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 * One thing we have to be careful of with a per-sb shrinker is that we don't
43 * drop the last active reference to the superblock from within the shrinker.
44 * If that happens we could trigger unregistering the shrinker from within the
45 * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we
46 * take a passive reference to the superblock to avoid this from occurring.
48 static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
50 struct super_block *sb;
54 sb = container_of(shrink, struct super_block, s_shrink);
57 * Deadlock avoidance. We may hold various FS locks, and we don't want
58 * to recurse into the FS that called us in clear_inode() and friends..
60 if (sc->nr_to_scan && !(sc->gfp_mask & __GFP_FS))
63 if (!grab_super_passive(sb))
66 if (sb->s_op && sb->s_op->nr_cached_objects)
67 fs_objects = sb->s_op->nr_cached_objects(sb);
69 total_objects = sb->s_nr_dentry_unused +
70 sb->s_nr_inodes_unused + fs_objects + 1;
76 /* proportion the scan between the caches */
77 dentries = (sc->nr_to_scan * sb->s_nr_dentry_unused) /
79 inodes = (sc->nr_to_scan * sb->s_nr_inodes_unused) /
82 fs_objects = (sc->nr_to_scan * fs_objects) /
85 * prune the dcache first as the icache is pinned by it, then
86 * prune the icache, followed by the filesystem specific caches
88 prune_dcache_sb(sb, dentries);
89 prune_icache_sb(sb, inodes);
91 if (fs_objects && sb->s_op->free_cached_objects) {
92 sb->s_op->free_cached_objects(sb, fs_objects);
93 fs_objects = sb->s_op->nr_cached_objects(sb);
95 total_objects = sb->s_nr_dentry_unused +
96 sb->s_nr_inodes_unused + fs_objects;
99 total_objects = (total_objects / 100) * sysctl_vfs_cache_pressure;
101 return total_objects;
105 * alloc_super - create new superblock
106 * @type: filesystem type superblock should belong to
108 * Allocates and initializes a new &struct super_block. alloc_super()
109 * returns a pointer new superblock or %NULL if allocation had failed.
111 static struct super_block *alloc_super(struct file_system_type *type)
113 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
114 static const struct super_operations default_op;
117 if (security_sb_alloc(s)) {
123 s->s_files = alloc_percpu(struct list_head);
132 for_each_possible_cpu(i)
133 INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));
136 INIT_LIST_HEAD(&s->s_files);
138 s->s_bdi = &default_backing_dev_info;
139 INIT_LIST_HEAD(&s->s_instances);
140 INIT_HLIST_BL_HEAD(&s->s_anon);
141 INIT_LIST_HEAD(&s->s_inodes);
142 INIT_LIST_HEAD(&s->s_dentry_lru);
143 INIT_LIST_HEAD(&s->s_inode_lru);
144 spin_lock_init(&s->s_inode_lru_lock);
145 init_rwsem(&s->s_umount);
146 mutex_init(&s->s_lock);
147 lockdep_set_class(&s->s_umount, &type->s_umount_key);
149 * The locking rules for s_lock are up to the
150 * filesystem. For example ext3fs has different
151 * lock ordering than usbfs:
153 lockdep_set_class(&s->s_lock, &type->s_lock_key);
155 * sget() can have s_umount recursion.
157 * When it cannot find a suitable sb, it allocates a new
158 * one (this one), and tries again to find a suitable old
161 * In case that succeeds, it will acquire the s_umount
162 * lock of the old one. Since these are clearly distrinct
163 * locks, and this object isn't exposed yet, there's no
166 * Annotate this by putting this lock in a different
169 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
171 atomic_set(&s->s_active, 1);
172 mutex_init(&s->s_vfs_rename_mutex);
173 lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
174 mutex_init(&s->s_dquot.dqio_mutex);
175 mutex_init(&s->s_dquot.dqonoff_mutex);
176 init_rwsem(&s->s_dquot.dqptr_sem);
177 init_waitqueue_head(&s->s_wait_unfrozen);
178 s->s_maxbytes = MAX_NON_LFS;
179 s->s_op = &default_op;
180 s->s_time_gran = 1000000000;
181 s->cleancache_poolid = -1;
183 s->s_shrink.seeks = DEFAULT_SEEKS;
184 s->s_shrink.shrink = prune_super;
191 * destroy_super - frees a superblock
192 * @s: superblock to free
194 * Frees a superblock.
196 static inline void destroy_super(struct super_block *s)
199 free_percpu(s->s_files);
207 /* Superblock refcounting */
210 * Drop a superblock's refcount. The caller must hold sb_lock.
212 void __put_super(struct super_block *sb)
214 if (!--sb->s_count) {
215 list_del_init(&sb->s_list);
221 * put_super - drop a temporary reference to superblock
222 * @sb: superblock in question
224 * Drops a temporary reference, frees superblock if there's no
227 void put_super(struct super_block *sb)
231 spin_unlock(&sb_lock);
236 * deactivate_locked_super - drop an active reference to superblock
237 * @s: superblock to deactivate
239 * Drops an active reference to superblock, converting it into a temprory
240 * one if there is no other active references left. In that case we
241 * tell fs driver to shut it down and drop the temporary reference we
244 * Caller holds exclusive lock on superblock; that lock is released.
246 void deactivate_locked_super(struct super_block *s)
248 struct file_system_type *fs = s->s_type;
249 if (atomic_dec_and_test(&s->s_active)) {
250 cleancache_flush_fs(s);
253 /* caches are now gone, we can safely kill the shrinker now */
254 unregister_shrinker(&s->s_shrink);
257 * We need to call rcu_barrier so all the delayed rcu free
258 * inodes are flushed before we release the fs module.
264 up_write(&s->s_umount);
268 EXPORT_SYMBOL(deactivate_locked_super);
271 * deactivate_super - drop an active reference to superblock
272 * @s: superblock to deactivate
274 * Variant of deactivate_locked_super(), except that superblock is *not*
275 * locked by caller. If we are going to drop the final active reference,
276 * lock will be acquired prior to that.
278 void deactivate_super(struct super_block *s)
280 if (!atomic_add_unless(&s->s_active, -1, 1)) {
281 down_write(&s->s_umount);
282 deactivate_locked_super(s);
286 EXPORT_SYMBOL(deactivate_super);
289 * grab_super - acquire an active reference
290 * @s: reference we are trying to make active
292 * Tries to acquire an active reference. grab_super() is used when we
293 * had just found a superblock in super_blocks or fs_type->fs_supers
294 * and want to turn it into a full-blown active reference. grab_super()
295 * is called with sb_lock held and drops it. Returns 1 in case of
296 * success, 0 if we had failed (superblock contents was already dead or
297 * dying when grab_super() had been called).
299 static int grab_super(struct super_block *s) __releases(sb_lock)
301 if (atomic_inc_not_zero(&s->s_active)) {
302 spin_unlock(&sb_lock);
305 /* it's going away */
307 spin_unlock(&sb_lock);
308 /* wait for it to die */
309 down_write(&s->s_umount);
310 up_write(&s->s_umount);
316 * grab_super_passive - acquire a passive reference
317 * @s: reference we are trying to grab
319 * Tries to acquire a passive reference. This is used in places where we
320 * cannot take an active reference but we need to ensure that the
321 * superblock does not go away while we are working on it. It returns
322 * false if a reference was not gained, and returns true with the s_umount
323 * lock held in read mode if a reference is gained. On successful return,
324 * the caller must drop the s_umount lock and the passive reference when
327 bool grab_super_passive(struct super_block *sb)
330 if (list_empty(&sb->s_instances)) {
331 spin_unlock(&sb_lock);
336 spin_unlock(&sb_lock);
338 if (down_read_trylock(&sb->s_umount)) {
341 up_read(&sb->s_umount);
349 * Superblock locking. We really ought to get rid of these two.
351 void lock_super(struct super_block * sb)
354 mutex_lock(&sb->s_lock);
357 void unlock_super(struct super_block * sb)
360 mutex_unlock(&sb->s_lock);
363 EXPORT_SYMBOL(lock_super);
364 EXPORT_SYMBOL(unlock_super);
367 * generic_shutdown_super - common helper for ->kill_sb()
368 * @sb: superblock to kill
370 * generic_shutdown_super() does all fs-independent work on superblock
371 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
372 * that need destruction out of superblock, call generic_shutdown_super()
373 * and release aforementioned objects. Note: dentries and inodes _are_
374 * taken care of and do not need specific handling.
376 * Upon calling this function, the filesystem may no longer alter or
377 * rearrange the set of dentries belonging to this super_block, nor may it
378 * change the attachments of dentries to inodes.
380 void generic_shutdown_super(struct super_block *sb)
382 const struct super_operations *sop = sb->s_op;
385 shrink_dcache_for_umount(sb);
388 sb->s_flags &= ~MS_ACTIVE;
390 fsnotify_unmount_inodes(&sb->s_inodes);
397 if (!list_empty(&sb->s_inodes)) {
398 printk("VFS: Busy inodes after unmount of %s. "
399 "Self-destruct in 5 seconds. Have a nice day...\n",
405 /* should be initialized for __put_super_and_need_restart() */
406 list_del_init(&sb->s_instances);
407 spin_unlock(&sb_lock);
408 up_write(&sb->s_umount);
411 EXPORT_SYMBOL(generic_shutdown_super);
414 * sget - find or create a superblock
415 * @type: filesystem type superblock should belong to
416 * @test: comparison callback
417 * @set: setup callback
418 * @data: argument to each of them
420 struct super_block *sget(struct file_system_type *type,
421 int (*test)(struct super_block *,void *),
422 int (*set)(struct super_block *,void *),
425 struct super_block *s = NULL;
426 struct super_block *old;
432 list_for_each_entry(old, &type->fs_supers, s_instances) {
433 if (!test(old, data))
435 if (!grab_super(old))
438 up_write(&s->s_umount);
442 down_write(&old->s_umount);
443 if (unlikely(!(old->s_flags & MS_BORN))) {
444 deactivate_locked_super(old);
451 spin_unlock(&sb_lock);
452 s = alloc_super(type);
454 return ERR_PTR(-ENOMEM);
460 spin_unlock(&sb_lock);
461 up_write(&s->s_umount);
466 strlcpy(s->s_id, type->name, sizeof(s->s_id));
467 list_add_tail(&s->s_list, &super_blocks);
468 list_add(&s->s_instances, &type->fs_supers);
469 spin_unlock(&sb_lock);
470 get_filesystem(type);
471 register_shrinker(&s->s_shrink);
477 void drop_super(struct super_block *sb)
479 up_read(&sb->s_umount);
483 EXPORT_SYMBOL(drop_super);
486 * sync_supers - helper for periodic superblock writeback
488 * Call the write_super method if present on all dirty superblocks in
489 * the system. This is for the periodic writeback used by most older
490 * filesystems. For data integrity superblock writeback use
491 * sync_filesystems() instead.
493 * Note: check the dirty flag before waiting, so we don't
494 * hold up the sync while mounting a device. (The newly
495 * mounted device won't need syncing.)
497 void sync_supers(void)
499 struct super_block *sb, *p = NULL;
502 list_for_each_entry(sb, &super_blocks, s_list) {
503 if (list_empty(&sb->s_instances))
505 if (sb->s_op->write_super && sb->s_dirt) {
507 spin_unlock(&sb_lock);
509 down_read(&sb->s_umount);
510 if (sb->s_root && sb->s_dirt)
511 sb->s_op->write_super(sb);
512 up_read(&sb->s_umount);
522 spin_unlock(&sb_lock);
526 * iterate_supers - call function for all active superblocks
527 * @f: function to call
528 * @arg: argument to pass to it
530 * Scans the superblock list and calls given function, passing it
531 * locked superblock and given argument.
533 void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
535 struct super_block *sb, *p = NULL;
538 list_for_each_entry(sb, &super_blocks, s_list) {
539 if (list_empty(&sb->s_instances))
542 spin_unlock(&sb_lock);
544 down_read(&sb->s_umount);
547 up_read(&sb->s_umount);
556 spin_unlock(&sb_lock);
560 * iterate_supers_type - call function for superblocks of given type
562 * @f: function to call
563 * @arg: argument to pass to it
565 * Scans the superblock list and calls given function, passing it
566 * locked superblock and given argument.
568 void iterate_supers_type(struct file_system_type *type,
569 void (*f)(struct super_block *, void *), void *arg)
571 struct super_block *sb, *p = NULL;
574 list_for_each_entry(sb, &type->fs_supers, s_instances) {
576 spin_unlock(&sb_lock);
578 down_read(&sb->s_umount);
581 up_read(&sb->s_umount);
590 spin_unlock(&sb_lock);
593 EXPORT_SYMBOL(iterate_supers_type);
596 * get_super - get the superblock of a device
597 * @bdev: device to get the superblock for
599 * Scans the superblock list and finds the superblock of the file system
600 * mounted on the device given. %NULL is returned if no match is found.
603 struct super_block *get_super(struct block_device *bdev)
605 struct super_block *sb;
612 list_for_each_entry(sb, &super_blocks, s_list) {
613 if (list_empty(&sb->s_instances))
615 if (sb->s_bdev == bdev) {
617 spin_unlock(&sb_lock);
618 down_read(&sb->s_umount);
622 up_read(&sb->s_umount);
623 /* nope, got unmounted */
629 spin_unlock(&sb_lock);
633 EXPORT_SYMBOL(get_super);
636 * get_active_super - get an active reference to the superblock of a device
637 * @bdev: device to get the superblock for
639 * Scans the superblock list and finds the superblock of the file system
640 * mounted on the device given. Returns the superblock with an active
641 * reference or %NULL if none was found.
643 struct super_block *get_active_super(struct block_device *bdev)
645 struct super_block *sb;
652 list_for_each_entry(sb, &super_blocks, s_list) {
653 if (list_empty(&sb->s_instances))
655 if (sb->s_bdev == bdev) {
656 if (grab_super(sb)) /* drops sb_lock */
662 spin_unlock(&sb_lock);
666 struct super_block *user_get_super(dev_t dev)
668 struct super_block *sb;
672 list_for_each_entry(sb, &super_blocks, s_list) {
673 if (list_empty(&sb->s_instances))
675 if (sb->s_dev == dev) {
677 spin_unlock(&sb_lock);
678 down_read(&sb->s_umount);
682 up_read(&sb->s_umount);
683 /* nope, got unmounted */
689 spin_unlock(&sb_lock);
694 * do_remount_sb - asks filesystem to change mount options.
695 * @sb: superblock in question
696 * @flags: numeric part of options
697 * @data: the rest of options
698 * @force: whether or not to force the change
700 * Alters the mount options of a mounted file system.
702 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
707 if (sb->s_frozen != SB_UNFROZEN)
711 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
715 if (flags & MS_RDONLY)
717 shrink_dcache_sb(sb);
720 remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
722 /* If we are remounting RDONLY and current sb is read/write,
723 make sure there are no rw files opened */
727 else if (!fs_may_remount_ro(sb))
731 if (sb->s_op->remount_fs) {
732 retval = sb->s_op->remount_fs(sb, &flags, data);
736 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
739 * Some filesystems modify their metadata via some other path than the
740 * bdev buffer cache (eg. use a private mapping, or directories in
741 * pagecache, etc). Also file data modifications go via their own
742 * mappings. So If we try to mount readonly then copy the filesystem
743 * from bdev, we could get stale data, so invalidate it to give a best
744 * effort at coherency.
746 if (remount_ro && sb->s_bdev)
747 invalidate_bdev(sb->s_bdev);
751 static void do_emergency_remount(struct work_struct *work)
753 struct super_block *sb, *p = NULL;
756 list_for_each_entry(sb, &super_blocks, s_list) {
757 if (list_empty(&sb->s_instances))
760 spin_unlock(&sb_lock);
761 down_write(&sb->s_umount);
762 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
764 * What lock protects sb->s_flags??
766 do_remount_sb(sb, MS_RDONLY, NULL, 1);
768 up_write(&sb->s_umount);
776 spin_unlock(&sb_lock);
778 printk("Emergency Remount complete\n");
781 void emergency_remount(void)
783 struct work_struct *work;
785 work = kmalloc(sizeof(*work), GFP_ATOMIC);
787 INIT_WORK(work, do_emergency_remount);
793 * Unnamed block devices are dummy devices used by virtual
794 * filesystems which don't use real block-devices. -- jrs
797 static DEFINE_IDA(unnamed_dev_ida);
798 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
799 static int unnamed_dev_start = 0; /* don't bother trying below it */
801 int get_anon_bdev(dev_t *p)
807 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
809 spin_lock(&unnamed_dev_lock);
810 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
812 unnamed_dev_start = dev + 1;
813 spin_unlock(&unnamed_dev_lock);
814 if (error == -EAGAIN)
815 /* We raced and lost with another CPU. */
820 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
821 spin_lock(&unnamed_dev_lock);
822 ida_remove(&unnamed_dev_ida, dev);
823 if (unnamed_dev_start > dev)
824 unnamed_dev_start = dev;
825 spin_unlock(&unnamed_dev_lock);
828 *p = MKDEV(0, dev & MINORMASK);
831 EXPORT_SYMBOL(get_anon_bdev);
833 void free_anon_bdev(dev_t dev)
835 int slot = MINOR(dev);
836 spin_lock(&unnamed_dev_lock);
837 ida_remove(&unnamed_dev_ida, slot);
838 if (slot < unnamed_dev_start)
839 unnamed_dev_start = slot;
840 spin_unlock(&unnamed_dev_lock);
842 EXPORT_SYMBOL(free_anon_bdev);
844 int set_anon_super(struct super_block *s, void *data)
846 int error = get_anon_bdev(&s->s_dev);
848 s->s_bdi = &noop_backing_dev_info;
852 EXPORT_SYMBOL(set_anon_super);
854 void kill_anon_super(struct super_block *sb)
856 dev_t dev = sb->s_dev;
857 generic_shutdown_super(sb);
861 EXPORT_SYMBOL(kill_anon_super);
863 void kill_litter_super(struct super_block *sb)
866 d_genocide(sb->s_root);
870 EXPORT_SYMBOL(kill_litter_super);
872 static int ns_test_super(struct super_block *sb, void *data)
874 return sb->s_fs_info == data;
877 static int ns_set_super(struct super_block *sb, void *data)
879 sb->s_fs_info = data;
880 return set_anon_super(sb, NULL);
883 struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
884 void *data, int (*fill_super)(struct super_block *, void *, int))
886 struct super_block *sb;
888 sb = sget(fs_type, ns_test_super, ns_set_super, data);
895 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
897 deactivate_locked_super(sb);
901 sb->s_flags |= MS_ACTIVE;
904 return dget(sb->s_root);
907 EXPORT_SYMBOL(mount_ns);
910 static int set_bdev_super(struct super_block *s, void *data)
913 s->s_dev = s->s_bdev->bd_dev;
916 * We set the bdi here to the queue backing, file systems can
917 * overwrite this in ->fill_super()
919 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
923 static int test_bdev_super(struct super_block *s, void *data)
925 return (void *)s->s_bdev == data;
928 struct dentry *mount_bdev(struct file_system_type *fs_type,
929 int flags, const char *dev_name, void *data,
930 int (*fill_super)(struct super_block *, void *, int))
932 struct block_device *bdev;
933 struct super_block *s;
934 fmode_t mode = FMODE_READ | FMODE_EXCL;
937 if (!(flags & MS_RDONLY))
940 bdev = blkdev_get_by_path(dev_name, mode, fs_type);
942 return ERR_CAST(bdev);
945 * once the super is inserted into the list by sget, s_umount
946 * will protect the lockfs code from trying to start a snapshot
947 * while we are mounting
949 mutex_lock(&bdev->bd_fsfreeze_mutex);
950 if (bdev->bd_fsfreeze_count > 0) {
951 mutex_unlock(&bdev->bd_fsfreeze_mutex);
955 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
956 mutex_unlock(&bdev->bd_fsfreeze_mutex);
961 if ((flags ^ s->s_flags) & MS_RDONLY) {
962 deactivate_locked_super(s);
968 * s_umount nests inside bd_mutex during
969 * __invalidate_device(). blkdev_put() acquires
970 * bd_mutex and can't be called under s_umount. Drop
971 * s_umount temporarily. This is safe as we're
972 * holding an active reference.
974 up_write(&s->s_umount);
975 blkdev_put(bdev, mode);
976 down_write(&s->s_umount);
978 char b[BDEVNAME_SIZE];
980 s->s_flags = flags | MS_NOSEC;
982 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
983 sb_set_blocksize(s, block_size(bdev));
984 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
986 deactivate_locked_super(s);
990 s->s_flags |= MS_ACTIVE;
994 return dget(s->s_root);
999 blkdev_put(bdev, mode);
1001 return ERR_PTR(error);
1003 EXPORT_SYMBOL(mount_bdev);
1005 void kill_block_super(struct super_block *sb)
1007 struct block_device *bdev = sb->s_bdev;
1008 fmode_t mode = sb->s_mode;
1010 bdev->bd_super = NULL;
1011 generic_shutdown_super(sb);
1012 sync_blockdev(bdev);
1013 WARN_ON_ONCE(!(mode & FMODE_EXCL));
1014 blkdev_put(bdev, mode | FMODE_EXCL);
1017 EXPORT_SYMBOL(kill_block_super);
1020 struct dentry *mount_nodev(struct file_system_type *fs_type,
1021 int flags, void *data,
1022 int (*fill_super)(struct super_block *, void *, int))
1025 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
1032 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1034 deactivate_locked_super(s);
1035 return ERR_PTR(error);
1037 s->s_flags |= MS_ACTIVE;
1038 return dget(s->s_root);
1040 EXPORT_SYMBOL(mount_nodev);
1042 static int compare_single(struct super_block *s, void *p)
1047 struct dentry *mount_single(struct file_system_type *fs_type,
1048 int flags, void *data,
1049 int (*fill_super)(struct super_block *, void *, int))
1051 struct super_block *s;
1054 s = sget(fs_type, compare_single, set_anon_super, NULL);
1059 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1061 deactivate_locked_super(s);
1062 return ERR_PTR(error);
1064 s->s_flags |= MS_ACTIVE;
1066 do_remount_sb(s, flags, data, 0);
1068 return dget(s->s_root);
1070 EXPORT_SYMBOL(mount_single);
1073 mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
1075 struct dentry *root;
1076 struct super_block *sb;
1077 char *secdata = NULL;
1078 int error = -ENOMEM;
1080 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
1081 secdata = alloc_secdata();
1085 error = security_sb_copy_data(data, secdata);
1087 goto out_free_secdata;
1090 root = type->mount(type, flags, name, data);
1092 error = PTR_ERR(root);
1093 goto out_free_secdata;
1097 WARN_ON(!sb->s_bdi);
1098 WARN_ON(sb->s_bdi == &default_backing_dev_info);
1099 sb->s_flags |= MS_BORN;
1101 error = security_sb_kern_mount(sb, flags, secdata);
1106 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
1107 * but s_maxbytes was an unsigned long long for many releases. Throw
1108 * this warning for a little while to try and catch filesystems that
1109 * violate this rule.
1111 WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
1112 "negative value (%lld)\n", type->name, sb->s_maxbytes);
1114 up_write(&sb->s_umount);
1115 free_secdata(secdata);
1119 deactivate_locked_super(sb);
1121 free_secdata(secdata);
1123 return ERR_PTR(error);
1127 * freeze_super - lock the filesystem and force it into a consistent state
1128 * @sb: the super to lock
1130 * Syncs the super to make sure the filesystem is consistent and calls the fs's
1131 * freeze_fs. Subsequent calls to this without first thawing the fs will return
1134 int freeze_super(struct super_block *sb)
1138 atomic_inc(&sb->s_active);
1139 down_write(&sb->s_umount);
1141 deactivate_locked_super(sb);
1145 if (sb->s_flags & MS_RDONLY) {
1146 sb->s_frozen = SB_FREEZE_TRANS;
1148 up_write(&sb->s_umount);
1152 sb->s_frozen = SB_FREEZE_WRITE;
1155 sync_filesystem(sb);
1157 sb->s_frozen = SB_FREEZE_TRANS;
1160 sync_blockdev(sb->s_bdev);
1161 if (sb->s_op->freeze_fs) {
1162 ret = sb->s_op->freeze_fs(sb);
1165 "VFS:Filesystem freeze failed\n");
1166 sb->s_frozen = SB_UNFROZEN;
1167 deactivate_locked_super(sb);
1171 up_write(&sb->s_umount);
1174 EXPORT_SYMBOL(freeze_super);
1177 * thaw_super -- unlock filesystem
1178 * @sb: the super to thaw
1180 * Unlocks the filesystem and marks it writeable again after freeze_super().
1182 int thaw_super(struct super_block *sb)
1186 down_write(&sb->s_umount);
1187 if (sb->s_frozen == SB_UNFROZEN) {
1188 up_write(&sb->s_umount);
1192 if (sb->s_flags & MS_RDONLY)
1195 if (sb->s_op->unfreeze_fs) {
1196 error = sb->s_op->unfreeze_fs(sb);
1199 "VFS:Filesystem thaw failed\n");
1200 sb->s_frozen = SB_FREEZE_TRANS;
1201 up_write(&sb->s_umount);
1207 sb->s_frozen = SB_UNFROZEN;
1209 wake_up(&sb->s_wait_unfrozen);
1210 deactivate_locked_super(sb);
1214 EXPORT_SYMBOL(thaw_super);