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 * grab_super_passive - acquire a passive reference
247 * @s: reference we are trying to grab
249 * Tries to acquire a passive reference. This is used in places where we
250 * cannot take an active reference but we need to ensure that the
251 * superblock does not go away while we are working on it. It returns
252 * false if a reference was not gained, and returns true with the s_umount
253 * lock held in read mode if a reference is gained. On successful return,
254 * the caller must drop the s_umount lock and the passive reference when
257 bool grab_super_passive(struct super_block *sb)
260 if (list_empty(&sb->s_instances)) {
261 spin_unlock(&sb_lock);
266 spin_unlock(&sb_lock);
268 if (down_read_trylock(&sb->s_umount)) {
271 up_read(&sb->s_umount);
279 * Superblock locking. We really ought to get rid of these two.
281 void lock_super(struct super_block * sb)
284 mutex_lock(&sb->s_lock);
287 void unlock_super(struct super_block * sb)
290 mutex_unlock(&sb->s_lock);
293 EXPORT_SYMBOL(lock_super);
294 EXPORT_SYMBOL(unlock_super);
297 * generic_shutdown_super - common helper for ->kill_sb()
298 * @sb: superblock to kill
300 * generic_shutdown_super() does all fs-independent work on superblock
301 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
302 * that need destruction out of superblock, call generic_shutdown_super()
303 * and release aforementioned objects. Note: dentries and inodes _are_
304 * taken care of and do not need specific handling.
306 * Upon calling this function, the filesystem may no longer alter or
307 * rearrange the set of dentries belonging to this super_block, nor may it
308 * change the attachments of dentries to inodes.
310 void generic_shutdown_super(struct super_block *sb)
312 const struct super_operations *sop = sb->s_op;
316 shrink_dcache_for_umount(sb);
319 sb->s_flags &= ~MS_ACTIVE;
321 fsnotify_unmount_inodes(&sb->s_inodes);
328 if (!list_empty(&sb->s_inodes)) {
329 printk("VFS: Busy inodes after unmount of %s. "
330 "Self-destruct in 5 seconds. Have a nice day...\n",
336 /* should be initialized for __put_super_and_need_restart() */
337 list_del_init(&sb->s_instances);
338 spin_unlock(&sb_lock);
339 up_write(&sb->s_umount);
342 EXPORT_SYMBOL(generic_shutdown_super);
345 * sget - find or create a superblock
346 * @type: filesystem type superblock should belong to
347 * @test: comparison callback
348 * @set: setup callback
349 * @data: argument to each of them
351 struct super_block *sget(struct file_system_type *type,
352 int (*test)(struct super_block *,void *),
353 int (*set)(struct super_block *,void *),
356 struct super_block *s = NULL;
357 struct super_block *old;
363 list_for_each_entry(old, &type->fs_supers, s_instances) {
364 if (!test(old, data))
366 if (!grab_super(old))
369 up_write(&s->s_umount);
373 down_write(&old->s_umount);
374 if (unlikely(!(old->s_flags & MS_BORN))) {
375 deactivate_locked_super(old);
382 spin_unlock(&sb_lock);
383 s = alloc_super(type);
385 return ERR_PTR(-ENOMEM);
391 spin_unlock(&sb_lock);
392 up_write(&s->s_umount);
397 strlcpy(s->s_id, type->name, sizeof(s->s_id));
398 list_add_tail(&s->s_list, &super_blocks);
399 list_add(&s->s_instances, &type->fs_supers);
400 spin_unlock(&sb_lock);
401 get_filesystem(type);
407 void drop_super(struct super_block *sb)
409 up_read(&sb->s_umount);
413 EXPORT_SYMBOL(drop_super);
416 * sync_supers - helper for periodic superblock writeback
418 * Call the write_super method if present on all dirty superblocks in
419 * the system. This is for the periodic writeback used by most older
420 * filesystems. For data integrity superblock writeback use
421 * sync_filesystems() instead.
423 * Note: check the dirty flag before waiting, so we don't
424 * hold up the sync while mounting a device. (The newly
425 * mounted device won't need syncing.)
427 void sync_supers(void)
429 struct super_block *sb, *p = NULL;
432 list_for_each_entry(sb, &super_blocks, s_list) {
433 if (list_empty(&sb->s_instances))
435 if (sb->s_op->write_super && sb->s_dirt) {
437 spin_unlock(&sb_lock);
439 down_read(&sb->s_umount);
440 if (sb->s_root && sb->s_dirt)
441 sb->s_op->write_super(sb);
442 up_read(&sb->s_umount);
452 spin_unlock(&sb_lock);
456 * iterate_supers - call function for all active superblocks
457 * @f: function to call
458 * @arg: argument to pass to it
460 * Scans the superblock list and calls given function, passing it
461 * locked superblock and given argument.
463 void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
465 struct super_block *sb, *p = NULL;
468 list_for_each_entry(sb, &super_blocks, s_list) {
469 if (list_empty(&sb->s_instances))
472 spin_unlock(&sb_lock);
474 down_read(&sb->s_umount);
477 up_read(&sb->s_umount);
486 spin_unlock(&sb_lock);
490 * iterate_supers_type - call function for superblocks of given type
492 * @f: function to call
493 * @arg: argument to pass to it
495 * Scans the superblock list and calls given function, passing it
496 * locked superblock and given argument.
498 void iterate_supers_type(struct file_system_type *type,
499 void (*f)(struct super_block *, void *), void *arg)
501 struct super_block *sb, *p = NULL;
504 list_for_each_entry(sb, &type->fs_supers, s_instances) {
506 spin_unlock(&sb_lock);
508 down_read(&sb->s_umount);
511 up_read(&sb->s_umount);
520 spin_unlock(&sb_lock);
523 EXPORT_SYMBOL(iterate_supers_type);
526 * get_super - get the superblock of a device
527 * @bdev: device to get the superblock for
529 * Scans the superblock list and finds the superblock of the file system
530 * mounted on the device given. %NULL is returned if no match is found.
533 struct super_block *get_super(struct block_device *bdev)
535 struct super_block *sb;
542 list_for_each_entry(sb, &super_blocks, s_list) {
543 if (list_empty(&sb->s_instances))
545 if (sb->s_bdev == bdev) {
547 spin_unlock(&sb_lock);
548 down_read(&sb->s_umount);
552 up_read(&sb->s_umount);
553 /* nope, got unmounted */
559 spin_unlock(&sb_lock);
563 EXPORT_SYMBOL(get_super);
566 * get_active_super - get an active reference to the superblock of a device
567 * @bdev: device to get the superblock for
569 * Scans the superblock list and finds the superblock of the file system
570 * mounted on the device given. Returns the superblock with an active
571 * reference or %NULL if none was found.
573 struct super_block *get_active_super(struct block_device *bdev)
575 struct super_block *sb;
582 list_for_each_entry(sb, &super_blocks, s_list) {
583 if (list_empty(&sb->s_instances))
585 if (sb->s_bdev == bdev) {
586 if (grab_super(sb)) /* drops sb_lock */
592 spin_unlock(&sb_lock);
596 struct super_block *user_get_super(dev_t dev)
598 struct super_block *sb;
602 list_for_each_entry(sb, &super_blocks, s_list) {
603 if (list_empty(&sb->s_instances))
605 if (sb->s_dev == dev) {
607 spin_unlock(&sb_lock);
608 down_read(&sb->s_umount);
612 up_read(&sb->s_umount);
613 /* nope, got unmounted */
619 spin_unlock(&sb_lock);
624 * do_remount_sb - asks filesystem to change mount options.
625 * @sb: superblock in question
626 * @flags: numeric part of options
627 * @data: the rest of options
628 * @force: whether or not to force the change
630 * Alters the mount options of a mounted file system.
632 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
637 if (sb->s_frozen != SB_UNFROZEN)
641 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
645 if (flags & MS_RDONLY)
647 shrink_dcache_sb(sb);
650 remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
652 /* If we are remounting RDONLY and current sb is read/write,
653 make sure there are no rw files opened */
657 else if (!fs_may_remount_ro(sb))
661 if (sb->s_op->remount_fs) {
662 retval = sb->s_op->remount_fs(sb, &flags, data);
666 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
669 * Some filesystems modify their metadata via some other path than the
670 * bdev buffer cache (eg. use a private mapping, or directories in
671 * pagecache, etc). Also file data modifications go via their own
672 * mappings. So If we try to mount readonly then copy the filesystem
673 * from bdev, we could get stale data, so invalidate it to give a best
674 * effort at coherency.
676 if (remount_ro && sb->s_bdev)
677 invalidate_bdev(sb->s_bdev);
681 static void do_emergency_remount(struct work_struct *work)
683 struct super_block *sb, *p = NULL;
686 list_for_each_entry(sb, &super_blocks, s_list) {
687 if (list_empty(&sb->s_instances))
690 spin_unlock(&sb_lock);
691 down_write(&sb->s_umount);
692 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
694 * What lock protects sb->s_flags??
696 do_remount_sb(sb, MS_RDONLY, NULL, 1);
698 up_write(&sb->s_umount);
706 spin_unlock(&sb_lock);
708 printk("Emergency Remount complete\n");
711 void emergency_remount(void)
713 struct work_struct *work;
715 work = kmalloc(sizeof(*work), GFP_ATOMIC);
717 INIT_WORK(work, do_emergency_remount);
723 * Unnamed block devices are dummy devices used by virtual
724 * filesystems which don't use real block-devices. -- jrs
727 static DEFINE_IDA(unnamed_dev_ida);
728 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
729 static int unnamed_dev_start = 0; /* don't bother trying below it */
731 int get_anon_bdev(dev_t *p)
737 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
739 spin_lock(&unnamed_dev_lock);
740 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
742 unnamed_dev_start = dev + 1;
743 spin_unlock(&unnamed_dev_lock);
744 if (error == -EAGAIN)
745 /* We raced and lost with another CPU. */
750 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
751 spin_lock(&unnamed_dev_lock);
752 ida_remove(&unnamed_dev_ida, dev);
753 if (unnamed_dev_start > dev)
754 unnamed_dev_start = dev;
755 spin_unlock(&unnamed_dev_lock);
758 *p = MKDEV(0, dev & MINORMASK);
761 EXPORT_SYMBOL(get_anon_bdev);
763 void free_anon_bdev(dev_t dev)
765 int slot = MINOR(dev);
766 spin_lock(&unnamed_dev_lock);
767 ida_remove(&unnamed_dev_ida, slot);
768 if (slot < unnamed_dev_start)
769 unnamed_dev_start = slot;
770 spin_unlock(&unnamed_dev_lock);
772 EXPORT_SYMBOL(free_anon_bdev);
774 int set_anon_super(struct super_block *s, void *data)
776 int error = get_anon_bdev(&s->s_dev);
778 s->s_bdi = &noop_backing_dev_info;
782 EXPORT_SYMBOL(set_anon_super);
784 void kill_anon_super(struct super_block *sb)
786 dev_t dev = sb->s_dev;
787 generic_shutdown_super(sb);
791 EXPORT_SYMBOL(kill_anon_super);
793 void kill_litter_super(struct super_block *sb)
796 d_genocide(sb->s_root);
800 EXPORT_SYMBOL(kill_litter_super);
802 static int ns_test_super(struct super_block *sb, void *data)
804 return sb->s_fs_info == data;
807 static int ns_set_super(struct super_block *sb, void *data)
809 sb->s_fs_info = data;
810 return set_anon_super(sb, NULL);
813 struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
814 void *data, int (*fill_super)(struct super_block *, void *, int))
816 struct super_block *sb;
818 sb = sget(fs_type, ns_test_super, ns_set_super, data);
825 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
827 deactivate_locked_super(sb);
831 sb->s_flags |= MS_ACTIVE;
834 return dget(sb->s_root);
837 EXPORT_SYMBOL(mount_ns);
840 static int set_bdev_super(struct super_block *s, void *data)
843 s->s_dev = s->s_bdev->bd_dev;
846 * We set the bdi here to the queue backing, file systems can
847 * overwrite this in ->fill_super()
849 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
853 static int test_bdev_super(struct super_block *s, void *data)
855 return (void *)s->s_bdev == data;
858 struct dentry *mount_bdev(struct file_system_type *fs_type,
859 int flags, const char *dev_name, void *data,
860 int (*fill_super)(struct super_block *, void *, int))
862 struct block_device *bdev;
863 struct super_block *s;
864 fmode_t mode = FMODE_READ | FMODE_EXCL;
867 if (!(flags & MS_RDONLY))
870 bdev = blkdev_get_by_path(dev_name, mode, fs_type);
872 return ERR_CAST(bdev);
875 * once the super is inserted into the list by sget, s_umount
876 * will protect the lockfs code from trying to start a snapshot
877 * while we are mounting
879 mutex_lock(&bdev->bd_fsfreeze_mutex);
880 if (bdev->bd_fsfreeze_count > 0) {
881 mutex_unlock(&bdev->bd_fsfreeze_mutex);
885 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
886 mutex_unlock(&bdev->bd_fsfreeze_mutex);
891 if ((flags ^ s->s_flags) & MS_RDONLY) {
892 deactivate_locked_super(s);
898 * s_umount nests inside bd_mutex during
899 * __invalidate_device(). blkdev_put() acquires
900 * bd_mutex and can't be called under s_umount. Drop
901 * s_umount temporarily. This is safe as we're
902 * holding an active reference.
904 up_write(&s->s_umount);
905 blkdev_put(bdev, mode);
906 down_write(&s->s_umount);
908 char b[BDEVNAME_SIZE];
910 s->s_flags = flags | MS_NOSEC;
912 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
913 sb_set_blocksize(s, block_size(bdev));
914 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
916 deactivate_locked_super(s);
920 s->s_flags |= MS_ACTIVE;
924 return dget(s->s_root);
929 blkdev_put(bdev, mode);
931 return ERR_PTR(error);
933 EXPORT_SYMBOL(mount_bdev);
935 void kill_block_super(struct super_block *sb)
937 struct block_device *bdev = sb->s_bdev;
938 fmode_t mode = sb->s_mode;
940 bdev->bd_super = NULL;
941 generic_shutdown_super(sb);
943 WARN_ON_ONCE(!(mode & FMODE_EXCL));
944 blkdev_put(bdev, mode | FMODE_EXCL);
947 EXPORT_SYMBOL(kill_block_super);
950 struct dentry *mount_nodev(struct file_system_type *fs_type,
951 int flags, void *data,
952 int (*fill_super)(struct super_block *, void *, int))
955 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
962 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
964 deactivate_locked_super(s);
965 return ERR_PTR(error);
967 s->s_flags |= MS_ACTIVE;
968 return dget(s->s_root);
970 EXPORT_SYMBOL(mount_nodev);
972 static int compare_single(struct super_block *s, void *p)
977 struct dentry *mount_single(struct file_system_type *fs_type,
978 int flags, void *data,
979 int (*fill_super)(struct super_block *, void *, int))
981 struct super_block *s;
984 s = sget(fs_type, compare_single, set_anon_super, NULL);
989 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
991 deactivate_locked_super(s);
992 return ERR_PTR(error);
994 s->s_flags |= MS_ACTIVE;
996 do_remount_sb(s, flags, data, 0);
998 return dget(s->s_root);
1000 EXPORT_SYMBOL(mount_single);
1003 mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
1005 struct dentry *root;
1006 struct super_block *sb;
1007 char *secdata = NULL;
1008 int error = -ENOMEM;
1010 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
1011 secdata = alloc_secdata();
1015 error = security_sb_copy_data(data, secdata);
1017 goto out_free_secdata;
1020 root = type->mount(type, flags, name, data);
1022 error = PTR_ERR(root);
1023 goto out_free_secdata;
1027 WARN_ON(!sb->s_bdi);
1028 WARN_ON(sb->s_bdi == &default_backing_dev_info);
1029 sb->s_flags |= MS_BORN;
1031 error = security_sb_kern_mount(sb, flags, secdata);
1036 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
1037 * but s_maxbytes was an unsigned long long for many releases. Throw
1038 * this warning for a little while to try and catch filesystems that
1039 * violate this rule.
1041 WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
1042 "negative value (%lld)\n", type->name, sb->s_maxbytes);
1044 up_write(&sb->s_umount);
1045 free_secdata(secdata);
1049 deactivate_locked_super(sb);
1051 free_secdata(secdata);
1053 return ERR_PTR(error);
1057 * freeze_super - lock the filesystem and force it into a consistent state
1058 * @sb: the super to lock
1060 * Syncs the super to make sure the filesystem is consistent and calls the fs's
1061 * freeze_fs. Subsequent calls to this without first thawing the fs will return
1064 int freeze_super(struct super_block *sb)
1068 atomic_inc(&sb->s_active);
1069 down_write(&sb->s_umount);
1071 deactivate_locked_super(sb);
1075 if (sb->s_flags & MS_RDONLY) {
1076 sb->s_frozen = SB_FREEZE_TRANS;
1078 up_write(&sb->s_umount);
1082 sb->s_frozen = SB_FREEZE_WRITE;
1085 sync_filesystem(sb);
1087 sb->s_frozen = SB_FREEZE_TRANS;
1090 sync_blockdev(sb->s_bdev);
1091 if (sb->s_op->freeze_fs) {
1092 ret = sb->s_op->freeze_fs(sb);
1095 "VFS:Filesystem freeze failed\n");
1096 sb->s_frozen = SB_UNFROZEN;
1097 deactivate_locked_super(sb);
1101 up_write(&sb->s_umount);
1104 EXPORT_SYMBOL(freeze_super);
1107 * thaw_super -- unlock filesystem
1108 * @sb: the super to thaw
1110 * Unlocks the filesystem and marks it writeable again after freeze_super().
1112 int thaw_super(struct super_block *sb)
1116 down_write(&sb->s_umount);
1117 if (sb->s_frozen == SB_UNFROZEN) {
1118 up_write(&sb->s_umount);
1122 if (sb->s_flags & MS_RDONLY)
1125 if (sb->s_op->unfreeze_fs) {
1126 error = sb->s_op->unfreeze_fs(sb);
1129 "VFS:Filesystem thaw failed\n");
1130 sb->s_frozen = SB_FREEZE_TRANS;
1131 up_write(&sb->s_umount);
1137 sb->s_frozen = SB_UNFROZEN;
1139 wake_up(&sb->s_wait_unfrozen);
1140 deactivate_locked_super(sb);
1144 EXPORT_SYMBOL(thaw_super);