blob: 425861cb1caa3ed7c1bbe623cfec889e0255b3fe [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);
Ingo Molnar7892f2f2006-01-09 15:59:25 -080075 mutex_init(&s->s_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 down_write(&s->s_umount);
77 s->s_count = S_BIAS;
78 atomic_set(&s->s_active, 1);
Arjan van de Vena11f3a02006-03-23 03:00:33 -080079 mutex_init(&s->s_vfs_rename_mutex);
Ingo Molnard3be9152006-03-23 03:00:29 -080080 mutex_init(&s->s_dquot.dqio_mutex);
81 mutex_init(&s->s_dquot.dqonoff_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 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);
Al Viro7b7b1ac2005-11-07 17:13:39 -0500174 DQUOT_OFF(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 down_write(&s->s_umount);
176 fs->kill_sb(s);
177 put_filesystem(fs);
178 put_super(s);
179 }
180}
181
182EXPORT_SYMBOL(deactivate_super);
183
184/**
185 * grab_super - acquire an active reference
186 * @s: reference we are trying to make active
187 *
188 * Tries to acquire an active reference. grab_super() is used when we
189 * had just found a superblock in super_blocks or fs_type->fs_supers
190 * and want to turn it into a full-blown active reference. grab_super()
191 * is called with sb_lock held and drops it. Returns 1 in case of
192 * success, 0 if we had failed (superblock contents was already dead or
193 * dying when grab_super() had been called).
194 */
195static int grab_super(struct super_block *s)
196{
197 s->s_count++;
198 spin_unlock(&sb_lock);
199 down_write(&s->s_umount);
200 if (s->s_root) {
201 spin_lock(&sb_lock);
202 if (s->s_count > S_BIAS) {
203 atomic_inc(&s->s_active);
204 s->s_count--;
205 spin_unlock(&sb_lock);
206 return 1;
207 }
208 spin_unlock(&sb_lock);
209 }
210 up_write(&s->s_umount);
211 put_super(s);
212 yield();
213 return 0;
214}
215
216/**
217 * generic_shutdown_super - common helper for ->kill_sb()
218 * @sb: superblock to kill
219 *
220 * generic_shutdown_super() does all fs-independent work on superblock
221 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
222 * that need destruction out of superblock, call generic_shutdown_super()
223 * and release aforementioned objects. Note: dentries and inodes _are_
224 * taken care of and do not need specific handling.
225 */
226void generic_shutdown_super(struct super_block *sb)
227{
228 struct dentry *root = sb->s_root;
229 struct super_operations *sop = sb->s_op;
230
231 if (root) {
232 sb->s_root = NULL;
233 shrink_dcache_parent(root);
234 shrink_dcache_anon(&sb->s_anon);
235 dput(root);
236 fsync_super(sb);
237 lock_super(sb);
238 sb->s_flags &= ~MS_ACTIVE;
239 /* bad name - it should be evict_inodes() */
240 invalidate_inodes(sb);
241 lock_kernel();
242
243 if (sop->write_super && sb->s_dirt)
244 sop->write_super(sb);
245 if (sop->put_super)
246 sop->put_super(sb);
247
248 /* Forget any remaining inodes */
249 if (invalidate_inodes(sb)) {
Dave Jones7b4fe292006-02-07 12:58:48 -0800250 printk("VFS: Busy inodes after unmount of %s. "
251 "Self-destruct in 5 seconds. Have a nice day...\n",
252 sb->s_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 }
254
255 unlock_kernel();
256 unlock_super(sb);
257 }
258 spin_lock(&sb_lock);
259 /* should be initialized for __put_super_and_need_restart() */
260 list_del_init(&sb->s_list);
261 list_del(&sb->s_instances);
262 spin_unlock(&sb_lock);
263 up_write(&sb->s_umount);
264}
265
266EXPORT_SYMBOL(generic_shutdown_super);
267
268/**
269 * sget - find or create a superblock
270 * @type: filesystem type superblock should belong to
271 * @test: comparison callback
272 * @set: setup callback
273 * @data: argument to each of them
274 */
275struct super_block *sget(struct file_system_type *type,
276 int (*test)(struct super_block *,void *),
277 int (*set)(struct super_block *,void *),
278 void *data)
279{
280 struct super_block *s = NULL;
281 struct list_head *p;
282 int err;
283
284retry:
285 spin_lock(&sb_lock);
286 if (test) list_for_each(p, &type->fs_supers) {
287 struct super_block *old;
288 old = list_entry(p, struct super_block, s_instances);
289 if (!test(old, data))
290 continue;
291 if (!grab_super(old))
292 goto retry;
293 if (s)
294 destroy_super(s);
295 return old;
296 }
297 if (!s) {
298 spin_unlock(&sb_lock);
299 s = alloc_super();
300 if (!s)
301 return ERR_PTR(-ENOMEM);
302 goto retry;
303 }
304
305 err = set(s, data);
306 if (err) {
307 spin_unlock(&sb_lock);
308 destroy_super(s);
309 return ERR_PTR(err);
310 }
311 s->s_type = type;
312 strlcpy(s->s_id, type->name, sizeof(s->s_id));
313 list_add_tail(&s->s_list, &super_blocks);
314 list_add(&s->s_instances, &type->fs_supers);
315 spin_unlock(&sb_lock);
316 get_filesystem(type);
317 return s;
318}
319
320EXPORT_SYMBOL(sget);
321
322void drop_super(struct super_block *sb)
323{
324 up_read(&sb->s_umount);
325 put_super(sb);
326}
327
328EXPORT_SYMBOL(drop_super);
329
330static inline void write_super(struct super_block *sb)
331{
332 lock_super(sb);
333 if (sb->s_root && sb->s_dirt)
334 if (sb->s_op->write_super)
335 sb->s_op->write_super(sb);
336 unlock_super(sb);
337}
338
339/*
340 * Note: check the dirty flag before waiting, so we don't
341 * hold up the sync while mounting a device. (The newly
342 * mounted device won't need syncing.)
343 */
344void sync_supers(void)
345{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700346 struct super_block *sb;
347
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700349restart:
350 list_for_each_entry(sb, &super_blocks, s_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 if (sb->s_dirt) {
352 sb->s_count++;
353 spin_unlock(&sb_lock);
354 down_read(&sb->s_umount);
355 write_super(sb);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700356 up_read(&sb->s_umount);
357 spin_lock(&sb_lock);
358 if (__put_super_and_need_restart(sb))
359 goto restart;
360 }
361 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 spin_unlock(&sb_lock);
363}
364
365/*
366 * Call the ->sync_fs super_op against all filesytems which are r/w and
367 * which implement it.
368 *
369 * This operation is careful to avoid the livelock which could easily happen
370 * if two or more filesystems are being continuously dirtied. s_need_sync_fs
371 * is used only here. We set it against all filesystems and then clear it as
372 * we sync them. So redirtied filesystems are skipped.
373 *
374 * But if process A is currently running sync_filesytems and then process B
375 * calls sync_filesystems as well, process B will set all the s_need_sync_fs
376 * flags again, which will cause process A to resync everything. Fix that with
377 * a local mutex.
378 *
379 * (Fabian) Avoid sync_fs with clean fs & wait mode 0
380 */
381void sync_filesystems(int wait)
382{
383 struct super_block *sb;
384 static DECLARE_MUTEX(mutex);
385
386 down(&mutex); /* Could be down_interruptible */
387 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700388 list_for_each_entry(sb, &super_blocks, s_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 if (!sb->s_op->sync_fs)
390 continue;
391 if (sb->s_flags & MS_RDONLY)
392 continue;
393 sb->s_need_sync_fs = 1;
394 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395
396restart:
Kirill Korotaev618f0632005-06-23 00:09:54 -0700397 list_for_each_entry(sb, &super_blocks, s_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 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);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700408 up_read(&sb->s_umount);
409 /* restart only when sb is no longer on the list */
410 spin_lock(&sb_lock);
411 if (__put_super_and_need_restart(sb))
412 goto restart;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 }
414 spin_unlock(&sb_lock);
415 up(&mutex);
416}
417
418/**
419 * get_super - get the superblock of a device
420 * @bdev: device to get the superblock for
421 *
422 * Scans the superblock list and finds the superblock of the file system
423 * mounted on the device given. %NULL is returned if no match is found.
424 */
425
426struct super_block * get_super(struct block_device *bdev)
427{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700428 struct super_block *sb;
429
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 if (!bdev)
431 return NULL;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700432
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700434rescan:
435 list_for_each_entry(sb, &super_blocks, s_list) {
436 if (sb->s_bdev == bdev) {
437 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700439 down_read(&sb->s_umount);
440 if (sb->s_root)
441 return sb;
442 up_read(&sb->s_umount);
443 /* restart only when sb is no longer on the list */
444 spin_lock(&sb_lock);
445 if (__put_super_and_need_restart(sb))
446 goto rescan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 }
448 }
449 spin_unlock(&sb_lock);
450 return NULL;
451}
452
453EXPORT_SYMBOL(get_super);
454
455struct super_block * user_get_super(dev_t dev)
456{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700457 struct super_block *sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700460rescan:
461 list_for_each_entry(sb, &super_blocks, s_list) {
462 if (sb->s_dev == dev) {
463 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700465 down_read(&sb->s_umount);
466 if (sb->s_root)
467 return sb;
468 up_read(&sb->s_umount);
469 /* restart only when sb is no longer on the list */
470 spin_lock(&sb_lock);
471 if (__put_super_and_need_restart(sb))
472 goto rescan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 }
474 }
475 spin_unlock(&sb_lock);
476 return NULL;
477}
478
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479asmlinkage long sys_ustat(unsigned dev, struct ustat __user * ubuf)
480{
481 struct super_block *s;
482 struct ustat tmp;
483 struct kstatfs sbuf;
484 int err = -EINVAL;
485
486 s = user_get_super(new_decode_dev(dev));
487 if (s == NULL)
488 goto out;
489 err = vfs_statfs(s, &sbuf);
490 drop_super(s);
491 if (err)
492 goto out;
493
494 memset(&tmp,0,sizeof(struct ustat));
495 tmp.f_tfree = sbuf.f_bfree;
496 tmp.f_tinode = sbuf.f_ffree;
497
498 err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
499out:
500 return err;
501}
502
503/**
504 * mark_files_ro
505 * @sb: superblock in question
506 *
507 * All files are marked read/only. We don't care about pending
508 * delete files so this should be used in 'force' mode only
509 */
510
511static void mark_files_ro(struct super_block *sb)
512{
513 struct file *f;
514
515 file_list_lock();
Eric Dumazet2f512012005-10-30 15:02:16 -0800516 list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 if (S_ISREG(f->f_dentry->d_inode->i_mode) && file_count(f))
518 f->f_mode &= ~FMODE_WRITE;
519 }
520 file_list_unlock();
521}
522
523/**
524 * do_remount_sb - asks filesystem to change mount options.
525 * @sb: superblock in question
526 * @flags: numeric part of options
527 * @data: the rest of options
528 * @force: whether or not to force the change
529 *
530 * Alters the mount options of a mounted file system.
531 */
532int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
533{
534 int retval;
535
536 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
537 return -EACCES;
538 if (flags & MS_RDONLY)
539 acct_auto_close(sb);
540 shrink_dcache_sb(sb);
541 fsync_super(sb);
542
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 }
551
552 if (sb->s_op->remount_fs) {
553 lock_super(sb);
554 retval = sb->s_op->remount_fs(sb, &flags, data);
555 unlock_super(sb);
556 if (retval)
557 return retval;
558 }
559 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
560 return 0;
561}
562
563static void do_emergency_remount(unsigned long foo)
564{
565 struct super_block *sb;
566
567 spin_lock(&sb_lock);
568 list_for_each_entry(sb, &super_blocks, s_list) {
569 sb->s_count++;
570 spin_unlock(&sb_lock);
571 down_read(&sb->s_umount);
572 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
573 /*
574 * ->remount_fs needs lock_kernel().
575 *
576 * What lock protects sb->s_flags??
577 */
578 lock_kernel();
579 do_remount_sb(sb, MS_RDONLY, NULL, 1);
580 unlock_kernel();
581 }
582 drop_super(sb);
583 spin_lock(&sb_lock);
584 }
585 spin_unlock(&sb_lock);
586 printk("Emergency Remount complete\n");
587}
588
589void emergency_remount(void)
590{
591 pdflush_operation(do_emergency_remount, 0);
592}
593
594/*
595 * Unnamed block devices are dummy devices used by virtual
596 * filesystems which don't use real block-devices. -- jrs
597 */
598
599static struct idr unnamed_dev_idr;
600static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
601
602int set_anon_super(struct super_block *s, void *data)
603{
604 int dev;
605 int error;
606
607 retry:
608 if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
609 return -ENOMEM;
610 spin_lock(&unnamed_dev_lock);
611 error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
612 spin_unlock(&unnamed_dev_lock);
613 if (error == -EAGAIN)
614 /* We raced and lost with another CPU. */
615 goto retry;
616 else if (error)
617 return -EAGAIN;
618
619 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
620 spin_lock(&unnamed_dev_lock);
621 idr_remove(&unnamed_dev_idr, dev);
622 spin_unlock(&unnamed_dev_lock);
623 return -EMFILE;
624 }
625 s->s_dev = MKDEV(0, dev & MINORMASK);
626 return 0;
627}
628
629EXPORT_SYMBOL(set_anon_super);
630
631void kill_anon_super(struct super_block *sb)
632{
633 int slot = MINOR(sb->s_dev);
634
635 generic_shutdown_super(sb);
636 spin_lock(&unnamed_dev_lock);
637 idr_remove(&unnamed_dev_idr, slot);
638 spin_unlock(&unnamed_dev_lock);
639}
640
641EXPORT_SYMBOL(kill_anon_super);
642
643void __init unnamed_dev_init(void)
644{
645 idr_init(&unnamed_dev_idr);
646}
647
648void kill_litter_super(struct super_block *sb)
649{
650 if (sb->s_root)
651 d_genocide(sb->s_root);
652 kill_anon_super(sb);
653}
654
655EXPORT_SYMBOL(kill_litter_super);
656
657static int set_bdev_super(struct super_block *s, void *data)
658{
659 s->s_bdev = data;
660 s->s_dev = s->s_bdev->bd_dev;
661 return 0;
662}
663
664static int test_bdev_super(struct super_block *s, void *data)
665{
666 return (void *)s->s_bdev == data;
667}
668
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800669static void bdev_uevent(struct block_device *bdev, enum kobject_action action)
670{
671 if (bdev->bd_disk) {
672 if (bdev->bd_part)
673 kobject_uevent(&bdev->bd_part->kobj, action);
674 else
675 kobject_uevent(&bdev->bd_disk->kobj, action);
676 }
677}
678
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679struct super_block *get_sb_bdev(struct file_system_type *fs_type,
680 int flags, const char *dev_name, void *data,
681 int (*fill_super)(struct super_block *, void *, int))
682{
683 struct block_device *bdev;
684 struct super_block *s;
685 int error = 0;
686
687 bdev = open_bdev_excl(dev_name, flags, fs_type);
688 if (IS_ERR(bdev))
689 return (struct super_block *)bdev;
690
691 /*
692 * once the super is inserted into the list by sget, s_umount
693 * will protect the lockfs code from trying to start a snapshot
694 * while we are mounting
695 */
Arjan van de Venc039e312006-03-23 03:00:28 -0800696 mutex_lock(&bdev->bd_mount_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
Arjan van de Venc039e312006-03-23 03:00:28 -0800698 mutex_unlock(&bdev->bd_mount_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 if (IS_ERR(s))
700 goto out;
701
702 if (s->s_root) {
703 if ((flags ^ s->s_flags) & MS_RDONLY) {
704 up_write(&s->s_umount);
705 deactivate_super(s);
706 s = ERR_PTR(-EBUSY);
707 }
708 goto out;
709 } else {
710 char b[BDEVNAME_SIZE];
711
712 s->s_flags = flags;
713 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
Pekka Enberge78c9a02006-01-08 01:03:39 -0800714 sb_set_blocksize(s, block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
716 if (error) {
717 up_write(&s->s_umount);
718 deactivate_super(s);
719 s = ERR_PTR(error);
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800720 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 s->s_flags |= MS_ACTIVE;
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800722 bdev_uevent(bdev, KOBJ_MOUNT);
723 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 }
725
726 return s;
727
728out:
729 close_bdev_excl(bdev);
730 return s;
731}
732
733EXPORT_SYMBOL(get_sb_bdev);
734
735void kill_block_super(struct super_block *sb)
736{
737 struct block_device *bdev = sb->s_bdev;
738
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800739 bdev_uevent(bdev, KOBJ_UMOUNT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 generic_shutdown_super(sb);
741 sync_blockdev(bdev);
742 close_bdev_excl(bdev);
743}
744
745EXPORT_SYMBOL(kill_block_super);
746
747struct super_block *get_sb_nodev(struct file_system_type *fs_type,
748 int flags, void *data,
749 int (*fill_super)(struct super_block *, void *, int))
750{
751 int error;
752 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
753
754 if (IS_ERR(s))
755 return s;
756
757 s->s_flags = flags;
758
759 error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
760 if (error) {
761 up_write(&s->s_umount);
762 deactivate_super(s);
763 return ERR_PTR(error);
764 }
765 s->s_flags |= MS_ACTIVE;
766 return s;
767}
768
769EXPORT_SYMBOL(get_sb_nodev);
770
771static int compare_single(struct super_block *s, void *p)
772{
773 return 1;
774}
775
776struct super_block *get_sb_single(struct file_system_type *fs_type,
777 int flags, void *data,
778 int (*fill_super)(struct super_block *, void *, int))
779{
780 struct super_block *s;
781 int error;
782
783 s = sget(fs_type, compare_single, set_anon_super, NULL);
784 if (IS_ERR(s))
785 return s;
786 if (!s->s_root) {
787 s->s_flags = flags;
788 error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
789 if (error) {
790 up_write(&s->s_umount);
791 deactivate_super(s);
792 return ERR_PTR(error);
793 }
794 s->s_flags |= MS_ACTIVE;
795 }
796 do_remount_sb(s, flags, data, 0);
797 return s;
798}
799
800EXPORT_SYMBOL(get_sb_single);
801
802struct vfsmount *
803do_kern_mount(const char *fstype, int flags, const char *name, void *data)
804{
805 struct file_system_type *type = get_fs_type(fstype);
806 struct super_block *sb = ERR_PTR(-ENOMEM);
807 struct vfsmount *mnt;
808 int error;
809 char *secdata = NULL;
810
811 if (!type)
812 return ERR_PTR(-ENODEV);
813
814 mnt = alloc_vfsmnt(name);
815 if (!mnt)
816 goto out;
817
818 if (data) {
819 secdata = alloc_secdata();
820 if (!secdata) {
821 sb = ERR_PTR(-ENOMEM);
822 goto out_mnt;
823 }
824
825 error = security_sb_copy_data(type, data, secdata);
826 if (error) {
827 sb = ERR_PTR(error);
828 goto out_free_secdata;
829 }
830 }
831
832 sb = type->get_sb(type, flags, name, data);
833 if (IS_ERR(sb))
834 goto out_free_secdata;
835 error = security_sb_kern_mount(sb, secdata);
836 if (error)
837 goto out_sb;
838 mnt->mnt_sb = sb;
839 mnt->mnt_root = dget(sb->s_root);
840 mnt->mnt_mountpoint = sb->s_root;
841 mnt->mnt_parent = mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 up_write(&sb->s_umount);
Gerald Schaefer8680e222005-06-21 17:15:16 -0700843 free_secdata(secdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 put_filesystem(type);
845 return mnt;
846out_sb:
847 up_write(&sb->s_umount);
848 deactivate_super(sb);
849 sb = ERR_PTR(error);
850out_free_secdata:
851 free_secdata(secdata);
852out_mnt:
853 free_vfsmnt(mnt);
854out:
855 put_filesystem(type);
856 return (struct vfsmount *)sb;
857}
858
859EXPORT_SYMBOL_GPL(do_kern_mount);
860
861struct vfsmount *kern_mount(struct file_system_type *type)
862{
863 return do_kern_mount(type->name, 0, type->name, NULL);
864}
865
866EXPORT_SYMBOL(kern_mount);