blob: 3a1b8ca04ba601b37ffa5dadb8f9695272952e39 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/super.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
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
12 *
13 * GK 2/5/95 - Changed to support mounting the root fs via NFS
14 *
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
21 */
22
23#include <linux/config.h>
24#include <linux/module.h>
25#include <linux/slab.h>
26#include <linux/init.h>
27#include <linux/smp_lock.h>
28#include <linux/acct.h>
29#include <linux/blkdev.h>
30#include <linux/quotaops.h>
31#include <linux/namei.h>
32#include <linux/buffer_head.h> /* for fsync_super() */
33#include <linux/mount.h>
34#include <linux/security.h>
35#include <linux/syscalls.h>
36#include <linux/vfs.h>
37#include <linux/writeback.h> /* for the emergency remount stuff */
38#include <linux/idr.h>
39#include <linux/kobject.h>
40#include <asm/uaccess.h>
41
42
43void get_filesystem(struct file_system_type *fs);
44void put_filesystem(struct file_system_type *fs);
45struct file_system_type *get_fs_type(const char *name);
46
47LIST_HEAD(super_blocks);
48DEFINE_SPINLOCK(sb_lock);
49
50/**
51 * alloc_super - create new superblock
52 *
53 * Allocates and initializes a new &struct super_block. alloc_super()
54 * returns a pointer new superblock or %NULL if allocation had failed.
55 */
56static struct super_block *alloc_super(void)
57{
58 struct super_block *s = kmalloc(sizeof(struct super_block), GFP_USER);
59 static struct super_operations default_op;
60
61 if (s) {
62 memset(s, 0, sizeof(struct super_block));
63 if (security_sb_alloc(s)) {
64 kfree(s);
65 s = NULL;
66 goto out;
67 }
68 INIT_LIST_HEAD(&s->s_dirty);
69 INIT_LIST_HEAD(&s->s_io);
70 INIT_LIST_HEAD(&s->s_files);
71 INIT_LIST_HEAD(&s->s_instances);
72 INIT_HLIST_HEAD(&s->s_anon);
73 INIT_LIST_HEAD(&s->s_inodes);
74 init_rwsem(&s->s_umount);
75 sema_init(&s->s_lock, 1);
76 down_write(&s->s_umount);
77 s->s_count = S_BIAS;
78 atomic_set(&s->s_active, 1);
79 sema_init(&s->s_vfs_rename_sem,1);
80 sema_init(&s->s_dquot.dqio_sem, 1);
81 sema_init(&s->s_dquot.dqonoff_sem, 1);
82 init_rwsem(&s->s_dquot.dqptr_sem);
83 init_waitqueue_head(&s->s_wait_unfrozen);
84 s->s_maxbytes = MAX_NON_LFS;
85 s->dq_op = sb_dquot_ops;
86 s->s_qcop = sb_quotactl_ops;
87 s->s_op = &default_op;
88 s->s_time_gran = 1000000000;
89 }
90out:
91 return s;
92}
93
94/**
95 * destroy_super - frees a superblock
96 * @s: superblock to free
97 *
98 * Frees a superblock.
99 */
100static inline void destroy_super(struct super_block *s)
101{
102 security_sb_free(s);
103 kfree(s);
104}
105
106/* Superblock refcounting */
107
108/*
109 * Drop a superblock's refcount. Returns non-zero if the superblock was
110 * destroyed. The caller must hold sb_lock.
111 */
112int __put_super(struct super_block *sb)
113{
114 int ret = 0;
115
116 if (!--sb->s_count) {
117 destroy_super(sb);
118 ret = 1;
119 }
120 return ret;
121}
122
123/*
124 * Drop a superblock's refcount.
125 * Returns non-zero if the superblock is about to be destroyed and
126 * at least is already removed from super_blocks list, so if we are
127 * making a loop through super blocks then we need to restart.
128 * The caller must hold sb_lock.
129 */
130int __put_super_and_need_restart(struct super_block *sb)
131{
132 /* check for race with generic_shutdown_super() */
133 if (list_empty(&sb->s_list)) {
134 /* super block is removed, need to restart... */
135 __put_super(sb);
136 return 1;
137 }
138 /* can't be the last, since s_list is still in use */
139 sb->s_count--;
140 BUG_ON(sb->s_count == 0);
141 return 0;
142}
143
144/**
145 * put_super - drop a temporary reference to superblock
146 * @sb: superblock in question
147 *
148 * Drops a temporary reference, frees superblock if there's no
149 * references left.
150 */
151static void put_super(struct super_block *sb)
152{
153 spin_lock(&sb_lock);
154 __put_super(sb);
155 spin_unlock(&sb_lock);
156}
157
158
159/**
160 * deactivate_super - drop an active reference to superblock
161 * @s: superblock to deactivate
162 *
163 * Drops an active reference to superblock, acquiring a temprory one if
164 * there is no active references left. In that case we lock superblock,
165 * tell fs driver to shut it down and drop the temporary reference we
166 * had just acquired.
167 */
168void deactivate_super(struct super_block *s)
169{
170 struct file_system_type *fs = s->s_type;
171 if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
172 s->s_count -= S_BIAS-1;
173 spin_unlock(&sb_lock);
174 down_write(&s->s_umount);
175 fs->kill_sb(s);
176 put_filesystem(fs);
177 put_super(s);
178 }
179}
180
181EXPORT_SYMBOL(deactivate_super);
182
183/**
184 * grab_super - acquire an active reference
185 * @s: reference we are trying to make active
186 *
187 * Tries to acquire an active reference. grab_super() is used when we
188 * had just found a superblock in super_blocks or fs_type->fs_supers
189 * and want to turn it into a full-blown active reference. grab_super()
190 * is called with sb_lock held and drops it. Returns 1 in case of
191 * success, 0 if we had failed (superblock contents was already dead or
192 * dying when grab_super() had been called).
193 */
194static int grab_super(struct super_block *s)
195{
196 s->s_count++;
197 spin_unlock(&sb_lock);
198 down_write(&s->s_umount);
199 if (s->s_root) {
200 spin_lock(&sb_lock);
201 if (s->s_count > S_BIAS) {
202 atomic_inc(&s->s_active);
203 s->s_count--;
204 spin_unlock(&sb_lock);
205 return 1;
206 }
207 spin_unlock(&sb_lock);
208 }
209 up_write(&s->s_umount);
210 put_super(s);
211 yield();
212 return 0;
213}
214
215/**
216 * generic_shutdown_super - common helper for ->kill_sb()
217 * @sb: superblock to kill
218 *
219 * generic_shutdown_super() does all fs-independent work on superblock
220 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
221 * that need destruction out of superblock, call generic_shutdown_super()
222 * and release aforementioned objects. Note: dentries and inodes _are_
223 * taken care of and do not need specific handling.
224 */
225void generic_shutdown_super(struct super_block *sb)
226{
227 struct dentry *root = sb->s_root;
228 struct super_operations *sop = sb->s_op;
229
230 if (root) {
231 sb->s_root = NULL;
232 shrink_dcache_parent(root);
233 shrink_dcache_anon(&sb->s_anon);
234 dput(root);
235 fsync_super(sb);
236 lock_super(sb);
237 sb->s_flags &= ~MS_ACTIVE;
238 /* bad name - it should be evict_inodes() */
239 invalidate_inodes(sb);
240 lock_kernel();
241
242 if (sop->write_super && sb->s_dirt)
243 sop->write_super(sb);
244 if (sop->put_super)
245 sop->put_super(sb);
246
247 /* Forget any remaining inodes */
248 if (invalidate_inodes(sb)) {
249 printk("VFS: Busy inodes after unmount. "
250 "Self-destruct in 5 seconds. Have a nice day...\n");
251 }
252
253 unlock_kernel();
254 unlock_super(sb);
255 }
256 spin_lock(&sb_lock);
257 /* should be initialized for __put_super_and_need_restart() */
258 list_del_init(&sb->s_list);
259 list_del(&sb->s_instances);
260 spin_unlock(&sb_lock);
261 up_write(&sb->s_umount);
262}
263
264EXPORT_SYMBOL(generic_shutdown_super);
265
266/**
267 * sget - find or create a superblock
268 * @type: filesystem type superblock should belong to
269 * @test: comparison callback
270 * @set: setup callback
271 * @data: argument to each of them
272 */
273struct super_block *sget(struct file_system_type *type,
274 int (*test)(struct super_block *,void *),
275 int (*set)(struct super_block *,void *),
276 void *data)
277{
278 struct super_block *s = NULL;
279 struct list_head *p;
280 int err;
281
282retry:
283 spin_lock(&sb_lock);
284 if (test) list_for_each(p, &type->fs_supers) {
285 struct super_block *old;
286 old = list_entry(p, struct super_block, s_instances);
287 if (!test(old, data))
288 continue;
289 if (!grab_super(old))
290 goto retry;
291 if (s)
292 destroy_super(s);
293 return old;
294 }
295 if (!s) {
296 spin_unlock(&sb_lock);
297 s = alloc_super();
298 if (!s)
299 return ERR_PTR(-ENOMEM);
300 goto retry;
301 }
302
303 err = set(s, data);
304 if (err) {
305 spin_unlock(&sb_lock);
306 destroy_super(s);
307 return ERR_PTR(err);
308 }
309 s->s_type = type;
310 strlcpy(s->s_id, type->name, sizeof(s->s_id));
311 list_add_tail(&s->s_list, &super_blocks);
312 list_add(&s->s_instances, &type->fs_supers);
313 spin_unlock(&sb_lock);
314 get_filesystem(type);
315 return s;
316}
317
318EXPORT_SYMBOL(sget);
319
320void drop_super(struct super_block *sb)
321{
322 up_read(&sb->s_umount);
323 put_super(sb);
324}
325
326EXPORT_SYMBOL(drop_super);
327
328static inline void write_super(struct super_block *sb)
329{
330 lock_super(sb);
331 if (sb->s_root && sb->s_dirt)
332 if (sb->s_op->write_super)
333 sb->s_op->write_super(sb);
334 unlock_super(sb);
335}
336
337/*
338 * Note: check the dirty flag before waiting, so we don't
339 * hold up the sync while mounting a device. (The newly
340 * mounted device won't need syncing.)
341 */
342void sync_supers(void)
343{
344 struct super_block * sb;
345restart:
346 spin_lock(&sb_lock);
347 sb = sb_entry(super_blocks.next);
348 while (sb != sb_entry(&super_blocks))
349 if (sb->s_dirt) {
350 sb->s_count++;
351 spin_unlock(&sb_lock);
352 down_read(&sb->s_umount);
353 write_super(sb);
354 drop_super(sb);
355 goto restart;
356 } else
357 sb = sb_entry(sb->s_list.next);
358 spin_unlock(&sb_lock);
359}
360
361/*
362 * Call the ->sync_fs super_op against all filesytems which are r/w and
363 * which implement it.
364 *
365 * This operation is careful to avoid the livelock which could easily happen
366 * if two or more filesystems are being continuously dirtied. s_need_sync_fs
367 * is used only here. We set it against all filesystems and then clear it as
368 * we sync them. So redirtied filesystems are skipped.
369 *
370 * But if process A is currently running sync_filesytems and then process B
371 * calls sync_filesystems as well, process B will set all the s_need_sync_fs
372 * flags again, which will cause process A to resync everything. Fix that with
373 * a local mutex.
374 *
375 * (Fabian) Avoid sync_fs with clean fs & wait mode 0
376 */
377void sync_filesystems(int wait)
378{
379 struct super_block *sb;
380 static DECLARE_MUTEX(mutex);
381
382 down(&mutex); /* Could be down_interruptible */
383 spin_lock(&sb_lock);
384 for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks);
385 sb = sb_entry(sb->s_list.next)) {
386 if (!sb->s_op->sync_fs)
387 continue;
388 if (sb->s_flags & MS_RDONLY)
389 continue;
390 sb->s_need_sync_fs = 1;
391 }
392 spin_unlock(&sb_lock);
393
394restart:
395 spin_lock(&sb_lock);
396 for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks);
397 sb = sb_entry(sb->s_list.next)) {
398 if (!sb->s_need_sync_fs)
399 continue;
400 sb->s_need_sync_fs = 0;
401 if (sb->s_flags & MS_RDONLY)
402 continue; /* hm. Was remounted r/o meanwhile */
403 sb->s_count++;
404 spin_unlock(&sb_lock);
405 down_read(&sb->s_umount);
406 if (sb->s_root && (wait || sb->s_dirt))
407 sb->s_op->sync_fs(sb, wait);
408 drop_super(sb);
409 goto restart;
410 }
411 spin_unlock(&sb_lock);
412 up(&mutex);
413}
414
415/**
416 * get_super - get the superblock of a device
417 * @bdev: device to get the superblock for
418 *
419 * Scans the superblock list and finds the superblock of the file system
420 * mounted on the device given. %NULL is returned if no match is found.
421 */
422
423struct super_block * get_super(struct block_device *bdev)
424{
425 struct list_head *p;
426 if (!bdev)
427 return NULL;
428rescan:
429 spin_lock(&sb_lock);
430 list_for_each(p, &super_blocks) {
431 struct super_block *s = sb_entry(p);
432 if (s->s_bdev == bdev) {
433 s->s_count++;
434 spin_unlock(&sb_lock);
435 down_read(&s->s_umount);
436 if (s->s_root)
437 return s;
438 drop_super(s);
439 goto rescan;
440 }
441 }
442 spin_unlock(&sb_lock);
443 return NULL;
444}
445
446EXPORT_SYMBOL(get_super);
447
448struct super_block * user_get_super(dev_t dev)
449{
450 struct list_head *p;
451
452rescan:
453 spin_lock(&sb_lock);
454 list_for_each(p, &super_blocks) {
455 struct super_block *s = sb_entry(p);
456 if (s->s_dev == dev) {
457 s->s_count++;
458 spin_unlock(&sb_lock);
459 down_read(&s->s_umount);
460 if (s->s_root)
461 return s;
462 drop_super(s);
463 goto rescan;
464 }
465 }
466 spin_unlock(&sb_lock);
467 return NULL;
468}
469
470EXPORT_SYMBOL(user_get_super);
471
472asmlinkage long sys_ustat(unsigned dev, struct ustat __user * ubuf)
473{
474 struct super_block *s;
475 struct ustat tmp;
476 struct kstatfs sbuf;
477 int err = -EINVAL;
478
479 s = user_get_super(new_decode_dev(dev));
480 if (s == NULL)
481 goto out;
482 err = vfs_statfs(s, &sbuf);
483 drop_super(s);
484 if (err)
485 goto out;
486
487 memset(&tmp,0,sizeof(struct ustat));
488 tmp.f_tfree = sbuf.f_bfree;
489 tmp.f_tinode = sbuf.f_ffree;
490
491 err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
492out:
493 return err;
494}
495
496/**
497 * mark_files_ro
498 * @sb: superblock in question
499 *
500 * All files are marked read/only. We don't care about pending
501 * delete files so this should be used in 'force' mode only
502 */
503
504static void mark_files_ro(struct super_block *sb)
505{
506 struct file *f;
507
508 file_list_lock();
509 list_for_each_entry(f, &sb->s_files, f_list) {
510 if (S_ISREG(f->f_dentry->d_inode->i_mode) && file_count(f))
511 f->f_mode &= ~FMODE_WRITE;
512 }
513 file_list_unlock();
514}
515
516/**
517 * do_remount_sb - asks filesystem to change mount options.
518 * @sb: superblock in question
519 * @flags: numeric part of options
520 * @data: the rest of options
521 * @force: whether or not to force the change
522 *
523 * Alters the mount options of a mounted file system.
524 */
525int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
526{
527 int retval;
528
529 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
530 return -EACCES;
531 if (flags & MS_RDONLY)
532 acct_auto_close(sb);
533 shrink_dcache_sb(sb);
534 fsync_super(sb);
535
536 /* If we are remounting RDONLY and current sb is read/write,
537 make sure there are no rw files opened */
538 if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
539 if (force)
540 mark_files_ro(sb);
541 else if (!fs_may_remount_ro(sb))
542 return -EBUSY;
543 }
544
545 if (sb->s_op->remount_fs) {
546 lock_super(sb);
547 retval = sb->s_op->remount_fs(sb, &flags, data);
548 unlock_super(sb);
549 if (retval)
550 return retval;
551 }
552 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
553 return 0;
554}
555
556static void do_emergency_remount(unsigned long foo)
557{
558 struct super_block *sb;
559
560 spin_lock(&sb_lock);
561 list_for_each_entry(sb, &super_blocks, s_list) {
562 sb->s_count++;
563 spin_unlock(&sb_lock);
564 down_read(&sb->s_umount);
565 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
566 /*
567 * ->remount_fs needs lock_kernel().
568 *
569 * What lock protects sb->s_flags??
570 */
571 lock_kernel();
572 do_remount_sb(sb, MS_RDONLY, NULL, 1);
573 unlock_kernel();
574 }
575 drop_super(sb);
576 spin_lock(&sb_lock);
577 }
578 spin_unlock(&sb_lock);
579 printk("Emergency Remount complete\n");
580}
581
582void emergency_remount(void)
583{
584 pdflush_operation(do_emergency_remount, 0);
585}
586
587/*
588 * Unnamed block devices are dummy devices used by virtual
589 * filesystems which don't use real block-devices. -- jrs
590 */
591
592static struct idr unnamed_dev_idr;
593static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
594
595int set_anon_super(struct super_block *s, void *data)
596{
597 int dev;
598 int error;
599
600 retry:
601 if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
602 return -ENOMEM;
603 spin_lock(&unnamed_dev_lock);
604 error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
605 spin_unlock(&unnamed_dev_lock);
606 if (error == -EAGAIN)
607 /* We raced and lost with another CPU. */
608 goto retry;
609 else if (error)
610 return -EAGAIN;
611
612 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
613 spin_lock(&unnamed_dev_lock);
614 idr_remove(&unnamed_dev_idr, dev);
615 spin_unlock(&unnamed_dev_lock);
616 return -EMFILE;
617 }
618 s->s_dev = MKDEV(0, dev & MINORMASK);
619 return 0;
620}
621
622EXPORT_SYMBOL(set_anon_super);
623
624void kill_anon_super(struct super_block *sb)
625{
626 int slot = MINOR(sb->s_dev);
627
628 generic_shutdown_super(sb);
629 spin_lock(&unnamed_dev_lock);
630 idr_remove(&unnamed_dev_idr, slot);
631 spin_unlock(&unnamed_dev_lock);
632}
633
634EXPORT_SYMBOL(kill_anon_super);
635
636void __init unnamed_dev_init(void)
637{
638 idr_init(&unnamed_dev_idr);
639}
640
641void kill_litter_super(struct super_block *sb)
642{
643 if (sb->s_root)
644 d_genocide(sb->s_root);
645 kill_anon_super(sb);
646}
647
648EXPORT_SYMBOL(kill_litter_super);
649
650static int set_bdev_super(struct super_block *s, void *data)
651{
652 s->s_bdev = data;
653 s->s_dev = s->s_bdev->bd_dev;
654 return 0;
655}
656
657static int test_bdev_super(struct super_block *s, void *data)
658{
659 return (void *)s->s_bdev == data;
660}
661
662static void bdev_uevent(struct block_device *bdev, enum kobject_action action)
663{
664 if (bdev->bd_disk) {
665 if (bdev->bd_part)
666 kobject_uevent(&bdev->bd_part->kobj, action, NULL);
667 else
668 kobject_uevent(&bdev->bd_disk->kobj, action, NULL);
669 }
670}
671
672struct super_block *get_sb_bdev(struct file_system_type *fs_type,
673 int flags, const char *dev_name, void *data,
674 int (*fill_super)(struct super_block *, void *, int))
675{
676 struct block_device *bdev;
677 struct super_block *s;
678 int error = 0;
679
680 bdev = open_bdev_excl(dev_name, flags, fs_type);
681 if (IS_ERR(bdev))
682 return (struct super_block *)bdev;
683
684 /*
685 * once the super is inserted into the list by sget, s_umount
686 * will protect the lockfs code from trying to start a snapshot
687 * while we are mounting
688 */
689 down(&bdev->bd_mount_sem);
690 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
691 up(&bdev->bd_mount_sem);
692 if (IS_ERR(s))
693 goto out;
694
695 if (s->s_root) {
696 if ((flags ^ s->s_flags) & MS_RDONLY) {
697 up_write(&s->s_umount);
698 deactivate_super(s);
699 s = ERR_PTR(-EBUSY);
700 }
701 goto out;
702 } else {
703 char b[BDEVNAME_SIZE];
704
705 s->s_flags = flags;
706 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
707 s->s_old_blocksize = block_size(bdev);
708 sb_set_blocksize(s, s->s_old_blocksize);
709 error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
710 if (error) {
711 up_write(&s->s_umount);
712 deactivate_super(s);
713 s = ERR_PTR(error);
714 } else {
715 s->s_flags |= MS_ACTIVE;
716 bdev_uevent(bdev, KOBJ_MOUNT);
717 }
718 }
719
720 return s;
721
722out:
723 close_bdev_excl(bdev);
724 return s;
725}
726
727EXPORT_SYMBOL(get_sb_bdev);
728
729void kill_block_super(struct super_block *sb)
730{
731 struct block_device *bdev = sb->s_bdev;
732
733 bdev_uevent(bdev, KOBJ_UMOUNT);
734 generic_shutdown_super(sb);
735 sync_blockdev(bdev);
736 close_bdev_excl(bdev);
737}
738
739EXPORT_SYMBOL(kill_block_super);
740
741struct super_block *get_sb_nodev(struct file_system_type *fs_type,
742 int flags, void *data,
743 int (*fill_super)(struct super_block *, void *, int))
744{
745 int error;
746 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
747
748 if (IS_ERR(s))
749 return s;
750
751 s->s_flags = flags;
752
753 error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
754 if (error) {
755 up_write(&s->s_umount);
756 deactivate_super(s);
757 return ERR_PTR(error);
758 }
759 s->s_flags |= MS_ACTIVE;
760 return s;
761}
762
763EXPORT_SYMBOL(get_sb_nodev);
764
765static int compare_single(struct super_block *s, void *p)
766{
767 return 1;
768}
769
770struct super_block *get_sb_single(struct file_system_type *fs_type,
771 int flags, void *data,
772 int (*fill_super)(struct super_block *, void *, int))
773{
774 struct super_block *s;
775 int error;
776
777 s = sget(fs_type, compare_single, set_anon_super, NULL);
778 if (IS_ERR(s))
779 return s;
780 if (!s->s_root) {
781 s->s_flags = flags;
782 error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
783 if (error) {
784 up_write(&s->s_umount);
785 deactivate_super(s);
786 return ERR_PTR(error);
787 }
788 s->s_flags |= MS_ACTIVE;
789 }
790 do_remount_sb(s, flags, data, 0);
791 return s;
792}
793
794EXPORT_SYMBOL(get_sb_single);
795
796struct vfsmount *
797do_kern_mount(const char *fstype, int flags, const char *name, void *data)
798{
799 struct file_system_type *type = get_fs_type(fstype);
800 struct super_block *sb = ERR_PTR(-ENOMEM);
801 struct vfsmount *mnt;
802 int error;
803 char *secdata = NULL;
804
805 if (!type)
806 return ERR_PTR(-ENODEV);
807
808 mnt = alloc_vfsmnt(name);
809 if (!mnt)
810 goto out;
811
812 if (data) {
813 secdata = alloc_secdata();
814 if (!secdata) {
815 sb = ERR_PTR(-ENOMEM);
816 goto out_mnt;
817 }
818
819 error = security_sb_copy_data(type, data, secdata);
820 if (error) {
821 sb = ERR_PTR(error);
822 goto out_free_secdata;
823 }
824 }
825
826 sb = type->get_sb(type, flags, name, data);
827 if (IS_ERR(sb))
828 goto out_free_secdata;
829 error = security_sb_kern_mount(sb, secdata);
830 if (error)
831 goto out_sb;
832 mnt->mnt_sb = sb;
833 mnt->mnt_root = dget(sb->s_root);
834 mnt->mnt_mountpoint = sb->s_root;
835 mnt->mnt_parent = mnt;
836 mnt->mnt_namespace = current->namespace;
837 up_write(&sb->s_umount);
838 put_filesystem(type);
839 return mnt;
840out_sb:
841 up_write(&sb->s_umount);
842 deactivate_super(sb);
843 sb = ERR_PTR(error);
844out_free_secdata:
845 free_secdata(secdata);
846out_mnt:
847 free_vfsmnt(mnt);
848out:
849 put_filesystem(type);
850 return (struct vfsmount *)sb;
851}
852
853EXPORT_SYMBOL_GPL(do_kern_mount);
854
855struct vfsmount *kern_mount(struct file_system_type *type)
856{
857 return do_kern_mount(type->name, 0, type->name, NULL);
858}
859
860EXPORT_SYMBOL(kern_mount);