blob: fc8ebedc6bed1aa901e24ebf8e34fd397cc6361e [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
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#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>
Ingo Molnar353ab6e2006-03-26 01:37:12 -080039#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070040#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
Henrik Kretzschmarfe2bbc42006-09-06 00:03:41 -070052 * @type: filesystem type superblock should belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 *
54 * Allocates and initializes a new &struct super_block. alloc_super()
55 * returns a pointer new superblock or %NULL if allocation had failed.
56 */
Ingo Molnarcf516242006-07-03 00:25:27 -070057static struct super_block *alloc_super(struct file_system_type *type)
Linus Torvalds1da177e2005-04-16 15:20:36 -070058{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -080059 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 static struct super_operations default_op;
61
62 if (s) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 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 Molnar7892f2f42006-01-09 15:59:25 -080075 mutex_init(&s->s_lock);
Arjan van de Ven897c6ff2006-07-03 00:25:28 -070076 lockdep_set_class(&s->s_umount, &type->s_umount_key);
Ingo Molnarcf516242006-07-03 00:25:27 -070077 /*
78 * The locking rules for s_lock are up to the
79 * filesystem. For example ext3fs has different
80 * lock ordering than usbfs:
81 */
82 lockdep_set_class(&s->s_lock, &type->s_lock_key);
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 down_write(&s->s_umount);
84 s->s_count = S_BIAS;
85 atomic_set(&s->s_active, 1);
Arjan van de Vena11f3a02006-03-23 03:00:33 -080086 mutex_init(&s->s_vfs_rename_mutex);
Ingo Molnard3be9152006-03-23 03:00:29 -080087 mutex_init(&s->s_dquot.dqio_mutex);
88 mutex_init(&s->s_dquot.dqonoff_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 init_rwsem(&s->s_dquot.dqptr_sem);
90 init_waitqueue_head(&s->s_wait_unfrozen);
91 s->s_maxbytes = MAX_NON_LFS;
92 s->dq_op = sb_dquot_ops;
93 s->s_qcop = sb_quotactl_ops;
94 s->s_op = &default_op;
95 s->s_time_gran = 1000000000;
96 }
97out:
98 return s;
99}
100
101/**
102 * destroy_super - frees a superblock
103 * @s: superblock to free
104 *
105 * Frees a superblock.
106 */
107static inline void destroy_super(struct super_block *s)
108{
109 security_sb_free(s);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -0700110 kfree(s->s_subtype);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 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 */
120int __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 */
138int __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 */
159static 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 */
176void 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);
Al Viro7b7b1ac2005-11-07 17:13:39 -0500182 DQUOT_OFF(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 down_write(&s->s_umount);
184 fs->kill_sb(s);
185 put_filesystem(fs);
186 put_super(s);
187 }
188}
189
190EXPORT_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 */
Josh Triplett9c4dbee2006-09-29 01:59:29 -0700203static int grab_super(struct super_block *s) __releases(sb_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204{
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
David Howellscf9a2ae2006-08-29 19:05:54 +0100224/*
Al Viro914e2632006-10-18 13:55:46 -0400225 * Superblock locking. We really ought to get rid of these two.
226 */
227void lock_super(struct super_block * sb)
228{
229 get_fs_excl();
230 mutex_lock(&sb->s_lock);
231}
232
233void unlock_super(struct super_block * sb)
234{
235 put_fs_excl();
236 mutex_unlock(&sb->s_lock);
237}
238
239EXPORT_SYMBOL(lock_super);
240EXPORT_SYMBOL(unlock_super);
241
242/*
David Howellscf9a2ae2006-08-29 19:05:54 +0100243 * 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 */
248void __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 */
267int fsync_super(struct super_block *sb)
268{
269 __fsync_super(sb);
270 return sync_blockdev(sb->s_bdev);
271}
272
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273/**
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.
David Howellsc636ebd2006-10-11 01:22:19 -0700282 *
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 */
287void generic_shutdown_super(struct super_block *sb)
288{
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800289 const struct super_operations *sop = sb->s_op;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290
David Howellsc636ebd2006-10-11 01:22:19 -0700291 if (sb->s_root) {
292 shrink_dcache_for_umount(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 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)) {
Dave Jones7b4fe292006-02-07 12:58:48 -0800307 printk("VFS: Busy inodes after unmount of %s. "
308 "Self-destruct in 5 seconds. Have a nice day...\n",
309 sb->s_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 }
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
323EXPORT_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 */
332struct 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 list_head *p;
339 int err;
340
341retry:
342 spin_lock(&sb_lock);
343 if (test) list_for_each(p, &type->fs_supers) {
344 struct super_block *old;
345 old = list_entry(p, struct super_block, s_instances);
346 if (!test(old, data))
347 continue;
348 if (!grab_super(old))
349 goto retry;
350 if (s)
351 destroy_super(s);
352 return old;
353 }
354 if (!s) {
355 spin_unlock(&sb_lock);
Ingo Molnarcf516242006-07-03 00:25:27 -0700356 s = alloc_super(type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 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
377EXPORT_SYMBOL(sget);
378
379void drop_super(struct super_block *sb)
380{
381 up_read(&sb->s_umount);
382 put_super(sb);
383}
384
385EXPORT_SYMBOL(drop_super);
386
387static 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 */
401void sync_supers(void)
402{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700403 struct super_block *sb;
404
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700406restart:
407 list_for_each_entry(sb, &super_blocks, s_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 if (sb->s_dirt) {
409 sb->s_count++;
410 spin_unlock(&sb_lock);
411 down_read(&sb->s_umount);
412 write_super(sb);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700413 up_read(&sb->s_umount);
414 spin_lock(&sb_lock);
415 if (__put_super_and_need_restart(sb))
416 goto restart;
417 }
418 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 spin_unlock(&sb_lock);
420}
421
422/*
423 * Call the ->sync_fs super_op against all filesytems 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_filesytems 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 */
438void sync_filesystems(int wait)
439{
440 struct super_block *sb;
Ingo Molnar353ab6e2006-03-26 01:37:12 -0800441 static DEFINE_MUTEX(mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442
Ingo Molnar353ab6e2006-03-26 01:37:12 -0800443 mutex_lock(&mutex); /* Could be down_interruptible */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700445 list_for_each_entry(sb, &super_blocks, s_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446 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 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452
453restart:
Kirill Korotaev618f0632005-06-23 00:09:54 -0700454 list_for_each_entry(sb, &super_blocks, s_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 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);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700465 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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 }
471 spin_unlock(&sb_lock);
Ingo Molnar353ab6e2006-03-26 01:37:12 -0800472 mutex_unlock(&mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473}
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
483struct super_block * get_super(struct block_device *bdev)
484{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700485 struct super_block *sb;
486
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 if (!bdev)
488 return NULL;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700489
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700491rescan:
492 list_for_each_entry(sb, &super_blocks, s_list) {
493 if (sb->s_bdev == bdev) {
494 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700496 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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 }
505 }
506 spin_unlock(&sb_lock);
507 return NULL;
508}
509
510EXPORT_SYMBOL(get_super);
511
512struct super_block * user_get_super(dev_t dev)
513{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700514 struct super_block *sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700517rescan:
518 list_for_each_entry(sb, &super_blocks, s_list) {
519 if (sb->s_dev == dev) {
520 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700522 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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530 }
531 }
532 spin_unlock(&sb_lock);
533 return NULL;
534}
535
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536asmlinkage 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;
David Howells726c3342006-06-23 02:02:58 -0700546 err = vfs_statfs(s->s_root, &sbuf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 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;
556out:
557 return err;
558}
559
560/**
561 * mark_files_ro
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
568static void mark_files_ro(struct super_block *sb)
569{
570 struct file *f;
571
572 file_list_lock();
Eric Dumazet2f512012005-10-30 15:02:16 -0800573 list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800574 if (S_ISREG(f->f_path.dentry->d_inode->i_mode) && file_count(f))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 f->f_mode &= ~FMODE_WRITE;
576 }
577 file_list_unlock();
578}
579
580/**
581 * do_remount_sb - asks filesystem to change mount options.
582 * @sb: superblock in question
583 * @flags: numeric part of options
584 * @data: the rest of options
585 * @force: whether or not to force the change
586 *
587 * Alters the mount options of a mounted file system.
588 */
589int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
590{
591 int retval;
592
David Howells93614012006-09-30 20:45:40 +0200593#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
595 return -EACCES;
David Howells93614012006-09-30 20:45:40 +0200596#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 if (flags & MS_RDONLY)
598 acct_auto_close(sb);
599 shrink_dcache_sb(sb);
600 fsync_super(sb);
601
602 /* If we are remounting RDONLY and current sb is read/write,
603 make sure there are no rw files opened */
604 if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
605 if (force)
606 mark_files_ro(sb);
607 else if (!fs_may_remount_ro(sb))
608 return -EBUSY;
609 }
610
611 if (sb->s_op->remount_fs) {
612 lock_super(sb);
613 retval = sb->s_op->remount_fs(sb, &flags, data);
614 unlock_super(sb);
615 if (retval)
616 return retval;
617 }
618 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
619 return 0;
620}
621
622static void do_emergency_remount(unsigned long foo)
623{
624 struct super_block *sb;
625
626 spin_lock(&sb_lock);
627 list_for_each_entry(sb, &super_blocks, s_list) {
628 sb->s_count++;
629 spin_unlock(&sb_lock);
630 down_read(&sb->s_umount);
631 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
632 /*
633 * ->remount_fs needs lock_kernel().
634 *
635 * What lock protects sb->s_flags??
636 */
637 lock_kernel();
638 do_remount_sb(sb, MS_RDONLY, NULL, 1);
639 unlock_kernel();
640 }
641 drop_super(sb);
642 spin_lock(&sb_lock);
643 }
644 spin_unlock(&sb_lock);
645 printk("Emergency Remount complete\n");
646}
647
648void emergency_remount(void)
649{
650 pdflush_operation(do_emergency_remount, 0);
651}
652
653/*
654 * Unnamed block devices are dummy devices used by virtual
655 * filesystems which don't use real block-devices. -- jrs
656 */
657
658static struct idr unnamed_dev_idr;
659static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
660
661int set_anon_super(struct super_block *s, void *data)
662{
663 int dev;
664 int error;
665
666 retry:
667 if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
668 return -ENOMEM;
669 spin_lock(&unnamed_dev_lock);
670 error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
671 spin_unlock(&unnamed_dev_lock);
672 if (error == -EAGAIN)
673 /* We raced and lost with another CPU. */
674 goto retry;
675 else if (error)
676 return -EAGAIN;
677
678 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
679 spin_lock(&unnamed_dev_lock);
680 idr_remove(&unnamed_dev_idr, dev);
681 spin_unlock(&unnamed_dev_lock);
682 return -EMFILE;
683 }
684 s->s_dev = MKDEV(0, dev & MINORMASK);
685 return 0;
686}
687
688EXPORT_SYMBOL(set_anon_super);
689
690void kill_anon_super(struct super_block *sb)
691{
692 int slot = MINOR(sb->s_dev);
693
694 generic_shutdown_super(sb);
695 spin_lock(&unnamed_dev_lock);
696 idr_remove(&unnamed_dev_idr, slot);
697 spin_unlock(&unnamed_dev_lock);
698}
699
700EXPORT_SYMBOL(kill_anon_super);
701
702void __init unnamed_dev_init(void)
703{
704 idr_init(&unnamed_dev_idr);
705}
706
707void kill_litter_super(struct super_block *sb)
708{
709 if (sb->s_root)
710 d_genocide(sb->s_root);
711 kill_anon_super(sb);
712}
713
714EXPORT_SYMBOL(kill_litter_super);
715
David Howells93614012006-09-30 20:45:40 +0200716#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717static int set_bdev_super(struct super_block *s, void *data)
718{
719 s->s_bdev = data;
720 s->s_dev = s->s_bdev->bd_dev;
721 return 0;
722}
723
724static int test_bdev_super(struct super_block *s, void *data)
725{
726 return (void *)s->s_bdev == data;
727}
728
David Howells454e2392006-06-23 02:02:57 -0700729int get_sb_bdev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 int flags, const char *dev_name, void *data,
David Howells454e2392006-06-23 02:02:57 -0700731 int (*fill_super)(struct super_block *, void *, int),
732 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733{
734 struct block_device *bdev;
735 struct super_block *s;
736 int error = 0;
737
738 bdev = open_bdev_excl(dev_name, flags, fs_type);
739 if (IS_ERR(bdev))
David Howells454e2392006-06-23 02:02:57 -0700740 return PTR_ERR(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741
742 /*
743 * once the super is inserted into the list by sget, s_umount
744 * will protect the lockfs code from trying to start a snapshot
745 * while we are mounting
746 */
David Chinnerf73ca1b2007-01-10 23:15:41 -0800747 down(&bdev->bd_mount_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
David Chinnerf73ca1b2007-01-10 23:15:41 -0800749 up(&bdev->bd_mount_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700751 goto error_s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752
753 if (s->s_root) {
754 if ((flags ^ s->s_flags) & MS_RDONLY) {
755 up_write(&s->s_umount);
756 deactivate_super(s);
David Howells454e2392006-06-23 02:02:57 -0700757 error = -EBUSY;
758 goto error_bdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 }
David Howells454e2392006-06-23 02:02:57 -0700760
761 close_bdev_excl(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 } else {
763 char b[BDEVNAME_SIZE];
764
765 s->s_flags = flags;
766 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
Pekka Enberge78c9a02006-01-08 01:03:39 -0800767 sb_set_blocksize(s, block_size(bdev));
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800768 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 if (error) {
770 up_write(&s->s_umount);
771 deactivate_super(s);
David Howells454e2392006-06-23 02:02:57 -0700772 goto error;
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800773 }
David Howells454e2392006-06-23 02:02:57 -0700774
775 s->s_flags |= MS_ACTIVE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 }
777
David Howells454e2392006-06-23 02:02:57 -0700778 return simple_set_mnt(mnt, s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779
David Howells454e2392006-06-23 02:02:57 -0700780error_s:
781 error = PTR_ERR(s);
782error_bdev:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783 close_bdev_excl(bdev);
David Howells454e2392006-06-23 02:02:57 -0700784error:
785 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786}
787
788EXPORT_SYMBOL(get_sb_bdev);
789
790void kill_block_super(struct super_block *sb)
791{
792 struct block_device *bdev = sb->s_bdev;
793
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 generic_shutdown_super(sb);
795 sync_blockdev(bdev);
796 close_bdev_excl(bdev);
797}
798
799EXPORT_SYMBOL(kill_block_super);
David Howells93614012006-09-30 20:45:40 +0200800#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801
David Howells454e2392006-06-23 02:02:57 -0700802int get_sb_nodev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803 int flags, void *data,
David Howells454e2392006-06-23 02:02:57 -0700804 int (*fill_super)(struct super_block *, void *, int),
805 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806{
807 int error;
808 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
809
810 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700811 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812
813 s->s_flags = flags;
814
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800815 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 if (error) {
817 up_write(&s->s_umount);
818 deactivate_super(s);
David Howells454e2392006-06-23 02:02:57 -0700819 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 }
821 s->s_flags |= MS_ACTIVE;
David Howells454e2392006-06-23 02:02:57 -0700822 return simple_set_mnt(mnt, s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823}
824
825EXPORT_SYMBOL(get_sb_nodev);
826
827static int compare_single(struct super_block *s, void *p)
828{
829 return 1;
830}
831
David Howells454e2392006-06-23 02:02:57 -0700832int get_sb_single(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 int flags, void *data,
David Howells454e2392006-06-23 02:02:57 -0700834 int (*fill_super)(struct super_block *, void *, int),
835 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836{
837 struct super_block *s;
838 int error;
839
840 s = sget(fs_type, compare_single, set_anon_super, NULL);
841 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700842 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 if (!s->s_root) {
844 s->s_flags = flags;
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800845 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 if (error) {
847 up_write(&s->s_umount);
848 deactivate_super(s);
David Howells454e2392006-06-23 02:02:57 -0700849 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 }
851 s->s_flags |= MS_ACTIVE;
852 }
853 do_remount_sb(s, flags, data, 0);
David Howells454e2392006-06-23 02:02:57 -0700854 return simple_set_mnt(mnt, s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855}
856
857EXPORT_SYMBOL(get_sb_single);
858
859struct vfsmount *
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400860vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 struct vfsmount *mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 char *secdata = NULL;
David Howells454e2392006-06-23 02:02:57 -0700864 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865
866 if (!type)
867 return ERR_PTR(-ENODEV);
868
David Howells454e2392006-06-23 02:02:57 -0700869 error = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 mnt = alloc_vfsmnt(name);
871 if (!mnt)
872 goto out;
873
874 if (data) {
875 secdata = alloc_secdata();
David Howells454e2392006-06-23 02:02:57 -0700876 if (!secdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 goto out_mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878
879 error = security_sb_copy_data(type, data, secdata);
David Howells454e2392006-06-23 02:02:57 -0700880 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881 goto out_free_secdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 }
883
David Howells454e2392006-06-23 02:02:57 -0700884 error = type->get_sb(type, flags, name, data, mnt);
885 if (error < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886 goto out_free_secdata;
Lee Schermerhornb4c07bc2007-07-15 23:40:54 -0700887 BUG_ON(!mnt->mnt_sb);
David Howells454e2392006-06-23 02:02:57 -0700888
889 error = security_sb_kern_mount(mnt->mnt_sb, secdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890 if (error)
891 goto out_sb;
David Howells454e2392006-06-23 02:02:57 -0700892
893 mnt->mnt_mountpoint = mnt->mnt_root;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 mnt->mnt_parent = mnt;
David Howells454e2392006-06-23 02:02:57 -0700895 up_write(&mnt->mnt_sb->s_umount);
Gerald Schaefer8680e222005-06-21 17:15:16 -0700896 free_secdata(secdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897 return mnt;
898out_sb:
David Howells454e2392006-06-23 02:02:57 -0700899 dput(mnt->mnt_root);
900 up_write(&mnt->mnt_sb->s_umount);
901 deactivate_super(mnt->mnt_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902out_free_secdata:
903 free_secdata(secdata);
904out_mnt:
905 free_vfsmnt(mnt);
906out:
David Howells454e2392006-06-23 02:02:57 -0700907 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908}
909
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400910EXPORT_SYMBOL_GPL(vfs_kern_mount);
911
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -0700912static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
913{
914 int err;
915 const char *subtype = strchr(fstype, '.');
916 if (subtype) {
917 subtype++;
918 err = -EINVAL;
919 if (!subtype[0])
920 goto err;
921 } else
922 subtype = "";
923
924 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
925 err = -ENOMEM;
926 if (!mnt->mnt_sb->s_subtype)
927 goto err;
928 return mnt;
929
930 err:
931 mntput(mnt);
932 return ERR_PTR(err);
933}
934
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400935struct vfsmount *
936do_kern_mount(const char *fstype, int flags, const char *name, void *data)
937{
938 struct file_system_type *type = get_fs_type(fstype);
939 struct vfsmount *mnt;
940 if (!type)
941 return ERR_PTR(-ENODEV);
942 mnt = vfs_kern_mount(type, flags, name, data);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -0700943 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
944 !mnt->mnt_sb->s_subtype)
945 mnt = fs_set_subtype(mnt, fstype);
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400946 put_filesystem(type);
947 return mnt;
948}
949
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950struct vfsmount *kern_mount(struct file_system_type *type)
951{
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400952 return vfs_kern_mount(type, 0, type->name, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953}
954
955EXPORT_SYMBOL(kern_mount);