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>
33 #include <linux/rculist_bl.h>
34 #include <linux/cleancache.h>
38 LIST_HEAD(super_blocks
);
39 DEFINE_SPINLOCK(sb_lock
);
42 * alloc_super - create new superblock
43 * @type: filesystem type superblock should belong to
45 * Allocates and initializes a new &struct super_block. alloc_super()
46 * returns a pointer new superblock or %NULL if allocation had failed.
48 static struct super_block
*alloc_super(struct file_system_type
*type
)
50 struct super_block
*s
= kzalloc(sizeof(struct super_block
), GFP_USER
);
51 static const struct super_operations default_op
;
54 if (security_sb_alloc(s
)) {
60 s
->s_files
= alloc_percpu(struct list_head
);
69 for_each_possible_cpu(i
)
70 INIT_LIST_HEAD(per_cpu_ptr(s
->s_files
, i
));
73 INIT_LIST_HEAD(&s
->s_files
);
75 s
->s_bdi
= &default_backing_dev_info
;
76 INIT_LIST_HEAD(&s
->s_instances
);
77 INIT_HLIST_BL_HEAD(&s
->s_anon
);
78 INIT_LIST_HEAD(&s
->s_inodes
);
79 INIT_LIST_HEAD(&s
->s_dentry_lru
);
80 INIT_LIST_HEAD(&s
->s_inode_lru
);
81 spin_lock_init(&s
->s_inode_lru_lock
);
82 init_rwsem(&s
->s_umount
);
83 mutex_init(&s
->s_lock
);
84 lockdep_set_class(&s
->s_umount
, &type
->s_umount_key
);
86 * The locking rules for s_lock are up to the
87 * filesystem. For example ext3fs has different
88 * lock ordering than usbfs:
90 lockdep_set_class(&s
->s_lock
, &type
->s_lock_key
);
92 * sget() can have s_umount recursion.
94 * When it cannot find a suitable sb, it allocates a new
95 * one (this one), and tries again to find a suitable old
98 * In case that succeeds, it will acquire the s_umount
99 * lock of the old one. Since these are clearly distrinct
100 * locks, and this object isn't exposed yet, there's no
103 * Annotate this by putting this lock in a different
106 down_write_nested(&s
->s_umount
, SINGLE_DEPTH_NESTING
);
108 atomic_set(&s
->s_active
, 1);
109 mutex_init(&s
->s_vfs_rename_mutex
);
110 lockdep_set_class(&s
->s_vfs_rename_mutex
, &type
->s_vfs_rename_key
);
111 mutex_init(&s
->s_dquot
.dqio_mutex
);
112 mutex_init(&s
->s_dquot
.dqonoff_mutex
);
113 init_rwsem(&s
->s_dquot
.dqptr_sem
);
114 init_waitqueue_head(&s
->s_wait_unfrozen
);
115 s
->s_maxbytes
= MAX_NON_LFS
;
116 s
->s_op
= &default_op
;
117 s
->s_time_gran
= 1000000000;
118 s
->cleancache_poolid
= -1;
125 * destroy_super - frees a superblock
126 * @s: superblock to free
128 * Frees a superblock.
130 static inline void destroy_super(struct super_block
*s
)
133 free_percpu(s
->s_files
);
141 /* Superblock refcounting */
144 * Drop a superblock's refcount. The caller must hold sb_lock.
146 void __put_super(struct super_block
*sb
)
148 if (!--sb
->s_count
) {
149 list_del_init(&sb
->s_list
);
155 * put_super - drop a temporary reference to superblock
156 * @sb: superblock in question
158 * Drops a temporary reference, frees superblock if there's no
161 void put_super(struct super_block
*sb
)
165 spin_unlock(&sb_lock
);
170 * deactivate_locked_super - drop an active reference to superblock
171 * @s: superblock to deactivate
173 * Drops an active reference to superblock, converting it into a temprory
174 * one if there is no other active references left. In that case we
175 * tell fs driver to shut it down and drop the temporary reference we
178 * Caller holds exclusive lock on superblock; that lock is released.
180 void deactivate_locked_super(struct super_block
*s
)
182 struct file_system_type
*fs
= s
->s_type
;
183 if (atomic_dec_and_test(&s
->s_active
)) {
184 cleancache_flush_fs(s
);
187 * We need to call rcu_barrier so all the delayed rcu free
188 * inodes are flushed before we release the fs module.
194 up_write(&s
->s_umount
);
198 EXPORT_SYMBOL(deactivate_locked_super
);
201 * deactivate_super - drop an active reference to superblock
202 * @s: superblock to deactivate
204 * Variant of deactivate_locked_super(), except that superblock is *not*
205 * locked by caller. If we are going to drop the final active reference,
206 * lock will be acquired prior to that.
208 void deactivate_super(struct super_block
*s
)
210 if (!atomic_add_unless(&s
->s_active
, -1, 1)) {
211 down_write(&s
->s_umount
);
212 deactivate_locked_super(s
);
216 EXPORT_SYMBOL(deactivate_super
);
219 * grab_super - acquire an active reference
220 * @s: reference we are trying to make active
222 * Tries to acquire an active reference. grab_super() is used when we
223 * had just found a superblock in super_blocks or fs_type->fs_supers
224 * and want to turn it into a full-blown active reference. grab_super()
225 * is called with sb_lock held and drops it. Returns 1 in case of
226 * success, 0 if we had failed (superblock contents was already dead or
227 * dying when grab_super() had been called).
229 static int grab_super(struct super_block
*s
) __releases(sb_lock
)
231 if (atomic_inc_not_zero(&s
->s_active
)) {
232 spin_unlock(&sb_lock
);
235 /* it's going away */
237 spin_unlock(&sb_lock
);
238 /* wait for it to die */
239 down_write(&s
->s_umount
);
240 up_write(&s
->s_umount
);
246 * Superblock locking. We really ought to get rid of these two.
248 void lock_super(struct super_block
* sb
)
251 mutex_lock(&sb
->s_lock
);
254 void unlock_super(struct super_block
* sb
)
257 mutex_unlock(&sb
->s_lock
);
260 EXPORT_SYMBOL(lock_super
);
261 EXPORT_SYMBOL(unlock_super
);
264 * generic_shutdown_super - common helper for ->kill_sb()
265 * @sb: superblock to kill
267 * generic_shutdown_super() does all fs-independent work on superblock
268 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
269 * that need destruction out of superblock, call generic_shutdown_super()
270 * and release aforementioned objects. Note: dentries and inodes _are_
271 * taken care of and do not need specific handling.
273 * Upon calling this function, the filesystem may no longer alter or
274 * rearrange the set of dentries belonging to this super_block, nor may it
275 * change the attachments of dentries to inodes.
277 void generic_shutdown_super(struct super_block
*sb
)
279 const struct super_operations
*sop
= sb
->s_op
;
283 shrink_dcache_for_umount(sb
);
286 sb
->s_flags
&= ~MS_ACTIVE
;
288 fsnotify_unmount_inodes(&sb
->s_inodes
);
295 if (!list_empty(&sb
->s_inodes
)) {
296 printk("VFS: Busy inodes after unmount of %s. "
297 "Self-destruct in 5 seconds. Have a nice day...\n",
303 /* should be initialized for __put_super_and_need_restart() */
304 list_del_init(&sb
->s_instances
);
305 spin_unlock(&sb_lock
);
306 up_write(&sb
->s_umount
);
309 EXPORT_SYMBOL(generic_shutdown_super
);
312 * sget - find or create a superblock
313 * @type: filesystem type superblock should belong to
314 * @test: comparison callback
315 * @set: setup callback
316 * @data: argument to each of them
318 struct super_block
*sget(struct file_system_type
*type
,
319 int (*test
)(struct super_block
*,void *),
320 int (*set
)(struct super_block
*,void *),
323 struct super_block
*s
= NULL
;
324 struct super_block
*old
;
330 list_for_each_entry(old
, &type
->fs_supers
, s_instances
) {
331 if (!test(old
, data
))
333 if (!grab_super(old
))
336 up_write(&s
->s_umount
);
340 down_write(&old
->s_umount
);
341 if (unlikely(!(old
->s_flags
& MS_BORN
))) {
342 deactivate_locked_super(old
);
349 spin_unlock(&sb_lock
);
350 s
= alloc_super(type
);
352 return ERR_PTR(-ENOMEM
);
358 spin_unlock(&sb_lock
);
359 up_write(&s
->s_umount
);
364 strlcpy(s
->s_id
, type
->name
, sizeof(s
->s_id
));
365 list_add_tail(&s
->s_list
, &super_blocks
);
366 list_add(&s
->s_instances
, &type
->fs_supers
);
367 spin_unlock(&sb_lock
);
368 get_filesystem(type
);
374 void drop_super(struct super_block
*sb
)
376 up_read(&sb
->s_umount
);
380 EXPORT_SYMBOL(drop_super
);
383 * sync_supers - helper for periodic superblock writeback
385 * Call the write_super method if present on all dirty superblocks in
386 * the system. This is for the periodic writeback used by most older
387 * filesystems. For data integrity superblock writeback use
388 * sync_filesystems() instead.
390 * Note: check the dirty flag before waiting, so we don't
391 * hold up the sync while mounting a device. (The newly
392 * mounted device won't need syncing.)
394 void sync_supers(void)
396 struct super_block
*sb
, *p
= NULL
;
399 list_for_each_entry(sb
, &super_blocks
, s_list
) {
400 if (list_empty(&sb
->s_instances
))
402 if (sb
->s_op
->write_super
&& sb
->s_dirt
) {
404 spin_unlock(&sb_lock
);
406 down_read(&sb
->s_umount
);
407 if (sb
->s_root
&& sb
->s_dirt
)
408 sb
->s_op
->write_super(sb
);
409 up_read(&sb
->s_umount
);
419 spin_unlock(&sb_lock
);
423 * iterate_supers - call function for all active superblocks
424 * @f: function to call
425 * @arg: argument to pass to it
427 * Scans the superblock list and calls given function, passing it
428 * locked superblock and given argument.
430 void iterate_supers(void (*f
)(struct super_block
*, void *), void *arg
)
432 struct super_block
*sb
, *p
= NULL
;
435 list_for_each_entry(sb
, &super_blocks
, s_list
) {
436 if (list_empty(&sb
->s_instances
))
439 spin_unlock(&sb_lock
);
441 down_read(&sb
->s_umount
);
444 up_read(&sb
->s_umount
);
453 spin_unlock(&sb_lock
);
457 * iterate_supers_type - call function for superblocks of given type
459 * @f: function to call
460 * @arg: argument to pass to it
462 * Scans the superblock list and calls given function, passing it
463 * locked superblock and given argument.
465 void iterate_supers_type(struct file_system_type
*type
,
466 void (*f
)(struct super_block
*, void *), void *arg
)
468 struct super_block
*sb
, *p
= NULL
;
471 list_for_each_entry(sb
, &type
->fs_supers
, s_instances
) {
473 spin_unlock(&sb_lock
);
475 down_read(&sb
->s_umount
);
478 up_read(&sb
->s_umount
);
487 spin_unlock(&sb_lock
);
490 EXPORT_SYMBOL(iterate_supers_type
);
493 * get_super - get the superblock of a device
494 * @bdev: device to get the superblock for
496 * Scans the superblock list and finds the superblock of the file system
497 * mounted on the device given. %NULL is returned if no match is found.
500 struct super_block
*get_super(struct block_device
*bdev
)
502 struct super_block
*sb
;
509 list_for_each_entry(sb
, &super_blocks
, s_list
) {
510 if (list_empty(&sb
->s_instances
))
512 if (sb
->s_bdev
== bdev
) {
514 spin_unlock(&sb_lock
);
515 down_read(&sb
->s_umount
);
519 up_read(&sb
->s_umount
);
520 /* nope, got unmounted */
526 spin_unlock(&sb_lock
);
530 EXPORT_SYMBOL(get_super
);
533 * get_active_super - get an active reference to the superblock of a device
534 * @bdev: device to get the superblock for
536 * Scans the superblock list and finds the superblock of the file system
537 * mounted on the device given. Returns the superblock with an active
538 * reference or %NULL if none was found.
540 struct super_block
*get_active_super(struct block_device
*bdev
)
542 struct super_block
*sb
;
549 list_for_each_entry(sb
, &super_blocks
, s_list
) {
550 if (list_empty(&sb
->s_instances
))
552 if (sb
->s_bdev
== bdev
) {
553 if (grab_super(sb
)) /* drops sb_lock */
559 spin_unlock(&sb_lock
);
563 struct super_block
*user_get_super(dev_t dev
)
565 struct super_block
*sb
;
569 list_for_each_entry(sb
, &super_blocks
, s_list
) {
570 if (list_empty(&sb
->s_instances
))
572 if (sb
->s_dev
== dev
) {
574 spin_unlock(&sb_lock
);
575 down_read(&sb
->s_umount
);
579 up_read(&sb
->s_umount
);
580 /* nope, got unmounted */
586 spin_unlock(&sb_lock
);
591 * do_remount_sb - asks filesystem to change mount options.
592 * @sb: superblock in question
593 * @flags: numeric part of options
594 * @data: the rest of options
595 * @force: whether or not to force the change
597 * Alters the mount options of a mounted file system.
599 int do_remount_sb(struct super_block
*sb
, int flags
, void *data
, int force
)
604 if (sb
->s_frozen
!= SB_UNFROZEN
)
608 if (!(flags
& MS_RDONLY
) && bdev_read_only(sb
->s_bdev
))
612 if (flags
& MS_RDONLY
)
614 shrink_dcache_sb(sb
);
617 remount_ro
= (flags
& MS_RDONLY
) && !(sb
->s_flags
& MS_RDONLY
);
619 /* If we are remounting RDONLY and current sb is read/write,
620 make sure there are no rw files opened */
624 else if (!fs_may_remount_ro(sb
))
628 if (sb
->s_op
->remount_fs
) {
629 retval
= sb
->s_op
->remount_fs(sb
, &flags
, data
);
633 sb
->s_flags
= (sb
->s_flags
& ~MS_RMT_MASK
) | (flags
& MS_RMT_MASK
);
636 * Some filesystems modify their metadata via some other path than the
637 * bdev buffer cache (eg. use a private mapping, or directories in
638 * pagecache, etc). Also file data modifications go via their own
639 * mappings. So If we try to mount readonly then copy the filesystem
640 * from bdev, we could get stale data, so invalidate it to give a best
641 * effort at coherency.
643 if (remount_ro
&& sb
->s_bdev
)
644 invalidate_bdev(sb
->s_bdev
);
648 static void do_emergency_remount(struct work_struct
*work
)
650 struct super_block
*sb
, *p
= NULL
;
653 list_for_each_entry(sb
, &super_blocks
, s_list
) {
654 if (list_empty(&sb
->s_instances
))
657 spin_unlock(&sb_lock
);
658 down_write(&sb
->s_umount
);
659 if (sb
->s_root
&& sb
->s_bdev
&& !(sb
->s_flags
& MS_RDONLY
)) {
661 * What lock protects sb->s_flags??
663 do_remount_sb(sb
, MS_RDONLY
, NULL
, 1);
665 up_write(&sb
->s_umount
);
673 spin_unlock(&sb_lock
);
675 printk("Emergency Remount complete\n");
678 void emergency_remount(void)
680 struct work_struct
*work
;
682 work
= kmalloc(sizeof(*work
), GFP_ATOMIC
);
684 INIT_WORK(work
, do_emergency_remount
);
690 * Unnamed block devices are dummy devices used by virtual
691 * filesystems which don't use real block-devices. -- jrs
694 static DEFINE_IDA(unnamed_dev_ida
);
695 static DEFINE_SPINLOCK(unnamed_dev_lock
);/* protects the above */
696 static int unnamed_dev_start
= 0; /* don't bother trying below it */
698 int get_anon_bdev(dev_t
*p
)
704 if (ida_pre_get(&unnamed_dev_ida
, GFP_ATOMIC
) == 0)
706 spin_lock(&unnamed_dev_lock
);
707 error
= ida_get_new_above(&unnamed_dev_ida
, unnamed_dev_start
, &dev
);
709 unnamed_dev_start
= dev
+ 1;
710 spin_unlock(&unnamed_dev_lock
);
711 if (error
== -EAGAIN
)
712 /* We raced and lost with another CPU. */
717 if ((dev
& MAX_ID_MASK
) == (1 << MINORBITS
)) {
718 spin_lock(&unnamed_dev_lock
);
719 ida_remove(&unnamed_dev_ida
, dev
);
720 if (unnamed_dev_start
> dev
)
721 unnamed_dev_start
= dev
;
722 spin_unlock(&unnamed_dev_lock
);
725 *p
= MKDEV(0, dev
& MINORMASK
);
728 EXPORT_SYMBOL(get_anon_bdev
);
730 void free_anon_bdev(dev_t dev
)
732 int slot
= MINOR(dev
);
733 spin_lock(&unnamed_dev_lock
);
734 ida_remove(&unnamed_dev_ida
, slot
);
735 if (slot
< unnamed_dev_start
)
736 unnamed_dev_start
= slot
;
737 spin_unlock(&unnamed_dev_lock
);
739 EXPORT_SYMBOL(free_anon_bdev
);
741 int set_anon_super(struct super_block
*s
, void *data
)
743 int error
= get_anon_bdev(&s
->s_dev
);
745 s
->s_bdi
= &noop_backing_dev_info
;
749 EXPORT_SYMBOL(set_anon_super
);
751 void kill_anon_super(struct super_block
*sb
)
753 dev_t dev
= sb
->s_dev
;
754 generic_shutdown_super(sb
);
758 EXPORT_SYMBOL(kill_anon_super
);
760 void kill_litter_super(struct super_block
*sb
)
763 d_genocide(sb
->s_root
);
767 EXPORT_SYMBOL(kill_litter_super
);
769 static int ns_test_super(struct super_block
*sb
, void *data
)
771 return sb
->s_fs_info
== data
;
774 static int ns_set_super(struct super_block
*sb
, void *data
)
776 sb
->s_fs_info
= data
;
777 return set_anon_super(sb
, NULL
);
780 struct dentry
*mount_ns(struct file_system_type
*fs_type
, int flags
,
781 void *data
, int (*fill_super
)(struct super_block
*, void *, int))
783 struct super_block
*sb
;
785 sb
= sget(fs_type
, ns_test_super
, ns_set_super
, data
);
792 err
= fill_super(sb
, data
, flags
& MS_SILENT
? 1 : 0);
794 deactivate_locked_super(sb
);
798 sb
->s_flags
|= MS_ACTIVE
;
801 return dget(sb
->s_root
);
804 EXPORT_SYMBOL(mount_ns
);
807 static int set_bdev_super(struct super_block
*s
, void *data
)
810 s
->s_dev
= s
->s_bdev
->bd_dev
;
813 * We set the bdi here to the queue backing, file systems can
814 * overwrite this in ->fill_super()
816 s
->s_bdi
= &bdev_get_queue(s
->s_bdev
)->backing_dev_info
;
820 static int test_bdev_super(struct super_block
*s
, void *data
)
822 return (void *)s
->s_bdev
== data
;
825 struct dentry
*mount_bdev(struct file_system_type
*fs_type
,
826 int flags
, const char *dev_name
, void *data
,
827 int (*fill_super
)(struct super_block
*, void *, int))
829 struct block_device
*bdev
;
830 struct super_block
*s
;
831 fmode_t mode
= FMODE_READ
| FMODE_EXCL
;
834 if (!(flags
& MS_RDONLY
))
837 bdev
= blkdev_get_by_path(dev_name
, mode
, fs_type
);
839 return ERR_CAST(bdev
);
842 * once the super is inserted into the list by sget, s_umount
843 * will protect the lockfs code from trying to start a snapshot
844 * while we are mounting
846 mutex_lock(&bdev
->bd_fsfreeze_mutex
);
847 if (bdev
->bd_fsfreeze_count
> 0) {
848 mutex_unlock(&bdev
->bd_fsfreeze_mutex
);
852 s
= sget(fs_type
, test_bdev_super
, set_bdev_super
, bdev
);
853 mutex_unlock(&bdev
->bd_fsfreeze_mutex
);
858 if ((flags
^ s
->s_flags
) & MS_RDONLY
) {
859 deactivate_locked_super(s
);
865 * s_umount nests inside bd_mutex during
866 * __invalidate_device(). blkdev_put() acquires
867 * bd_mutex and can't be called under s_umount. Drop
868 * s_umount temporarily. This is safe as we're
869 * holding an active reference.
871 up_write(&s
->s_umount
);
872 blkdev_put(bdev
, mode
);
873 down_write(&s
->s_umount
);
875 char b
[BDEVNAME_SIZE
];
877 s
->s_flags
= flags
| MS_NOSEC
;
879 strlcpy(s
->s_id
, bdevname(bdev
, b
), sizeof(s
->s_id
));
880 sb_set_blocksize(s
, block_size(bdev
));
881 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
883 deactivate_locked_super(s
);
887 s
->s_flags
|= MS_ACTIVE
;
891 return dget(s
->s_root
);
896 blkdev_put(bdev
, mode
);
898 return ERR_PTR(error
);
900 EXPORT_SYMBOL(mount_bdev
);
902 void kill_block_super(struct super_block
*sb
)
904 struct block_device
*bdev
= sb
->s_bdev
;
905 fmode_t mode
= sb
->s_mode
;
907 bdev
->bd_super
= NULL
;
908 generic_shutdown_super(sb
);
910 WARN_ON_ONCE(!(mode
& FMODE_EXCL
));
911 blkdev_put(bdev
, mode
| FMODE_EXCL
);
914 EXPORT_SYMBOL(kill_block_super
);
917 struct dentry
*mount_nodev(struct file_system_type
*fs_type
,
918 int flags
, void *data
,
919 int (*fill_super
)(struct super_block
*, void *, int))
922 struct super_block
*s
= sget(fs_type
, NULL
, set_anon_super
, NULL
);
929 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
931 deactivate_locked_super(s
);
932 return ERR_PTR(error
);
934 s
->s_flags
|= MS_ACTIVE
;
935 return dget(s
->s_root
);
937 EXPORT_SYMBOL(mount_nodev
);
939 static int compare_single(struct super_block
*s
, void *p
)
944 struct dentry
*mount_single(struct file_system_type
*fs_type
,
945 int flags
, void *data
,
946 int (*fill_super
)(struct super_block
*, void *, int))
948 struct super_block
*s
;
951 s
= sget(fs_type
, compare_single
, set_anon_super
, NULL
);
956 error
= fill_super(s
, data
, flags
& MS_SILENT
? 1 : 0);
958 deactivate_locked_super(s
);
959 return ERR_PTR(error
);
961 s
->s_flags
|= MS_ACTIVE
;
963 do_remount_sb(s
, flags
, data
, 0);
965 return dget(s
->s_root
);
967 EXPORT_SYMBOL(mount_single
);
970 mount_fs(struct file_system_type
*type
, int flags
, const char *name
, void *data
)
973 struct super_block
*sb
;
974 char *secdata
= NULL
;
977 if (data
&& !(type
->fs_flags
& FS_BINARY_MOUNTDATA
)) {
978 secdata
= alloc_secdata();
982 error
= security_sb_copy_data(data
, secdata
);
984 goto out_free_secdata
;
987 root
= type
->mount(type
, flags
, name
, data
);
989 error
= PTR_ERR(root
);
990 goto out_free_secdata
;
995 WARN_ON(sb
->s_bdi
== &default_backing_dev_info
);
996 sb
->s_flags
|= MS_BORN
;
998 error
= security_sb_kern_mount(sb
, flags
, secdata
);
1003 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
1004 * but s_maxbytes was an unsigned long long for many releases. Throw
1005 * this warning for a little while to try and catch filesystems that
1006 * violate this rule.
1008 WARN((sb
->s_maxbytes
< 0), "%s set sb->s_maxbytes to "
1009 "negative value (%lld)\n", type
->name
, sb
->s_maxbytes
);
1011 up_write(&sb
->s_umount
);
1012 free_secdata(secdata
);
1016 deactivate_locked_super(sb
);
1018 free_secdata(secdata
);
1020 return ERR_PTR(error
);
1024 * freeze_super - lock the filesystem and force it into a consistent state
1025 * @sb: the super to lock
1027 * Syncs the super to make sure the filesystem is consistent and calls the fs's
1028 * freeze_fs. Subsequent calls to this without first thawing the fs will return
1031 int freeze_super(struct super_block
*sb
)
1035 atomic_inc(&sb
->s_active
);
1036 down_write(&sb
->s_umount
);
1038 deactivate_locked_super(sb
);
1042 if (sb
->s_flags
& MS_RDONLY
) {
1043 sb
->s_frozen
= SB_FREEZE_TRANS
;
1045 up_write(&sb
->s_umount
);
1049 sb
->s_frozen
= SB_FREEZE_WRITE
;
1052 sync_filesystem(sb
);
1054 sb
->s_frozen
= SB_FREEZE_TRANS
;
1057 sync_blockdev(sb
->s_bdev
);
1058 if (sb
->s_op
->freeze_fs
) {
1059 ret
= sb
->s_op
->freeze_fs(sb
);
1062 "VFS:Filesystem freeze failed\n");
1063 sb
->s_frozen
= SB_UNFROZEN
;
1064 deactivate_locked_super(sb
);
1068 up_write(&sb
->s_umount
);
1071 EXPORT_SYMBOL(freeze_super
);
1074 * thaw_super -- unlock filesystem
1075 * @sb: the super to thaw
1077 * Unlocks the filesystem and marks it writeable again after freeze_super().
1079 int thaw_super(struct super_block
*sb
)
1083 down_write(&sb
->s_umount
);
1084 if (sb
->s_frozen
== SB_UNFROZEN
) {
1085 up_write(&sb
->s_umount
);
1089 if (sb
->s_flags
& MS_RDONLY
)
1092 if (sb
->s_op
->unfreeze_fs
) {
1093 error
= sb
->s_op
->unfreeze_fs(sb
);
1096 "VFS:Filesystem thaw failed\n");
1097 sb
->s_frozen
= SB_FREEZE_TRANS
;
1098 up_write(&sb
->s_umount
);
1104 sb
->s_frozen
= SB_UNFROZEN
;
1106 wake_up(&sb
->s_wait_unfrozen
);
1107 deactivate_locked_super(sb
);
1111 EXPORT_SYMBOL(thaw_super
);