Merge branch 'media_fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab...
[cris-mirror.git] / fs / super.c
blob74e149efed8194b9ad45b06f654533cd884f0ca1
1 /*
2 * linux/fs/super.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * super.c contains code to handle: - mount structures
7 * - super-block tables
8 * - filesystem drivers list
9 * - mount system call
10 * - umount system call
11 * - ustat 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 "internal.h"
37 LIST_HEAD(super_blocks);
38 DEFINE_SPINLOCK(sb_lock);
40 /**
41 * alloc_super - create new superblock
42 * @type: filesystem type superblock should belong to
44 * Allocates and initializes a new &struct super_block. alloc_super()
45 * returns a pointer new superblock or %NULL if allocation had failed.
47 static struct super_block *alloc_super(struct file_system_type *type)
49 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
50 static const struct super_operations default_op;
52 if (s) {
53 if (security_sb_alloc(s)) {
54 kfree(s);
55 s = NULL;
56 goto out;
58 #ifdef CONFIG_SMP
59 s->s_files = alloc_percpu(struct list_head);
60 if (!s->s_files) {
61 security_sb_free(s);
62 kfree(s);
63 s = NULL;
64 goto out;
65 } else {
66 int i;
68 for_each_possible_cpu(i)
69 INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));
71 #else
72 INIT_LIST_HEAD(&s->s_files);
73 #endif
74 INIT_LIST_HEAD(&s->s_instances);
75 INIT_HLIST_BL_HEAD(&s->s_anon);
76 INIT_LIST_HEAD(&s->s_inodes);
77 INIT_LIST_HEAD(&s->s_dentry_lru);
78 init_rwsem(&s->s_umount);
79 mutex_init(&s->s_lock);
80 lockdep_set_class(&s->s_umount, &type->s_umount_key);
82 * The locking rules for s_lock are up to the
83 * filesystem. For example ext3fs has different
84 * lock ordering than usbfs:
86 lockdep_set_class(&s->s_lock, &type->s_lock_key);
88 * sget() can have s_umount recursion.
90 * When it cannot find a suitable sb, it allocates a new
91 * one (this one), and tries again to find a suitable old
92 * one.
94 * In case that succeeds, it will acquire the s_umount
95 * lock of the old one. Since these are clearly distrinct
96 * locks, and this object isn't exposed yet, there's no
97 * risk of deadlocks.
99 * Annotate this by putting this lock in a different
100 * subclass.
102 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
103 s->s_count = 1;
104 atomic_set(&s->s_active, 1);
105 mutex_init(&s->s_vfs_rename_mutex);
106 lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
107 mutex_init(&s->s_dquot.dqio_mutex);
108 mutex_init(&s->s_dquot.dqonoff_mutex);
109 init_rwsem(&s->s_dquot.dqptr_sem);
110 init_waitqueue_head(&s->s_wait_unfrozen);
111 s->s_maxbytes = MAX_NON_LFS;
112 s->s_op = &default_op;
113 s->s_time_gran = 1000000000;
115 out:
116 return s;
120 * destroy_super - frees a superblock
121 * @s: superblock to free
123 * Frees a superblock.
125 static inline void destroy_super(struct super_block *s)
127 #ifdef CONFIG_SMP
128 free_percpu(s->s_files);
129 #endif
130 security_sb_free(s);
131 kfree(s->s_subtype);
132 kfree(s->s_options);
133 kfree(s);
136 /* Superblock refcounting */
139 * Drop a superblock's refcount. The caller must hold sb_lock.
141 void __put_super(struct super_block *sb)
143 if (!--sb->s_count) {
144 list_del_init(&sb->s_list);
145 destroy_super(sb);
150 * put_super - drop a temporary reference to superblock
151 * @sb: superblock in question
153 * Drops a temporary reference, frees superblock if there's no
154 * references left.
156 void put_super(struct super_block *sb)
158 spin_lock(&sb_lock);
159 __put_super(sb);
160 spin_unlock(&sb_lock);
165 * deactivate_locked_super - drop an active reference to superblock
166 * @s: superblock to deactivate
168 * Drops an active reference to superblock, converting it into a temprory
169 * one if there is no other active references left. In that case we
170 * tell fs driver to shut it down and drop the temporary reference we
171 * had just acquired.
173 * Caller holds exclusive lock on superblock; that lock is released.
175 void deactivate_locked_super(struct super_block *s)
177 struct file_system_type *fs = s->s_type;
178 if (atomic_dec_and_test(&s->s_active)) {
179 fs->kill_sb(s);
180 put_filesystem(fs);
181 put_super(s);
182 } else {
183 up_write(&s->s_umount);
187 EXPORT_SYMBOL(deactivate_locked_super);
190 * deactivate_super - drop an active reference to superblock
191 * @s: superblock to deactivate
193 * Variant of deactivate_locked_super(), except that superblock is *not*
194 * locked by caller. If we are going to drop the final active reference,
195 * lock will be acquired prior to that.
197 void deactivate_super(struct super_block *s)
199 if (!atomic_add_unless(&s->s_active, -1, 1)) {
200 down_write(&s->s_umount);
201 deactivate_locked_super(s);
205 EXPORT_SYMBOL(deactivate_super);
208 * grab_super - acquire an active reference
209 * @s: reference we are trying to make active
211 * Tries to acquire an active reference. grab_super() is used when we
212 * had just found a superblock in super_blocks or fs_type->fs_supers
213 * and want to turn it into a full-blown active reference. grab_super()
214 * is called with sb_lock held and drops it. Returns 1 in case of
215 * success, 0 if we had failed (superblock contents was already dead or
216 * dying when grab_super() had been called).
218 static int grab_super(struct super_block *s) __releases(sb_lock)
220 if (atomic_inc_not_zero(&s->s_active)) {
221 spin_unlock(&sb_lock);
222 return 1;
224 /* it's going away */
225 s->s_count++;
226 spin_unlock(&sb_lock);
227 /* wait for it to die */
228 down_write(&s->s_umount);
229 up_write(&s->s_umount);
230 put_super(s);
231 return 0;
235 * Superblock locking. We really ought to get rid of these two.
237 void lock_super(struct super_block * sb)
239 get_fs_excl();
240 mutex_lock(&sb->s_lock);
243 void unlock_super(struct super_block * sb)
245 put_fs_excl();
246 mutex_unlock(&sb->s_lock);
249 EXPORT_SYMBOL(lock_super);
250 EXPORT_SYMBOL(unlock_super);
253 * generic_shutdown_super - common helper for ->kill_sb()
254 * @sb: superblock to kill
256 * generic_shutdown_super() does all fs-independent work on superblock
257 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
258 * that need destruction out of superblock, call generic_shutdown_super()
259 * and release aforementioned objects. Note: dentries and inodes _are_
260 * taken care of and do not need specific handling.
262 * Upon calling this function, the filesystem may no longer alter or
263 * rearrange the set of dentries belonging to this super_block, nor may it
264 * change the attachments of dentries to inodes.
266 void generic_shutdown_super(struct super_block *sb)
268 const struct super_operations *sop = sb->s_op;
271 if (sb->s_root) {
272 shrink_dcache_for_umount(sb);
273 sync_filesystem(sb);
274 get_fs_excl();
275 sb->s_flags &= ~MS_ACTIVE;
277 fsnotify_unmount_inodes(&sb->s_inodes);
279 evict_inodes(sb);
281 if (sop->put_super)
282 sop->put_super(sb);
284 if (!list_empty(&sb->s_inodes)) {
285 printk("VFS: Busy inodes after unmount of %s. "
286 "Self-destruct in 5 seconds. Have a nice day...\n",
287 sb->s_id);
289 put_fs_excl();
291 spin_lock(&sb_lock);
292 /* should be initialized for __put_super_and_need_restart() */
293 list_del_init(&sb->s_instances);
294 spin_unlock(&sb_lock);
295 up_write(&sb->s_umount);
298 EXPORT_SYMBOL(generic_shutdown_super);
301 * sget - find or create a superblock
302 * @type: filesystem type superblock should belong to
303 * @test: comparison callback
304 * @set: setup callback
305 * @data: argument to each of them
307 struct super_block *sget(struct file_system_type *type,
308 int (*test)(struct super_block *,void *),
309 int (*set)(struct super_block *,void *),
310 void *data)
312 struct super_block *s = NULL;
313 struct super_block *old;
314 int err;
316 retry:
317 spin_lock(&sb_lock);
318 if (test) {
319 list_for_each_entry(old, &type->fs_supers, s_instances) {
320 if (!test(old, data))
321 continue;
322 if (!grab_super(old))
323 goto retry;
324 if (s) {
325 up_write(&s->s_umount);
326 destroy_super(s);
327 s = NULL;
329 down_write(&old->s_umount);
330 if (unlikely(!(old->s_flags & MS_BORN))) {
331 deactivate_locked_super(old);
332 goto retry;
334 return old;
337 if (!s) {
338 spin_unlock(&sb_lock);
339 s = alloc_super(type);
340 if (!s)
341 return ERR_PTR(-ENOMEM);
342 goto retry;
345 err = set(s, data);
346 if (err) {
347 spin_unlock(&sb_lock);
348 up_write(&s->s_umount);
349 destroy_super(s);
350 return ERR_PTR(err);
352 s->s_type = type;
353 strlcpy(s->s_id, type->name, sizeof(s->s_id));
354 list_add_tail(&s->s_list, &super_blocks);
355 list_add(&s->s_instances, &type->fs_supers);
356 spin_unlock(&sb_lock);
357 get_filesystem(type);
358 return s;
361 EXPORT_SYMBOL(sget);
363 void drop_super(struct super_block *sb)
365 up_read(&sb->s_umount);
366 put_super(sb);
369 EXPORT_SYMBOL(drop_super);
372 * sync_supers - helper for periodic superblock writeback
374 * Call the write_super method if present on all dirty superblocks in
375 * the system. This is for the periodic writeback used by most older
376 * filesystems. For data integrity superblock writeback use
377 * sync_filesystems() instead.
379 * Note: check the dirty flag before waiting, so we don't
380 * hold up the sync while mounting a device. (The newly
381 * mounted device won't need syncing.)
383 void sync_supers(void)
385 struct super_block *sb, *p = NULL;
387 spin_lock(&sb_lock);
388 list_for_each_entry(sb, &super_blocks, s_list) {
389 if (list_empty(&sb->s_instances))
390 continue;
391 if (sb->s_op->write_super && sb->s_dirt) {
392 sb->s_count++;
393 spin_unlock(&sb_lock);
395 down_read(&sb->s_umount);
396 if (sb->s_root && sb->s_dirt)
397 sb->s_op->write_super(sb);
398 up_read(&sb->s_umount);
400 spin_lock(&sb_lock);
401 if (p)
402 __put_super(p);
403 p = sb;
406 if (p)
407 __put_super(p);
408 spin_unlock(&sb_lock);
412 * iterate_supers - call function for all active superblocks
413 * @f: function to call
414 * @arg: argument to pass to it
416 * Scans the superblock list and calls given function, passing it
417 * locked superblock and given argument.
419 void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
421 struct super_block *sb, *p = NULL;
423 spin_lock(&sb_lock);
424 list_for_each_entry(sb, &super_blocks, s_list) {
425 if (list_empty(&sb->s_instances))
426 continue;
427 sb->s_count++;
428 spin_unlock(&sb_lock);
430 down_read(&sb->s_umount);
431 if (sb->s_root)
432 f(sb, arg);
433 up_read(&sb->s_umount);
435 spin_lock(&sb_lock);
436 if (p)
437 __put_super(p);
438 p = sb;
440 if (p)
441 __put_super(p);
442 spin_unlock(&sb_lock);
446 * get_super - get the superblock of a device
447 * @bdev: device to get the superblock for
449 * Scans the superblock list and finds the superblock of the file system
450 * mounted on the device given. %NULL is returned if no match is found.
453 struct super_block *get_super(struct block_device *bdev)
455 struct super_block *sb;
457 if (!bdev)
458 return NULL;
460 spin_lock(&sb_lock);
461 rescan:
462 list_for_each_entry(sb, &super_blocks, s_list) {
463 if (list_empty(&sb->s_instances))
464 continue;
465 if (sb->s_bdev == bdev) {
466 sb->s_count++;
467 spin_unlock(&sb_lock);
468 down_read(&sb->s_umount);
469 /* still alive? */
470 if (sb->s_root)
471 return sb;
472 up_read(&sb->s_umount);
473 /* nope, got unmounted */
474 spin_lock(&sb_lock);
475 __put_super(sb);
476 goto rescan;
479 spin_unlock(&sb_lock);
480 return NULL;
483 EXPORT_SYMBOL(get_super);
486 * get_active_super - get an active reference to the superblock of a device
487 * @bdev: device to get the superblock for
489 * Scans the superblock list and finds the superblock of the file system
490 * mounted on the device given. Returns the superblock with an active
491 * reference or %NULL if none was found.
493 struct super_block *get_active_super(struct block_device *bdev)
495 struct super_block *sb;
497 if (!bdev)
498 return NULL;
500 restart:
501 spin_lock(&sb_lock);
502 list_for_each_entry(sb, &super_blocks, s_list) {
503 if (list_empty(&sb->s_instances))
504 continue;
505 if (sb->s_bdev == bdev) {
506 if (grab_super(sb)) /* drops sb_lock */
507 return sb;
508 else
509 goto restart;
512 spin_unlock(&sb_lock);
513 return NULL;
516 struct super_block *user_get_super(dev_t dev)
518 struct super_block *sb;
520 spin_lock(&sb_lock);
521 rescan:
522 list_for_each_entry(sb, &super_blocks, s_list) {
523 if (list_empty(&sb->s_instances))
524 continue;
525 if (sb->s_dev == dev) {
526 sb->s_count++;
527 spin_unlock(&sb_lock);
528 down_read(&sb->s_umount);
529 /* still alive? */
530 if (sb->s_root)
531 return sb;
532 up_read(&sb->s_umount);
533 /* nope, got unmounted */
534 spin_lock(&sb_lock);
535 __put_super(sb);
536 goto rescan;
539 spin_unlock(&sb_lock);
540 return NULL;
544 * do_remount_sb - asks filesystem to change mount options.
545 * @sb: superblock in question
546 * @flags: numeric part of options
547 * @data: the rest of options
548 * @force: whether or not to force the change
550 * Alters the mount options of a mounted file system.
552 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
554 int retval;
555 int remount_ro;
557 if (sb->s_frozen != SB_UNFROZEN)
558 return -EBUSY;
560 #ifdef CONFIG_BLOCK
561 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
562 return -EACCES;
563 #endif
565 if (flags & MS_RDONLY)
566 acct_auto_close(sb);
567 shrink_dcache_sb(sb);
568 sync_filesystem(sb);
570 remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
572 /* If we are remounting RDONLY and current sb is read/write,
573 make sure there are no rw files opened */
574 if (remount_ro) {
575 if (force)
576 mark_files_ro(sb);
577 else if (!fs_may_remount_ro(sb))
578 return -EBUSY;
581 if (sb->s_op->remount_fs) {
582 retval = sb->s_op->remount_fs(sb, &flags, data);
583 if (retval)
584 return retval;
586 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
589 * Some filesystems modify their metadata via some other path than the
590 * bdev buffer cache (eg. use a private mapping, or directories in
591 * pagecache, etc). Also file data modifications go via their own
592 * mappings. So If we try to mount readonly then copy the filesystem
593 * from bdev, we could get stale data, so invalidate it to give a best
594 * effort at coherency.
596 if (remount_ro && sb->s_bdev)
597 invalidate_bdev(sb->s_bdev);
598 return 0;
601 static void do_emergency_remount(struct work_struct *work)
603 struct super_block *sb, *p = NULL;
605 spin_lock(&sb_lock);
606 list_for_each_entry(sb, &super_blocks, s_list) {
607 if (list_empty(&sb->s_instances))
608 continue;
609 sb->s_count++;
610 spin_unlock(&sb_lock);
611 down_write(&sb->s_umount);
612 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
614 * What lock protects sb->s_flags??
616 do_remount_sb(sb, MS_RDONLY, NULL, 1);
618 up_write(&sb->s_umount);
619 spin_lock(&sb_lock);
620 if (p)
621 __put_super(p);
622 p = sb;
624 if (p)
625 __put_super(p);
626 spin_unlock(&sb_lock);
627 kfree(work);
628 printk("Emergency Remount complete\n");
631 void emergency_remount(void)
633 struct work_struct *work;
635 work = kmalloc(sizeof(*work), GFP_ATOMIC);
636 if (work) {
637 INIT_WORK(work, do_emergency_remount);
638 schedule_work(work);
643 * Unnamed block devices are dummy devices used by virtual
644 * filesystems which don't use real block-devices. -- jrs
647 static DEFINE_IDA(unnamed_dev_ida);
648 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
649 static int unnamed_dev_start = 0; /* don't bother trying below it */
651 int set_anon_super(struct super_block *s, void *data)
653 int dev;
654 int error;
656 retry:
657 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
658 return -ENOMEM;
659 spin_lock(&unnamed_dev_lock);
660 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
661 if (!error)
662 unnamed_dev_start = dev + 1;
663 spin_unlock(&unnamed_dev_lock);
664 if (error == -EAGAIN)
665 /* We raced and lost with another CPU. */
666 goto retry;
667 else if (error)
668 return -EAGAIN;
670 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
671 spin_lock(&unnamed_dev_lock);
672 ida_remove(&unnamed_dev_ida, dev);
673 if (unnamed_dev_start > dev)
674 unnamed_dev_start = dev;
675 spin_unlock(&unnamed_dev_lock);
676 return -EMFILE;
678 s->s_dev = MKDEV(0, dev & MINORMASK);
679 s->s_bdi = &noop_backing_dev_info;
680 return 0;
683 EXPORT_SYMBOL(set_anon_super);
685 void kill_anon_super(struct super_block *sb)
687 int slot = MINOR(sb->s_dev);
689 generic_shutdown_super(sb);
690 spin_lock(&unnamed_dev_lock);
691 ida_remove(&unnamed_dev_ida, slot);
692 if (slot < unnamed_dev_start)
693 unnamed_dev_start = slot;
694 spin_unlock(&unnamed_dev_lock);
697 EXPORT_SYMBOL(kill_anon_super);
699 void kill_litter_super(struct super_block *sb)
701 if (sb->s_root)
702 d_genocide(sb->s_root);
703 kill_anon_super(sb);
706 EXPORT_SYMBOL(kill_litter_super);
708 static int ns_test_super(struct super_block *sb, void *data)
710 return sb->s_fs_info == data;
713 static int ns_set_super(struct super_block *sb, void *data)
715 sb->s_fs_info = data;
716 return set_anon_super(sb, NULL);
719 struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
720 void *data, int (*fill_super)(struct super_block *, void *, int))
722 struct super_block *sb;
724 sb = sget(fs_type, ns_test_super, ns_set_super, data);
725 if (IS_ERR(sb))
726 return ERR_CAST(sb);
728 if (!sb->s_root) {
729 int err;
730 sb->s_flags = flags;
731 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
732 if (err) {
733 deactivate_locked_super(sb);
734 return ERR_PTR(err);
737 sb->s_flags |= MS_ACTIVE;
740 return dget(sb->s_root);
743 EXPORT_SYMBOL(mount_ns);
745 #ifdef CONFIG_BLOCK
746 static int set_bdev_super(struct super_block *s, void *data)
748 s->s_bdev = data;
749 s->s_dev = s->s_bdev->bd_dev;
752 * We set the bdi here to the queue backing, file systems can
753 * overwrite this in ->fill_super()
755 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
756 return 0;
759 static int test_bdev_super(struct super_block *s, void *data)
761 return (void *)s->s_bdev == data;
764 struct dentry *mount_bdev(struct file_system_type *fs_type,
765 int flags, const char *dev_name, void *data,
766 int (*fill_super)(struct super_block *, void *, int))
768 struct block_device *bdev;
769 struct super_block *s;
770 fmode_t mode = FMODE_READ | FMODE_EXCL;
771 int error = 0;
773 if (!(flags & MS_RDONLY))
774 mode |= FMODE_WRITE;
776 bdev = blkdev_get_by_path(dev_name, mode, fs_type);
777 if (IS_ERR(bdev))
778 return ERR_CAST(bdev);
781 * once the super is inserted into the list by sget, s_umount
782 * will protect the lockfs code from trying to start a snapshot
783 * while we are mounting
785 mutex_lock(&bdev->bd_fsfreeze_mutex);
786 if (bdev->bd_fsfreeze_count > 0) {
787 mutex_unlock(&bdev->bd_fsfreeze_mutex);
788 error = -EBUSY;
789 goto error_bdev;
791 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
792 mutex_unlock(&bdev->bd_fsfreeze_mutex);
793 if (IS_ERR(s))
794 goto error_s;
796 if (s->s_root) {
797 if ((flags ^ s->s_flags) & MS_RDONLY) {
798 deactivate_locked_super(s);
799 error = -EBUSY;
800 goto error_bdev;
804 * s_umount nests inside bd_mutex during
805 * __invalidate_device(). blkdev_put() acquires
806 * bd_mutex and can't be called under s_umount. Drop
807 * s_umount temporarily. This is safe as we're
808 * holding an active reference.
810 up_write(&s->s_umount);
811 blkdev_put(bdev, mode);
812 down_write(&s->s_umount);
813 } else {
814 char b[BDEVNAME_SIZE];
816 s->s_flags = flags;
817 s->s_mode = mode;
818 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
819 sb_set_blocksize(s, block_size(bdev));
820 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
821 if (error) {
822 deactivate_locked_super(s);
823 goto error;
826 s->s_flags |= MS_ACTIVE;
827 bdev->bd_super = s;
830 return dget(s->s_root);
832 error_s:
833 error = PTR_ERR(s);
834 error_bdev:
835 blkdev_put(bdev, mode);
836 error:
837 return ERR_PTR(error);
839 EXPORT_SYMBOL(mount_bdev);
841 int get_sb_bdev(struct file_system_type *fs_type,
842 int flags, const char *dev_name, void *data,
843 int (*fill_super)(struct super_block *, void *, int),
844 struct vfsmount *mnt)
846 struct dentry *root;
848 root = mount_bdev(fs_type, flags, dev_name, data, fill_super);
849 if (IS_ERR(root))
850 return PTR_ERR(root);
851 mnt->mnt_root = root;
852 mnt->mnt_sb = root->d_sb;
853 return 0;
856 EXPORT_SYMBOL(get_sb_bdev);
858 void kill_block_super(struct super_block *sb)
860 struct block_device *bdev = sb->s_bdev;
861 fmode_t mode = sb->s_mode;
863 bdev->bd_super = NULL;
864 generic_shutdown_super(sb);
865 sync_blockdev(bdev);
866 WARN_ON_ONCE(!(mode & FMODE_EXCL));
867 blkdev_put(bdev, mode | FMODE_EXCL);
870 EXPORT_SYMBOL(kill_block_super);
871 #endif
873 struct dentry *mount_nodev(struct file_system_type *fs_type,
874 int flags, void *data,
875 int (*fill_super)(struct super_block *, void *, int))
877 int error;
878 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
880 if (IS_ERR(s))
881 return ERR_CAST(s);
883 s->s_flags = flags;
885 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
886 if (error) {
887 deactivate_locked_super(s);
888 return ERR_PTR(error);
890 s->s_flags |= MS_ACTIVE;
891 return dget(s->s_root);
893 EXPORT_SYMBOL(mount_nodev);
895 int get_sb_nodev(struct file_system_type *fs_type,
896 int flags, void *data,
897 int (*fill_super)(struct super_block *, void *, int),
898 struct vfsmount *mnt)
900 struct dentry *root;
902 root = mount_nodev(fs_type, flags, data, fill_super);
903 if (IS_ERR(root))
904 return PTR_ERR(root);
905 mnt->mnt_root = root;
906 mnt->mnt_sb = root->d_sb;
907 return 0;
909 EXPORT_SYMBOL(get_sb_nodev);
911 static int compare_single(struct super_block *s, void *p)
913 return 1;
916 struct dentry *mount_single(struct file_system_type *fs_type,
917 int flags, void *data,
918 int (*fill_super)(struct super_block *, void *, int))
920 struct super_block *s;
921 int error;
923 s = sget(fs_type, compare_single, set_anon_super, NULL);
924 if (IS_ERR(s))
925 return ERR_CAST(s);
926 if (!s->s_root) {
927 s->s_flags = flags;
928 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
929 if (error) {
930 deactivate_locked_super(s);
931 return ERR_PTR(error);
933 s->s_flags |= MS_ACTIVE;
934 } else {
935 do_remount_sb(s, flags, data, 0);
937 return dget(s->s_root);
939 EXPORT_SYMBOL(mount_single);
941 int get_sb_single(struct file_system_type *fs_type,
942 int flags, void *data,
943 int (*fill_super)(struct super_block *, void *, int),
944 struct vfsmount *mnt)
946 struct dentry *root;
947 root = mount_single(fs_type, flags, data, fill_super);
948 if (IS_ERR(root))
949 return PTR_ERR(root);
950 mnt->mnt_root = root;
951 mnt->mnt_sb = root->d_sb;
952 return 0;
955 EXPORT_SYMBOL(get_sb_single);
957 struct vfsmount *
958 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
960 struct vfsmount *mnt;
961 struct dentry *root;
962 char *secdata = NULL;
963 int error;
965 if (!type)
966 return ERR_PTR(-ENODEV);
968 error = -ENOMEM;
969 mnt = alloc_vfsmnt(name);
970 if (!mnt)
971 goto out;
973 if (flags & MS_KERNMOUNT)
974 mnt->mnt_flags = MNT_INTERNAL;
976 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
977 secdata = alloc_secdata();
978 if (!secdata)
979 goto out_mnt;
981 error = security_sb_copy_data(data, secdata);
982 if (error)
983 goto out_free_secdata;
986 if (type->mount) {
987 root = type->mount(type, flags, name, data);
988 if (IS_ERR(root)) {
989 error = PTR_ERR(root);
990 goto out_free_secdata;
992 mnt->mnt_root = root;
993 mnt->mnt_sb = root->d_sb;
994 } else {
995 error = type->get_sb(type, flags, name, data, mnt);
996 if (error < 0)
997 goto out_free_secdata;
999 BUG_ON(!mnt->mnt_sb);
1000 WARN_ON(!mnt->mnt_sb->s_bdi);
1001 mnt->mnt_sb->s_flags |= MS_BORN;
1003 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
1004 if (error)
1005 goto out_sb;
1008 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
1009 * but s_maxbytes was an unsigned long long for many releases. Throw
1010 * this warning for a little while to try and catch filesystems that
1011 * violate this rule. This warning should be either removed or
1012 * converted to a BUG() in 2.6.34.
1014 WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
1015 "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
1017 mnt->mnt_mountpoint = mnt->mnt_root;
1018 mnt->mnt_parent = mnt;
1019 up_write(&mnt->mnt_sb->s_umount);
1020 free_secdata(secdata);
1021 return mnt;
1022 out_sb:
1023 dput(mnt->mnt_root);
1024 deactivate_locked_super(mnt->mnt_sb);
1025 out_free_secdata:
1026 free_secdata(secdata);
1027 out_mnt:
1028 free_vfsmnt(mnt);
1029 out:
1030 return ERR_PTR(error);
1033 EXPORT_SYMBOL_GPL(vfs_kern_mount);
1036 * freeze_super - lock the filesystem and force it into a consistent state
1037 * @sb: the super to lock
1039 * Syncs the super to make sure the filesystem is consistent and calls the fs's
1040 * freeze_fs. Subsequent calls to this without first thawing the fs will return
1041 * -EBUSY.
1043 int freeze_super(struct super_block *sb)
1045 int ret;
1047 atomic_inc(&sb->s_active);
1048 down_write(&sb->s_umount);
1049 if (sb->s_frozen) {
1050 deactivate_locked_super(sb);
1051 return -EBUSY;
1054 if (sb->s_flags & MS_RDONLY) {
1055 sb->s_frozen = SB_FREEZE_TRANS;
1056 smp_wmb();
1057 up_write(&sb->s_umount);
1058 return 0;
1061 sb->s_frozen = SB_FREEZE_WRITE;
1062 smp_wmb();
1064 sync_filesystem(sb);
1066 sb->s_frozen = SB_FREEZE_TRANS;
1067 smp_wmb();
1069 sync_blockdev(sb->s_bdev);
1070 if (sb->s_op->freeze_fs) {
1071 ret = sb->s_op->freeze_fs(sb);
1072 if (ret) {
1073 printk(KERN_ERR
1074 "VFS:Filesystem freeze failed\n");
1075 sb->s_frozen = SB_UNFROZEN;
1076 deactivate_locked_super(sb);
1077 return ret;
1080 up_write(&sb->s_umount);
1081 return 0;
1083 EXPORT_SYMBOL(freeze_super);
1086 * thaw_super -- unlock filesystem
1087 * @sb: the super to thaw
1089 * Unlocks the filesystem and marks it writeable again after freeze_super().
1091 int thaw_super(struct super_block *sb)
1093 int error;
1095 down_write(&sb->s_umount);
1096 if (sb->s_frozen == SB_UNFROZEN) {
1097 up_write(&sb->s_umount);
1098 return -EINVAL;
1101 if (sb->s_flags & MS_RDONLY)
1102 goto out;
1104 if (sb->s_op->unfreeze_fs) {
1105 error = sb->s_op->unfreeze_fs(sb);
1106 if (error) {
1107 printk(KERN_ERR
1108 "VFS:Filesystem thaw failed\n");
1109 sb->s_frozen = SB_FREEZE_TRANS;
1110 up_write(&sb->s_umount);
1111 return error;
1115 out:
1116 sb->s_frozen = SB_UNFROZEN;
1117 smp_wmb();
1118 wake_up(&sb->s_wait_unfrozen);
1119 deactivate_locked_super(sb);
1121 return 0;
1123 EXPORT_SYMBOL(thaw_super);
1125 static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
1127 int err;
1128 const char *subtype = strchr(fstype, '.');
1129 if (subtype) {
1130 subtype++;
1131 err = -EINVAL;
1132 if (!subtype[0])
1133 goto err;
1134 } else
1135 subtype = "";
1137 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
1138 err = -ENOMEM;
1139 if (!mnt->mnt_sb->s_subtype)
1140 goto err;
1141 return mnt;
1143 err:
1144 mntput(mnt);
1145 return ERR_PTR(err);
1148 struct vfsmount *
1149 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
1151 struct file_system_type *type = get_fs_type(fstype);
1152 struct vfsmount *mnt;
1153 if (!type)
1154 return ERR_PTR(-ENODEV);
1155 mnt = vfs_kern_mount(type, flags, name, data);
1156 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
1157 !mnt->mnt_sb->s_subtype)
1158 mnt = fs_set_subtype(mnt, fstype);
1159 put_filesystem(type);
1160 return mnt;
1162 EXPORT_SYMBOL_GPL(do_kern_mount);
1164 struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
1166 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
1169 EXPORT_SYMBOL_GPL(kern_mount_data);