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)) {
58 s->s_files = alloc_percpu(struct list_head);
67 for_each_possible_cpu(i)
68 INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));
71 INIT_LIST_HEAD(&s->s_files);
73 INIT_LIST_HEAD(&s->s_instances);
74 INIT_HLIST_HEAD(&s->s_anon);
75 INIT_LIST_HEAD(&s->s_inodes);
76 INIT_LIST_HEAD(&s->s_dentry_lru);
77 init_rwsem(&s->s_umount);
78 mutex_init(&s->s_lock);
79 lockdep_set_class(&s->s_umount, &type->s_umount_key);
81 * The locking rules for s_lock are up to the
82 * filesystem. For example ext3fs has different
83 * lock ordering than usbfs:
85 lockdep_set_class(&s->s_lock, &type->s_lock_key);
87 * sget() can have s_umount recursion.
89 * When it cannot find a suitable sb, it allocates a new
90 * one (this one), and tries again to find a suitable old
93 * In case that succeeds, it will acquire the s_umount
94 * lock of the old one. Since these are clearly distrinct
95 * locks, and this object isn't exposed yet, there's no
98 * Annotate this by putting this lock in a different
101 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
103 atomic_set(&s->s_active, 1);
104 mutex_init(&s->s_vfs_rename_mutex);
105 lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
106 mutex_init(&s->s_dquot.dqio_mutex);
107 mutex_init(&s->s_dquot.dqonoff_mutex);
108 init_rwsem(&s->s_dquot.dqptr_sem);
109 init_waitqueue_head(&s->s_wait_unfrozen);
110 s->s_maxbytes = MAX_NON_LFS;
111 s->s_op = &default_op;
112 s->s_time_gran = 1000000000;
119 * destroy_super - frees a superblock
120 * @s: superblock to free
122 * Frees a superblock.
124 static inline void destroy_super(struct super_block *s)
127 free_percpu(s->s_files);
135 /* Superblock refcounting */
138 * Drop a superblock's refcount. The caller must hold sb_lock.
140 void __put_super(struct super_block *sb)
142 if (!--sb->s_count) {
143 list_del_init(&sb->s_list);
149 * put_super - drop a temporary reference to superblock
150 * @sb: superblock in question
152 * Drops a temporary reference, frees superblock if there's no
155 void put_super(struct super_block *sb)
159 spin_unlock(&sb_lock);
164 * deactivate_locked_super - drop an active reference to superblock
165 * @s: superblock to deactivate
167 * Drops an active reference to superblock, converting it into a temprory
168 * one if there is no other active references left. In that case we
169 * tell fs driver to shut it down and drop the temporary reference we
172 * Caller holds exclusive lock on superblock; that lock is released.
174 void deactivate_locked_super(struct super_block *s)
176 struct file_system_type *fs = s->s_type;
177 if (atomic_dec_and_test(&s->s_active)) {
182 up_write(&s->s_umount);
186 EXPORT_SYMBOL(deactivate_locked_super);
189 * deactivate_super - drop an active reference to superblock
190 * @s: superblock to deactivate
192 * Variant of deactivate_locked_super(), except that superblock is *not*
193 * locked by caller. If we are going to drop the final active reference,
194 * lock will be acquired prior to that.
196 void deactivate_super(struct super_block *s)
198 if (!atomic_add_unless(&s->s_active, -1, 1)) {
199 down_write(&s->s_umount);
200 deactivate_locked_super(s);
204 EXPORT_SYMBOL(deactivate_super);
207 * grab_super - acquire an active reference
208 * @s: reference we are trying to make active
210 * Tries to acquire an active reference. grab_super() is used when we
211 * had just found a superblock in super_blocks or fs_type->fs_supers
212 * and want to turn it into a full-blown active reference. grab_super()
213 * is called with sb_lock held and drops it. Returns 1 in case of
214 * success, 0 if we had failed (superblock contents was already dead or
215 * dying when grab_super() had been called).
217 static int grab_super(struct super_block *s) __releases(sb_lock)
219 if (atomic_inc_not_zero(&s->s_active)) {
220 spin_unlock(&sb_lock);
223 /* it's going away */
225 spin_unlock(&sb_lock);
226 /* wait for it to die */
227 down_write(&s->s_umount);
228 up_write(&s->s_umount);
234 * Superblock locking. We really ought to get rid of these two.
236 void lock_super(struct super_block * sb)
239 mutex_lock(&sb->s_lock);
242 void unlock_super(struct super_block * sb)
245 mutex_unlock(&sb->s_lock);
248 EXPORT_SYMBOL(lock_super);
249 EXPORT_SYMBOL(unlock_super);
252 * generic_shutdown_super - common helper for ->kill_sb()
253 * @sb: superblock to kill
255 * generic_shutdown_super() does all fs-independent work on superblock
256 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
257 * that need destruction out of superblock, call generic_shutdown_super()
258 * and release aforementioned objects. Note: dentries and inodes _are_
259 * taken care of and do not need specific handling.
261 * Upon calling this function, the filesystem may no longer alter or
262 * rearrange the set of dentries belonging to this super_block, nor may it
263 * change the attachments of dentries to inodes.
265 void generic_shutdown_super(struct super_block *sb)
267 const struct super_operations *sop = sb->s_op;
271 shrink_dcache_for_umount(sb);
274 sb->s_flags &= ~MS_ACTIVE;
276 /* bad name - it should be evict_inodes() */
277 invalidate_inodes(sb);
282 /* Forget any remaining inodes */
283 if (invalidate_inodes(sb)) {
284 printk("VFS: Busy inodes after unmount of %s. "
285 "Self-destruct in 5 seconds. Have a nice day...\n",
291 /* should be initialized for __put_super_and_need_restart() */
292 list_del_init(&sb->s_instances);
293 spin_unlock(&sb_lock);
294 up_write(&sb->s_umount);
297 EXPORT_SYMBOL(generic_shutdown_super);
300 * sget - find or create a superblock
301 * @type: filesystem type superblock should belong to
302 * @test: comparison callback
303 * @set: setup callback
304 * @data: argument to each of them
306 struct super_block *sget(struct file_system_type *type,
307 int (*test)(struct super_block *,void *),
308 int (*set)(struct super_block *,void *),
311 struct super_block *s = NULL;
312 struct super_block *old;
318 list_for_each_entry(old, &type->fs_supers, s_instances) {
319 if (!test(old, data))
321 if (!grab_super(old))
324 up_write(&s->s_umount);
328 down_write(&old->s_umount);
329 if (unlikely(!(old->s_flags & MS_BORN))) {
330 deactivate_locked_super(old);
337 spin_unlock(&sb_lock);
338 s = alloc_super(type);
340 return ERR_PTR(-ENOMEM);
346 spin_unlock(&sb_lock);
347 up_write(&s->s_umount);
352 strlcpy(s->s_id, type->name, sizeof(s->s_id));
353 list_add_tail(&s->s_list, &super_blocks);
354 list_add(&s->s_instances, &type->fs_supers);
355 spin_unlock(&sb_lock);
356 get_filesystem(type);
362 void drop_super(struct super_block *sb)
364 up_read(&sb->s_umount);
368 EXPORT_SYMBOL(drop_super);
371 * sync_supers - helper for periodic superblock writeback
373 * Call the write_super method if present on all dirty superblocks in
374 * the system. This is for the periodic writeback used by most older
375 * filesystems. For data integrity superblock writeback use
376 * sync_filesystems() instead.
378 * Note: check the dirty flag before waiting, so we don't
379 * hold up the sync while mounting a device. (The newly
380 * mounted device won't need syncing.)
382 void sync_supers(void)
384 struct super_block *sb, *p = NULL;
387 list_for_each_entry(sb, &super_blocks, s_list) {
388 if (list_empty(&sb->s_instances))
390 if (sb->s_op->write_super && sb->s_dirt) {
392 spin_unlock(&sb_lock);
394 down_read(&sb->s_umount);
395 if (sb->s_root && sb->s_dirt)
396 sb->s_op->write_super(sb);
397 up_read(&sb->s_umount);
407 spin_unlock(&sb_lock);
411 * iterate_supers - call function for all active superblocks
412 * @f: function to call
413 * @arg: argument to pass to it
415 * Scans the superblock list and calls given function, passing it
416 * locked superblock and given argument.
418 void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
420 struct super_block *sb, *p = NULL;
423 list_for_each_entry(sb, &super_blocks, s_list) {
424 if (list_empty(&sb->s_instances))
427 spin_unlock(&sb_lock);
429 down_read(&sb->s_umount);
432 up_read(&sb->s_umount);
441 spin_unlock(&sb_lock);
445 * get_super - get the superblock of a device
446 * @bdev: device to get the superblock for
448 * Scans the superblock list and finds the superblock of the file system
449 * mounted on the device given. %NULL is returned if no match is found.
452 struct super_block *get_super(struct block_device *bdev)
454 struct super_block *sb;
461 list_for_each_entry(sb, &super_blocks, s_list) {
462 if (list_empty(&sb->s_instances))
464 if (sb->s_bdev == bdev) {
466 spin_unlock(&sb_lock);
467 down_read(&sb->s_umount);
471 up_read(&sb->s_umount);
472 /* nope, got unmounted */
478 spin_unlock(&sb_lock);
482 EXPORT_SYMBOL(get_super);
485 * get_active_super - get an active reference to the superblock of a device
486 * @bdev: device to get the superblock for
488 * Scans the superblock list and finds the superblock of the file system
489 * mounted on the device given. Returns the superblock with an active
490 * reference or %NULL if none was found.
492 struct super_block *get_active_super(struct block_device *bdev)
494 struct super_block *sb;
501 list_for_each_entry(sb, &super_blocks, s_list) {
502 if (list_empty(&sb->s_instances))
504 if (sb->s_bdev == bdev) {
505 if (grab_super(sb)) /* drops sb_lock */
511 spin_unlock(&sb_lock);
515 struct super_block *user_get_super(dev_t dev)
517 struct super_block *sb;
521 list_for_each_entry(sb, &super_blocks, s_list) {
522 if (list_empty(&sb->s_instances))
524 if (sb->s_dev == dev) {
526 spin_unlock(&sb_lock);
527 down_read(&sb->s_umount);
531 up_read(&sb->s_umount);
532 /* nope, got unmounted */
538 spin_unlock(&sb_lock);
543 * do_remount_sb - asks filesystem to change mount options.
544 * @sb: superblock in question
545 * @flags: numeric part of options
546 * @data: the rest of options
547 * @force: whether or not to force the change
549 * Alters the mount options of a mounted file system.
551 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
556 if (sb->s_frozen != SB_UNFROZEN)
560 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
564 if (flags & MS_RDONLY)
566 shrink_dcache_sb(sb);
569 remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
571 /* If we are remounting RDONLY and current sb is read/write,
572 make sure there are no rw files opened */
576 else if (!fs_may_remount_ro(sb))
580 if (sb->s_op->remount_fs) {
581 retval = sb->s_op->remount_fs(sb, &flags, data);
585 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
588 * Some filesystems modify their metadata via some other path than the
589 * bdev buffer cache (eg. use a private mapping, or directories in
590 * pagecache, etc). Also file data modifications go via their own
591 * mappings. So If we try to mount readonly then copy the filesystem
592 * from bdev, we could get stale data, so invalidate it to give a best
593 * effort at coherency.
595 if (remount_ro && sb->s_bdev)
596 invalidate_bdev(sb->s_bdev);
600 static void do_emergency_remount(struct work_struct *work)
602 struct super_block *sb, *p = NULL;
605 list_for_each_entry(sb, &super_blocks, s_list) {
606 if (list_empty(&sb->s_instances))
609 spin_unlock(&sb_lock);
610 down_write(&sb->s_umount);
611 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
613 * What lock protects sb->s_flags??
615 do_remount_sb(sb, MS_RDONLY, NULL, 1);
617 up_write(&sb->s_umount);
625 spin_unlock(&sb_lock);
627 printk("Emergency Remount complete\n");
630 void emergency_remount(void)
632 struct work_struct *work;
634 work = kmalloc(sizeof(*work), GFP_ATOMIC);
636 INIT_WORK(work, do_emergency_remount);
642 * Unnamed block devices are dummy devices used by virtual
643 * filesystems which don't use real block-devices. -- jrs
646 static DEFINE_IDA(unnamed_dev_ida);
647 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
648 static int unnamed_dev_start = 0; /* don't bother trying below it */
650 int set_anon_super(struct super_block *s, void *data)
656 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
658 spin_lock(&unnamed_dev_lock);
659 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
661 unnamed_dev_start = dev + 1;
662 spin_unlock(&unnamed_dev_lock);
663 if (error == -EAGAIN)
664 /* We raced and lost with another CPU. */
669 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
670 spin_lock(&unnamed_dev_lock);
671 ida_remove(&unnamed_dev_ida, dev);
672 if (unnamed_dev_start > dev)
673 unnamed_dev_start = dev;
674 spin_unlock(&unnamed_dev_lock);
677 s->s_dev = MKDEV(0, dev & MINORMASK);
678 s->s_bdi = &noop_backing_dev_info;
682 EXPORT_SYMBOL(set_anon_super);
684 void kill_anon_super(struct super_block *sb)
686 int slot = MINOR(sb->s_dev);
688 generic_shutdown_super(sb);
689 spin_lock(&unnamed_dev_lock);
690 ida_remove(&unnamed_dev_ida, slot);
691 if (slot < unnamed_dev_start)
692 unnamed_dev_start = slot;
693 spin_unlock(&unnamed_dev_lock);
696 EXPORT_SYMBOL(kill_anon_super);
698 void kill_litter_super(struct super_block *sb)
701 d_genocide(sb->s_root);
705 EXPORT_SYMBOL(kill_litter_super);
707 static int ns_test_super(struct super_block *sb, void *data)
709 return sb->s_fs_info == data;
712 static int ns_set_super(struct super_block *sb, void *data)
714 sb->s_fs_info = data;
715 return set_anon_super(sb, NULL);
718 int get_sb_ns(struct file_system_type *fs_type, int flags, void *data,
719 int (*fill_super)(struct super_block *, void *, int),
720 struct vfsmount *mnt)
722 struct super_block *sb;
724 sb = sget(fs_type, ns_test_super, ns_set_super, data);
731 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
733 deactivate_locked_super(sb);
737 sb->s_flags |= MS_ACTIVE;
740 simple_set_mnt(mnt, sb);
744 EXPORT_SYMBOL(get_sb_ns);
747 static int set_bdev_super(struct super_block *s, void *data)
750 s->s_dev = s->s_bdev->bd_dev;
753 * We set the bdi here to the queue backing, file systems can
754 * overwrite this in ->fill_super()
756 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
760 static int test_bdev_super(struct super_block *s, void *data)
762 return (void *)s->s_bdev == data;
765 int get_sb_bdev(struct file_system_type *fs_type,
766 int flags, const char *dev_name, void *data,
767 int (*fill_super)(struct super_block *, void *, int),
768 struct vfsmount *mnt)
770 struct block_device *bdev;
771 struct super_block *s;
772 fmode_t mode = FMODE_READ;
775 if (!(flags & MS_RDONLY))
778 bdev = open_bdev_exclusive(dev_name, mode, fs_type);
780 return PTR_ERR(bdev);
783 * once the super is inserted into the list by sget, s_umount
784 * will protect the lockfs code from trying to start a snapshot
785 * while we are mounting
787 mutex_lock(&bdev->bd_fsfreeze_mutex);
788 if (bdev->bd_fsfreeze_count > 0) {
789 mutex_unlock(&bdev->bd_fsfreeze_mutex);
793 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
794 mutex_unlock(&bdev->bd_fsfreeze_mutex);
799 if ((flags ^ s->s_flags) & MS_RDONLY) {
800 deactivate_locked_super(s);
806 * s_umount nests inside bd_mutex during
807 * __invalidate_device(). close_bdev_exclusive()
808 * acquires bd_mutex and can't be called under
809 * s_umount. Drop s_umount temporarily. This is safe
810 * as we're holding an active reference.
812 up_write(&s->s_umount);
813 close_bdev_exclusive(bdev, mode);
814 down_write(&s->s_umount);
816 char b[BDEVNAME_SIZE];
820 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
821 sb_set_blocksize(s, block_size(bdev));
822 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
824 deactivate_locked_super(s);
828 s->s_flags |= MS_ACTIVE;
832 simple_set_mnt(mnt, s);
838 close_bdev_exclusive(bdev, mode);
843 EXPORT_SYMBOL(get_sb_bdev);
845 void kill_block_super(struct super_block *sb)
847 struct block_device *bdev = sb->s_bdev;
848 fmode_t mode = sb->s_mode;
850 bdev->bd_super = NULL;
851 generic_shutdown_super(sb);
853 close_bdev_exclusive(bdev, mode);
856 EXPORT_SYMBOL(kill_block_super);
859 int get_sb_nodev(struct file_system_type *fs_type,
860 int flags, void *data,
861 int (*fill_super)(struct super_block *, void *, int),
862 struct vfsmount *mnt)
865 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
872 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
874 deactivate_locked_super(s);
877 s->s_flags |= MS_ACTIVE;
878 simple_set_mnt(mnt, s);
882 EXPORT_SYMBOL(get_sb_nodev);
884 static int compare_single(struct super_block *s, void *p)
889 int get_sb_single(struct file_system_type *fs_type,
890 int flags, void *data,
891 int (*fill_super)(struct super_block *, void *, int),
892 struct vfsmount *mnt)
894 struct super_block *s;
897 s = sget(fs_type, compare_single, set_anon_super, NULL);
902 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
904 deactivate_locked_super(s);
907 s->s_flags |= MS_ACTIVE;
909 do_remount_sb(s, flags, data, 0);
911 simple_set_mnt(mnt, s);
915 EXPORT_SYMBOL(get_sb_single);
918 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
920 struct vfsmount *mnt;
921 char *secdata = NULL;
925 return ERR_PTR(-ENODEV);
928 mnt = alloc_vfsmnt(name);
932 if (flags & MS_KERNMOUNT)
933 mnt->mnt_flags = MNT_INTERNAL;
935 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
936 secdata = alloc_secdata();
940 error = security_sb_copy_data(data, secdata);
942 goto out_free_secdata;
945 error = type->get_sb(type, flags, name, data, mnt);
947 goto out_free_secdata;
948 BUG_ON(!mnt->mnt_sb);
949 WARN_ON(!mnt->mnt_sb->s_bdi);
950 mnt->mnt_sb->s_flags |= MS_BORN;
952 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
957 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
958 * but s_maxbytes was an unsigned long long for many releases. Throw
959 * this warning for a little while to try and catch filesystems that
960 * violate this rule. This warning should be either removed or
961 * converted to a BUG() in 2.6.34.
963 WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
964 "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
966 mnt->mnt_mountpoint = mnt->mnt_root;
967 mnt->mnt_parent = mnt;
968 up_write(&mnt->mnt_sb->s_umount);
969 free_secdata(secdata);
973 deactivate_locked_super(mnt->mnt_sb);
975 free_secdata(secdata);
979 return ERR_PTR(error);
982 EXPORT_SYMBOL_GPL(vfs_kern_mount);
985 * freeze_super - lock the filesystem and force it into a consistent state
986 * @sb: the super to lock
988 * Syncs the super to make sure the filesystem is consistent and calls the fs's
989 * freeze_fs. Subsequent calls to this without first thawing the fs will return
992 int freeze_super(struct super_block *sb)
996 atomic_inc(&sb->s_active);
997 down_write(&sb->s_umount);
999 deactivate_locked_super(sb);
1003 if (sb->s_flags & MS_RDONLY) {
1004 sb->s_frozen = SB_FREEZE_TRANS;
1006 up_write(&sb->s_umount);
1010 sb->s_frozen = SB_FREEZE_WRITE;
1013 sync_filesystem(sb);
1015 sb->s_frozen = SB_FREEZE_TRANS;
1018 sync_blockdev(sb->s_bdev);
1019 if (sb->s_op->freeze_fs) {
1020 ret = sb->s_op->freeze_fs(sb);
1023 "VFS:Filesystem freeze failed\n");
1024 sb->s_frozen = SB_UNFROZEN;
1025 deactivate_locked_super(sb);
1029 up_write(&sb->s_umount);
1032 EXPORT_SYMBOL(freeze_super);
1035 * thaw_super -- unlock filesystem
1036 * @sb: the super to thaw
1038 * Unlocks the filesystem and marks it writeable again after freeze_super().
1040 int thaw_super(struct super_block *sb)
1044 down_write(&sb->s_umount);
1045 if (sb->s_frozen == SB_UNFROZEN) {
1046 up_write(&sb->s_umount);
1050 if (sb->s_flags & MS_RDONLY)
1053 if (sb->s_op->unfreeze_fs) {
1054 error = sb->s_op->unfreeze_fs(sb);
1057 "VFS:Filesystem thaw failed\n");
1058 sb->s_frozen = SB_FREEZE_TRANS;
1059 up_write(&sb->s_umount);
1065 sb->s_frozen = SB_UNFROZEN;
1067 wake_up(&sb->s_wait_unfrozen);
1068 deactivate_locked_super(sb);
1072 EXPORT_SYMBOL(thaw_super);
1074 static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
1077 const char *subtype = strchr(fstype, '.');
1086 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
1088 if (!mnt->mnt_sb->s_subtype)
1094 return ERR_PTR(err);
1098 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
1100 struct file_system_type *type = get_fs_type(fstype);
1101 struct vfsmount *mnt;
1103 return ERR_PTR(-ENODEV);
1104 mnt = vfs_kern_mount(type, flags, name, data);
1105 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
1106 !mnt->mnt_sb->s_subtype)
1107 mnt = fs_set_subtype(mnt, fstype);
1108 put_filesystem(type);
1111 EXPORT_SYMBOL_GPL(do_kern_mount);
1113 struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
1115 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
1118 EXPORT_SYMBOL_GPL(kern_mount_data);