dm exception store: fix failed set_chunk_size error path
[linux-2.6/verdex.git] / fs / super.c
blob2761d3e22ed92321f204a34f8de08491db6f3083
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/init.h>
26 #include <linux/smp_lock.h>
27 #include <linux/acct.h>
28 #include <linux/blkdev.h>
29 #include <linux/quotaops.h>
30 #include <linux/namei.h>
31 #include <linux/mount.h>
32 #include <linux/security.h>
33 #include <linux/syscalls.h>
34 #include <linux/vfs.h>
35 #include <linux/writeback.h> /* for the emergency remount stuff */
36 #include <linux/idr.h>
37 #include <linux/kobject.h>
38 #include <linux/mutex.h>
39 #include <linux/file.h>
40 #include <asm/uaccess.h>
41 #include "internal.h"
44 LIST_HEAD(super_blocks);
45 DEFINE_SPINLOCK(sb_lock);
47 /**
48 * alloc_super - create new superblock
49 * @type: filesystem type superblock should belong to
51 * Allocates and initializes a new &struct super_block. alloc_super()
52 * returns a pointer new superblock or %NULL if allocation had failed.
54 static struct super_block *alloc_super(struct file_system_type *type)
56 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
57 static struct super_operations default_op;
59 if (s) {
60 if (security_sb_alloc(s)) {
61 kfree(s);
62 s = NULL;
63 goto out;
65 INIT_LIST_HEAD(&s->s_dirty);
66 INIT_LIST_HEAD(&s->s_io);
67 INIT_LIST_HEAD(&s->s_more_io);
68 INIT_LIST_HEAD(&s->s_files);
69 INIT_LIST_HEAD(&s->s_instances);
70 INIT_HLIST_HEAD(&s->s_anon);
71 INIT_LIST_HEAD(&s->s_inodes);
72 INIT_LIST_HEAD(&s->s_dentry_lru);
73 init_rwsem(&s->s_umount);
74 mutex_init(&s->s_lock);
75 lockdep_set_class(&s->s_umount, &type->s_umount_key);
77 * The locking rules for s_lock are up to the
78 * filesystem. For example ext3fs has different
79 * lock ordering than usbfs:
81 lockdep_set_class(&s->s_lock, &type->s_lock_key);
83 * sget() can have s_umount recursion.
85 * When it cannot find a suitable sb, it allocates a new
86 * one (this one), and tries again to find a suitable old
87 * one.
89 * In case that succeeds, it will acquire the s_umount
90 * lock of the old one. Since these are clearly distrinct
91 * locks, and this object isn't exposed yet, there's no
92 * risk of deadlocks.
94 * Annotate this by putting this lock in a different
95 * subclass.
97 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
98 s->s_count = S_BIAS;
99 atomic_set(&s->s_active, 1);
100 mutex_init(&s->s_vfs_rename_mutex);
101 mutex_init(&s->s_dquot.dqio_mutex);
102 mutex_init(&s->s_dquot.dqonoff_mutex);
103 init_rwsem(&s->s_dquot.dqptr_sem);
104 init_waitqueue_head(&s->s_wait_unfrozen);
105 s->s_maxbytes = MAX_NON_LFS;
106 s->dq_op = sb_dquot_ops;
107 s->s_qcop = sb_quotactl_ops;
108 s->s_op = &default_op;
109 s->s_time_gran = 1000000000;
111 out:
112 return s;
116 * destroy_super - frees a superblock
117 * @s: superblock to free
119 * Frees a superblock.
121 static inline void destroy_super(struct super_block *s)
123 security_sb_free(s);
124 kfree(s->s_subtype);
125 kfree(s->s_options);
126 kfree(s);
129 /* Superblock refcounting */
132 * Drop a superblock's refcount. Returns non-zero if the superblock was
133 * destroyed. The caller must hold sb_lock.
135 static int __put_super(struct super_block *sb)
137 int ret = 0;
139 if (!--sb->s_count) {
140 destroy_super(sb);
141 ret = 1;
143 return ret;
147 * Drop a superblock's refcount.
148 * Returns non-zero if the superblock is about to be destroyed and
149 * at least is already removed from super_blocks list, so if we are
150 * making a loop through super blocks then we need to restart.
151 * The caller must hold sb_lock.
153 int __put_super_and_need_restart(struct super_block *sb)
155 /* check for race with generic_shutdown_super() */
156 if (list_empty(&sb->s_list)) {
157 /* super block is removed, need to restart... */
158 __put_super(sb);
159 return 1;
161 /* can't be the last, since s_list is still in use */
162 sb->s_count--;
163 BUG_ON(sb->s_count == 0);
164 return 0;
168 * put_super - drop a temporary reference to superblock
169 * @sb: superblock in question
171 * Drops a temporary reference, frees superblock if there's no
172 * references left.
174 static void put_super(struct super_block *sb)
176 spin_lock(&sb_lock);
177 __put_super(sb);
178 spin_unlock(&sb_lock);
183 * deactivate_super - drop an active reference to superblock
184 * @s: superblock to deactivate
186 * Drops an active reference to superblock, acquiring a temprory one if
187 * there is no active references left. In that case we lock superblock,
188 * tell fs driver to shut it down and drop the temporary reference we
189 * had just acquired.
191 void deactivate_super(struct super_block *s)
193 struct file_system_type *fs = s->s_type;
194 if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
195 s->s_count -= S_BIAS-1;
196 spin_unlock(&sb_lock);
197 vfs_dq_off(s, 0);
198 down_write(&s->s_umount);
199 fs->kill_sb(s);
200 put_filesystem(fs);
201 put_super(s);
205 EXPORT_SYMBOL(deactivate_super);
208 * deactivate_locked_super - drop an active reference to superblock
209 * @s: superblock to deactivate
211 * Equivalent of up_write(&s->s_umount); deactivate_super(s);, except that
212 * it does not unlock it until it's all over. As the result, it's safe to
213 * use to dispose of new superblock on ->get_sb() failure exits - nobody
214 * will see the sucker until it's all over. Equivalent using up_write +
215 * deactivate_super is safe for that purpose only if superblock is either
216 * safe to use or has NULL ->s_root when we unlock.
218 void deactivate_locked_super(struct super_block *s)
220 struct file_system_type *fs = s->s_type;
221 if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
222 s->s_count -= S_BIAS-1;
223 spin_unlock(&sb_lock);
224 vfs_dq_off(s, 0);
225 fs->kill_sb(s);
226 put_filesystem(fs);
227 put_super(s);
228 } else {
229 up_write(&s->s_umount);
233 EXPORT_SYMBOL(deactivate_locked_super);
236 * grab_super - acquire an active reference
237 * @s: reference we are trying to make active
239 * Tries to acquire an active reference. grab_super() is used when we
240 * had just found a superblock in super_blocks or fs_type->fs_supers
241 * and want to turn it into a full-blown active reference. grab_super()
242 * is called with sb_lock held and drops it. Returns 1 in case of
243 * success, 0 if we had failed (superblock contents was already dead or
244 * dying when grab_super() had been called).
246 static int grab_super(struct super_block *s) __releases(sb_lock)
248 s->s_count++;
249 spin_unlock(&sb_lock);
250 down_write(&s->s_umount);
251 if (s->s_root) {
252 spin_lock(&sb_lock);
253 if (s->s_count > S_BIAS) {
254 atomic_inc(&s->s_active);
255 s->s_count--;
256 spin_unlock(&sb_lock);
257 return 1;
259 spin_unlock(&sb_lock);
261 up_write(&s->s_umount);
262 put_super(s);
263 yield();
264 return 0;
268 * Superblock locking. We really ought to get rid of these two.
270 void lock_super(struct super_block * sb)
272 get_fs_excl();
273 mutex_lock(&sb->s_lock);
276 void unlock_super(struct super_block * sb)
278 put_fs_excl();
279 mutex_unlock(&sb->s_lock);
282 EXPORT_SYMBOL(lock_super);
283 EXPORT_SYMBOL(unlock_super);
286 * generic_shutdown_super - common helper for ->kill_sb()
287 * @sb: superblock to kill
289 * generic_shutdown_super() does all fs-independent work on superblock
290 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
291 * that need destruction out of superblock, call generic_shutdown_super()
292 * and release aforementioned objects. Note: dentries and inodes _are_
293 * taken care of and do not need specific handling.
295 * Upon calling this function, the filesystem may no longer alter or
296 * rearrange the set of dentries belonging to this super_block, nor may it
297 * change the attachments of dentries to inodes.
299 void generic_shutdown_super(struct super_block *sb)
301 const struct super_operations *sop = sb->s_op;
304 if (sb->s_root) {
305 shrink_dcache_for_umount(sb);
306 sync_filesystem(sb);
307 get_fs_excl();
308 sb->s_flags &= ~MS_ACTIVE;
310 /* bad name - it should be evict_inodes() */
311 invalidate_inodes(sb);
313 if (sop->put_super)
314 sop->put_super(sb);
316 /* Forget any remaining inodes */
317 if (invalidate_inodes(sb)) {
318 printk("VFS: Busy inodes after unmount of %s. "
319 "Self-destruct in 5 seconds. Have a nice day...\n",
320 sb->s_id);
322 put_fs_excl();
324 spin_lock(&sb_lock);
325 /* should be initialized for __put_super_and_need_restart() */
326 list_del_init(&sb->s_list);
327 list_del(&sb->s_instances);
328 spin_unlock(&sb_lock);
329 up_write(&sb->s_umount);
332 EXPORT_SYMBOL(generic_shutdown_super);
335 * sget - find or create a superblock
336 * @type: filesystem type superblock should belong to
337 * @test: comparison callback
338 * @set: setup callback
339 * @data: argument to each of them
341 struct super_block *sget(struct file_system_type *type,
342 int (*test)(struct super_block *,void *),
343 int (*set)(struct super_block *,void *),
344 void *data)
346 struct super_block *s = NULL;
347 struct super_block *old;
348 int err;
350 retry:
351 spin_lock(&sb_lock);
352 if (test) {
353 list_for_each_entry(old, &type->fs_supers, s_instances) {
354 if (!test(old, data))
355 continue;
356 if (!grab_super(old))
357 goto retry;
358 if (s) {
359 up_write(&s->s_umount);
360 destroy_super(s);
362 return old;
365 if (!s) {
366 spin_unlock(&sb_lock);
367 s = alloc_super(type);
368 if (!s)
369 return ERR_PTR(-ENOMEM);
370 goto retry;
373 err = set(s, data);
374 if (err) {
375 spin_unlock(&sb_lock);
376 up_write(&s->s_umount);
377 destroy_super(s);
378 return ERR_PTR(err);
380 s->s_type = type;
381 strlcpy(s->s_id, type->name, sizeof(s->s_id));
382 list_add_tail(&s->s_list, &super_blocks);
383 list_add(&s->s_instances, &type->fs_supers);
384 spin_unlock(&sb_lock);
385 get_filesystem(type);
386 return s;
389 EXPORT_SYMBOL(sget);
391 void drop_super(struct super_block *sb)
393 up_read(&sb->s_umount);
394 put_super(sb);
397 EXPORT_SYMBOL(drop_super);
400 * sync_supers - helper for periodic superblock writeback
402 * Call the write_super method if present on all dirty superblocks in
403 * the system. This is for the periodic writeback used by most older
404 * filesystems. For data integrity superblock writeback use
405 * sync_filesystems() instead.
407 * Note: check the dirty flag before waiting, so we don't
408 * hold up the sync while mounting a device. (The newly
409 * mounted device won't need syncing.)
411 void sync_supers(void)
413 struct super_block *sb;
415 spin_lock(&sb_lock);
416 restart:
417 list_for_each_entry(sb, &super_blocks, s_list) {
418 if (sb->s_op->write_super && sb->s_dirt) {
419 sb->s_count++;
420 spin_unlock(&sb_lock);
422 down_read(&sb->s_umount);
423 if (sb->s_root && sb->s_dirt)
424 sb->s_op->write_super(sb);
425 up_read(&sb->s_umount);
427 spin_lock(&sb_lock);
428 if (__put_super_and_need_restart(sb))
429 goto restart;
432 spin_unlock(&sb_lock);
436 * get_super - get the superblock of a device
437 * @bdev: device to get the superblock for
439 * Scans the superblock list and finds the superblock of the file system
440 * mounted on the device given. %NULL is returned if no match is found.
443 struct super_block * get_super(struct block_device *bdev)
445 struct super_block *sb;
447 if (!bdev)
448 return NULL;
450 spin_lock(&sb_lock);
451 rescan:
452 list_for_each_entry(sb, &super_blocks, s_list) {
453 if (sb->s_bdev == bdev) {
454 sb->s_count++;
455 spin_unlock(&sb_lock);
456 down_read(&sb->s_umount);
457 if (sb->s_root)
458 return sb;
459 up_read(&sb->s_umount);
460 /* restart only when sb is no longer on the list */
461 spin_lock(&sb_lock);
462 if (__put_super_and_need_restart(sb))
463 goto rescan;
466 spin_unlock(&sb_lock);
467 return NULL;
470 EXPORT_SYMBOL(get_super);
472 struct super_block * user_get_super(dev_t dev)
474 struct super_block *sb;
476 spin_lock(&sb_lock);
477 rescan:
478 list_for_each_entry(sb, &super_blocks, s_list) {
479 if (sb->s_dev == dev) {
480 sb->s_count++;
481 spin_unlock(&sb_lock);
482 down_read(&sb->s_umount);
483 if (sb->s_root)
484 return sb;
485 up_read(&sb->s_umount);
486 /* restart only when sb is no longer on the list */
487 spin_lock(&sb_lock);
488 if (__put_super_and_need_restart(sb))
489 goto rescan;
492 spin_unlock(&sb_lock);
493 return NULL;
496 SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
498 struct super_block *s;
499 struct ustat tmp;
500 struct kstatfs sbuf;
501 int err = -EINVAL;
503 s = user_get_super(new_decode_dev(dev));
504 if (s == NULL)
505 goto out;
506 err = vfs_statfs(s->s_root, &sbuf);
507 drop_super(s);
508 if (err)
509 goto out;
511 memset(&tmp,0,sizeof(struct ustat));
512 tmp.f_tfree = sbuf.f_bfree;
513 tmp.f_tinode = sbuf.f_ffree;
515 err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
516 out:
517 return err;
521 * do_remount_sb - asks filesystem to change mount options.
522 * @sb: superblock in question
523 * @flags: numeric part of options
524 * @data: the rest of options
525 * @force: whether or not to force the change
527 * Alters the mount options of a mounted file system.
529 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
531 int retval;
532 int remount_rw;
534 #ifdef CONFIG_BLOCK
535 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
536 return -EACCES;
537 #endif
538 if (flags & MS_RDONLY)
539 acct_auto_close(sb);
540 shrink_dcache_sb(sb);
541 sync_filesystem(sb);
543 /* If we are remounting RDONLY and current sb is read/write,
544 make sure there are no rw files opened */
545 if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
546 if (force)
547 mark_files_ro(sb);
548 else if (!fs_may_remount_ro(sb))
549 return -EBUSY;
550 retval = vfs_dq_off(sb, 1);
551 if (retval < 0 && retval != -ENOSYS)
552 return -EBUSY;
554 remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
556 if (sb->s_op->remount_fs) {
557 retval = sb->s_op->remount_fs(sb, &flags, data);
558 if (retval)
559 return retval;
561 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
562 if (remount_rw)
563 vfs_dq_quota_on_remount(sb);
564 return 0;
567 static void do_emergency_remount(struct work_struct *work)
569 struct super_block *sb;
571 spin_lock(&sb_lock);
572 list_for_each_entry(sb, &super_blocks, s_list) {
573 sb->s_count++;
574 spin_unlock(&sb_lock);
575 down_write(&sb->s_umount);
576 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
578 * ->remount_fs needs lock_kernel().
580 * What lock protects sb->s_flags??
582 do_remount_sb(sb, MS_RDONLY, NULL, 1);
584 up_write(&sb->s_umount);
585 put_super(sb);
586 spin_lock(&sb_lock);
588 spin_unlock(&sb_lock);
589 kfree(work);
590 printk("Emergency Remount complete\n");
593 void emergency_remount(void)
595 struct work_struct *work;
597 work = kmalloc(sizeof(*work), GFP_ATOMIC);
598 if (work) {
599 INIT_WORK(work, do_emergency_remount);
600 schedule_work(work);
605 * Unnamed block devices are dummy devices used by virtual
606 * filesystems which don't use real block-devices. -- jrs
609 static DEFINE_IDA(unnamed_dev_ida);
610 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
611 static int unnamed_dev_start = 0; /* don't bother trying below it */
613 int set_anon_super(struct super_block *s, void *data)
615 int dev;
616 int error;
618 retry:
619 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
620 return -ENOMEM;
621 spin_lock(&unnamed_dev_lock);
622 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
623 if (!error)
624 unnamed_dev_start = dev + 1;
625 spin_unlock(&unnamed_dev_lock);
626 if (error == -EAGAIN)
627 /* We raced and lost with another CPU. */
628 goto retry;
629 else if (error)
630 return -EAGAIN;
632 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
633 spin_lock(&unnamed_dev_lock);
634 ida_remove(&unnamed_dev_ida, dev);
635 if (unnamed_dev_start > dev)
636 unnamed_dev_start = dev;
637 spin_unlock(&unnamed_dev_lock);
638 return -EMFILE;
640 s->s_dev = MKDEV(0, dev & MINORMASK);
641 return 0;
644 EXPORT_SYMBOL(set_anon_super);
646 void kill_anon_super(struct super_block *sb)
648 int slot = MINOR(sb->s_dev);
650 generic_shutdown_super(sb);
651 spin_lock(&unnamed_dev_lock);
652 ida_remove(&unnamed_dev_ida, slot);
653 if (slot < unnamed_dev_start)
654 unnamed_dev_start = slot;
655 spin_unlock(&unnamed_dev_lock);
658 EXPORT_SYMBOL(kill_anon_super);
660 void kill_litter_super(struct super_block *sb)
662 if (sb->s_root)
663 d_genocide(sb->s_root);
664 kill_anon_super(sb);
667 EXPORT_SYMBOL(kill_litter_super);
669 static int ns_test_super(struct super_block *sb, void *data)
671 return sb->s_fs_info == data;
674 static int ns_set_super(struct super_block *sb, void *data)
676 sb->s_fs_info = data;
677 return set_anon_super(sb, NULL);
680 int get_sb_ns(struct file_system_type *fs_type, int flags, void *data,
681 int (*fill_super)(struct super_block *, void *, int),
682 struct vfsmount *mnt)
684 struct super_block *sb;
686 sb = sget(fs_type, ns_test_super, ns_set_super, data);
687 if (IS_ERR(sb))
688 return PTR_ERR(sb);
690 if (!sb->s_root) {
691 int err;
692 sb->s_flags = flags;
693 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
694 if (err) {
695 deactivate_locked_super(sb);
696 return err;
699 sb->s_flags |= MS_ACTIVE;
702 simple_set_mnt(mnt, sb);
703 return 0;
706 EXPORT_SYMBOL(get_sb_ns);
708 #ifdef CONFIG_BLOCK
709 static int set_bdev_super(struct super_block *s, void *data)
711 s->s_bdev = data;
712 s->s_dev = s->s_bdev->bd_dev;
713 return 0;
716 static int test_bdev_super(struct super_block *s, void *data)
718 return (void *)s->s_bdev == data;
721 int get_sb_bdev(struct file_system_type *fs_type,
722 int flags, const char *dev_name, void *data,
723 int (*fill_super)(struct super_block *, void *, int),
724 struct vfsmount *mnt)
726 struct block_device *bdev;
727 struct super_block *s;
728 fmode_t mode = FMODE_READ;
729 int error = 0;
731 if (!(flags & MS_RDONLY))
732 mode |= FMODE_WRITE;
734 bdev = open_bdev_exclusive(dev_name, mode, fs_type);
735 if (IS_ERR(bdev))
736 return PTR_ERR(bdev);
739 * once the super is inserted into the list by sget, s_umount
740 * will protect the lockfs code from trying to start a snapshot
741 * while we are mounting
743 down(&bdev->bd_mount_sem);
744 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
745 up(&bdev->bd_mount_sem);
746 if (IS_ERR(s))
747 goto error_s;
749 if (s->s_root) {
750 if ((flags ^ s->s_flags) & MS_RDONLY) {
751 deactivate_locked_super(s);
752 error = -EBUSY;
753 goto error_bdev;
756 close_bdev_exclusive(bdev, mode);
757 } else {
758 char b[BDEVNAME_SIZE];
760 s->s_flags = flags;
761 s->s_mode = mode;
762 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
763 sb_set_blocksize(s, block_size(bdev));
764 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
765 if (error) {
766 deactivate_locked_super(s);
767 goto error;
770 s->s_flags |= MS_ACTIVE;
771 bdev->bd_super = s;
774 simple_set_mnt(mnt, s);
775 return 0;
777 error_s:
778 error = PTR_ERR(s);
779 error_bdev:
780 close_bdev_exclusive(bdev, mode);
781 error:
782 return error;
785 EXPORT_SYMBOL(get_sb_bdev);
787 void kill_block_super(struct super_block *sb)
789 struct block_device *bdev = sb->s_bdev;
790 fmode_t mode = sb->s_mode;
792 bdev->bd_super = NULL;
793 generic_shutdown_super(sb);
794 sync_blockdev(bdev);
795 close_bdev_exclusive(bdev, mode);
798 EXPORT_SYMBOL(kill_block_super);
799 #endif
801 int get_sb_nodev(struct file_system_type *fs_type,
802 int flags, void *data,
803 int (*fill_super)(struct super_block *, void *, int),
804 struct vfsmount *mnt)
806 int error;
807 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
809 if (IS_ERR(s))
810 return PTR_ERR(s);
812 s->s_flags = flags;
814 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
815 if (error) {
816 deactivate_locked_super(s);
817 return error;
819 s->s_flags |= MS_ACTIVE;
820 simple_set_mnt(mnt, s);
821 return 0;
824 EXPORT_SYMBOL(get_sb_nodev);
826 static int compare_single(struct super_block *s, void *p)
828 return 1;
831 int get_sb_single(struct file_system_type *fs_type,
832 int flags, void *data,
833 int (*fill_super)(struct super_block *, void *, int),
834 struct vfsmount *mnt)
836 struct super_block *s;
837 int error;
839 s = sget(fs_type, compare_single, set_anon_super, NULL);
840 if (IS_ERR(s))
841 return PTR_ERR(s);
842 if (!s->s_root) {
843 s->s_flags = flags;
844 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
845 if (error) {
846 deactivate_locked_super(s);
847 return error;
849 s->s_flags |= MS_ACTIVE;
851 do_remount_sb(s, flags, data, 0);
852 simple_set_mnt(mnt, s);
853 return 0;
856 EXPORT_SYMBOL(get_sb_single);
858 struct vfsmount *
859 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
861 struct vfsmount *mnt;
862 char *secdata = NULL;
863 int error;
865 if (!type)
866 return ERR_PTR(-ENODEV);
868 error = -ENOMEM;
869 mnt = alloc_vfsmnt(name);
870 if (!mnt)
871 goto out;
873 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
874 secdata = alloc_secdata();
875 if (!secdata)
876 goto out_mnt;
878 error = security_sb_copy_data(data, secdata);
879 if (error)
880 goto out_free_secdata;
883 error = type->get_sb(type, flags, name, data, mnt);
884 if (error < 0)
885 goto out_free_secdata;
886 BUG_ON(!mnt->mnt_sb);
888 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
889 if (error)
890 goto out_sb;
892 mnt->mnt_mountpoint = mnt->mnt_root;
893 mnt->mnt_parent = mnt;
894 up_write(&mnt->mnt_sb->s_umount);
895 free_secdata(secdata);
896 return mnt;
897 out_sb:
898 dput(mnt->mnt_root);
899 deactivate_locked_super(mnt->mnt_sb);
900 out_free_secdata:
901 free_secdata(secdata);
902 out_mnt:
903 free_vfsmnt(mnt);
904 out:
905 return ERR_PTR(error);
908 EXPORT_SYMBOL_GPL(vfs_kern_mount);
910 static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
912 int err;
913 const char *subtype = strchr(fstype, '.');
914 if (subtype) {
915 subtype++;
916 err = -EINVAL;
917 if (!subtype[0])
918 goto err;
919 } else
920 subtype = "";
922 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
923 err = -ENOMEM;
924 if (!mnt->mnt_sb->s_subtype)
925 goto err;
926 return mnt;
928 err:
929 mntput(mnt);
930 return ERR_PTR(err);
933 struct vfsmount *
934 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
936 struct file_system_type *type = get_fs_type(fstype);
937 struct vfsmount *mnt;
938 if (!type)
939 return ERR_PTR(-ENODEV);
940 mnt = vfs_kern_mount(type, flags, name, data);
941 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
942 !mnt->mnt_sb->s_subtype)
943 mnt = fs_set_subtype(mnt, fstype);
944 put_filesystem(type);
945 return mnt;
947 EXPORT_SYMBOL_GPL(do_kern_mount);
949 struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
951 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
954 EXPORT_SYMBOL_GPL(kern_mount_data);