering than usbfs:
71 lockdep_set_class(&s
->s_lock
, &type
->s_lock_key
);
73 * sget() can have s_umount recursion.
75 * When it cannot find a suitable sb, it allocates a new
76 * one (this one), and tries again to find a suitable old
79 * In case that succeeds, it will acquire the s_umount
80 * lock of the old one. Since these are clearly distrinct
81 * locks, and this object isn't exposed yet, there's no
84 * Annotate this by putting this lock in a different
87 down_write_nested(&s
->s_umount
, SINGLE_DEPTH_NESTING
);
89 atomic_set(&s
->s_active
, 1);
90 mutex_init(&s
->s_vfs_rename_mutex
);
91 lockdep_set_class(&s
->s_vfs_rename_mutex
, &type
->s_vfs_rename_key
);
92 mutex_init(&s
->s_dquot
.dqio_mutex
);
93 mutex_init(&s
->s_dquot
.dqonoff_mutex
);
94 init_rwsem(&s
->s_dquot
.dqptr_sem
);
95 init_waitqueue_head(&s
->s_wait_unfrozen
);
96 s
->s_maxbytes
= MAX_NON_LFS
;
97 s
->dq_op
= sb_dquot_ops
;
98 s
->s_qcop
= sb_quotactl_ops
;
99 s
->s_op
= &default_op
;
100 s
->s_time_gran
= 1000000000;
107 * destroy_super - frees a superblock
108 * @s: superblock to free
110 * Frees a superblock.
112 static inline void destroy_super(struct super_block
*s
)
120 /* Superblock refcounting */
123 * Drop a superblock's refcount. The caller must hold sb_lock.
125 void __put_super(struct super_block
*sb
)
127 if (!--sb
->s_count
) {
128 list_del_init(&sb
->s_list
);
134 * put_super - drop a temporary reference to superblock
135 * @sb: superblock in question
137 * Drops a temporary reference, frees superblock if there's no
140 void put_super(struct super_block
*sb
)
144 spin_unlock(&sb_lock
);
149 * deactivate_locked_super - drop an active reference to superblock
150 * @s: superblock to deactivate
152 * Drops an active reference to superblock, converting it into a temprory
153 * one if there is no other active references left. In that case we
154 * tell fs driver to shut it down and drop the temporary reference we
157 * Caller holds exclusive lock on superblock; that lock is released.
159 void deactivate_locked_super(struct super_block
*s
)
161 struct file_system_type
*fs
= s
->s_type
;
162 if (atomic_dec_and_test(&s
->s_active
)) {
168 up_write(&s
->s_umount
);
172 EXPORT_SYMBOL(deactivate_locked_super
);
175 * deactivate_super - drop an active reference to superblock
176 * @s: superblock to deactivate
178 * Variant of deactivate_locked_super(), except that superblock is *not*
179 * locked by caller. If we are going to drop the final active reference,
180 * lock will be acquired prior to that.
182 void deactivate_super(struct super_block
*s
)
184 if (!atomic_add_unless(&s
->s_active
, -1, 1)) {
185 down_write(&s
->s_umount
);
186 deactivate_locked_super(s
);
190 EXPORT_SYMBOL(deactivate_super
);
193 * grab_super - acquire an active reference
194 * @s: reference we are trying to make active
196 * Tries to acquire an active reference. grab_super() is used when we
197 * had just found a superblock in super_blocks or fs_type->fs_supers
198 * and want to turn it into a full-blown active reference. grab_super()
199 * is called with sb_lock held and drops it. Returns 1 in case of
200 * success, 0 if we had failed (superblock contents was already dead or
201 * dying when grab_super() had been called).
203 static int grab_super(struct super_block
*s
) __releases(sb_lock
)
205 if (atomic_inc_not_zero(&s
->s_active
)) {
206 spin_unlock(&sb_lock
);
209 /* it's going away */
211 spin_unlock(&sb_lock
);
212 /* wait for it to die */
213 down_write(&s
->s_umount
);
214 up_write(&s
->s_umount
);
220 * Superblock locking. We really ought to get rid of these two.
222 void lock_super(struct super_block
* sb
)
225 mutex_lock(&sb
->s_lock
);
228 void unlock_super(struct super_block
* sb
)
231 mutex_unlock(&sb
->s_lock
);
234 EXPORT_SYMBOL(lock_super
);
235 EXPORT_SYMBOL(unlock_super
);
238 * generic_shutdown_super - common helper for ->kill_sb()
239 * @sb: superblock to kill
241 * generic_shutdown_super() does all fs-independent work on superblock
242 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
243 * that need destruction out of superblock, call generic_shutdown_super()
244 * and release aforementioned objects. Note: dentries and inodes _are_
245 * taken care of and do not need specific handling.
247 * Upon calling this function, the filesystem may no longer alter or
248 * rearrange the set of dentries belonging to this super_block, nor may it
249 * change the attachments of dentries to inodes.
251 void generic_shutdown_super(struct super_block
*sb
)
253 const struct super_operations
*sop
= sb
->s_op
;
257 shrink_dcache_for_umount(sb
);
260 sb
->s_flags
&= ~MS_ACTIVE
;
262 /* bad name - it should be evict_inodes() */
263 invalidate_inodes(sb
);
268 /* Forget any remaining inodes */
269 if (invalidate_inodes(sb
)) {
270 printk("VFS: Busy inodes after unmount of %s. "
271 "Self-destruct in 5 seconds. Have a nice day...\n",
277 /* should be initialized for __put_super_and_need_restart() */
278 list_del_init(&sb
->s_instances
);
279 spin_unlock(&sb_lock
);
280 up_write(&sb
->s_umount
);
283 EXPORT_SYMBOL(generic_shutdown_super
);
286 * sget - find or create a superblock
287 * @type: filesystem type superblock should belong to
288 * @test: comparison callback
289 * @set: setup callback
290 * @data: argument to each of them
292 struct super_block
*sget(struct file_system_type
*type
,
293 int (*test
)(struct super_block
*,void *),
294 int (*set
)(struct super_block
*,void *),
297 struct super_block
*s
= NULL
;
298 struct super_block
*old
;
304 list_for_each_entry(old
, &type
->fs_supers
, s_instances
) {
305 if (!test(old
, data
))
307 if (!grab_super(old
))
310 up_write(&s
->s_umount
);
313 down_write(&old
->s_umount
);
318 spin_unlock(&sb_lock
);
319 s
= alloc_super(type
);
321 return ERR_PTR(-ENOMEM
);
327 spin_unlock(&sb_lock
);
328 up_write(&s
->s_umount
);
333 strlcpy(s
->s_id
, type
->name
, sizeof(s
->s_id
));
334 list_add_tail(&s
->s_list
, &super_blocks
);
335 list_add(&s
->s_instances
, &type
->fs_supers
);
336 spin_unlock(&sb_lock
);
337 get_filesystem(type
);
343 void drop_super(struct super_block
*sb
)
345 up_read(&sb
->s_umount
);
349 EXPORT_SYMBOL(drop_super
);
352 * sync_supers - helper for periodic superblock writeback
354 * Call the write_super method if present on all dirty superblocks in
355 * the system. This is for the periodic writeback used by most older
356 * filesystems. For data integrity superblock writeback use
357 * sync_filesystems() instead.
359 * Note: check the dirty flag before waiting, so we don't
360 * hold up the sync while mounting a device. (The newly
361 * mounted device won't need syncing.)
363 void sync_supers(void)
365 struct super_block
*sb
, *n
;
368 list_for_each_entry_safe(sb
, n
, &super_blocks
, s_list
) {
369 if (list_empty(&sb
->s_instances
))
371 if (sb
->s_op
->write_super
&& sb
->s_dirt
) {
373 spin_unlock(&sb_lock
);
375 down_read(&sb
->s_umount
);
376 if (sb
->s_root
&& sb
->s_dirt
)
377 sb
->s_op
->write_super(sb
);
378 up_read(&sb
->s_umount
);
384 spin_unlock(&sb_lock
);
388 * iterate_supers - call function for all active superblocks
389 * @f: function to call
390 * @arg: argument to pass to it
392 * Scans the superblock list and calls given function, passing it
393 * locked superblock and given argument.
395 void iterate_supers(void (*f
)(struct super_block
*, void *), void *arg
)
397 struct super_block
*sb
, *n
;
400 list_for_each_entry_safe(sb
, n
, &super_blocks
, s_list
) {
401 if (list_empty(&sb
->s_instances
))
404 spin_unlock(&sb_lock
);
406 down_read(&sb
->s_umount
);
409 up_read(&sb
->s_umount
);
414 spin_unlock(&sb_lock
);
418 * get_super - get the superblock of a device
419 * @bdev: device to get the superblock for
421 * Scans the superblock list and finds the superblock of the file system
422 * mounted on the device given. %NULL is returned if no match is found.
425 struct super_block
*get_super(struct block_device
*bdev
)
427 struct super_block
*sb
;
434 list_for_each_entry(sb
, &super_blocks
, s_list
) {
435 if (list_empty(&sb
->s_instances
))
437 if (sb
->s_bdev
== bdev
) {
439 spin_unlock(&sb_lock
);
440 down_read(&sb
->s_umount
);
444 up_read(&sb
->s_umount
);
445 /* nope, got unmounted */
451 spin_unlock(&sb_lock
);
455 EXPORT_SYMBOL(get_super
);
458 * get_active_super - get an active reference to the superblock of a device
459 * @bdev: device to get the superblock for
461 * Scans the superblock list and finds the superblock of the file system
462 * mounted on the device given. Returns the superblock with an active
463 * reference or %NULL if none was found.
465 struct super_block
*get_active_super(struct block_device
*bdev
)
467 struct super_block
*sb
;
474 list_for_each_entry(sb
, &super_blocks
, s_list
) {
475 if (list_empty(&sb
->s_instances
))
477 if (sb
->s_bdev
== bdev
) {
478 if (grab_super(sb
)) /* drops sb_lock */
484 spin_unlock(&sb_lock
);
488 struct super_block
*user_get_super(dev_t dev
)
490 struct super_block
*sb
;
494 list_for_each_entry(sb
, &super_blocks
, s_list
) {
495 if (list_empty(&sb
->s_instances
))
497 if (sb
->s_dev
== dev
) {
499 spin_unlock(&sb_lock
);
500 down_read(&sb
->s_umount
);
504 up_read(&sb
->s_umount
);
505 /* nope, got unmounted */
511 spin_unlock(&sb_lock
);
516 * do_remount_sb - asks filesystem to change mount options.
517 * @sb: superblock in question
518 * @flags: numeric part of options
519 * @data: the rest of options
520 * @force: whether or not to force the change
522 * Alters the mount options of a mounted file system.
524 int do_remount_sb(struct super_block
*sb
, int flags
, void *data
, int force
)
527 int remount_rw
, remount_ro
;
529 if (sb
->s_frozen
!= SB_UNFROZEN
)
533 if (!(flags
& MS_RDONLY
) && bdev_read_only(sb
->s_bdev
))
537 if (flags
& MS_RDONLY
)
539 shrink_dcache_sb(sb
);
542 remount_ro
= (flags
& MS_RDONLY
) && !(sb
->s_flags
& MS_RDONLY
);
543 remount_rw
= !(flags
& MS_RDONLY
) && (sb
->s_flags
& MS_RDONLY
);
545 /* If we are remounting RDONLY and current sb is read/write,
546 make sure there are no rw files opened */
550 else if (!fs_may_remount_ro(sb
))
552 retval
= vfs_dq_off(sb
, 1);
553 if (retval
< 0 && retval
!= -ENOSYS
)
557 if (sb
->s_op
->remount_fs
) {
558 retval
= sb
->s_op
->remount_fs(sb
, &flags
, data
);
562 sb
->s_flags
= (sb
->s_flags
& ~MS_RMT_MASK
) | (flags
& MS_RMT_MASK
);
564 vfs_dq_quota_on_remount(sb
);
566 * Some filesystems modify their metadata via some other path than the
567 * bdev buffer cache (eg. use a private mapping, or directories in
568 * pagecache, etc). Also file data modifications go via their own
569 * mappings. So If we try to mount readonly then copy the filesystem
570 * from bdev, we could get stale data, so invalidate it to give a best
571 * effort at coherency.
573 if (remount_ro
&& sb
->s_bdev
)
574 invalidate_bdev(sb
->s_bdev
);
578 static void do_emergency_remount(struct work_struct
*work
)
580 struct super_block
*sb
, *n
;
583 list_for_each_entry_safe(sb
, n
, &super_blocks
, s_list
) {
584 if (list_empty(&sb
->s_instances
))
587 spin_unlock(&sb_lock
);
588 down_write(&sb
->s_umount
);
589 if (sb
->s_root
&& sb
->s_bdev
&& !(sb
->s_flags
& MS_RDONLY
)) {
591 * What lock protects sb->s_flags??
593 do_remount_sb(sb
, MS_RDONLY
, NULL
, 1);
595 up_write(&sb
->s_umount
);
599 spin_unlock(&sb_lock
);
601 printk("Emergency Remount complete\n");
604 void emergency_remount(void)
606 struct work_struct
*work
;
608 work
= kmalloc(sizeof(*work
), GFP_ATOMIC
);
610 INIT_WORK(work
, do_emergency_remount
);
616 * Unnamed block devices are dummy devices used by virtual
617 * filesystems which don't use real block-devices. -- jrs
620 static DEFINE_IDA(unnamed_dev_ida
);
621 static DEFINE_SPINLOCK(unnamed_dev_lock
);/* protects the above */
622 static int unnamed_dev_start
= 0; /* don't bother trying below it */
624 int set_anon_super(struct super_block
*s
, void *data
)
630 if (ida_pre_get(&unnamed_dev_ida
, GFP_ATOMIC
) == 0)
632 spin_lock(&unnamed_dev_lock
);
633 error
= ida_get_new_above(&unnamed_dev_ida
, unnamed_dev_start
, &dev
);
635 unnamed_dev_start
= dev
+ 1;
636 spin_unlock(&unnamed_dev_lock
);
637 if (error
== -EAGAIN
)
638 /* We raced and lost with another CPU. */
643 if ((dev
& MAX_ID_MASK
) == (1 << MINORBITS
)) {
644 spin_lock(&unnamed_dev_lock
);
645 ida_remove(&unnamed_dev_ida
, dev
);
646 if (unnamed_dev_start
> dev
)
647 unnamed_dev_start
= dev
;
648 spin_unlock(&unnamed_dev_lock
);
651 s
->s_dev
= MKDEV(0, dev
& MINORMASK
);
652 s
->s_bdi
= &noop_backing_dev_info
;
656 EXPORT_SYMBOL(set_anon_super
);
658 void kill_anon_super(struct super_block
*sb
)
660 int slot
= MINOR(sb
->s_dev
);
662 generic_shutdown_super(sb
);
663 spin_lock(&unnamed_dev_lock
);
664 ida_remove(&unnamed_dev_ida
, slot
);
665 if (slot
< unnamed_dev_start
)
666 unnamed_dev_start
= slot
;
667 spin_unlock(&unnamed_dev_lock
);
670 EXPORT_SYMBOL(kill_anon_super
);
672 void kill_litter_super(struct super_block
*sb
)
675 d_genocide(sb
->s_root
);
679 EXPORT_SYMBOL(kill_litter_super
);
681 static int ns_test_super(struct super_block
*sb
, void *data
)
683 return sb
->s_fs_info
== data
;
686 static int ns_set_super(struct super_block
*sb
, void *data
)
688 sb
->s_fs_info
= data
;
689 return set_anon_super(sb
, NULL
);
692 int get_sb_ns(struct file_system_type
*fs_type
, int flags
, void *data
,
693 int (*fill_super
)(struct super_block
*, void *, int),
694 struct vfsmount
*mnt
)
696 struct super_block
*sb
;
698 sb
= sget(fs_type
, ns_test_super
, ns_set_super
, data
);
705 err
= fill_super(sb
, data
, flags
& MS_SILENT
? 1 : 0);
707 deactivate_locked_super(sb
);
711 sb
->s_flags
|= MS_ACTIVE
;
714 simple_set_mnt(mnt
, sb
);
718 EXPORT_SYMBOL(get_sb_ns
);
721 static int set_bdev_super(struct super_block
*s
, void *data
)
724 s
->s_dev
= s
->s_bdev
->bd_dev
;
727 * We set the bdi here to the queue backing, file systems can
728 * overwrite this in ->fill_super()
730 s
->s_bdi
= &bdev_get_queue(s
->s_bdev
)->backing_dev_info
;
734 static int test_bdev_super(struct super_block
*s
, void *data
)
736 return (void *)s
->s_bdev
== data
;
739 int get_sb_bdev(struct file_system_type
*fs_type
,
740 int flags
, const char *dev_name
, void *data
,
741 int (*fill_super
)(struct super_block
*, void *, int),
742 struct vfsmount
*mnt
)
744 struct block_device
*bdev
;
745 struct super_block
*s
;
746 fmode_t mode
= FMODE_READ
;
749 if (!(flags
& MS_RDONLY
))
752 bdev
= open_bdev_exclusive(dev_name
, mode
, fs_type
);
754 return PTR_ERR(bdev
);
757 * once the super is inserted into the list by sget, s_umount
758 * will protect the lockfs code from trying to start a snapshot
759 * while we are mounting
761 mutex_lock(&bdev
->bd_fsfreeze_mutex
);
762 if (bdev
->bd_fsfreeze_count
> 0) {
763 mutex_unlock(&bdev
->bd_fsfreeze_mutex
);
767 s
= sget(fs_type
, test_bdev_super
, set_bdev_super
, bdev
);
768 mutex_unlock(&bdev
->bd_fsfreeze_mutex
);
773 if ((flags
^ s
->s_flags
) & MS_RDONLY
) {
774 deactivate_locked_super(s
);
779 close_bdev_exclusive(bdev
, mode
);
781 char b
[BDEVNAME_SIZE
];
785 strlcpy(s
->s_id
, bdevname(bdev
, b
), sizeof(s
->s_id
));
786 sb_set_blocksize(s
, block_size(bdev
));
787 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
789 deactivate_locked_super(s
);
793 s
->s_flags
|= MS_ACTIVE
;
797 simple_set_mnt(mnt
, s
);
803 close_bdev_exclusive(bdev
, mode
);
808 EXPORT_SYMBOL(get_sb_bdev
);
810 void kill_block_super(struct super_block
*sb
)
812 struct block_device
*bdev
= sb
->s_bdev
;
813 fmode_t mode
= sb
->s_mode
;
815 bdev
->bd_super
= NULL
;
816 generic_shutdown_super(sb
);
818 close_bdev_exclusive(bdev
, mode
);
821 EXPORT_SYMBOL(kill_block_super
);
824 int get_sb_nodev(struct file_system_type
*fs_type
,
825 int flags
, void *data
,
826 int (*fill_super
)(struct super_block
*, void *, int),
827 struct vfsmount
*mnt
)
830 struct super_block
*s
= sget(fs_type
, NULL
, set_anon_super
, NULL
);
837 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
839 deactivate_locked_super(s
);
842 s
->s_flags
|= MS_ACTIVE
;
843 simple_set_mnt(mnt
, s
);
847 EXPORT_SYMBOL(get_sb_nodev
);
849 static int compare_single(struct super_block
*s
, void *p
)
854 int get_sb_single(struct file_system_type
*fs_type
,
855 int flags
, void *data
,
856 int (*fill_super
)(struct super_block
*, void *, int),
857 struct vfsmount
*mnt
)
859 struct super_block
*s
;
862 s
= sget(fs_type
, compare_single
, set_anon_super
, NULL
);
867 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
869 deactivate_locked_super(s
);
872 s
->s_flags
|= MS_ACTIVE
;
874 do_remount_sb(s
, flags
, data
, 0);
876 simple_set_mnt(mnt
, s
);
880 EXPORT_SYMBOL(get_sb_single
);
883 vfs_kern_mount(struct file_system_type
*type
, int flags
, const char *name
, void *data
)
885 struct vfsmount
*mnt
;
886 char *secdata
= NULL
;
890 return ERR_PTR(-ENODEV
);
893 mnt
= alloc_vfsmnt(name
);
897 if (flags
& MS_KERNMOUNT
)
898 mnt
->mnt_flags
= MNT_INTERNAL
;
900 if (data
&& !(type
->fs_flags
& FS_BINARY_MOUNTDATA
)) {
901 secdata
= alloc_secdata();
905 error
= security_sb_copy_data(data
, secdata
);
907 goto out_free_secdata
;
910 error
= type
->get_sb(type
, flags
, name
, data
, mnt
);
912 goto out_free_secdata
;
913 BUG_ON(!mnt
->mnt_sb
);
914 WARN_ON(!mnt
->mnt_sb
->s_bdi
);
916 error
= security_sb_kern_mount(mnt
->mnt_sb
, flags
, secdata
);
921 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
922 * but s_maxbytes was an unsigned long long for many releases. Throw
923 * this warning for a little while to try and catch filesystems that
924 * violate this rule. This warning should be either removed or
925 * converted to a BUG() in 2.6.34.
927 WARN((mnt
->mnt_sb
->s_maxbytes
< 0), "%s set sb->s_maxbytes to "
928 "negative value (%lld)\n", type
->name
, mnt
->mnt_sb
->s_maxbytes
);
930 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
931 mnt
->mnt_parent
= mnt
;
932 up_write(&mnt
->mnt_sb
->s_umount
);
933 free_secdata(secdata
);
937 deactivate_locked_super(mnt
->mnt_sb
);
939 free_secdata(secdata
);
943 return ERR_PTR(error
);
946 EXPORT_SYMBOL_GPL(vfs_kern_mount
);
949 * freeze_super -- lock the filesystem and force it into a consistent state
950 * @super: the super to lock
952 * Syncs the super to make sure the filesystem is consistent and calls the fs's
953 * freeze_fs. Subsequent calls to this without first thawing the fs will return
956 int freeze_super(struct super_block
*sb
)
960 atomic_inc(&sb
->s_active
);
961 down_write(&sb
->s_umount
);
963 deactivate_locked_super(sb
);
967 if (sb
->s_flags
& MS_RDONLY
) {
968 sb
->s_frozen
= SB_FREEZE_TRANS
;
970 up_write(&sb
->s_umount
);
974 sb
->s_frozen
= SB_FREEZE_WRITE
;
979 sb
->s_frozen
= SB_FREEZE_TRANS
;
982 sync_blockdev(sb
->s_bdev
);
983 if (sb
->s_op
->freeze_fs
) {
984 ret
= sb
->s_op
->freeze_fs(sb
);
987 "VFS:Filesystem freeze failed\n");
988 sb
->s_frozen
= SB_UNFROZEN
;
989 deactivate_locked_super(sb
);
993 up_write(&sb
->s_umount
);
996 EXPORT_SYMBOL(freeze_super
);
999 * thaw_super -- unlock filesystem
1000 * @sb: the super to thaw
1002 * Unlocks the filesystem and marks it writeable again after freeze_super().
1004 int thaw_super(struct super_block
*sb
)
1008 down_write(&sb
->s_umount
);
1009 if (sb
->s_frozen
== SB_UNFROZEN
) {
1010 up_write(&sb
->s_umount
);
1014 if (sb
->s_flags
& MS_RDONLY
)
1017 if (sb
->s_op
->unfreeze_fs
) {
1018 error
= sb
->s_op
->unfreeze_fs(sb
);
1021 "VFS:Filesystem thaw failed\n");
1022 sb
->s_frozen
= SB_FREEZE_TRANS
;
1023 up_write(&sb
->s_umount
);
1029 sb
->s_frozen
= SB_UNFROZEN
;
1031 wake_up(&sb
->s_wait_unfrozen
);
1032 deactivate_locked_super(sb
);
1036 EXPORT_SYMBOL(thaw_super
);
1038 static struct vfsmount
*fs_set_subtype(struct vfsmount
*mnt
, const char *fstype
)
1041 const char *subtype
= strchr(fstype
, '.');
1050 mnt
->mnt_sb
->s_subtype
= kstrdup(subtype
, GFP_KERNEL
);
1052 if (!mnt
->mnt_sb
->s_subtype
)
1058 return ERR_PTR(err
);
1062 do_kern_mount(const char *fstype
, int flags
, const char *name
, void *data
)
1064 struct file_system_type
*type
= get_fs_type(fstype
);
1065 struct vfsmount
*mnt
;
1067 return ERR_PTR(-ENODEV
);
1068 mnt
= vfs_kern_mount(type
, flags
, name
, data
);
1069 if (!IS_ERR(mnt
) && (type
->fs_flags
& FS_HAS_SUBTYPE
) &&
1070 !mnt
->mnt_sb
->s_subtype
)
1071 mnt
= fs_set_subtype(mnt
, fstype
);
1072 put_filesystem(type
);
1075 EXPORT_SYMBOL_GPL(do_kern_mount
);
1077 struct vfsmount
*kern_mount_data(struct file_system_type
*type
, void *data
)
1079 return vfs_kern_mount(type
, MS_KERNMOUNT
, type
->name
, data
);
1082 EXPORT_SYMBOL_GPL(kern_mount_data
);