Commit | Line | Data |
---|---|---|
1da177e4 LT |
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: | |
96de0e25 | 18 | * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996. |
1da177e4 LT |
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 | ||
1da177e4 LT |
23 | #include <linux/module.h> |
24 | #include <linux/slab.h> | |
1da177e4 LT |
25 | #include <linux/acct.h> |
26 | #include <linux/blkdev.h> | |
1da177e4 LT |
27 | #include <linux/mount.h> |
28 | #include <linux/security.h> | |
1da177e4 LT |
29 | #include <linux/writeback.h> /* for the emergency remount stuff */ |
30 | #include <linux/idr.h> | |
353ab6e9 | 31 | #include <linux/mutex.h> |
5477d0fa | 32 | #include <linux/backing-dev.h> |
ceb5bdc2 | 33 | #include <linux/rculist_bl.h> |
c515e1fd | 34 | #include <linux/cleancache.h> |
6d59e7f5 | 35 | #include "internal.h" |
1da177e4 LT |
36 | |
37 | ||
1da177e4 LT |
38 | LIST_HEAD(super_blocks); |
39 | DEFINE_SPINLOCK(sb_lock); | |
40 | ||
41 | /** | |
42 | * alloc_super - create new superblock | |
fe2bbc48 | 43 | * @type: filesystem type superblock should belong to |
1da177e4 LT |
44 | * |
45 | * Allocates and initializes a new &struct super_block. alloc_super() | |
46 | * returns a pointer new superblock or %NULL if allocation had failed. | |
47 | */ | |
cf516249 | 48 | static struct super_block *alloc_super(struct file_system_type *type) |
1da177e4 | 49 | { |
11b0b5ab | 50 | struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); |
b87221de | 51 | static const struct super_operations default_op; |
1da177e4 LT |
52 | |
53 | if (s) { | |
1da177e4 LT |
54 | if (security_sb_alloc(s)) { |
55 | kfree(s); | |
56 | s = NULL; | |
57 | goto out; | |
58 | } | |
6416ccb7 NP |
59 | #ifdef CONFIG_SMP |
60 | s->s_files = alloc_percpu(struct list_head); | |
61 | if (!s->s_files) { | |
62 | security_sb_free(s); | |
63 | kfree(s); | |
64 | s = NULL; | |
65 | goto out; | |
66 | } else { | |
67 | int i; | |
68 | ||
69 | for_each_possible_cpu(i) | |
70 | INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i)); | |
71 | } | |
72 | #else | |
1da177e4 | 73 | INIT_LIST_HEAD(&s->s_files); |
6416ccb7 | 74 | #endif |
95f28604 | 75 | s->s_bdi = &default_backing_dev_info; |
1da177e4 | 76 | INIT_LIST_HEAD(&s->s_instances); |
ceb5bdc2 | 77 | INIT_HLIST_BL_HEAD(&s->s_anon); |
1da177e4 | 78 | INIT_LIST_HEAD(&s->s_inodes); |
da3bbdd4 | 79 | INIT_LIST_HEAD(&s->s_dentry_lru); |
98b745c6 | 80 | INIT_LIST_HEAD(&s->s_inode_lru); |
09cc9fc7 | 81 | spin_lock_init(&s->s_inode_lru_lock); |
1da177e4 | 82 | init_rwsem(&s->s_umount); |
7892f2f4 | 83 | mutex_init(&s->s_lock); |
897c6ff9 | 84 | lockdep_set_class(&s->s_umount, &type->s_umount_key); |
cf516249 IM |
85 | /* |
86 | * The locking rules for s_lock are up to the | |
87 | * filesystem. For example ext3fs has different | |
88 | * lock ordering than usbfs: | |
89 | */ | |
90 | lockdep_set_class(&s->s_lock, &type->s_lock_key); | |
ada723dc PZ |
91 | /* |
92 | * sget() can have s_umount recursion. | |
93 | * | |
94 | * When it cannot find a suitable sb, it allocates a new | |
95 | * one (this one), and tries again to find a suitable old | |
96 | * one. | |
97 | * | |
98 | * In case that succeeds, it will acquire the s_umount | |
99 | * lock of the old one. Since these are clearly distrinct | |
100 | * locks, and this object isn't exposed yet, there's no | |
101 | * risk of deadlocks. | |
102 | * | |
103 | * Annotate this by putting this lock in a different | |
104 | * subclass. | |
105 | */ | |
106 | down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); | |
b20bd1a5 | 107 | s->s_count = 1; |
1da177e4 | 108 | atomic_set(&s->s_active, 1); |
a11f3a05 | 109 | mutex_init(&s->s_vfs_rename_mutex); |
51ee049e | 110 | lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key); |
d3be915f IM |
111 | mutex_init(&s->s_dquot.dqio_mutex); |
112 | mutex_init(&s->s_dquot.dqonoff_mutex); | |
1da177e4 LT |
113 | init_rwsem(&s->s_dquot.dqptr_sem); |
114 | init_waitqueue_head(&s->s_wait_unfrozen); | |
115 | s->s_maxbytes = MAX_NON_LFS; | |
1da177e4 LT |
116 | s->s_op = &default_op; |
117 | s->s_time_gran = 1000000000; | |
c515e1fd | 118 | s->cleancache_poolid = -1; |
1da177e4 LT |
119 | } |
120 | out: | |
121 | return s; | |
122 | } | |
123 | ||
124 | /** | |
125 | * destroy_super - frees a superblock | |
126 | * @s: superblock to free | |
127 | * | |
128 | * Frees a superblock. | |
129 | */ | |
130 | static inline void destroy_super(struct super_block *s) | |
131 | { | |
6416ccb7 NP |
132 | #ifdef CONFIG_SMP |
133 | free_percpu(s->s_files); | |
134 | #endif | |
1da177e4 | 135 | security_sb_free(s); |
79c0b2df | 136 | kfree(s->s_subtype); |
b3b304a2 | 137 | kfree(s->s_options); |
1da177e4 LT |
138 | kfree(s); |
139 | } | |
140 | ||
141 | /* Superblock refcounting */ | |
142 | ||
143 | /* | |
35cf7ba0 | 144 | * Drop a superblock's refcount. The caller must hold sb_lock. |
1da177e4 | 145 | */ |
35cf7ba0 | 146 | void __put_super(struct super_block *sb) |
1da177e4 | 147 | { |
1da177e4 | 148 | if (!--sb->s_count) { |
551de6f3 | 149 | list_del_init(&sb->s_list); |
1da177e4 | 150 | destroy_super(sb); |
1da177e4 | 151 | } |
1da177e4 LT |
152 | } |
153 | ||
154 | /** | |
155 | * put_super - drop a temporary reference to superblock | |
156 | * @sb: superblock in question | |
157 | * | |
158 | * Drops a temporary reference, frees superblock if there's no | |
159 | * references left. | |
160 | */ | |
03ba3782 | 161 | void put_super(struct super_block *sb) |
1da177e4 LT |
162 | { |
163 | spin_lock(&sb_lock); | |
164 | __put_super(sb); | |
165 | spin_unlock(&sb_lock); | |
166 | } | |
167 | ||
168 | ||
169 | /** | |
1712ac8f | 170 | * deactivate_locked_super - drop an active reference to superblock |
1da177e4 LT |
171 | * @s: superblock to deactivate |
172 | * | |
1712ac8f AV |
173 | * Drops an active reference to superblock, converting it into a temprory |
174 | * one if there is no other active references left. In that case we | |
1da177e4 LT |
175 | * tell fs driver to shut it down and drop the temporary reference we |
176 | * had just acquired. | |
1712ac8f AV |
177 | * |
178 | * Caller holds exclusive lock on superblock; that lock is released. | |
1da177e4 | 179 | */ |
1712ac8f | 180 | void deactivate_locked_super(struct super_block *s) |
1da177e4 LT |
181 | { |
182 | struct file_system_type *fs = s->s_type; | |
b20bd1a5 | 183 | if (atomic_dec_and_test(&s->s_active)) { |
c515e1fd | 184 | cleancache_flush_fs(s); |
1da177e4 | 185 | fs->kill_sb(s); |
d863b50a BH |
186 | /* |
187 | * We need to call rcu_barrier so all the delayed rcu free | |
188 | * inodes are flushed before we release the fs module. | |
189 | */ | |
190 | rcu_barrier(); | |
1da177e4 LT |
191 | put_filesystem(fs); |
192 | put_super(s); | |
1712ac8f AV |
193 | } else { |
194 | up_write(&s->s_umount); | |
1da177e4 LT |
195 | } |
196 | } | |
197 | ||
1712ac8f | 198 | EXPORT_SYMBOL(deactivate_locked_super); |
1da177e4 | 199 | |
74dbbdd7 | 200 | /** |
1712ac8f | 201 | * deactivate_super - drop an active reference to superblock |
74dbbdd7 AV |
202 | * @s: superblock to deactivate |
203 | * | |
1712ac8f AV |
204 | * Variant of deactivate_locked_super(), except that superblock is *not* |
205 | * locked by caller. If we are going to drop the final active reference, | |
206 | * lock will be acquired prior to that. | |
74dbbdd7 | 207 | */ |
1712ac8f | 208 | void deactivate_super(struct super_block *s) |
74dbbdd7 | 209 | { |
1712ac8f AV |
210 | if (!atomic_add_unless(&s->s_active, -1, 1)) { |
211 | down_write(&s->s_umount); | |
212 | deactivate_locked_super(s); | |
74dbbdd7 AV |
213 | } |
214 | } | |
215 | ||
1712ac8f | 216 | EXPORT_SYMBOL(deactivate_super); |
74dbbdd7 | 217 | |
1da177e4 LT |
218 | /** |
219 | * grab_super - acquire an active reference | |
220 | * @s: reference we are trying to make active | |
221 | * | |
222 | * Tries to acquire an active reference. grab_super() is used when we | |
223 | * had just found a superblock in super_blocks or fs_type->fs_supers | |
224 | * and want to turn it into a full-blown active reference. grab_super() | |
225 | * is called with sb_lock held and drops it. Returns 1 in case of | |
226 | * success, 0 if we had failed (superblock contents was already dead or | |
227 | * dying when grab_super() had been called). | |
228 | */ | |
9c4dbee7 | 229 | static int grab_super(struct super_block *s) __releases(sb_lock) |
1da177e4 | 230 | { |
b20bd1a5 AV |
231 | if (atomic_inc_not_zero(&s->s_active)) { |
232 | spin_unlock(&sb_lock); | |
b20bd1a5 AV |
233 | return 1; |
234 | } | |
235 | /* it's going away */ | |
1da177e4 LT |
236 | s->s_count++; |
237 | spin_unlock(&sb_lock); | |
1712ac8f | 238 | /* wait for it to die */ |
1da177e4 | 239 | down_write(&s->s_umount); |
1da177e4 LT |
240 | up_write(&s->s_umount); |
241 | put_super(s); | |
1da177e4 LT |
242 | return 0; |
243 | } | |
244 | ||
914e2637 AV |
245 | /* |
246 | * Superblock locking. We really ought to get rid of these two. | |
247 | */ | |
248 | void lock_super(struct super_block * sb) | |
249 | { | |
250 | get_fs_excl(); | |
251 | mutex_lock(&sb->s_lock); | |
252 | } | |
253 | ||
254 | void unlock_super(struct super_block * sb) | |
255 | { | |
256 | put_fs_excl(); | |
257 | mutex_unlock(&sb->s_lock); | |
258 | } | |
259 | ||
260 | EXPORT_SYMBOL(lock_super); | |
261 | EXPORT_SYMBOL(unlock_super); | |
262 | ||
1da177e4 LT |
263 | /** |
264 | * generic_shutdown_super - common helper for ->kill_sb() | |
265 | * @sb: superblock to kill | |
266 | * | |
267 | * generic_shutdown_super() does all fs-independent work on superblock | |
268 | * shutdown. Typical ->kill_sb() should pick all fs-specific objects | |
269 | * that need destruction out of superblock, call generic_shutdown_super() | |
270 | * and release aforementioned objects. Note: dentries and inodes _are_ | |
271 | * taken care of and do not need specific handling. | |
c636ebdb DH |
272 | * |
273 | * Upon calling this function, the filesystem may no longer alter or | |
274 | * rearrange the set of dentries belonging to this super_block, nor may it | |
275 | * change the attachments of dentries to inodes. | |
1da177e4 LT |
276 | */ |
277 | void generic_shutdown_super(struct super_block *sb) | |
278 | { | |
ee9b6d61 | 279 | const struct super_operations *sop = sb->s_op; |
1da177e4 | 280 | |
efaee192 | 281 | |
c636ebdb DH |
282 | if (sb->s_root) { |
283 | shrink_dcache_for_umount(sb); | |
60b0680f | 284 | sync_filesystem(sb); |
a9e220f8 | 285 | get_fs_excl(); |
1da177e4 | 286 | sb->s_flags &= ~MS_ACTIVE; |
efaee192 | 287 | |
63997e98 AV |
288 | fsnotify_unmount_inodes(&sb->s_inodes); |
289 | ||
290 | evict_inodes(sb); | |
1da177e4 | 291 | |
1da177e4 LT |
292 | if (sop->put_super) |
293 | sop->put_super(sb); | |
294 | ||
63997e98 | 295 | if (!list_empty(&sb->s_inodes)) { |
7b4fe29e DJ |
296 | printk("VFS: Busy inodes after unmount of %s. " |
297 | "Self-destruct in 5 seconds. Have a nice day...\n", | |
298 | sb->s_id); | |
1da177e4 | 299 | } |
a9e220f8 | 300 | put_fs_excl(); |
1da177e4 LT |
301 | } |
302 | spin_lock(&sb_lock); | |
303 | /* should be initialized for __put_super_and_need_restart() */ | |
551de6f3 | 304 | list_del_init(&sb->s_instances); |
1da177e4 LT |
305 | spin_unlock(&sb_lock); |
306 | up_write(&sb->s_umount); | |
307 | } | |
308 | ||
309 | EXPORT_SYMBOL(generic_shutdown_super); | |
310 | ||
311 | /** | |
312 | * sget - find or create a superblock | |
313 | * @type: filesystem type superblock should belong to | |
314 | * @test: comparison callback | |
315 | * @set: setup callback | |
316 | * @data: argument to each of them | |
317 | */ | |
318 | struct super_block *sget(struct file_system_type *type, | |
319 | int (*test)(struct super_block *,void *), | |
320 | int (*set)(struct super_block *,void *), | |
321 | void *data) | |
322 | { | |
323 | struct super_block *s = NULL; | |
d4730127 | 324 | struct super_block *old; |
1da177e4 LT |
325 | int err; |
326 | ||
327 | retry: | |
328 | spin_lock(&sb_lock); | |
d4730127 MK |
329 | if (test) { |
330 | list_for_each_entry(old, &type->fs_supers, s_instances) { | |
331 | if (!test(old, data)) | |
332 | continue; | |
333 | if (!grab_super(old)) | |
334 | goto retry; | |
a3cfbb53 LZ |
335 | if (s) { |
336 | up_write(&s->s_umount); | |
d4730127 | 337 | destroy_super(s); |
7a4dec53 | 338 | s = NULL; |
a3cfbb53 | 339 | } |
d3f21473 | 340 | down_write(&old->s_umount); |
7a4dec53 AV |
341 | if (unlikely(!(old->s_flags & MS_BORN))) { |
342 | deactivate_locked_super(old); | |
343 | goto retry; | |
344 | } | |
d4730127 MK |
345 | return old; |
346 | } | |
1da177e4 LT |
347 | } |
348 | if (!s) { | |
349 | spin_unlock(&sb_lock); | |
cf516249 | 350 | s = alloc_super(type); |
1da177e4 LT |
351 | if (!s) |
352 | return ERR_PTR(-ENOMEM); | |
353 | goto retry; | |
354 | } | |
355 | ||
356 | err = set(s, data); | |
357 | if (err) { | |
358 | spin_unlock(&sb_lock); | |
a3cfbb53 | 359 | up_write(&s->s_umount); |
1da177e4 LT |
360 | destroy_super(s); |
361 | return ERR_PTR(err); | |
362 | } | |
363 | s->s_type = type; | |
364 | strlcpy(s->s_id, type->name, sizeof(s->s_id)); | |
365 | list_add_tail(&s->s_list, &super_blocks); | |
366 | list_add(&s->s_instances, &type->fs_supers); | |
367 | spin_unlock(&sb_lock); | |
368 | get_filesystem(type); | |
369 | return s; | |
370 | } | |
371 | ||
372 | EXPORT_SYMBOL(sget); | |
373 | ||
374 | void drop_super(struct super_block *sb) | |
375 | { | |
376 | up_read(&sb->s_umount); | |
377 | put_super(sb); | |
378 | } | |
379 | ||
380 | EXPORT_SYMBOL(drop_super); | |
381 | ||
e5004753 CH |
382 | /** |
383 | * sync_supers - helper for periodic superblock writeback | |
384 | * | |
385 | * Call the write_super method if present on all dirty superblocks in | |
386 | * the system. This is for the periodic writeback used by most older | |
387 | * filesystems. For data integrity superblock writeback use | |
388 | * sync_filesystems() instead. | |
389 | * | |
1da177e4 LT |
390 | * Note: check the dirty flag before waiting, so we don't |
391 | * hold up the sync while mounting a device. (The newly | |
392 | * mounted device won't need syncing.) | |
393 | */ | |
394 | void sync_supers(void) | |
395 | { | |
dca33252 | 396 | struct super_block *sb, *p = NULL; |
618f0636 | 397 | |
1da177e4 | 398 | spin_lock(&sb_lock); |
dca33252 | 399 | list_for_each_entry(sb, &super_blocks, s_list) { |
551de6f3 AV |
400 | if (list_empty(&sb->s_instances)) |
401 | continue; | |
e5004753 | 402 | if (sb->s_op->write_super && sb->s_dirt) { |
1da177e4 LT |
403 | sb->s_count++; |
404 | spin_unlock(&sb_lock); | |
e5004753 | 405 | |
1da177e4 | 406 | down_read(&sb->s_umount); |
e5004753 CH |
407 | if (sb->s_root && sb->s_dirt) |
408 | sb->s_op->write_super(sb); | |
618f0636 | 409 | up_read(&sb->s_umount); |
e5004753 | 410 | |
618f0636 | 411 | spin_lock(&sb_lock); |
dca33252 AV |
412 | if (p) |
413 | __put_super(p); | |
414 | p = sb; | |
618f0636 KK |
415 | } |
416 | } | |
dca33252 AV |
417 | if (p) |
418 | __put_super(p); | |
1da177e4 LT |
419 | spin_unlock(&sb_lock); |
420 | } | |
421 | ||
01a05b33 AV |
422 | /** |
423 | * iterate_supers - call function for all active superblocks | |
424 | * @f: function to call | |
425 | * @arg: argument to pass to it | |
426 | * | |
427 | * Scans the superblock list and calls given function, passing it | |
428 | * locked superblock and given argument. | |
429 | */ | |
430 | void iterate_supers(void (*f)(struct super_block *, void *), void *arg) | |
431 | { | |
dca33252 | 432 | struct super_block *sb, *p = NULL; |
01a05b33 AV |
433 | |
434 | spin_lock(&sb_lock); | |
dca33252 | 435 | list_for_each_entry(sb, &super_blocks, s_list) { |
01a05b33 AV |
436 | if (list_empty(&sb->s_instances)) |
437 | continue; | |
438 | sb->s_count++; | |
439 | spin_unlock(&sb_lock); | |
440 | ||
441 | down_read(&sb->s_umount); | |
442 | if (sb->s_root) | |
443 | f(sb, arg); | |
444 | up_read(&sb->s_umount); | |
445 | ||
446 | spin_lock(&sb_lock); | |
dca33252 AV |
447 | if (p) |
448 | __put_super(p); | |
449 | p = sb; | |
01a05b33 | 450 | } |
dca33252 AV |
451 | if (p) |
452 | __put_super(p); | |
01a05b33 AV |
453 | spin_unlock(&sb_lock); |
454 | } | |
455 | ||
43e15cdb AV |
456 | /** |
457 | * iterate_supers_type - call function for superblocks of given type | |
458 | * @type: fs type | |
459 | * @f: function to call | |
460 | * @arg: argument to pass to it | |
461 | * | |
462 | * Scans the superblock list and calls given function, passing it | |
463 | * locked superblock and given argument. | |
464 | */ | |
465 | void iterate_supers_type(struct file_system_type *type, | |
466 | void (*f)(struct super_block *, void *), void *arg) | |
467 | { | |
468 | struct super_block *sb, *p = NULL; | |
469 | ||
470 | spin_lock(&sb_lock); | |
471 | list_for_each_entry(sb, &type->fs_supers, s_instances) { | |
472 | sb->s_count++; | |
473 | spin_unlock(&sb_lock); | |
474 | ||
475 | down_read(&sb->s_umount); | |
476 | if (sb->s_root) | |
477 | f(sb, arg); | |
478 | up_read(&sb->s_umount); | |
479 | ||
480 | spin_lock(&sb_lock); | |
481 | if (p) | |
482 | __put_super(p); | |
483 | p = sb; | |
484 | } | |
485 | if (p) | |
486 | __put_super(p); | |
487 | spin_unlock(&sb_lock); | |
488 | } | |
489 | ||
490 | EXPORT_SYMBOL(iterate_supers_type); | |
491 | ||
1da177e4 LT |
492 | /** |
493 | * get_super - get the superblock of a device | |
494 | * @bdev: device to get the superblock for | |
495 | * | |
496 | * Scans the superblock list and finds the superblock of the file system | |
497 | * mounted on the device given. %NULL is returned if no match is found. | |
498 | */ | |
499 | ||
df40c01a | 500 | struct super_block *get_super(struct block_device *bdev) |
1da177e4 | 501 | { |
618f0636 KK |
502 | struct super_block *sb; |
503 | ||
1da177e4 LT |
504 | if (!bdev) |
505 | return NULL; | |
618f0636 | 506 | |
1da177e4 | 507 | spin_lock(&sb_lock); |
618f0636 KK |
508 | rescan: |
509 | list_for_each_entry(sb, &super_blocks, s_list) { | |
551de6f3 AV |
510 | if (list_empty(&sb->s_instances)) |
511 | continue; | |
618f0636 KK |
512 | if (sb->s_bdev == bdev) { |
513 | sb->s_count++; | |
1da177e4 | 514 | spin_unlock(&sb_lock); |
618f0636 | 515 | down_read(&sb->s_umount); |
df40c01a | 516 | /* still alive? */ |
618f0636 KK |
517 | if (sb->s_root) |
518 | return sb; | |
519 | up_read(&sb->s_umount); | |
df40c01a | 520 | /* nope, got unmounted */ |
618f0636 | 521 | spin_lock(&sb_lock); |
df40c01a AV |
522 | __put_super(sb); |
523 | goto rescan; | |
1da177e4 LT |
524 | } |
525 | } | |
526 | spin_unlock(&sb_lock); | |
527 | return NULL; | |
528 | } | |
529 | ||
530 | EXPORT_SYMBOL(get_super); | |
4504230a CH |
531 | |
532 | /** | |
533 | * get_active_super - get an active reference to the superblock of a device | |
534 | * @bdev: device to get the superblock for | |
535 | * | |
536 | * Scans the superblock list and finds the superblock of the file system | |
537 | * mounted on the device given. Returns the superblock with an active | |
d3f21473 | 538 | * reference or %NULL if none was found. |
4504230a CH |
539 | */ |
540 | struct super_block *get_active_super(struct block_device *bdev) | |
541 | { | |
542 | struct super_block *sb; | |
543 | ||
544 | if (!bdev) | |
545 | return NULL; | |
546 | ||
1494583d | 547 | restart: |
4504230a CH |
548 | spin_lock(&sb_lock); |
549 | list_for_each_entry(sb, &super_blocks, s_list) { | |
551de6f3 AV |
550 | if (list_empty(&sb->s_instances)) |
551 | continue; | |
1494583d AV |
552 | if (sb->s_bdev == bdev) { |
553 | if (grab_super(sb)) /* drops sb_lock */ | |
554 | return sb; | |
555 | else | |
556 | goto restart; | |
557 | } | |
4504230a CH |
558 | } |
559 | spin_unlock(&sb_lock); | |
560 | return NULL; | |
561 | } | |
1da177e4 | 562 | |
df40c01a | 563 | struct super_block *user_get_super(dev_t dev) |
1da177e4 | 564 | { |
618f0636 | 565 | struct super_block *sb; |
1da177e4 | 566 | |
1da177e4 | 567 | spin_lock(&sb_lock); |
618f0636 KK |
568 | rescan: |
569 | list_for_each_entry(sb, &super_blocks, s_list) { | |
551de6f3 AV |
570 | if (list_empty(&sb->s_instances)) |
571 | continue; | |
618f0636 KK |
572 | if (sb->s_dev == dev) { |
573 | sb->s_count++; | |
1da177e4 | 574 | spin_unlock(&sb_lock); |
618f0636 | 575 | down_read(&sb->s_umount); |
df40c01a | 576 | /* still alive? */ |
618f0636 KK |
577 | if (sb->s_root) |
578 | return sb; | |
579 | up_read(&sb->s_umount); | |
df40c01a | 580 | /* nope, got unmounted */ |
618f0636 | 581 | spin_lock(&sb_lock); |
df40c01a AV |
582 | __put_super(sb); |
583 | goto rescan; | |
1da177e4 LT |
584 | } |
585 | } | |
586 | spin_unlock(&sb_lock); | |
587 | return NULL; | |
588 | } | |
589 | ||
1da177e4 LT |
590 | /** |
591 | * do_remount_sb - asks filesystem to change mount options. | |
592 | * @sb: superblock in question | |
593 | * @flags: numeric part of options | |
594 | * @data: the rest of options | |
595 | * @force: whether or not to force the change | |
596 | * | |
597 | * Alters the mount options of a mounted file system. | |
598 | */ | |
599 | int do_remount_sb(struct super_block *sb, int flags, void *data, int force) | |
600 | { | |
601 | int retval; | |
c79d967d | 602 | int remount_ro; |
4504230a CH |
603 | |
604 | if (sb->s_frozen != SB_UNFROZEN) | |
605 | return -EBUSY; | |
606 | ||
9361401e | 607 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
608 | if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) |
609 | return -EACCES; | |
9361401e | 610 | #endif |
4504230a | 611 | |
1da177e4 LT |
612 | if (flags & MS_RDONLY) |
613 | acct_auto_close(sb); | |
614 | shrink_dcache_sb(sb); | |
60b0680f | 615 | sync_filesystem(sb); |
1da177e4 | 616 | |
d208bbdd | 617 | remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); |
d208bbdd | 618 | |
1da177e4 LT |
619 | /* If we are remounting RDONLY and current sb is read/write, |
620 | make sure there are no rw files opened */ | |
d208bbdd | 621 | if (remount_ro) { |
1da177e4 LT |
622 | if (force) |
623 | mark_files_ro(sb); | |
b0895513 | 624 | else if (!fs_may_remount_ro(sb)) |
1da177e4 LT |
625 | return -EBUSY; |
626 | } | |
627 | ||
628 | if (sb->s_op->remount_fs) { | |
1da177e4 | 629 | retval = sb->s_op->remount_fs(sb, &flags, data); |
b0895513 | 630 | if (retval) |
1da177e4 LT |
631 | return retval; |
632 | } | |
633 | sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); | |
c79d967d | 634 | |
d208bbdd NP |
635 | /* |
636 | * Some filesystems modify their metadata via some other path than the | |
637 | * bdev buffer cache (eg. use a private mapping, or directories in | |
638 | * pagecache, etc). Also file data modifications go via their own | |
639 | * mappings. So If we try to mount readonly then copy the filesystem | |
640 | * from bdev, we could get stale data, so invalidate it to give a best | |
641 | * effort at coherency. | |
642 | */ | |
643 | if (remount_ro && sb->s_bdev) | |
644 | invalidate_bdev(sb->s_bdev); | |
1da177e4 LT |
645 | return 0; |
646 | } | |
647 | ||
a2a9537a | 648 | static void do_emergency_remount(struct work_struct *work) |
1da177e4 | 649 | { |
dca33252 | 650 | struct super_block *sb, *p = NULL; |
1da177e4 LT |
651 | |
652 | spin_lock(&sb_lock); | |
dca33252 | 653 | list_for_each_entry(sb, &super_blocks, s_list) { |
551de6f3 AV |
654 | if (list_empty(&sb->s_instances)) |
655 | continue; | |
1da177e4 LT |
656 | sb->s_count++; |
657 | spin_unlock(&sb_lock); | |
443b94ba | 658 | down_write(&sb->s_umount); |
1da177e4 LT |
659 | if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) { |
660 | /* | |
1da177e4 LT |
661 | * What lock protects sb->s_flags?? |
662 | */ | |
1da177e4 | 663 | do_remount_sb(sb, MS_RDONLY, NULL, 1); |
1da177e4 | 664 | } |
443b94ba | 665 | up_write(&sb->s_umount); |
1da177e4 | 666 | spin_lock(&sb_lock); |
dca33252 AV |
667 | if (p) |
668 | __put_super(p); | |
669 | p = sb; | |
1da177e4 | 670 | } |
dca33252 AV |
671 | if (p) |
672 | __put_super(p); | |
1da177e4 | 673 | spin_unlock(&sb_lock); |
a2a9537a | 674 | kfree(work); |
1da177e4 LT |
675 | printk("Emergency Remount complete\n"); |
676 | } | |
677 | ||
678 | void emergency_remount(void) | |
679 | { | |
a2a9537a JA |
680 | struct work_struct *work; |
681 | ||
682 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
683 | if (work) { | |
684 | INIT_WORK(work, do_emergency_remount); | |
685 | schedule_work(work); | |
686 | } | |
1da177e4 LT |
687 | } |
688 | ||
689 | /* | |
690 | * Unnamed block devices are dummy devices used by virtual | |
691 | * filesystems which don't use real block-devices. -- jrs | |
692 | */ | |
693 | ||
ad76cbc6 | 694 | static DEFINE_IDA(unnamed_dev_ida); |
1da177e4 | 695 | static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ |
c63e09ec | 696 | static int unnamed_dev_start = 0; /* don't bother trying below it */ |
1da177e4 | 697 | |
0ee5dc67 | 698 | int get_anon_bdev(dev_t *p) |
1da177e4 LT |
699 | { |
700 | int dev; | |
701 | int error; | |
702 | ||
703 | retry: | |
ad76cbc6 | 704 | if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) |
1da177e4 LT |
705 | return -ENOMEM; |
706 | spin_lock(&unnamed_dev_lock); | |
c63e09ec | 707 | error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev); |
f21f6220 AV |
708 | if (!error) |
709 | unnamed_dev_start = dev + 1; | |
1da177e4 LT |
710 | spin_unlock(&unnamed_dev_lock); |
711 | if (error == -EAGAIN) | |
712 | /* We raced and lost with another CPU. */ | |
713 | goto retry; | |
714 | else if (error) | |
715 | return -EAGAIN; | |
716 | ||
717 | if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { | |
718 | spin_lock(&unnamed_dev_lock); | |
ad76cbc6 | 719 | ida_remove(&unnamed_dev_ida, dev); |
f21f6220 AV |
720 | if (unnamed_dev_start > dev) |
721 | unnamed_dev_start = dev; | |
1da177e4 LT |
722 | spin_unlock(&unnamed_dev_lock); |
723 | return -EMFILE; | |
724 | } | |
0ee5dc67 | 725 | *p = MKDEV(0, dev & MINORMASK); |
1da177e4 LT |
726 | return 0; |
727 | } | |
0ee5dc67 | 728 | EXPORT_SYMBOL(get_anon_bdev); |
1da177e4 | 729 | |
0ee5dc67 | 730 | void free_anon_bdev(dev_t dev) |
1da177e4 | 731 | { |
0ee5dc67 | 732 | int slot = MINOR(dev); |
1da177e4 | 733 | spin_lock(&unnamed_dev_lock); |
ad76cbc6 | 734 | ida_remove(&unnamed_dev_ida, slot); |
c63e09ec AV |
735 | if (slot < unnamed_dev_start) |
736 | unnamed_dev_start = slot; | |
1da177e4 LT |
737 | spin_unlock(&unnamed_dev_lock); |
738 | } | |
0ee5dc67 AV |
739 | EXPORT_SYMBOL(free_anon_bdev); |
740 | ||
741 | int set_anon_super(struct super_block *s, void *data) | |
742 | { | |
743 | int error = get_anon_bdev(&s->s_dev); | |
744 | if (!error) | |
745 | s->s_bdi = &noop_backing_dev_info; | |
746 | return error; | |
747 | } | |
748 | ||
749 | EXPORT_SYMBOL(set_anon_super); | |
750 | ||
751 | void kill_anon_super(struct super_block *sb) | |
752 | { | |
753 | dev_t dev = sb->s_dev; | |
754 | generic_shutdown_super(sb); | |
755 | free_anon_bdev(dev); | |
756 | } | |
1da177e4 LT |
757 | |
758 | EXPORT_SYMBOL(kill_anon_super); | |
759 | ||
1da177e4 LT |
760 | void kill_litter_super(struct super_block *sb) |
761 | { | |
762 | if (sb->s_root) | |
763 | d_genocide(sb->s_root); | |
764 | kill_anon_super(sb); | |
765 | } | |
766 | ||
767 | EXPORT_SYMBOL(kill_litter_super); | |
768 | ||
909e6d94 SH |
769 | static int ns_test_super(struct super_block *sb, void *data) |
770 | { | |
771 | return sb->s_fs_info == data; | |
772 | } | |
773 | ||
774 | static int ns_set_super(struct super_block *sb, void *data) | |
775 | { | |
776 | sb->s_fs_info = data; | |
777 | return set_anon_super(sb, NULL); | |
778 | } | |
779 | ||
ceefda69 AV |
780 | struct dentry *mount_ns(struct file_system_type *fs_type, int flags, |
781 | void *data, int (*fill_super)(struct super_block *, void *, int)) | |
909e6d94 SH |
782 | { |
783 | struct super_block *sb; | |
784 | ||
785 | sb = sget(fs_type, ns_test_super, ns_set_super, data); | |
786 | if (IS_ERR(sb)) | |
ceefda69 | 787 | return ERR_CAST(sb); |
909e6d94 SH |
788 | |
789 | if (!sb->s_root) { | |
790 | int err; | |
791 | sb->s_flags = flags; | |
792 | err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); | |
793 | if (err) { | |
74dbbdd7 | 794 | deactivate_locked_super(sb); |
ceefda69 | 795 | return ERR_PTR(err); |
909e6d94 SH |
796 | } |
797 | ||
798 | sb->s_flags |= MS_ACTIVE; | |
799 | } | |
800 | ||
ceefda69 | 801 | return dget(sb->s_root); |
909e6d94 SH |
802 | } |
803 | ||
ceefda69 | 804 | EXPORT_SYMBOL(mount_ns); |
909e6d94 | 805 | |
9361401e | 806 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
807 | static int set_bdev_super(struct super_block *s, void *data) |
808 | { | |
809 | s->s_bdev = data; | |
810 | s->s_dev = s->s_bdev->bd_dev; | |
32a88aa1 JA |
811 | |
812 | /* | |
813 | * We set the bdi here to the queue backing, file systems can | |
814 | * overwrite this in ->fill_super() | |
815 | */ | |
816 | s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info; | |
1da177e4 LT |
817 | return 0; |
818 | } | |
819 | ||
820 | static int test_bdev_super(struct super_block *s, void *data) | |
821 | { | |
822 | return (void *)s->s_bdev == data; | |
823 | } | |
824 | ||
152a0836 | 825 | struct dentry *mount_bdev(struct file_system_type *fs_type, |
1da177e4 | 826 | int flags, const char *dev_name, void *data, |
152a0836 | 827 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
828 | { |
829 | struct block_device *bdev; | |
830 | struct super_block *s; | |
d4d77629 | 831 | fmode_t mode = FMODE_READ | FMODE_EXCL; |
1da177e4 LT |
832 | int error = 0; |
833 | ||
30c40d2c AV |
834 | if (!(flags & MS_RDONLY)) |
835 | mode |= FMODE_WRITE; | |
836 | ||
d4d77629 | 837 | bdev = blkdev_get_by_path(dev_name, mode, fs_type); |
1da177e4 | 838 | if (IS_ERR(bdev)) |
152a0836 | 839 | return ERR_CAST(bdev); |
1da177e4 LT |
840 | |
841 | /* | |
842 | * once the super is inserted into the list by sget, s_umount | |
843 | * will protect the lockfs code from trying to start a snapshot | |
844 | * while we are mounting | |
845 | */ | |
4fadd7bb CH |
846 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
847 | if (bdev->bd_fsfreeze_count > 0) { | |
848 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
849 | error = -EBUSY; | |
850 | goto error_bdev; | |
851 | } | |
1da177e4 | 852 | s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); |
4fadd7bb | 853 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
1da177e4 | 854 | if (IS_ERR(s)) |
454e2398 | 855 | goto error_s; |
1da177e4 LT |
856 | |
857 | if (s->s_root) { | |
858 | if ((flags ^ s->s_flags) & MS_RDONLY) { | |
74dbbdd7 | 859 | deactivate_locked_super(s); |
454e2398 DH |
860 | error = -EBUSY; |
861 | goto error_bdev; | |
1da177e4 | 862 | } |
454e2398 | 863 | |
4f331f01 TH |
864 | /* |
865 | * s_umount nests inside bd_mutex during | |
e525fd89 TH |
866 | * __invalidate_device(). blkdev_put() acquires |
867 | * bd_mutex and can't be called under s_umount. Drop | |
868 | * s_umount temporarily. This is safe as we're | |
869 | * holding an active reference. | |
4f331f01 TH |
870 | */ |
871 | up_write(&s->s_umount); | |
d4d77629 | 872 | blkdev_put(bdev, mode); |
4f331f01 | 873 | down_write(&s->s_umount); |
1da177e4 LT |
874 | } else { |
875 | char b[BDEVNAME_SIZE]; | |
876 | ||
9e1f1de0 | 877 | s->s_flags = flags | MS_NOSEC; |
30c40d2c | 878 | s->s_mode = mode; |
1da177e4 | 879 | strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); |
e78c9a00 | 880 | sb_set_blocksize(s, block_size(bdev)); |
9b04c997 | 881 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 882 | if (error) { |
74dbbdd7 | 883 | deactivate_locked_super(s); |
454e2398 | 884 | goto error; |
fa675765 | 885 | } |
454e2398 DH |
886 | |
887 | s->s_flags |= MS_ACTIVE; | |
87d8fe1e | 888 | bdev->bd_super = s; |
1da177e4 LT |
889 | } |
890 | ||
152a0836 | 891 | return dget(s->s_root); |
1da177e4 | 892 | |
454e2398 DH |
893 | error_s: |
894 | error = PTR_ERR(s); | |
895 | error_bdev: | |
d4d77629 | 896 | blkdev_put(bdev, mode); |
454e2398 | 897 | error: |
152a0836 AV |
898 | return ERR_PTR(error); |
899 | } | |
900 | EXPORT_SYMBOL(mount_bdev); | |
901 | ||
1da177e4 LT |
902 | void kill_block_super(struct super_block *sb) |
903 | { | |
904 | struct block_device *bdev = sb->s_bdev; | |
30c40d2c | 905 | fmode_t mode = sb->s_mode; |
1da177e4 | 906 | |
ddbaaf30 | 907 | bdev->bd_super = NULL; |
1da177e4 LT |
908 | generic_shutdown_super(sb); |
909 | sync_blockdev(bdev); | |
d4d77629 | 910 | WARN_ON_ONCE(!(mode & FMODE_EXCL)); |
e525fd89 | 911 | blkdev_put(bdev, mode | FMODE_EXCL); |
1da177e4 LT |
912 | } |
913 | ||
914 | EXPORT_SYMBOL(kill_block_super); | |
9361401e | 915 | #endif |
1da177e4 | 916 | |
3c26ff6e | 917 | struct dentry *mount_nodev(struct file_system_type *fs_type, |
1da177e4 | 918 | int flags, void *data, |
3c26ff6e | 919 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
920 | { |
921 | int error; | |
922 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
923 | ||
924 | if (IS_ERR(s)) | |
3c26ff6e | 925 | return ERR_CAST(s); |
1da177e4 LT |
926 | |
927 | s->s_flags = flags; | |
928 | ||
9b04c997 | 929 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 930 | if (error) { |
74dbbdd7 | 931 | deactivate_locked_super(s); |
3c26ff6e | 932 | return ERR_PTR(error); |
1da177e4 LT |
933 | } |
934 | s->s_flags |= MS_ACTIVE; | |
3c26ff6e | 935 | return dget(s->s_root); |
1da177e4 | 936 | } |
3c26ff6e AV |
937 | EXPORT_SYMBOL(mount_nodev); |
938 | ||
1da177e4 LT |
939 | static int compare_single(struct super_block *s, void *p) |
940 | { | |
941 | return 1; | |
942 | } | |
943 | ||
fc14f2fe | 944 | struct dentry *mount_single(struct file_system_type *fs_type, |
1da177e4 | 945 | int flags, void *data, |
fc14f2fe | 946 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
947 | { |
948 | struct super_block *s; | |
949 | int error; | |
950 | ||
951 | s = sget(fs_type, compare_single, set_anon_super, NULL); | |
952 | if (IS_ERR(s)) | |
fc14f2fe | 953 | return ERR_CAST(s); |
1da177e4 LT |
954 | if (!s->s_root) { |
955 | s->s_flags = flags; | |
9b04c997 | 956 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 957 | if (error) { |
74dbbdd7 | 958 | deactivate_locked_super(s); |
fc14f2fe | 959 | return ERR_PTR(error); |
1da177e4 LT |
960 | } |
961 | s->s_flags |= MS_ACTIVE; | |
9329d1be KS |
962 | } else { |
963 | do_remount_sb(s, flags, data, 0); | |
1da177e4 | 964 | } |
fc14f2fe AV |
965 | return dget(s->s_root); |
966 | } | |
967 | EXPORT_SYMBOL(mount_single); | |
968 | ||
9d412a43 AV |
969 | struct dentry * |
970 | mount_fs(struct file_system_type *type, int flags, const char *name, void *data) | |
1da177e4 | 971 | { |
c96e41e9 | 972 | struct dentry *root; |
9d412a43 | 973 | struct super_block *sb; |
1da177e4 | 974 | char *secdata = NULL; |
9d412a43 | 975 | int error = -ENOMEM; |
8089352a | 976 | |
e0007529 | 977 | if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { |
1da177e4 | 978 | secdata = alloc_secdata(); |
454e2398 | 979 | if (!secdata) |
9d412a43 | 980 | goto out; |
1da177e4 | 981 | |
e0007529 | 982 | error = security_sb_copy_data(data, secdata); |
454e2398 | 983 | if (error) |
1da177e4 | 984 | goto out_free_secdata; |
1da177e4 LT |
985 | } |
986 | ||
1a102ff9 AV |
987 | root = type->mount(type, flags, name, data); |
988 | if (IS_ERR(root)) { | |
989 | error = PTR_ERR(root); | |
990 | goto out_free_secdata; | |
c96e41e9 | 991 | } |
9d412a43 AV |
992 | sb = root->d_sb; |
993 | BUG_ON(!sb); | |
994 | WARN_ON(!sb->s_bdi); | |
6c510389 | 995 | WARN_ON(sb->s_bdi == &default_backing_dev_info); |
9d412a43 | 996 | sb->s_flags |= MS_BORN; |
454e2398 | 997 | |
9d412a43 | 998 | error = security_sb_kern_mount(sb, flags, secdata); |
5129a469 JE |
999 | if (error) |
1000 | goto out_sb; | |
454e2398 | 1001 | |
42cb56ae JL |
1002 | /* |
1003 | * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE | |
1004 | * but s_maxbytes was an unsigned long long for many releases. Throw | |
1005 | * this warning for a little while to try and catch filesystems that | |
4358b567 | 1006 | * violate this rule. |
42cb56ae | 1007 | */ |
9d412a43 AV |
1008 | WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " |
1009 | "negative value (%lld)\n", type->name, sb->s_maxbytes); | |
42cb56ae | 1010 | |
9d412a43 | 1011 | up_write(&sb->s_umount); |
8680e22f | 1012 | free_secdata(secdata); |
9d412a43 | 1013 | return root; |
1da177e4 | 1014 | out_sb: |
9d412a43 AV |
1015 | dput(root); |
1016 | deactivate_locked_super(sb); | |
1da177e4 LT |
1017 | out_free_secdata: |
1018 | free_secdata(secdata); | |
1da177e4 | 1019 | out: |
454e2398 | 1020 | return ERR_PTR(error); |
1da177e4 LT |
1021 | } |
1022 | ||
18e9e510 | 1023 | /** |
7000d3c4 RD |
1024 | * freeze_super - lock the filesystem and force it into a consistent state |
1025 | * @sb: the super to lock | |
18e9e510 JB |
1026 | * |
1027 | * Syncs the super to make sure the filesystem is consistent and calls the fs's | |
1028 | * freeze_fs. Subsequent calls to this without first thawing the fs will return | |
1029 | * -EBUSY. | |
1030 | */ | |
1031 | int freeze_super(struct super_block *sb) | |
1032 | { | |
1033 | int ret; | |
1034 | ||
1035 | atomic_inc(&sb->s_active); | |
1036 | down_write(&sb->s_umount); | |
1037 | if (sb->s_frozen) { | |
1038 | deactivate_locked_super(sb); | |
1039 | return -EBUSY; | |
1040 | } | |
1041 | ||
1042 | if (sb->s_flags & MS_RDONLY) { | |
1043 | sb->s_frozen = SB_FREEZE_TRANS; | |
1044 | smp_wmb(); | |
1045 | up_write(&sb->s_umount); | |
1046 | return 0; | |
1047 | } | |
1048 | ||
1049 | sb->s_frozen = SB_FREEZE_WRITE; | |
1050 | smp_wmb(); | |
1051 | ||
1052 | sync_filesystem(sb); | |
1053 | ||
1054 | sb->s_frozen = SB_FREEZE_TRANS; | |
1055 | smp_wmb(); | |
1056 | ||
1057 | sync_blockdev(sb->s_bdev); | |
1058 | if (sb->s_op->freeze_fs) { | |
1059 | ret = sb->s_op->freeze_fs(sb); | |
1060 | if (ret) { | |
1061 | printk(KERN_ERR | |
1062 | "VFS:Filesystem freeze failed\n"); | |
1063 | sb->s_frozen = SB_UNFROZEN; | |
1064 | deactivate_locked_super(sb); | |
1065 | return ret; | |
1066 | } | |
1067 | } | |
1068 | up_write(&sb->s_umount); | |
1069 | return 0; | |
1070 | } | |
1071 | EXPORT_SYMBOL(freeze_super); | |
1072 | ||
1073 | /** | |
1074 | * thaw_super -- unlock filesystem | |
1075 | * @sb: the super to thaw | |
1076 | * | |
1077 | * Unlocks the filesystem and marks it writeable again after freeze_super(). | |
1078 | */ | |
1079 | int thaw_super(struct super_block *sb) | |
1080 | { | |
1081 | int error; | |
1082 | ||
1083 | down_write(&sb->s_umount); | |
1084 | if (sb->s_frozen == SB_UNFROZEN) { | |
1085 | up_write(&sb->s_umount); | |
1086 | return -EINVAL; | |
1087 | } | |
1088 | ||
1089 | if (sb->s_flags & MS_RDONLY) | |
1090 | goto out; | |
1091 | ||
1092 | if (sb->s_op->unfreeze_fs) { | |
1093 | error = sb->s_op->unfreeze_fs(sb); | |
1094 | if (error) { | |
1095 | printk(KERN_ERR | |
1096 | "VFS:Filesystem thaw failed\n"); | |
1097 | sb->s_frozen = SB_FREEZE_TRANS; | |
1098 | up_write(&sb->s_umount); | |
1099 | return error; | |
1100 | } | |
1101 | } | |
1102 | ||
1103 | out: | |
1104 | sb->s_frozen = SB_UNFROZEN; | |
1105 | smp_wmb(); | |
1106 | wake_up(&sb->s_wait_unfrozen); | |
1107 | deactivate_locked_super(sb); | |
1108 | ||
1109 | return 0; | |
1110 | } | |
1111 | EXPORT_SYMBOL(thaw_super); |