1 /*
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/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/buffer_head.h> /* for fsync_super() */
32 #include <linux/mount.h>
33 #include <linux/security.h>
34 #include <linux/syscalls.h>
35 #include <linux/vfs.h>
36 #include <linux/writeback.h> /* for the emergency remount stuff */
37 #include <linux/idr.h>
38 #include <linux/kobject.h>
39 #include <linux/mutex.h>
40 #include <asm/uaccess.h>
41
42
43 LIST_HEAD(super_blocks);
44 DEFINE_SPINLOCK(sb_lock);
45
46 /**
47 * alloc_super - create new superblock
48 * @type: filesystem type superblock should belong to
49 *
50 * Allocates and initializes a new &struct super_block. alloc_super()
51 * returns a pointer new superblock or %NULL if allocation had failed.
52 */
53 static struct super_block *alloc_super(struct file_system_type *type)
54 {
55 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
56 static struct super_operations default_op;
57
58 if (s) {
59 if (security_sb_alloc(s)) {
60 kfree(s);
61 s = NULL;
62 goto out;
63 }
64 INIT_LIST_HEAD(&s->s_dirty);
65 INIT_LIST_HEAD(&s->s_io);
66 INIT_LIST_HEAD(&s->s_more_io);
67 percpu_list_init(&s->s_files);
68 init_qrcu_struct(&s->s_qrcu);
69 INIT_LIST_HEAD(&s->s_instances);
70 INIT_HLIST_HEAD(&s->s_anon);
71 INIT_LIST_HEAD(&s->s_inodes);
72 init_rwsem(&s->s_umount);
73 mutex_init(&s->s_lock);
74 lockdep_set_class(&s->s_umount, &type->s_umount_key);
75 /*
76 * The locking rules for s_lock are up to the
77 * filesystem. For example ext3fs has different
78 * lock ordering than usbfs:
79 */
80 lockdep_set_class(&s->s_lock, &type->s_lock_key);
81 down_write(&s->s_umount);
82 s->s_count = S_BIAS;
83 atomic_set(&s->s_active, 1);
84 mutex_init(&s->s_vfs_rename_mutex);
85 mutex_init(&s->s_dquot.dqio_mutex);
86 mutex_init(&s->s_dquot.dqonoff_mutex);
87 init_rwsem(&s->s_dquot.dqptr_sem);
88 init_waitqueue_head(&s->s_wait_unfrozen);
89 s->s_maxbytes = MAX_NON_LFS;
90 s->dq_op = sb_dquot_ops;
91 s->s_qcop = sb_quotactl_ops;
92 s->s_op = &default_op;
93 s->s_time_gran = 1000000000;
94 }
95 out:
96 return s;
97 }
98
99 /**
100 * destroy_super - frees a superblock
101 * @s: superblock to free
102 *
103 * Frees a superblock.
104 */
105 static inline void destroy_super(struct super_block *s)
106 {
107 percpu_list_destroy(&s->s_files);
108 security_sb_free(s);
109 kfree(s->s_subtype);
110 kfree(s->s_options);
111 kfree(s);
112 }
113
114 /* Superblock refcounting */
115
116 /*
117 * Drop a superblock's refcount. Returns non-zero if the superblock was
118 * destroyed. The caller must hold sb_lock.
119 */
120 int __put_super(struct super_block *sb)
121 {
122 int ret = 0;
123
124 if (!--sb->s_count) {
125 destroy_super(sb);
126 ret = 1;
127 }
128 return ret;
129 }
130
131 /*
132 * Drop a superblock's refcount.
133 * Returns non-zero if the superblock is about to be destroyed and
134 * at least is already removed from super_blocks list, so if we are
135 * making a loop through super blocks then we need to restart.
136 * The caller must hold sb_lock.
137 */
138 int __put_super_and_need_restart(struct super_block *sb)
139 {
140 /* check for race with generic_shutdown_super() */
141 if (list_empty(&sb->s_list)) {
142 /* super block is removed, need to restart... */
143 __put_super(sb);
144 return 1;
145 }
146 /* can't be the last, since s_list is still in use */
147 sb->s_count--;
148 BUG_ON(sb->s_count == 0);
149 return 0;
150 }
151
152 /**
153 * put_super - drop a temporary reference to superblock
154 * @sb: superblock in question
155 *
156 * Drops a temporary reference, frees superblock if there's no
157 * references left.
158 */
159 static void put_super(struct super_block *sb)
160 {
161 spin_lock(&sb_lock);
162 __put_super(sb);
163 spin_unlock(&sb_lock);
164 }
165
166
167 /**
168 * deactivate_super - drop an active reference to superblock
169 * @s: superblock to deactivate
170 *
171 * Drops an active reference to superblock, acquiring a temprory one if
172 * there is no active references left. In that case we lock superblock,
173 * tell fs driver to shut it down and drop the temporary reference we
174 * had just acquired.
175 */
176 void deactivate_super(struct super_block *s)
177 {
178 struct file_system_type *fs = s->s_type;
179 if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
180 s->s_count -= S_BIAS-1;
181 spin_unlock(&sb_lock);
182 DQUOT_OFF(s);
183 down_write(&s->s_umount);
184 fs->kill_sb(s);
185 put_filesystem(fs);
186 put_super(s);
187 }
188 }
189
190 EXPORT_SYMBOL(deactivate_super);
191
192 /**
193 * grab_super - acquire an active reference
194 * @s: reference we are trying to make active
195 *
196 * Tries to acquire an active reference. grab_super() is used when we
197 * had just found a superblock in super_blocks or fs_type->fs_supers
198 * and want to turn it into a full-blown active reference. grab_super()
199 * is called with sb_lock held and drops it. Returns 1 in case of
200 * success, 0 if we had failed (superblock contents was already dead or
201 * dying when grab_super() had been called).
202 */
203 static int grab_super(struct super_block *s) __releases(sb_lock)
204 {
205 s->s_count++;
206 spin_unlock(&sb_lock);
207 down_write(&s->s_umount);
208 if (s->s_root) {
209 spin_lock(&sb_lock);
210 if (s->s_count > S_BIAS) {
211 atomic_inc(&s->s_active);
212 s->s_count--;
213 spin_unlock(&sb_lock);
214 return 1;
215 }
216 spin_unlock(&sb_lock);
217 }
218 up_write(&s->s_umount);
219 put_super(s);
220 yield();
221 return 0;
222 }
223
224 /*
225 * Superblock locking. We really ought to get rid of these two.
226 */
227 void lock_super(struct super_block * sb)
228 {
229 get_fs_excl();
230 mutex_lock(&sb->s_lock);
231 }
232
233 void unlock_super(struct super_block * sb)
234 {
235 put_fs_excl();
236 mutex_unlock(&sb->s_lock);
237 }
238
239 EXPORT_SYMBOL(lock_super);
240 EXPORT_SYMBOL(unlock_super);
241
242 /*
243 * Write out and wait upon all dirty data associated with this
244 * superblock. Filesystem data as well as the underlying block
245 * device. Takes the superblock lock. Requires a second blkdev
246 * flush by the caller to complete the operation.
247 */
248 void __fsync_super(struct super_block *sb)
249 {
250 sync_inodes_sb(sb, 0);
251 DQUOT_SYNC(sb);
252 lock_super(sb);
253 if (sb->s_dirt && sb->s_op->write_super)
254 sb->s_op->write_super(sb);
255 unlock_super(sb);
256 if (sb->s_op->sync_fs)
257 sb->s_op->sync_fs(sb, 1);
258 sync_blockdev(sb->s_bdev);
259 sync_inodes_sb(sb, 1);
260 }
261
262 /*
263 * Write out and wait upon all dirty data associated with this
264 * superblock. Filesystem data as well as the underlying block
265 * device. Takes the superblock lock.
266 */
267 int fsync_super(struct super_block *sb)
268 {
269 __fsync_super(sb);
270 return sync_blockdev(sb->s_bdev);
271 }
272
273 /**
274 * generic_shutdown_super - common helper for ->kill_sb()
275 * @sb: superblock to kill
276 *
277 * generic_shutdown_super() does all fs-independent work on superblock
278 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
279 * that need destruction out of superblock, call generic_shutdown_super()
280 * and release aforementioned objects. Note: dentries and inodes _are_
281 * taken care of and do not need specific handling.
282 *
283 * Upon calling this function, the filesystem may no longer alter or
284 * rearrange the set of dentries belonging to this super_block, nor may it
285 * change the attachments of dentries to inodes.
286 */
287 void generic_shutdown_super(struct super_block *sb)
288 {
289 const struct super_operations *sop = sb->s_op;
290
291 if (sb->s_root) {
292 shrink_dcache_for_umount(sb);
293 fsync_super(sb);
294 lock_super(sb);
295 sb->s_flags &= ~MS_ACTIVE;
296 /* bad name - it should be evict_inodes() */
297 invalidate_inodes(sb);
298 lock_kernel();
299
300 if (sop->write_super && sb->s_dirt)
301 sop->write_super(sb);
302 if (sop->put_super)
303 sop->put_super(sb);
304
305 /* Forget any remaining inodes */
306 if (invalidate_inodes(sb)) {
307 printk("VFS: Busy inodes after unmount of %s. "
308 "Self-destruct in 5 seconds. Have a nice day...\n",
309 sb->s_id);
310 }
311
312 unlock_kernel();
313 unlock_super(sb);
314 }
315 spin_lock(&sb_lock);
316 /* should be initialized for __put_super_and_need_restart() */
317 list_del_init(&sb->s_list);
318 list_del(&sb->s_instances);
319 spin_unlock(&sb_lock);
320 up_write(&sb->s_umount);
321 }
322
323 EXPORT_SYMBOL(generic_shutdown_super);
324
325 /**
326 * sget - find or create a superblock
327 * @type: filesystem type superblock should belong to
328 * @test: comparison callback
329 * @set: setup callback
330 * @data: argument to each of them
331 */
332 struct super_block *sget(struct file_system_type *type,
333 int (*test)(struct super_block *,void *),
334 int (*set)(struct super_block *,void *),
335 void *data)
336 {
337 struct super_block *s = NULL;
338 struct super_block *old;
339 int err;
340
341 retry:
342 spin_lock(&sb_lock);
343 if (test) {
344 list_for_each_entry(old, &type->fs_supers, s_instances) {
345 if (!test(old, data))
346 continue;
347 if (!grab_super(old))
348 goto retry;
349 if (s)
350 destroy_super(s);
351 return old;
352 }
353 }
354 if (!s) {
355 spin_unlock(&sb_lock);
356 s = alloc_super(type);
357 if (!s)
358 return ERR_PTR(-ENOMEM);
359 goto retry;
360 }
361
362 err = set(s, data);
363 if (err) {
364 spin_unlock(&sb_lock);
365 destroy_super(s);
366 return ERR_PTR(err);
367 }
368 s->s_type = type;
369 strlcpy(s->s_id, type->name, sizeof(s->s_id));
370 list_add_tail(&s->s_list, &super_blocks);
371 list_add(&s->s_instances, &type->fs_supers);
372 spin_unlock(&sb_lock);
373 get_filesystem(type);
374 return s;
375 }
376
377 EXPORT_SYMBOL(sget);
378
379 void drop_super(struct super_block *sb)
380 {
381 up_read(&sb->s_umount);
382 put_super(sb);
383 }
384
385 EXPORT_SYMBOL(drop_super);
386
387 static inline void write_super(struct super_block *sb)
388 {
389 lock_super(sb);
390 if (sb->s_root && sb->s_dirt)
391 if (sb->s_op->write_super)
392 sb->s_op->write_super(sb);
393 unlock_super(sb);
394 }
395
396 /*
397 * Note: check the dirty flag before waiting, so we don't
398 * hold up the sync while mounting a device. (The newly
399 * mounted device won't need syncing.)
400 */
401 void sync_supers(void)
402 {
403 struct super_block *sb;
404
405 spin_lock(&sb_lock);
406 restart:
407 list_for_each_entry(sb, &super_blocks, s_list) {
408 if (sb->s_dirt) {
409 sb->s_count++;
410 spin_unlock(&sb_lock);
411 down_read(&sb->s_umount);
412 write_super(sb);
413 up_read(&sb->s_umount);
414 spin_lock(&sb_lock);
415 if (__put_super_and_need_restart(sb))
416 goto restart;
417 }
418 }
419 spin_unlock(&sb_lock);
420 }
421
422 /*
423 * Call the ->sync_fs super_op against all filesystems which are r/w and
424 * which implement it.
425 *
426 * This operation is careful to avoid the livelock which could easily happen
427 * if two or more filesystems are being continuously dirtied. s_need_sync_fs
428 * is used only here. We set it against all filesystems and then clear it as
429 * we sync them. So redirtied filesystems are skipped.
430 *
431 * But if process A is currently running sync_filesystems and then process B
432 * calls sync_filesystems as well, process B will set all the s_need_sync_fs
433 * flags again, which will cause process A to resync everything. Fix that with
434 * a local mutex.
435 *
436 * (Fabian) Avoid sync_fs with clean fs & wait mode 0
437 */
438 void sync_filesystems(int wait)
439 {
440 struct super_block *sb;
441 static DEFINE_MUTEX(mutex);
442
443 mutex_lock(&mutex); /* Could be down_interruptible */
444 spin_lock(&sb_lock);
445 list_for_each_entry(sb, &super_blocks, s_list) {
446 if (!sb->s_op->sync_fs)
447 continue;
448 if (sb->s_flags & MS_RDONLY)
449 continue;
450 sb->s_need_sync_fs = 1;
451 }
452
453 restart:
454 list_for_each_entry(sb, &super_blocks, s_list) {
455 if (!sb->s_need_sync_fs)
456 continue;
457 sb->s_need_sync_fs = 0;
458 if (sb->s_flags & MS_RDONLY)
459 continue; /* hm. Was remounted r/o meanwhile */
460 sb->s_count++;
461 spin_unlock(&sb_lock);
462 down_read(&sb->s_umount);
463 if (sb->s_root && (wait || sb->s_dirt))
464 sb->s_op->sync_fs(sb, wait);
465 up_read(&sb->s_umount);
466 /* restart only when sb is no longer on the list */
467 spin_lock(&sb_lock);
468 if (__put_super_and_need_restart(sb))
469 goto restart;
470 }
471 spin_unlock(&sb_lock);
472 mutex_unlock(&mutex);
473 }
474
475 /**
476 * get_super - get the superblock of a device
477 * @bdev: device to get the superblock for
478 *
479 * Scans the superblock list and finds the superblock of the file system
480 * mounted on the device given. %NULL is returned if no match is found.
481 */
482
483 struct super_block * get_super(struct block_device *bdev)
484 {
485 struct super_block *sb;
486
487 if (!bdev)
488 return NULL;
489
490 spin_lock(&sb_lock);
491 rescan:
492 list_for_each_entry(sb, &super_blocks, s_list) {
493 if (sb->s_bdev == bdev) {
494 sb->s_count++;
495 spin_unlock(&sb_lock);
496 down_read(&sb->s_umount);
497 if (sb->s_root)
498 return sb;
499 up_read(&sb->s_umount);
500 /* restart only when sb is no longer on the list */
501 spin_lock(&sb_lock);
502 if (__put_super_and_need_restart(sb))
503 goto rescan;
504 }
505 }
506 spin_unlock(&sb_lock);
507 return NULL;
508 }
509
510 EXPORT_SYMBOL(get_super);
511
512 struct super_block * user_get_super(dev_t dev)
513 {
514 struct super_block *sb;
515
516 spin_lock(&sb_lock);
517 rescan:
518 list_for_each_entry(sb, &super_blocks, s_list) {
519 if (sb->s_dev == dev) {
520 sb->s_count++;
521 spin_unlock(&sb_lock);
522 down_read(&sb->s_umount);
523 if (sb->s_root)
524 return sb;
525 up_read(&sb->s_umount);
526 /* restart only when sb is no longer on the list */
527 spin_lock(&sb_lock);
528 if (__put_super_and_need_restart(sb))
529 goto rescan;
530 }
531 }
532 spin_unlock(&sb_lock);
533 return NULL;
534 }
535
536 asmlinkage long sys_ustat(unsigned dev, struct ustat __user * ubuf)
537 {
538 struct super_block *s;
539 struct ustat tmp;
540 struct kstatfs sbuf;
541 int err = -EINVAL;
542
543 s = user_get_super(new_decode_dev(dev));
544 if (s == NULL)
545 goto out;
546 err = vfs_statfs(s->s_root, &sbuf);
547 drop_super(s);
548 if (err)
549 goto out;
550
551 memset(&tmp,0,sizeof(struct ustat));
552 tmp.f_tfree = sbuf.f_bfree;
553 tmp.f_tinode = sbuf.f_ffree;
554
555 err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
556 out:
557 return err;
558 }
559
560 /**
561 * mark_files_ro - mark all files read-only
562 * @sb: superblock in question
563 *
564 * All files are marked read-only. We don't care about pending
565 * delete files so this should be used in 'force' mode only.
566 */
567
568 static void mark_files_ro(struct super_block *sb)
569 {
570 struct file *f;
571 int idx;
572
573 idx = qrcu_read_lock(&sb->s_qrcu);
574 percpu_list_fold(&sb->s_files);
575 lock_list_for_each_entry(f, percpu_list_head(&sb->s_files), f_u.fu_llist) {
576 if (S_ISREG(f->f_path.dentry->d_inode->i_mode) && file_count(f))
577 f->f_mode &= ~FMODE_WRITE;
578 }
579 qrcu_read_unlock(&sb->s_qrcu, idx);
580 }
581
582 /**
583 * do_remount_sb - asks filesystem to change mount options.
584 * @sb: superblock in question
585 * @flags: numeric part of options
586 * @data: the rest of options
587 * @force: whether or not to force the change
588 *
589 * Alters the mount options of a mounted file system.
590 */
591 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
592 {
593 int retval;
594
595 #ifdef CONFIG_BLOCK
596 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
597 return -EACCES;
598 #endif
599 if (flags & MS_RDONLY)
600 acct_auto_close(sb);
601 shrink_dcache_sb(sb);
602 fsync_super(sb);
603
604 /* If we are remounting RDONLY and current sb is read/write,
605 make sure there are no rw files opened */
606 if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
607 if (force)
608 mark_files_ro(sb);
609 else if (!fs_may_remount_ro(sb))
610 return -EBUSY;
611 DQUOT_OFF(sb);
612 }
613
614 if (sb->s_op->remount_fs) {
615 lock_super(sb);
616 retval = sb->s_op->remount_fs(sb, &flags, data);
617 unlock_super(sb);
618 if (retval)
619 return retval;
620 }
621 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
622 return 0;
623 }
624
625 static void do_emergency_remount(unsigned long foo)
626 {
627 struct super_block *sb;
628
629 spin_lock(&sb_lock);
630 list_for_each_entry(sb, &super_blocks, s_list) {
631 sb->s_count++;
632 spin_unlock(&sb_lock);
633 down_read(&sb->s_umount);
634 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
635 /*
636 * ->remount_fs needs lock_kernel().
637 *
638 * What lock protects sb->s_flags??
639 */
640 lock_kernel();
641 do_remount_sb(sb, MS_RDONLY, NULL, 1);
642 unlock_kernel();
643 }
644 drop_super(sb);
645 spin_lock(&sb_lock);
646 }
647 spin_unlock(&sb_lock);
648 printk("Emergency Remount complete\n");
649 }
650
651 void emergency_remount(void)
652 {
653 pdflush_operation(do_emergency_remount, 0);
654 }
655
656 /*
657 * Unnamed block devices are dummy devices used by virtual
658 * filesystems which don't use real block-devices. -- jrs
659 */
660
661 static struct idr unnamed_dev_idr;
662 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
663
664 int set_anon_super(struct super_block *s, void *data)
665 {
666 int dev;
667 int error;
668
669 retry:
670 if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
671 return -ENOMEM;
672 spin_lock(&unnamed_dev_lock);
673 error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
674 spin_unlock(&unnamed_dev_lock);
675 if (error == -EAGAIN)
676 /* We raced and lost with another CPU. */
677 goto retry;
678 else if (error)
679 return -EAGAIN;
680
681 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
682 spin_lock(&unnamed_dev_lock);
683 idr_remove(&unnamed_dev_idr, dev);
684 spin_unlock(&unnamed_dev_lock);
685 return -EMFILE;
686 }
687 s->s_dev = MKDEV(0, dev & MINORMASK);
688 return 0;
689 }
690
691 EXPORT_SYMBOL(set_anon_super);
692
693 void kill_anon_super(struct super_block *sb)
694 {
695 int slot = MINOR(sb->s_dev);
696
697 generic_shutdown_super(sb);
698 spin_lock(&unnamed_dev_lock);
699 idr_remove(&unnamed_dev_idr, slot);
700 spin_unlock(&unnamed_dev_lock);
701 }
702
703 EXPORT_SYMBOL(kill_anon_super);
704
705 void __init unnamed_dev_init(void)
706 {
707 idr_init(&unnamed_dev_idr);
708 }
709
710 void kill_litter_super(struct super_block *sb)
711 {
712 if (sb->s_root)
713 d_genocide(sb->s_root);
714 kill_anon_super(sb);
715 }
716
717 EXPORT_SYMBOL(kill_litter_super);
718
719 #ifdef CONFIG_BLOCK
720 static int set_bdev_super(struct super_block *s, void *data)
721 {
722 s->s_bdev = data;
723 s->s_dev = s->s_bdev->bd_dev;
724 return 0;
725 }
726
727 static int test_bdev_super(struct super_block *s, void *data)
728 {
729 return (void *)s->s_bdev == data;
730 }
731
732 int get_sb_bdev(struct file_system_type *fs_type,
733 int flags, const char *dev_name, void *data,
734 int (*fill_super)(struct super_block *, void *, int),
735 struct vfsmount *mnt)
736 {
737 struct block_device *bdev;
738 struct super_block *s;
739 int error = 0;
740
741 bdev = open_bdev_excl(dev_name, flags, fs_type);
742 if (IS_ERR(bdev))
743 return PTR_ERR(bdev);
744
745 /*
746 * once the super is inserted into the list by sget, s_umount
747 * will protect the lockfs code from trying to start a snapshot
748 * while we are mounting
749 */
750 down(&bdev->bd_mount_sem);
751 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
752 up(&bdev->bd_mount_sem);
753 if (IS_ERR(s))
754 goto error_s;
755
756 if (s->s_root) {
757 if ((flags ^ s->s_flags) & MS_RDONLY) {
758 up_write(&s->s_umount);
759 deactivate_super(s);
760 error = -EBUSY;
761 goto error_bdev;
762 }
763
764 close_bdev_excl(bdev);
765 } else {
766 char b[BDEVNAME_SIZE];
767
768 s->s_flags = flags;
769 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
770 sb_set_blocksize(s, block_size(bdev));
771 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
772 if (error) {
773 up_write(&s->s_umount);
774 deactivate_super(s);
775 goto error;
776 }
777
778 s->s_flags |= MS_ACTIVE;
779 }
780
781 return simple_set_mnt(mnt, s);
782
783 error_s:
784 error = PTR_ERR(s);
785 error_bdev:
786 close_bdev_excl(bdev);
787 error:
788 return error;
789 }
790
791 EXPORT_SYMBOL(get_sb_bdev);
792
793 void kill_block_super(struct super_block *sb)
794 {
795 struct block_device *bdev = sb->s_bdev;
796
797 generic_shutdown_super(sb);
798 sync_blockdev(bdev);
799 close_bdev_excl(bdev);
800 }
801
802 EXPORT_SYMBOL(kill_block_super);
803 #endif
804
805 int get_sb_nodev(struct file_system_type *fs_type,
806 int flags, void *data,
807 int (*fill_super)(struct super_block *, void *, int),
808 struct vfsmount *mnt)
809 {
810 int error;
811 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
812
813 if (IS_ERR(s))
814 return PTR_ERR(s);
815
816 s->s_flags = flags;
817
818 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
819 if (error) {
820 up_write(&s->s_umount);
821 deactivate_super(s);
822 return error;
823 }
824 s->s_flags |= MS_ACTIVE;
825 return simple_set_mnt(mnt, s);
826 }
827
828 EXPORT_SYMBOL(get_sb_nodev);
829
830 static int compare_single(struct super_block *s, void *p)
831 {
832 return 1;
833 }
834
835 int get_sb_single(struct file_system_type *fs_type,
836 int flags, void *data,
837 int (*fill_super)(struct super_block *, void *, int),
838 struct vfsmount *mnt)
839 {
840 struct super_block *s;
841 int error;
842
843 s = sget(fs_type, compare_single, set_anon_super, NULL);
844 if (IS_ERR(s))
845 return PTR_ERR(s);
846 if (!s->s_root) {
847 s->s_flags = flags;
848 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
849 if (error) {
850 up_write(&s->s_umount);
851 deactivate_super(s);
852 return error;
853 }
854 s->s_flags |= MS_ACTIVE;
855 }
856 do_remount_sb(s, flags, data, 0);
857 return simple_set_mnt(mnt, s);
858 }
859
860 EXPORT_SYMBOL(get_sb_single);
861
862 struct vfsmount *
863 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
864 {
865 struct vfsmount *mnt;
866 char *secdata = NULL;
867 int error;
868
869 if (!type)
870 return ERR_PTR(-ENODEV);
871
872 error = -ENOMEM;
873 mnt = alloc_vfsmnt(name);
874 if (!mnt)
875 goto out;
876
877 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
878 secdata = alloc_secdata();
879 if (!secdata)
880 goto out_mnt;
881
882 error = security_sb_copy_data(data, secdata);
883 if (error)
884 goto out_free_secdata;
885 }
886
887 error = type->get_sb(type, flags, name, data, mnt);
888 if (error < 0)
889 goto out_free_secdata;
890 BUG_ON(!mnt->mnt_sb);
891
892 error = security_sb_kern_mount(mnt->mnt_sb, secdata);
893 if (error)
894 goto out_sb;
895
896 mnt->mnt_mountpoint = mnt->mnt_root;
897 mnt->mnt_parent = mnt;
898 up_write(&mnt->mnt_sb->s_umount);
899 free_secdata(secdata);
900 return mnt;
901 out_sb:
902 dput(mnt->mnt_root);
903 up_write(&mnt->mnt_sb->s_umount);
904 deactivate_super(mnt->mnt_sb);
905 out_free_secdata:
906 free_secdata(secdata);
907 out_mnt:
908 free_vfsmnt(mnt);
909 out:
910 return ERR_PTR(error);
911 }
912
913 EXPORT_SYMBOL_GPL(vfs_kern_mount);
914
915 static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
916 {
917 int err;
918 const char *subtype = strchr(fstype, '.');
919 if (subtype) {
920 subtype++;
921 err = -EINVAL;
922 if (!subtype[0])
923 goto err;
924 } else
925 subtype = "";
926
927 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
928 err = -ENOMEM;
929 if (!mnt->mnt_sb->s_subtype)
930 goto err;
931 return mnt;
932
933 err:
934 mntput(mnt);
935 return ERR_PTR(err);
936 }
937
938 struct vfsmount *
939 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
940 {
941 struct file_system_type *type = get_fs_type(fstype);
942 struct vfsmount *mnt;
943 if (!type)
944 return ERR_PTR(-ENODEV);
945 mnt = vfs_kern_mount(type, flags, name, data);
946 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
947 !mnt->mnt_sb->s_subtype)
948 mnt = fs_set_subtype(mnt, fstype);
949 put_filesystem(type);
950 return mnt;
951 }
952 EXPORT_SYMBOL_GPL(do_kern_mount);
953
954 struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
955 {
956 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
957 }
958
959 EXPORT_SYMBOL_GPL(kern_mount_data);
960
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