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/mount.h>
28 #include <linux/security.h>
29 #include <linux/writeback.h> /* for the emergency remount stuff */
30 #include <linux/idr.h>
31 #include <linux/mutex.h>
32 #include <linux/backing-dev.h>
36 LIST_HEAD(super_blocks
);
37 DEFINE_SPINLOCK(sb_lock
);
40 * alloc_super - create new superblock
41 * @type: filesystem type superblock should belong to
43 * Allocates and initializes a new &struct super_block. alloc_super()
44 * returns a pointer new superblock or %NULL if allocation had failed.
46 static struct super_block
*alloc_super(struct file_system_type
*type
)
48 struct super_block
*s
= kzalloc(sizeof(struct super_block
), GFP_USER
);
49 static const struct super_operations default_op
;
52 if (security_sb_alloc(s
)) {
57 INIT_LIST_HEAD(&s
->s_files
);
58 INIT_LIST_HEAD(&s
->s_instances
);
59 INIT_HLIST_HEAD(&s
->s_anon
);
60 INIT_LIST_HEAD(&s
->s_inodes
);
61 INIT_LIST_HEAD(&s
->s_dentry_lru
);
62 init_rwsem(&s
->s_umount
);
63 mutex_init(&s
->s_lock
);
64 lockdep_set_class(&s
->s_umount
, &type
->s_umount_key
);
66 * The locking rules for s_lock are up to the
67 * filesystem. For example ext3fs has different
68 * lock ordering than usbfs:
70 lockdep_set_class(&s
->s_lock
, &type
->s_lock_key
);
72 * sget() can have s_umount recursion.
74 * When it cannot find a suitable sb, it allocates a new
75 * one (this one), and tries again to find a suitable old
78 * In case that succeeds, it will acquire the s_umount
79 * lock of the old one. Since these are clearly distrinct
80 * locks, and this object isn't exposed yet, there's no
83 * Annotate this by putting this lock in a different
86 down_write_nested(&s
->s_umount
, SINGLE_DEPTH_NESTING
);
88 atomic_set(&s
->s_active
, 1);
89 mutex_init(&s
->s_vfs_rename_mutex
);
90 lockdep_set_class(&s
->s_vfs_rename_mutex
, &type
->s_vfs_rename_key
);
91 mutex_init(&s
->s_dquot
.dqio_mutex
);
92 mutex_init(&s
->s_dquot
.dqonoff_mutex
);
93 init_rwsem(&s
->s_dquot
.dqptr_sem
);
94 init_waitqueue_head(&s
->s_wait_unfrozen
);
95 s
->s_maxbytes
= MAX_NON_LFS
;
96 s
->s_op
= &default_op
;
97 s
->s_time_gran
= 1000000000;
104 * destroy_super - frees a superblock
105 * @s: superblock to free
107 * Frees a superblock.
109 static inline void destroy_super(struct super_block
*s
)
117 /* Superblock refcounting */
120 * Drop a superblock's refcount. The caller must hold sb_lock.
122 void __put_super(struct super_block
*sb
)
124 if (!--sb
->s_count
) {
125 list_del_init(&sb
->s_list
);
131 * put_super - drop a temporary reference to superblock
132 * @sb: superblock in question
134 * Drops a temporary reference, frees superblock if there's no
137 void put_super(struct super_block
*sb
)
141 spin_unlock(&sb_lock
);
146 * deactivate_locked_super - drop an active reference to superblock
147 * @s: superblock to deactivate
149 * Drops an active reference to superblock, converting it into a temprory
150 * one if there is no other active references left. In that case we
151 * tell fs driver to shut it down and drop the temporary reference we
154 * Caller holds exclusive lock on superblock; that lock is released.
156 void deactivate_locked_super(struct super_block
*s
)
158 struct file_system_type
*fs
= s
->s_type
;
159 if (atomic_dec_and_test(&s
->s_active
)) {
164 up_write(&s
->s_umount
);
168 EXPORT_SYMBOL(deactivate_locked_super
);
171 * deactivate_super - drop an active reference to superblock
172 * @s: superblock to deactivate
174 * Variant of deactivate_locked_super(), except that superblock is *not*
175 * locked by caller. If we are going to drop the final active reference,
176 * lock will be acquired prior to that.
178 void deactivate_super(struct super_block
*s
)
180 if (!atomic_add_unless(&s
->s_active
, -1, 1)) {
181 down_write(&s
->s_umount
);
182 deactivate_locked_super(s
);
186 EXPORT_SYMBOL(deactivate_super
);
189 * grab_super - acquire an active reference
190 * @s: reference we are trying to make active
192 * Tries to acquire an active reference. grab_super() is used when we
193 * had just found a superblock in super_blocks or fs_type->fs_supers
194 * and want to turn it into a full-blown active reference. grab_super()
195 * is called with sb_lock held and drops it. Returns 1 in case of
196 * success, 0 if we had failed (superblock contents was already dead or
197 * dying when grab_super() had been called).
199 static int grab_super(struct super_block
*s
) __releases(sb_lock
)
201 if (atomic_inc_not_zero(&s
->s_active
)) {
202 spin_unlock(&sb_lock
);
205 /* it's going away */
207 spin_unlock(&sb_lock
);
208 /* wait for it to die */
209 down_write(&s
->s_umount
);
210 up_write(&s
->s_umount
);
216 * Superblock locking. We really ought to get rid of these two.
218 void lock_super(struct super_block
* sb
)
221 mutex_lock(&sb
->s_lock
);
224 void unlock_super(struct super_block
* sb
)
227 mutex_unlock(&sb
->s_lock
);
230 EXPORT_SYMBOL(lock_super
);
231 EXPORT_SYMBOL(unlock_super
);
234 * generic_shutdown_super - common helper for ->kill_sb()
235 * @sb: superblock to kill
237 * generic_shutdown_super() does all fs-independent work on superblock
238 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
239 * that need destruction out of superblock, call generic_shutdown_super()
240 * and release aforementioned objects. Note: dentries and inodes _are_
241 * taken care of and do not need specific handling.
243 * Upon calling this function, the filesystem may no longer alter or
244 * rearrange the set of dentries belonging to this super_block, nor may it
245 * change the attachments of dentries to inodes.
247 void generic_shutdown_super(struct super_block
*sb
)
249 const struct super_operations
*sop
= sb
->s_op
;
253 shrink_dcache_for_umount(sb
);
256 sb
->s_flags
&= ~MS_ACTIVE
;
258 /* bad name - it should be evict_inodes() */
259 invalidate_inodes(sb
);
264 /* Forget any remaining inodes */
265 if (invalidate_inodes(sb
)) {
266 printk("VFS: Busy inodes after unmount of %s. "
267 "Self-destruct in 5 seconds. Have a nice day...\n",
273 /* should be initialized for __put_super_and_need_restart() */
274 list_del_init(&sb
->s_instances
);
275 spin_unlock(&sb_lock
);
276 up_write(&sb
->s_umount
);
279 EXPORT_SYMBOL(generic_shutdown_super
);
282 * sget - find or create a superblock
283 * @type: filesystem type superblock should belong to
284 * @test: comparison callback
285 * @set: setup callback
286 * @data: argument to each of them
288 struct super_block
*sget(struct file_system_type
*type
,
289 int (*test
)(struct super_block
*,void *),
290 int (*set
)(struct super_block
*,void *),
293 struct super_block
*s
= NULL
;
294 struct super_block
*old
;
300 list_for_each_entry(old
, &type
->fs_supers
, s_instances
) {
301 if (!test(old
, data
))
303 if (!grab_super(old
))
306 up_write(&s
->s_umount
);
309 down_write(&old
->s_umount
);
314 spin_unlock(&sb_lock
);
315 s
= alloc_super(type
);
317 return ERR_PTR(-ENOMEM
);
323 spin_unlock(&sb_lock
);
324 up_write(&s
->s_umount
);
329 strlcpy(s
->s_id
, type
->name
, sizeof(s
->s_id
));
330 list_add_tail(&s
->s_list
, &super_blocks
);
331 list_add(&s
->s_instances
, &type
->fs_supers
);
332 spin_unlock(&sb_lock
);
333 get_filesystem(type
);
339 void drop_super(struct super_block
*sb
)
341 up_read(&sb
->s_umount
);
345 EXPORT_SYMBOL(drop_super
);
348 * sync_supers - helper for periodic superblock writeback
350 * Call the write_super method if present on all dirty superblocks in
351 * the system. This is for the periodic writeback used by most older
352 * filesystems. For data integrity superblock writeback use
353 * sync_filesystems() instead.
355 * Note: check the dirty flag before waiting, so we don't
356 * hold up the sync while mounting a device. (The newly
357 * mounted device won't need syncing.)
359 void sync_supers(void)
361 struct super_block
*sb
, *n
;
364 list_for_each_entry_safe(sb
, n
, &super_blocks
, s_list
) {
365 if (list_empty(&sb
->s_instances
))
367 if (sb
->s_op
->write_super
&& sb
->s_dirt
) {
369 spin_unlock(&sb_lock
);
371 down_read(&sb
->s_umount
);
372 if (sb
->s_root
&& sb
->s_dirt
)
373 sb
->s_op
->write_super(sb
);
374 up_read(&sb
->s_umount
);
377 /* lock was dropped, must reset next */
378 list_safe_reset_next(sb
, n
, s_list
);
382 spin_unlock(&sb_lock
);
386 * iterate_supers - call function for all active superblocks
387 * @f: function to call
388 * @arg: argument to pass to it
390 * Scans the superblock list and calls given function, passing it
391 * locked superblock and given argument.
393 void iterate_supers(void (*f
)(struct super_block
*, void *), void *arg
)
395 struct super_block
*sb
, *n
;
398 list_for_each_entry_safe(sb
, n
, &super_blocks
, s_list
) {
399 if (list_empty(&sb
->s_instances
))
402 spin_unlock(&sb_lock
);
404 down_read(&sb
->s_umount
);
407 up_read(&sb
->s_umount
);
410 /* lock was dropped, must reset next */
411 list_safe_reset_next(sb
, n
, s_list
);
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
)
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
);
544 /* If we are remounting RDONLY and current sb is read/write,
545 make sure there are no rw files opened */
549 else if (!fs_may_remount_ro(sb
))
553 if (sb
->s_op
->remount_fs
) {
554 retval
= sb
->s_op
->remount_fs(sb
, &flags
, data
);
558 sb
->s_flags
= (sb
->s_flags
& ~MS_RMT_MASK
) | (flags
& MS_RMT_MASK
);
561 * Some filesystems modify their metadata via some other path than the
562 * bdev buffer cache (eg. use a private mapping, or directories in
563 * pagecache, etc). Also file data modifications go via their own
564 * mappings. So If we try to mount readonly then copy the filesystem
565 * from bdev, we could get stale data, so invalidate it to give a best
566 * effort at coherency.
568 if (remount_ro
&& sb
->s_bdev
)
569 invalidate_bdev(sb
->s_bdev
);
573 static void do_emergency_remount(struct work_struct
*work
)
575 struct super_block
*sb
, *n
;
578 list_for_each_entry_safe(sb
, n
, &super_blocks
, s_list
) {
579 if (list_empty(&sb
->s_instances
))
582 spin_unlock(&sb_lock
);
583 down_write(&sb
->s_umount
);
584 if (sb
->s_root
&& sb
->s_bdev
&& !(sb
->s_flags
& MS_RDONLY
)) {
586 * What lock protects sb->s_flags??
588 do_remount_sb(sb
, MS_RDONLY
, NULL
, 1);
590 up_write(&sb
->s_umount
);
592 /* lock was dropped, must reset next */
593 list_safe_reset_next(sb
, n
, s_list
);
596 spin_unlock(&sb_lock
);
598 printk("Emergency Remount complete\n");
601 void emergency_remount(void)
603 struct work_struct
*work
;
605 work
= kmalloc(sizeof(*work
), GFP_ATOMIC
);
607 INIT_WORK(work
, do_emergency_remount
);
613 * Unnamed block devices are dummy devices used by virtual
614 * filesystems which don't use real block-devices. -- jrs
617 static DEFINE_IDA(unnamed_dev_ida
);
618 static DEFINE_SPINLOCK(unnamed_dev_lock
);/* protects the above */
619 static int unnamed_dev_start
= 0; /* don't bother trying below it */
621 int set_anon_super(struct super_block
*s
, void *data
)
627 if (ida_pre_get(&unnamed_dev_ida
, GFP_ATOMIC
) == 0)
629 spin_lock(&unnamed_dev_lock
);
630 error
= ida_get_new_above(&unnamed_dev_ida
, unnamed_dev_start
, &dev
);
632 unnamed_dev_start
= dev
+ 1;
633 spin_unlock(&unnamed_dev_lock
);
634 if (error
== -EAGAIN
)
635 /* We raced and lost with another CPU. */
640 if ((dev
& MAX_ID_MASK
) == (1 << MINORBITS
)) {
641 spin_lock(&unnamed_dev_lock
);
642 ida_remove(&unnamed_dev_ida
, dev
);
643 if (unnamed_dev_start
> dev
)
644 unnamed_dev_start
= dev
;
645 spin_unlock(&unnamed_dev_lock
);
648 s
->s_dev
= MKDEV(0, dev
& MINORMASK
);
649 s
->s_bdi
= &noop_backing_dev_info
;
653 EXPORT_SYMBOL(set_anon_super
);
655 void kill_anon_super(struct super_block
*sb
)
657 int slot
= MINOR(sb
->s_dev
);
659 generic_shutdown_super(sb
);
660 spin_lock(&unnamed_dev_lock
);
661 ida_remove(&unnamed_dev_ida
, slot
);
662 if (slot
< unnamed_dev_start
)
663 unnamed_dev_start
= slot
;
664 spin_unlock(&unnamed_dev_lock
);
667 EXPORT_SYMBOL(kill_anon_super
);
669 void kill_litter_super(struct super_block
*sb
)
672 d_genocide(sb
->s_root
);
676 EXPORT_SYMBOL(kill_litter_super
);
678 static int ns_test_super(struct super_block
*sb
, void *data
)
680 return sb
->s_fs_info
== data
;
683 static int ns_set_super(struct super_block
*sb
, void *data
)
685 sb
->s_fs_info
= data
;
686 return set_anon_super(sb
, NULL
);
689 int get_sb_ns(struct file_system_type
*fs_type
, int flags
, void *data
,
690 int (*fill_super
)(struct super_block
*, void *, int),
691 struct vfsmount
*mnt
)
693 struct super_block
*sb
;
695 sb
= sget(fs_type
, ns_test_super
, ns_set_super
, data
);
702 err
= fill_super(sb
, data
, flags
& MS_SILENT
? 1 : 0);
704 deactivate_locked_super(sb
);
708 sb
->s_flags
|= MS_ACTIVE
;
711 simple_set_mnt(mnt
, sb
);
715 EXPORT_SYMBOL(get_sb_ns
);
718 static int set_bdev_super(struct super_block
*s
, void *data
)
721 s
->s_dev
= s
->s_bdev
->bd_dev
;
724 * We set the bdi here to the queue backing, file systems can
725 * overwrite this in ->fill_super()
727 s
->s_bdi
= &bdev_get_queue(s
->s_bdev
)->backing_dev_info
;
731 static int test_bdev_super(struct super_block
*s
, void *data
)
733 return (void *)s
->s_bdev
== data
;
736 int get_sb_bdev(struct file_system_type
*fs_type
,
737 int flags
, const char *dev_name
, void *data
,
738 int (*fill_super
)(struct super_block
*, void *, int),
739 struct vfsmount
*mnt
)
741 struct block_device
*bdev
;
742 struct super_block
*s
;
743 fmode_t mode
= FMODE_READ
;
746 if (!(flags
& MS_RDONLY
))
749 bdev
= open_bdev_exclusive(dev_name
, mode
, fs_type
);
751 return PTR_ERR(bdev
);
754 * once the super is inserted into the list by sget, s_umount
755 * will protect the lockfs code from trying to start a snapshot
756 * while we are mounting
758 mutex_lock(&bdev
->bd_fsfreeze_mutex
);
759 if (bdev
->bd_fsfreeze_count
> 0) {
760 mutex_unlock(&bdev
->bd_fsfreeze_mutex
);
764 s
= sget(fs_type
, test_bdev_super
, set_bdev_super
, bdev
);
765 mutex_unlock(&bdev
->bd_fsfreeze_mutex
);
770 if ((flags
^ s
->s_flags
) & MS_RDONLY
) {
771 deactivate_locked_super(s
);
777 * s_umount nests inside bd_mutex during
778 * __invalidate_device(). close_bdev_exclusive()
779 * acquires bd_mutex and can't be called under
780 * s_umount. Drop s_umount temporarily. This is safe
781 * as we're holding an active reference.
783 up_write(&s
->s_umount
);
784 close_bdev_exclusive(bdev
, mode
);
785 down_write(&s
->s_umount
);
787 char b
[BDEVNAME_SIZE
];
791 strlcpy(s
->s_id
, bdevname(bdev
, b
), sizeof(s
->s_id
));
792 sb_set_blocksize(s
, block_size(bdev
));
793 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
795 deactivate_locked_super(s
);
799 s
->s_flags
|= MS_ACTIVE
;
803 simple_set_mnt(mnt
, s
);
809 close_bdev_exclusive(bdev
, mode
);
814 EXPORT_SYMBOL(get_sb_bdev
);
816 void kill_block_super(struct super_block
*sb
)
818 struct block_device
*bdev
= sb
->s_bdev
;
819 fmode_t mode
= sb
->s_mode
;
821 bdev
->bd_super
= NULL
;
822 generic_shutdown_super(sb
);
824 close_bdev_exclusive(bdev
, mode
);
827 EXPORT_SYMBOL(kill_block_super
);
830 int get_sb_nodev(struct file_system_type
*fs_type
,
831 int flags
, void *data
,
832 int (*fill_super
)(struct super_block
*, void *, int),
833 struct vfsmount
*mnt
)
836 struct super_block
*s
= sget(fs_type
, NULL
, set_anon_super
, NULL
);
843 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
845 deactivate_locked_super(s
);
848 s
->s_flags
|= MS_ACTIVE
;
849 simple_set_mnt(mnt
, s
);
853 EXPORT_SYMBOL(get_sb_nodev
);
855 static int compare_single(struct super_block
*s
, void *p
)
860 int get_sb_single(struct file_system_type
*fs_type
,
861 int flags
, void *data
,
862 int (*fill_super
)(struct super_block
*, void *, int),
863 struct vfsmount
*mnt
)
865 struct super_block
*s
;
868 s
= sget(fs_type
, compare_single
, set_anon_super
, NULL
);
873 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
875 deactivate_locked_super(s
);
878 s
->s_flags
|= MS_ACTIVE
;
880 do_remount_sb(s
, flags
, data
, 0);
882 simple_set_mnt(mnt
, s
);
886 EXPORT_SYMBOL(get_sb_single
);
889 vfs_kern_mount(struct file_system_type
*type
, int flags
, const char *name
, void *data
)
891 struct vfsmount
*mnt
;
892 char *secdata
= NULL
;
896 return ERR_PTR(-ENODEV
);
899 mnt
= alloc_vfsmnt(name
);
903 if (flags
& MS_KERNMOUNT
)
904 mnt
->mnt_flags
= MNT_INTERNAL
;
906 if (data
&& !(type
->fs_flags
& FS_BINARY_MOUNTDATA
)) {
907 secdata
= alloc_secdata();
911 error
= security_sb_copy_data(data
, secdata
);
913 goto out_free_secdata
;
916 error
= type
->get_sb(type
, flags
, name
, data
, mnt
);
918 goto out_free_secdata
;
919 BUG_ON(!mnt
->mnt_sb
);
920 WARN_ON(!mnt
->mnt_sb
->s_bdi
);
922 error
= security_sb_kern_mount(mnt
->mnt_sb
, flags
, secdata
);
927 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
928 * but s_maxbytes was an unsigned long long for many releases. Throw
929 * this warning for a little while to try and catch filesystems that
930 * violate this rule. This warning should be either removed or
931 * converted to a BUG() in 2.6.34.
933 WARN((mnt
->mnt_sb
->s_maxbytes
< 0), "%s set sb->s_maxbytes to "
934 "negative value (%lld)\n", type
->name
, mnt
->mnt_sb
->s_maxbytes
);
936 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
937 mnt
->mnt_parent
= mnt
;
938 up_write(&mnt
->mnt_sb
->s_umount
);
939 free_secdata(secdata
);
943 deactivate_locked_super(mnt
->mnt_sb
);
945 free_secdata(secdata
);
949 return ERR_PTR(error
);
952 EXPORT_SYMBOL_GPL(vfs_kern_mount
);
955 * freeze_super - lock the filesystem and force it into a consistent state
956 * @sb: the super to lock
958 * Syncs the super to make sure the filesystem is consistent and calls the fs's
959 * freeze_fs. Subsequent calls to this without first thawing the fs will return
962 int freeze_super(struct super_block
*sb
)
966 atomic_inc(&sb
->s_active
);
967 down_write(&sb
->s_umount
);
969 deactivate_locked_super(sb
);
973 if (sb
->s_flags
& MS_RDONLY
) {
974 sb
->s_frozen
= SB_FREEZE_TRANS
;
976 up_write(&sb
->s_umount
);
980 sb
->s_frozen
= SB_FREEZE_WRITE
;
985 sb
->s_frozen
= SB_FREEZE_TRANS
;
988 sync_blockdev(sb
->s_bdev
);
989 if (sb
->s_op
->freeze_fs
) {
990 ret
= sb
->s_op
->freeze_fs(sb
);
993 "VFS:Filesystem freeze failed\n");
994 sb
->s_frozen
= SB_UNFROZEN
;
995 deactivate_locked_super(sb
);
999 up_write(&sb
->s_umount
);
1002 EXPORT_SYMBOL(freeze_super
);
1005 * thaw_super -- unlock filesystem
1006 * @sb: the super to thaw
1008 * Unlocks the filesystem and marks it writeable again after freeze_super().
1010 int thaw_super(struct super_block
*sb
)
1014 down_write(&sb
->s_umount
);
1015 if (sb
->s_frozen
== SB_UNFROZEN
) {
1016 up_write(&sb
->s_umount
);
1020 if (sb
->s_flags
& MS_RDONLY
)
1023 if (sb
->s_op
->unfreeze_fs
) {
1024 error
= sb
->s_op
->unfreeze_fs(sb
);
1027 "VFS:Filesystem thaw failed\n");
1028 sb
->s_frozen
= SB_FREEZE_TRANS
;
1029 up_write(&sb
->s_umount
);
1035 sb
->s_frozen
= SB_UNFROZEN
;
1037 wake_up(&sb
->s_wait_unfrozen
);
1038 deactivate_locked_super(sb
);
1042 EXPORT_SYMBOL(thaw_super
);
1044 static struct vfsmount
*fs_set_subtype(struct vfsmount
*mnt
, const char *fstype
)
1047 const char *subtype
= strchr(fstype
, '.');
1056 mnt
->mnt_sb
->s_subtype
= kstrdup(subtype
, GFP_KERNEL
);
1058 if (!mnt
->mnt_sb
->s_subtype
)
1064 return ERR_PTR(err
);
1068 do_kern_mount(const char *fstype
, int flags
, const char *name
, void *data
)
1070 struct file_system_type
*type
= get_fs_type(fstype
);
1071 struct vfsmount
*mnt
;
1073 return ERR_PTR(-ENODEV
);
1074 mnt
= vfs_kern_mount(type
, flags
, name
, data
);
1075 if (!IS_ERR(mnt
) && (type
->fs_flags
& FS_HAS_SUBTYPE
) &&
1076 !mnt
->mnt_sb
->s_subtype
)
1077 mnt
= fs_set_subtype(mnt
, fstype
);
1078 put_filesystem(type
);
1081 EXPORT_SYMBOL_GPL(do_kern_mount
);
1083 struct vfsmount
*kern_mount_data(struct file_system_type
*type
, void *data
)
1085 return vfs_kern_mount(type
, MS_KERNMOUNT
, type
->name
, data
);
1088 EXPORT_SYMBOL_GPL(kern_mount_data
);