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
);
310 down_write(&old
->s_umount
);
311 if (unlikely(!(old
->s_flags
& MS_BORN
))) {
312 deactivate_locked_super(old
);
319 spin_unlock(&sb_lock
);
320 s
= alloc_super(type
);
322 return ERR_PTR(-ENOMEM
);
328 spin_unlock(&sb_lock
);
329 up_write(&s
->s_umount
);
334 strlcpy(s
->s_id
, type
->name
, sizeof(s
->s_id
));
335 list_add_tail(&s
->s_list
, &super_blocks
);
336 list_add(&s
->s_instances
, &type
->fs_supers
);
337 spin_unlock(&sb_lock
);
338 get_filesystem(type
);
344 void drop_super(struct super_block
*sb
)
346 up_read(&sb
->s_umount
);
350 EXPORT_SYMBOL(drop_super
);
353 * sync_supers - helper for periodic superblock writeback
355 * Call the write_super method if present on all dirty superblocks in
356 * the system. This is for the periodic writeback used by most older
357 * filesystems. For data integrity superblock writeback use
358 * sync_filesystems() instead.
360 * Note: check the dirty flag before waiting, so we don't
361 * hold up the sync while mounting a device. (The newly
362 * mounted device won't need syncing.)
364 void sync_supers(void)
366 struct super_block
*sb
, *p
= NULL
;
369 list_for_each_entry(sb
, &super_blocks
, s_list
) {
370 if (list_empty(&sb
->s_instances
))
372 if (sb
->s_op
->write_super
&& sb
->s_dirt
) {
374 spin_unlock(&sb_lock
);
376 down_read(&sb
->s_umount
);
377 if (sb
->s_root
&& sb
->s_dirt
)
378 sb
->s_op
->write_super(sb
);
379 up_read(&sb
->s_umount
);
389 spin_unlock(&sb_lock
);
393 * iterate_supers - call function for all active superblocks
394 * @f: function to call
395 * @arg: argument to pass to it
397 * Scans the superblock list and calls given function, passing it
398 * locked superblock and given argument.
400 void iterate_supers(void (*f
)(struct super_block
*, void *), void *arg
)
402 struct super_block
*sb
, *p
= NULL
;
405 list_for_each_entry(sb
, &super_blocks
, s_list
) {
406 if (list_empty(&sb
->s_instances
))
409 spin_unlock(&sb_lock
);
411 down_read(&sb
->s_umount
);
414 up_read(&sb
->s_umount
);
423 spin_unlock(&sb_lock
);
427 * get_super - get the superblock of a device
428 * @bdev: device to get the superblock for
430 * Scans the superblock list and finds the superblock of the file system
431 * mounted on the device given. %NULL is returned if no match is found.
434 struct super_block
*get_super(struct block_device
*bdev
)
436 struct super_block
*sb
;
443 list_for_each_entry(sb
, &super_blocks
, s_list
) {
444 if (list_empty(&sb
->s_instances
))
446 if (sb
->s_bdev
== bdev
) {
448 spin_unlock(&sb_lock
);
449 down_read(&sb
->s_umount
);
453 up_read(&sb
->s_umount
);
454 /* nope, got unmounted */
460 spin_unlock(&sb_lock
);
464 EXPORT_SYMBOL(get_super
);
467 * get_active_super - get an active reference to the superblock of a device
468 * @bdev: device to get the superblock for
470 * Scans the superblock list and finds the superblock of the file system
471 * mounted on the device given. Returns the superblock with an active
472 * reference or %NULL if none was found.
474 struct super_block
*get_active_super(struct block_device
*bdev
)
476 struct super_block
*sb
;
483 list_for_each_entry(sb
, &super_blocks
, s_list
) {
484 if (list_empty(&sb
->s_instances
))
486 if (sb
->s_bdev
== bdev
) {
487 if (grab_super(sb
)) /* drops sb_lock */
493 spin_unlock(&sb_lock
);
497 struct super_block
*user_get_super(dev_t dev
)
499 struct super_block
*sb
;
503 list_for_each_entry(sb
, &super_blocks
, s_list
) {
504 if (list_empty(&sb
->s_instances
))
506 if (sb
->s_dev
== dev
) {
508 spin_unlock(&sb_lock
);
509 down_read(&sb
->s_umount
);
513 up_read(&sb
->s_umount
);
514 /* nope, got unmounted */
520 spin_unlock(&sb_lock
);
525 * do_remount_sb - asks filesystem to change mount options.
526 * @sb: superblock in question
527 * @flags: numeric part of options
528 * @data: the rest of options
529 * @force: whether or not to force the change
531 * Alters the mount options of a mounted file system.
533 int do_remount_sb(struct super_block
*sb
, int flags
, void *data
, int force
)
538 if (sb
->s_frozen
!= SB_UNFROZEN
)
542 if (!(flags
& MS_RDONLY
) && bdev_read_only(sb
->s_bdev
))
546 if (flags
& MS_RDONLY
)
548 shrink_dcache_sb(sb
);
551 remount_ro
= (flags
& MS_RDONLY
) && !(sb
->s_flags
& MS_RDONLY
);
553 /* If we are remounting RDONLY and current sb is read/write,
554 make sure there are no rw files opened */
558 else if (!fs_may_remount_ro(sb
))
562 if (sb
->s_op
->remount_fs
) {
563 retval
= sb
->s_op
->remount_fs(sb
, &flags
, data
);
567 sb
->s_flags
= (sb
->s_flags
& ~MS_RMT_MASK
) | (flags
& MS_RMT_MASK
);
570 * Some filesystems modify their metadata via some other path than the
571 * bdev buffer cache (eg. use a private mapping, or directories in
572 * pagecache, etc). Also file data modifications go via their own
573 * mappings. So If we try to mount readonly then copy the filesystem
574 * from bdev, we could get stale data, so invalidate it to give a best
575 * effort at coherency.
577 if (remount_ro
&& sb
->s_bdev
)
578 invalidate_bdev(sb
->s_bdev
);
582 static void do_emergency_remount(struct work_struct
*work
)
584 struct super_block
*sb
, *p
= NULL
;
587 list_for_each_entry(sb
, &super_blocks
, s_list
) {
588 if (list_empty(&sb
->s_instances
))
591 spin_unlock(&sb_lock
);
592 down_write(&sb
->s_umount
);
593 if (sb
->s_root
&& sb
->s_bdev
&& !(sb
->s_flags
& MS_RDONLY
)) {
595 * What lock protects sb->s_flags??
597 do_remount_sb(sb
, MS_RDONLY
, NULL
, 1);
599 up_write(&sb
->s_umount
);
607 spin_unlock(&sb_lock
);
609 printk("Emergency Remount complete\n");
612 void emergency_remount(void)
614 struct work_struct
*work
;
616 work
= kmalloc(sizeof(*work
), GFP_ATOMIC
);
618 INIT_WORK(work
, do_emergency_remount
);
624 * Unnamed block devices are dummy devices used by virtual
625 * filesystems which don't use real block-devices. -- jrs
628 static DEFINE_IDA(unnamed_dev_ida
);
629 static DEFINE_SPINLOCK(unnamed_dev_lock
);/* protects the above */
630 static int unnamed_dev_start
= 0; /* don't bother trying below it */
632 int set_anon_super(struct super_block
*s
, void *data
)
638 if (ida_pre_get(&unnamed_dev_ida
, GFP_ATOMIC
) == 0)
640 spin_lock(&unnamed_dev_lock
);
641 error
= ida_get_new_above(&unnamed_dev_ida
, unnamed_dev_start
, &dev
);
643 unnamed_dev_start
= dev
+ 1;
644 spin_unlock(&unnamed_dev_lock
);
645 if (error
== -EAGAIN
)
646 /* We raced and lost with another CPU. */
651 if ((dev
& MAX_ID_MASK
) == (1 << MINORBITS
)) {
652 spin_lock(&unnamed_dev_lock
);
653 ida_remove(&unnamed_dev_ida
, dev
);
654 if (unnamed_dev_start
> dev
)
655 unnamed_dev_start
= dev
;
656 spin_unlock(&unnamed_dev_lock
);
659 s
->s_dev
= MKDEV(0, dev
& MINORMASK
);
660 s
->s_bdi
= &noop_backing_dev_info
;
664 EXPORT_SYMBOL(set_anon_super
);
666 void kill_anon_super(struct super_block
*sb
)
668 int slot
= MINOR(sb
->s_dev
);
670 generic_shutdown_super(sb
);
671 spin_lock(&unnamed_dev_lock
);
672 ida_remove(&unnamed_dev_ida
, slot
);
673 if (slot
< unnamed_dev_start
)
674 unnamed_dev_start
= slot
;
675 spin_unlock(&unnamed_dev_lock
);
678 EXPORT_SYMBOL(kill_anon_super
);
680 void kill_litter_super(struct super_block
*sb
)
683 d_genocide(sb
->s_root
);
687 EXPORT_SYMBOL(kill_litter_super
);
689 static int ns_test_super(struct super_block
*sb
, void *data
)
691 return sb
->s_fs_info
== data
;
694 static int ns_set_super(struct super_block
*sb
, void *data
)
696 sb
->s_fs_info
= data
;
697 return set_anon_super(sb
, NULL
);
700 int get_sb_ns(struct file_system_type
*fs_type
, int flags
, void *data
,
701 int (*fill_super
)(struct super_block
*, void *, int),
702 struct vfsmount
*mnt
)
704 struct super_block
*sb
;
706 sb
= sget(fs_type
, ns_test_super
, ns_set_super
, data
);
713 err
= fill_super(sb
, data
, flags
& MS_SILENT
? 1 : 0);
715 deactivate_locked_super(sb
);
719 sb
->s_flags
|= MS_ACTIVE
;
722 simple_set_mnt(mnt
, sb
);
726 EXPORT_SYMBOL(get_sb_ns
);
729 static int set_bdev_super(struct super_block
*s
, void *data
)
732 s
->s_dev
= s
->s_bdev
->bd_dev
;
735 * We set the bdi here to the queue backing, file systems can
736 * overwrite this in ->fill_super()
738 s
->s_bdi
= &bdev_get_queue(s
->s_bdev
)->backing_dev_info
;
742 static int test_bdev_super(struct super_block
*s
, void *data
)
744 return (void *)s
->s_bdev
== data
;
747 int get_sb_bdev(struct file_system_type
*fs_type
,
748 int flags
, const char *dev_name
, void *data
,
749 int (*fill_super
)(struct super_block
*, void *, int),
750 struct vfsmount
*mnt
)
752 struct block_device
*bdev
;
753 struct super_block
*s
;
754 fmode_t mode
= FMODE_READ
;
757 if (!(flags
& MS_RDONLY
))
760 bdev
= open_bdev_exclusive(dev_name
, mode
, fs_type
);
762 return PTR_ERR(bdev
);
765 * once the super is inserted into the list by sget, s_umount
766 * will protect the lockfs code from trying to start a snapshot
767 * while we are mounting
769 mutex_lock(&bdev
->bd_fsfreeze_mutex
);
770 if (bdev
->bd_fsfreeze_count
> 0) {
771 mutex_unlock(&bdev
->bd_fsfreeze_mutex
);
775 s
= sget(fs_type
, test_bdev_super
, set_bdev_super
, bdev
);
776 mutex_unlock(&bdev
->bd_fsfreeze_mutex
);
781 if ((flags
^ s
->s_flags
) & MS_RDONLY
) {
782 deactivate_locked_super(s
);
788 * s_umount nests inside bd_mutex during
789 * __invalidate_device(). close_bdev_exclusive()
790 * acquires bd_mutex and can't be called under
791 * s_umount. Drop s_umount temporarily. This is safe
792 * as we're holding an active reference.
794 up_write(&s
->s_umount
);
795 close_bdev_exclusive(bdev
, mode
);
796 down_write(&s
->s_umount
);
798 char b
[BDEVNAME_SIZE
];
802 strlcpy(s
->s_id
, bdevname(bdev
, b
), sizeof(s
->s_id
));
803 sb_set_blocksize(s
, block_size(bdev
));
804 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
806 deactivate_locked_super(s
);
810 s
->s_flags
|= MS_ACTIVE
;
814 simple_set_mnt(mnt
, s
);
820 close_bdev_exclusive(bdev
, mode
);
825 EXPORT_SYMBOL(get_sb_bdev
);
827 void kill_block_super(struct super_block
*sb
)
829 struct block_device
*bdev
= sb
->s_bdev
;
830 fmode_t mode
= sb
->s_mode
;
832 bdev
->bd_super
= NULL
;
833 generic_shutdown_super(sb
);
835 close_bdev_exclusive(bdev
, mode
);
838 EXPORT_SYMBOL(kill_block_super
);
841 int get_sb_nodev(struct file_system_type
*fs_type
,
842 int flags
, void *data
,
843 int (*fill_super
)(struct super_block
*, void *, int),
844 struct vfsmount
*mnt
)
847 struct super_block
*s
= sget(fs_type
, NULL
, set_anon_super
, NULL
);
854 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
856 deactivate_locked_super(s
);
859 s
->s_flags
|= MS_ACTIVE
;
860 simple_set_mnt(mnt
, s
);
864 EXPORT_SYMBOL(get_sb_nodev
);
866 static int compare_single(struct super_block
*s
, void *p
)
871 int get_sb_single(struct file_system_type
*fs_type
,
872 int flags
, void *data
,
873 int (*fill_super
)(struct super_block
*, void *, int),
874 struct vfsmount
*mnt
)
876 struct super_block
*s
;
879 s
= sget(fs_type
, compare_single
, set_anon_super
, NULL
);
884 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
886 deactivate_locked_super(s
);
889 s
->s_flags
|= MS_ACTIVE
;
891 do_remount_sb(s
, flags
, data
, 0);
893 simple_set_mnt(mnt
, s
);
897 EXPORT_SYMBOL(get_sb_single
);
900 vfs_kern_mount(struct file_system_type
*type
, int flags
, const char *name
, void *data
)
902 struct vfsmount
*mnt
;
903 char *secdata
= NULL
;
907 return ERR_PTR(-ENODEV
);
910 mnt
= alloc_vfsmnt(name
);
914 if (flags
& MS_KERNMOUNT
)
915 mnt
->mnt_flags
= MNT_INTERNAL
;
917 if (data
&& !(type
->fs_flags
& FS_BINARY_MOUNTDATA
)) {
918 secdata
= alloc_secdata();
922 error
= security_sb_copy_data(data
, secdata
);
924 goto out_free_secdata
;
927 error
= type
->get_sb(type
, flags
, name
, data
, mnt
);
929 goto out_free_secdata
;
930 BUG_ON(!mnt
->mnt_sb
);
931 WARN_ON(!mnt
->mnt_sb
->s_bdi
);
932 mnt
->mnt_sb
->s_flags
|= MS_BORN
;
934 error
= security_sb_kern_mount(mnt
->mnt_sb
, flags
, secdata
);
939 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
940 * but s_maxbytes was an unsigned long long for many releases. Throw
941 * this warning for a little while to try and catch filesystems that
942 * violate this rule. This warning should be either removed or
943 * converted to a BUG() in 2.6.34.
945 WARN((mnt
->mnt_sb
->s_maxbytes
< 0), "%s set sb->s_maxbytes to "
946 "negative value (%lld)\n", type
->name
, mnt
->mnt_sb
->s_maxbytes
);
948 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
949 mnt
->mnt_parent
= mnt
;
950 up_write(&mnt
->mnt_sb
->s_umount
);
951 free_secdata(secdata
);
955 deactivate_locked_super(mnt
->mnt_sb
);
957 free_secdata(secdata
);
961 return ERR_PTR(error
);
964 EXPORT_SYMBOL_GPL(vfs_kern_mount
);
967 * freeze_super - lock the filesystem and force it into a consistent state
968 * @sb: the super to lock
970 * Syncs the super to make sure the filesystem is consistent and calls the fs's
971 * freeze_fs. Subsequent calls to this without first thawing the fs will return
974 int freeze_super(struct super_block
*sb
)
978 atomic_inc(&sb
->s_active
);
979 down_write(&sb
->s_umount
);
981 deactivate_locked_super(sb
);
985 if (sb
->s_flags
& MS_RDONLY
) {
986 sb
->s_frozen
= SB_FREEZE_TRANS
;
988 up_write(&sb
->s_umount
);
992 sb
->s_frozen
= SB_FREEZE_WRITE
;
997 sb
->s_frozen
= SB_FREEZE_TRANS
;
1000 sync_blockdev(sb
->s_bdev
);
1001 if (sb
->s_op
->freeze_fs
) {
1002 ret
= sb
->s_op
->freeze_fs(sb
);
1005 "VFS:Filesystem freeze failed\n");
1006 sb
->s_frozen
= SB_UNFROZEN
;
1007 deactivate_locked_super(sb
);
1011 up_write(&sb
->s_umount
);
1014 EXPORT_SYMBOL(freeze_super
);
1017 * thaw_super -- unlock filesystem
1018 * @sb: the super to thaw
1020 * Unlocks the filesystem and marks it writeable again after freeze_super().
1022 int thaw_super(struct super_block
*sb
)
1026 down_write(&sb
->s_umount
);
1027 if (sb
->s_frozen
== SB_UNFROZEN
) {
1028 up_write(&sb
->s_umount
);
1032 if (sb
->s_flags
& MS_RDONLY
)
1035 if (sb
->s_op
->unfreeze_fs
) {
1036 error
= sb
->s_op
->unfreeze_fs(sb
);
1039 "VFS:Filesystem thaw failed\n");
1040 sb
->s_frozen
= SB_FREEZE_TRANS
;
1041 up_write(&sb
->s_umount
);
1047 sb
->s_frozen
= SB_UNFROZEN
;
1049 wake_up(&sb
->s_wait_unfrozen
);
1050 deactivate_locked_super(sb
);
1054 EXPORT_SYMBOL(thaw_super
);
1056 static struct vfsmount
*fs_set_subtype(struct vfsmount
*mnt
, const char *fstype
)
1059 const char *subtype
= strchr(fstype
, '.');
1068 mnt
->mnt_sb
->s_subtype
= kstrdup(subtype
, GFP_KERNEL
);
1070 if (!mnt
->mnt_sb
->s_subtype
)
1076 return ERR_PTR(err
);
1080 do_kern_mount(const char *fstype
, int flags
, const char *name
, void *data
)
1082 struct file_system_type
*type
= get_fs_type(fstype
);
1083 struct vfsmount
*mnt
;
1085 return ERR_PTR(-ENODEV
);
1086 mnt
= vfs_kern_mount(type
, flags
, name
, data
);
1087 if (!IS_ERR(mnt
) && (type
->fs_flags
& FS_HAS_SUBTYPE
) &&
1088 !mnt
->mnt_sb
->s_subtype
)
1089 mnt
= fs_set_subtype(mnt
, fstype
);
1090 put_filesystem(type
);
1093 EXPORT_SYMBOL_GPL(do_kern_mount
);
1095 struct vfsmount
*kern_mount_data(struct file_system_type
*type
, void *data
)
1097 return vfs_kern_mount(type
, MS_KERNMOUNT
, type
->name
, data
);
1100 EXPORT_SYMBOL_GPL(kern_mount_data
);