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Commit | Line | Data |
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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 | ||
12ad3ab6 DC |
245 | /* |
246 | * grab_super_passive - acquire a passive reference | |
247 | * @s: reference we are trying to grab | |
248 | * | |
249 | * Tries to acquire a passive reference. This is used in places where we | |
250 | * cannot take an active reference but we need to ensure that the | |
251 | * superblock does not go away while we are working on it. It returns | |
252 | * false if a reference was not gained, and returns true with the s_umount | |
253 | * lock held in read mode if a reference is gained. On successful return, | |
254 | * the caller must drop the s_umount lock and the passive reference when | |
255 | * done. | |
256 | */ | |
257 | bool grab_super_passive(struct super_block *sb) | |
258 | { | |
259 | spin_lock(&sb_lock); | |
260 | if (list_empty(&sb->s_instances)) { | |
261 | spin_unlock(&sb_lock); | |
262 | return false; | |
263 | } | |
264 | ||
265 | sb->s_count++; | |
266 | spin_unlock(&sb_lock); | |
267 | ||
268 | if (down_read_trylock(&sb->s_umount)) { | |
269 | if (sb->s_root) | |
270 | return true; | |
271 | up_read(&sb->s_umount); | |
272 | } | |
273 | ||
274 | put_super(sb); | |
275 | return false; | |
276 | } | |
277 | ||
914e2637 AV |
278 | /* |
279 | * Superblock locking. We really ought to get rid of these two. | |
280 | */ | |
281 | void lock_super(struct super_block * sb) | |
282 | { | |
283 | get_fs_excl(); | |
284 | mutex_lock(&sb->s_lock); | |
285 | } | |
286 | ||
287 | void unlock_super(struct super_block * sb) | |
288 | { | |
289 | put_fs_excl(); | |
290 | mutex_unlock(&sb->s_lock); | |
291 | } | |
292 | ||
293 | EXPORT_SYMBOL(lock_super); | |
294 | EXPORT_SYMBOL(unlock_super); | |
295 | ||
1da177e4 LT |
296 | /** |
297 | * generic_shutdown_super - common helper for ->kill_sb() | |
298 | * @sb: superblock to kill | |
299 | * | |
300 | * generic_shutdown_super() does all fs-independent work on superblock | |
301 | * shutdown. Typical ->kill_sb() should pick all fs-specific objects | |
302 | * that need destruction out of superblock, call generic_shutdown_super() | |
303 | * and release aforementioned objects. Note: dentries and inodes _are_ | |
304 | * taken care of and do not need specific handling. | |
c636ebdb DH |
305 | * |
306 | * Upon calling this function, the filesystem may no longer alter or | |
307 | * rearrange the set of dentries belonging to this super_block, nor may it | |
308 | * change the attachments of dentries to inodes. | |
1da177e4 LT |
309 | */ |
310 | void generic_shutdown_super(struct super_block *sb) | |
311 | { | |
ee9b6d61 | 312 | const struct super_operations *sop = sb->s_op; |
1da177e4 | 313 | |
efaee192 | 314 | |
c636ebdb DH |
315 | if (sb->s_root) { |
316 | shrink_dcache_for_umount(sb); | |
60b0680f | 317 | sync_filesystem(sb); |
a9e220f8 | 318 | get_fs_excl(); |
1da177e4 | 319 | sb->s_flags &= ~MS_ACTIVE; |
efaee192 | 320 | |
63997e98 AV |
321 | fsnotify_unmount_inodes(&sb->s_inodes); |
322 | ||
323 | evict_inodes(sb); | |
1da177e4 | 324 | |
1da177e4 LT |
325 | if (sop->put_super) |
326 | sop->put_super(sb); | |
327 | ||
63997e98 | 328 | if (!list_empty(&sb->s_inodes)) { |
7b4fe29e DJ |
329 | printk("VFS: Busy inodes after unmount of %s. " |
330 | "Self-destruct in 5 seconds. Have a nice day...\n", | |
331 | sb->s_id); | |
1da177e4 | 332 | } |
a9e220f8 | 333 | put_fs_excl(); |
1da177e4 LT |
334 | } |
335 | spin_lock(&sb_lock); | |
336 | /* should be initialized for __put_super_and_need_restart() */ | |
551de6f3 | 337 | list_del_init(&sb->s_instances); |
1da177e4 LT |
338 | spin_unlock(&sb_lock); |
339 | up_write(&sb->s_umount); | |
340 | } | |
341 | ||
342 | EXPORT_SYMBOL(generic_shutdown_super); | |
343 | ||
344 | /** | |
345 | * sget - find or create a superblock | |
346 | * @type: filesystem type superblock should belong to | |
347 | * @test: comparison callback | |
348 | * @set: setup callback | |
349 | * @data: argument to each of them | |
350 | */ | |
351 | struct super_block *sget(struct file_system_type *type, | |
352 | int (*test)(struct super_block *,void *), | |
353 | int (*set)(struct super_block *,void *), | |
354 | void *data) | |
355 | { | |
356 | struct super_block *s = NULL; | |
d4730127 | 357 | struct super_block *old; |
1da177e4 LT |
358 | int err; |
359 | ||
360 | retry: | |
361 | spin_lock(&sb_lock); | |
d4730127 MK |
362 | if (test) { |
363 | list_for_each_entry(old, &type->fs_supers, s_instances) { | |
364 | if (!test(old, data)) | |
365 | continue; | |
366 | if (!grab_super(old)) | |
367 | goto retry; | |
a3cfbb53 LZ |
368 | if (s) { |
369 | up_write(&s->s_umount); | |
d4730127 | 370 | destroy_super(s); |
7a4dec53 | 371 | s = NULL; |
a3cfbb53 | 372 | } |
d3f21473 | 373 | down_write(&old->s_umount); |
7a4dec53 AV |
374 | if (unlikely(!(old->s_flags & MS_BORN))) { |
375 | deactivate_locked_super(old); | |
376 | goto retry; | |
377 | } | |
d4730127 MK |
378 | return old; |
379 | } | |
1da177e4 LT |
380 | } |
381 | if (!s) { | |
382 | spin_unlock(&sb_lock); | |
cf516249 | 383 | s = alloc_super(type); |
1da177e4 LT |
384 | if (!s) |
385 | return ERR_PTR(-ENOMEM); | |
386 | goto retry; | |
387 | } | |
388 | ||
389 | err = set(s, data); | |
390 | if (err) { | |
391 | spin_unlock(&sb_lock); | |
a3cfbb53 | 392 | up_write(&s->s_umount); |
1da177e4 LT |
393 | destroy_super(s); |
394 | return ERR_PTR(err); | |
395 | } | |
396 | s->s_type = type; | |
397 | strlcpy(s->s_id, type->name, sizeof(s->s_id)); | |
398 | list_add_tail(&s->s_list, &super_blocks); | |
399 | list_add(&s->s_instances, &type->fs_supers); | |
400 | spin_unlock(&sb_lock); | |
401 | get_filesystem(type); | |
402 | return s; | |
403 | } | |
404 | ||
405 | EXPORT_SYMBOL(sget); | |
406 | ||
407 | void drop_super(struct super_block *sb) | |
408 | { | |
409 | up_read(&sb->s_umount); | |
410 | put_super(sb); | |
411 | } | |
412 | ||
413 | EXPORT_SYMBOL(drop_super); | |
414 | ||
e5004753 CH |
415 | /** |
416 | * sync_supers - helper for periodic superblock writeback | |
417 | * | |
418 | * Call the write_super method if present on all dirty superblocks in | |
419 | * the system. This is for the periodic writeback used by most older | |
420 | * filesystems. For data integrity superblock writeback use | |
421 | * sync_filesystems() instead. | |
422 | * | |
1da177e4 LT |
423 | * Note: check the dirty flag before waiting, so we don't |
424 | * hold up the sync while mounting a device. (The newly | |
425 | * mounted device won't need syncing.) | |
426 | */ | |
427 | void sync_supers(void) | |
428 | { | |
dca33252 | 429 | struct super_block *sb, *p = NULL; |
618f0636 | 430 | |
1da177e4 | 431 | spin_lock(&sb_lock); |
dca33252 | 432 | list_for_each_entry(sb, &super_blocks, s_list) { |
551de6f3 AV |
433 | if (list_empty(&sb->s_instances)) |
434 | continue; | |
e5004753 | 435 | if (sb->s_op->write_super && sb->s_dirt) { |
1da177e4 LT |
436 | sb->s_count++; |
437 | spin_unlock(&sb_lock); | |
e5004753 | 438 | |
1da177e4 | 439 | down_read(&sb->s_umount); |
e5004753 CH |
440 | if (sb->s_root && sb->s_dirt) |
441 | sb->s_op->write_super(sb); | |
618f0636 | 442 | up_read(&sb->s_umount); |
e5004753 | 443 | |
618f0636 | 444 | spin_lock(&sb_lock); |
dca33252 AV |
445 | if (p) |
446 | __put_super(p); | |
447 | p = sb; | |
618f0636 KK |
448 | } |
449 | } | |
dca33252 AV |
450 | if (p) |
451 | __put_super(p); | |
1da177e4 LT |
452 | spin_unlock(&sb_lock); |
453 | } | |
454 | ||
01a05b33 AV |
455 | /** |
456 | * iterate_supers - call function for all active superblocks | |
457 | * @f: function to call | |
458 | * @arg: argument to pass to it | |
459 | * | |
460 | * Scans the superblock list and calls given function, passing it | |
461 | * locked superblock and given argument. | |
462 | */ | |
463 | void iterate_supers(void (*f)(struct super_block *, void *), void *arg) | |
464 | { | |
dca33252 | 465 | struct super_block *sb, *p = NULL; |
01a05b33 AV |
466 | |
467 | spin_lock(&sb_lock); | |
dca33252 | 468 | list_for_each_entry(sb, &super_blocks, s_list) { |
01a05b33 AV |
469 | if (list_empty(&sb->s_instances)) |
470 | continue; | |
471 | sb->s_count++; | |
472 | spin_unlock(&sb_lock); | |
473 | ||
474 | down_read(&sb->s_umount); | |
475 | if (sb->s_root) | |
476 | f(sb, arg); | |
477 | up_read(&sb->s_umount); | |
478 | ||
479 | spin_lock(&sb_lock); | |
dca33252 AV |
480 | if (p) |
481 | __put_super(p); | |
482 | p = sb; | |
01a05b33 | 483 | } |
dca33252 AV |
484 | if (p) |
485 | __put_super(p); | |
01a05b33 AV |
486 | spin_unlock(&sb_lock); |
487 | } | |
488 | ||
43e15cdb AV |
489 | /** |
490 | * iterate_supers_type - call function for superblocks of given type | |
491 | * @type: fs type | |
492 | * @f: function to call | |
493 | * @arg: argument to pass to it | |
494 | * | |
495 | * Scans the superblock list and calls given function, passing it | |
496 | * locked superblock and given argument. | |
497 | */ | |
498 | void iterate_supers_type(struct file_system_type *type, | |
499 | void (*f)(struct super_block *, void *), void *arg) | |
500 | { | |
501 | struct super_block *sb, *p = NULL; | |
502 | ||
503 | spin_lock(&sb_lock); | |
504 | list_for_each_entry(sb, &type->fs_supers, s_instances) { | |
505 | sb->s_count++; | |
506 | spin_unlock(&sb_lock); | |
507 | ||
508 | down_read(&sb->s_umount); | |
509 | if (sb->s_root) | |
510 | f(sb, arg); | |
511 | up_read(&sb->s_umount); | |
512 | ||
513 | spin_lock(&sb_lock); | |
514 | if (p) | |
515 | __put_super(p); | |
516 | p = sb; | |
517 | } | |
518 | if (p) | |
519 | __put_super(p); | |
520 | spin_unlock(&sb_lock); | |
521 | } | |
522 | ||
523 | EXPORT_SYMBOL(iterate_supers_type); | |
524 | ||
1da177e4 LT |
525 | /** |
526 | * get_super - get the superblock of a device | |
527 | * @bdev: device to get the superblock for | |
528 | * | |
529 | * Scans the superblock list and finds the superblock of the file system | |
530 | * mounted on the device given. %NULL is returned if no match is found. | |
531 | */ | |
532 | ||
df40c01a | 533 | struct super_block *get_super(struct block_device *bdev) |
1da177e4 | 534 | { |
618f0636 KK |
535 | struct super_block *sb; |
536 | ||
1da177e4 LT |
537 | if (!bdev) |
538 | return NULL; | |
618f0636 | 539 | |
1da177e4 | 540 | spin_lock(&sb_lock); |
618f0636 KK |
541 | rescan: |
542 | list_for_each_entry(sb, &super_blocks, s_list) { | |
551de6f3 AV |
543 | if (list_empty(&sb->s_instances)) |
544 | continue; | |
618f0636 KK |
545 | if (sb->s_bdev == bdev) { |
546 | sb->s_count++; | |
1da177e4 | 547 | spin_unlock(&sb_lock); |
618f0636 | 548 | down_read(&sb->s_umount); |
df40c01a | 549 | /* still alive? */ |
618f0636 KK |
550 | if (sb->s_root) |
551 | return sb; | |
552 | up_read(&sb->s_umount); | |
df40c01a | 553 | /* nope, got unmounted */ |
618f0636 | 554 | spin_lock(&sb_lock); |
df40c01a AV |
555 | __put_super(sb); |
556 | goto rescan; | |
1da177e4 LT |
557 | } |
558 | } | |
559 | spin_unlock(&sb_lock); | |
560 | return NULL; | |
561 | } | |
562 | ||
563 | EXPORT_SYMBOL(get_super); | |
4504230a CH |
564 | |
565 | /** | |
566 | * get_active_super - get an active reference to the superblock of a device | |
567 | * @bdev: device to get the superblock for | |
568 | * | |
569 | * Scans the superblock list and finds the superblock of the file system | |
570 | * mounted on the device given. Returns the superblock with an active | |
d3f21473 | 571 | * reference or %NULL if none was found. |
4504230a CH |
572 | */ |
573 | struct super_block *get_active_super(struct block_device *bdev) | |
574 | { | |
575 | struct super_block *sb; | |
576 | ||
577 | if (!bdev) | |
578 | return NULL; | |
579 | ||
1494583d | 580 | restart: |
4504230a CH |
581 | spin_lock(&sb_lock); |
582 | list_for_each_entry(sb, &super_blocks, s_list) { | |
551de6f3 AV |
583 | if (list_empty(&sb->s_instances)) |
584 | continue; | |
1494583d AV |
585 | if (sb->s_bdev == bdev) { |
586 | if (grab_super(sb)) /* drops sb_lock */ | |
587 | return sb; | |
588 | else | |
589 | goto restart; | |
590 | } | |
4504230a CH |
591 | } |
592 | spin_unlock(&sb_lock); | |
593 | return NULL; | |
594 | } | |
1da177e4 | 595 | |
df40c01a | 596 | struct super_block *user_get_super(dev_t dev) |
1da177e4 | 597 | { |
618f0636 | 598 | struct super_block *sb; |
1da177e4 | 599 | |
1da177e4 | 600 | spin_lock(&sb_lock); |
618f0636 KK |
601 | rescan: |
602 | list_for_each_entry(sb, &super_blocks, s_list) { | |
551de6f3 AV |
603 | if (list_empty(&sb->s_instances)) |
604 | continue; | |
618f0636 KK |
605 | if (sb->s_dev == dev) { |
606 | sb->s_count++; | |
1da177e4 | 607 | spin_unlock(&sb_lock); |
618f0636 | 608 | down_read(&sb->s_umount); |
df40c01a | 609 | /* still alive? */ |
618f0636 KK |
610 | if (sb->s_root) |
611 | return sb; | |
612 | up_read(&sb->s_umount); | |
df40c01a | 613 | /* nope, got unmounted */ |
618f0636 | 614 | spin_lock(&sb_lock); |
df40c01a AV |
615 | __put_super(sb); |
616 | goto rescan; | |
1da177e4 LT |
617 | } |
618 | } | |
619 | spin_unlock(&sb_lock); | |
620 | return NULL; | |
621 | } | |
622 | ||
1da177e4 LT |
623 | /** |
624 | * do_remount_sb - asks filesystem to change mount options. | |
625 | * @sb: superblock in question | |
626 | * @flags: numeric part of options | |
627 | * @data: the rest of options | |
628 | * @force: whether or not to force the change | |
629 | * | |
630 | * Alters the mount options of a mounted file system. | |
631 | */ | |
632 | int do_remount_sb(struct super_block *sb, int flags, void *data, int force) | |
633 | { | |
634 | int retval; | |
c79d967d | 635 | int remount_ro; |
4504230a CH |
636 | |
637 | if (sb->s_frozen != SB_UNFROZEN) | |
638 | return -EBUSY; | |
639 | ||
9361401e | 640 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
641 | if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) |
642 | return -EACCES; | |
9361401e | 643 | #endif |
4504230a | 644 | |
1da177e4 LT |
645 | if (flags & MS_RDONLY) |
646 | acct_auto_close(sb); | |
647 | shrink_dcache_sb(sb); | |
60b0680f | 648 | sync_filesystem(sb); |
1da177e4 | 649 | |
d208bbdd | 650 | remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); |
d208bbdd | 651 | |
1da177e4 LT |
652 | /* If we are remounting RDONLY and current sb is read/write, |
653 | make sure there are no rw files opened */ | |
d208bbdd | 654 | if (remount_ro) { |
1da177e4 LT |
655 | if (force) |
656 | mark_files_ro(sb); | |
b0895513 | 657 | else if (!fs_may_remount_ro(sb)) |
1da177e4 LT |
658 | return -EBUSY; |
659 | } | |
660 | ||
661 | if (sb->s_op->remount_fs) { | |
1da177e4 | 662 | retval = sb->s_op->remount_fs(sb, &flags, data); |
b0895513 | 663 | if (retval) |
1da177e4 LT |
664 | return retval; |
665 | } | |
666 | sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); | |
c79d967d | 667 | |
d208bbdd NP |
668 | /* |
669 | * Some filesystems modify their metadata via some other path than the | |
670 | * bdev buffer cache (eg. use a private mapping, or directories in | |
671 | * pagecache, etc). Also file data modifications go via their own | |
672 | * mappings. So If we try to mount readonly then copy the filesystem | |
673 | * from bdev, we could get stale data, so invalidate it to give a best | |
674 | * effort at coherency. | |
675 | */ | |
676 | if (remount_ro && sb->s_bdev) | |
677 | invalidate_bdev(sb->s_bdev); | |
1da177e4 LT |
678 | return 0; |
679 | } | |
680 | ||
a2a9537a | 681 | static void do_emergency_remount(struct work_struct *work) |
1da177e4 | 682 | { |
dca33252 | 683 | struct super_block *sb, *p = NULL; |
1da177e4 LT |
684 | |
685 | spin_lock(&sb_lock); | |
dca33252 | 686 | list_for_each_entry(sb, &super_blocks, s_list) { |
551de6f3 AV |
687 | if (list_empty(&sb->s_instances)) |
688 | continue; | |
1da177e4 LT |
689 | sb->s_count++; |
690 | spin_unlock(&sb_lock); | |
443b94ba | 691 | down_write(&sb->s_umount); |
1da177e4 LT |
692 | if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) { |
693 | /* | |
1da177e4 LT |
694 | * What lock protects sb->s_flags?? |
695 | */ | |
1da177e4 | 696 | do_remount_sb(sb, MS_RDONLY, NULL, 1); |
1da177e4 | 697 | } |
443b94ba | 698 | up_write(&sb->s_umount); |
1da177e4 | 699 | spin_lock(&sb_lock); |
dca33252 AV |
700 | if (p) |
701 | __put_super(p); | |
702 | p = sb; | |
1da177e4 | 703 | } |
dca33252 AV |
704 | if (p) |
705 | __put_super(p); | |
1da177e4 | 706 | spin_unlock(&sb_lock); |
a2a9537a | 707 | kfree(work); |
1da177e4 LT |
708 | printk("Emergency Remount complete\n"); |
709 | } | |
710 | ||
711 | void emergency_remount(void) | |
712 | { | |
a2a9537a JA |
713 | struct work_struct *work; |
714 | ||
715 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
716 | if (work) { | |
717 | INIT_WORK(work, do_emergency_remount); | |
718 | schedule_work(work); | |
719 | } | |
1da177e4 LT |
720 | } |
721 | ||
722 | /* | |
723 | * Unnamed block devices are dummy devices used by virtual | |
724 | * filesystems which don't use real block-devices. -- jrs | |
725 | */ | |
726 | ||
ad76cbc6 | 727 | static DEFINE_IDA(unnamed_dev_ida); |
1da177e4 | 728 | static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ |
c63e09ec | 729 | static int unnamed_dev_start = 0; /* don't bother trying below it */ |
1da177e4 | 730 | |
0ee5dc67 | 731 | int get_anon_bdev(dev_t *p) |
1da177e4 LT |
732 | { |
733 | int dev; | |
734 | int error; | |
735 | ||
736 | retry: | |
ad76cbc6 | 737 | if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) |
1da177e4 LT |
738 | return -ENOMEM; |
739 | spin_lock(&unnamed_dev_lock); | |
c63e09ec | 740 | error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev); |
f21f6220 AV |
741 | if (!error) |
742 | unnamed_dev_start = dev + 1; | |
1da177e4 LT |
743 | spin_unlock(&unnamed_dev_lock); |
744 | if (error == -EAGAIN) | |
745 | /* We raced and lost with another CPU. */ | |
746 | goto retry; | |
747 | else if (error) | |
748 | return -EAGAIN; | |
749 | ||
750 | if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { | |
751 | spin_lock(&unnamed_dev_lock); | |
ad76cbc6 | 752 | ida_remove(&unnamed_dev_ida, dev); |
f21f6220 AV |
753 | if (unnamed_dev_start > dev) |
754 | unnamed_dev_start = dev; | |
1da177e4 LT |
755 | spin_unlock(&unnamed_dev_lock); |
756 | return -EMFILE; | |
757 | } | |
0ee5dc67 | 758 | *p = MKDEV(0, dev & MINORMASK); |
1da177e4 LT |
759 | return 0; |
760 | } | |
0ee5dc67 | 761 | EXPORT_SYMBOL(get_anon_bdev); |
1da177e4 | 762 | |
0ee5dc67 | 763 | void free_anon_bdev(dev_t dev) |
1da177e4 | 764 | { |
0ee5dc67 | 765 | int slot = MINOR(dev); |
1da177e4 | 766 | spin_lock(&unnamed_dev_lock); |
ad76cbc6 | 767 | ida_remove(&unnamed_dev_ida, slot); |
c63e09ec AV |
768 | if (slot < unnamed_dev_start) |
769 | unnamed_dev_start = slot; | |
1da177e4 LT |
770 | spin_unlock(&unnamed_dev_lock); |
771 | } | |
0ee5dc67 AV |
772 | EXPORT_SYMBOL(free_anon_bdev); |
773 | ||
774 | int set_anon_super(struct super_block *s, void *data) | |
775 | { | |
776 | int error = get_anon_bdev(&s->s_dev); | |
777 | if (!error) | |
778 | s->s_bdi = &noop_backing_dev_info; | |
779 | return error; | |
780 | } | |
781 | ||
782 | EXPORT_SYMBOL(set_anon_super); | |
783 | ||
784 | void kill_anon_super(struct super_block *sb) | |
785 | { | |
786 | dev_t dev = sb->s_dev; | |
787 | generic_shutdown_super(sb); | |
788 | free_anon_bdev(dev); | |
789 | } | |
1da177e4 LT |
790 | |
791 | EXPORT_SYMBOL(kill_anon_super); | |
792 | ||
1da177e4 LT |
793 | void kill_litter_super(struct super_block *sb) |
794 | { | |
795 | if (sb->s_root) | |
796 | d_genocide(sb->s_root); | |
797 | kill_anon_super(sb); | |
798 | } | |
799 | ||
800 | EXPORT_SYMBOL(kill_litter_super); | |
801 | ||
909e6d94 SH |
802 | static int ns_test_super(struct super_block *sb, void *data) |
803 | { | |
804 | return sb->s_fs_info == data; | |
805 | } | |
806 | ||
807 | static int ns_set_super(struct super_block *sb, void *data) | |
808 | { | |
809 | sb->s_fs_info = data; | |
810 | return set_anon_super(sb, NULL); | |
811 | } | |
812 | ||
ceefda69 AV |
813 | struct dentry *mount_ns(struct file_system_type *fs_type, int flags, |
814 | void *data, int (*fill_super)(struct super_block *, void *, int)) | |
909e6d94 SH |
815 | { |
816 | struct super_block *sb; | |
817 | ||
818 | sb = sget(fs_type, ns_test_super, ns_set_super, data); | |
819 | if (IS_ERR(sb)) | |
ceefda69 | 820 | return ERR_CAST(sb); |
909e6d94 SH |
821 | |
822 | if (!sb->s_root) { | |
823 | int err; | |
824 | sb->s_flags = flags; | |
825 | err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); | |
826 | if (err) { | |
74dbbdd7 | 827 | deactivate_locked_super(sb); |
ceefda69 | 828 | return ERR_PTR(err); |
909e6d94 SH |
829 | } |
830 | ||
831 | sb->s_flags |= MS_ACTIVE; | |
832 | } | |
833 | ||
ceefda69 | 834 | return dget(sb->s_root); |
909e6d94 SH |
835 | } |
836 | ||
ceefda69 | 837 | EXPORT_SYMBOL(mount_ns); |
909e6d94 | 838 | |
9361401e | 839 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
840 | static int set_bdev_super(struct super_block *s, void *data) |
841 | { | |
842 | s->s_bdev = data; | |
843 | s->s_dev = s->s_bdev->bd_dev; | |
32a88aa1 JA |
844 | |
845 | /* | |
846 | * We set the bdi here to the queue backing, file systems can | |
847 | * overwrite this in ->fill_super() | |
848 | */ | |
849 | s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info; | |
1da177e4 LT |
850 | return 0; |
851 | } | |
852 | ||
853 | static int test_bdev_super(struct super_block *s, void *data) | |
854 | { | |
855 | return (void *)s->s_bdev == data; | |
856 | } | |
857 | ||
152a0836 | 858 | struct dentry *mount_bdev(struct file_system_type *fs_type, |
1da177e4 | 859 | int flags, const char *dev_name, void *data, |
152a0836 | 860 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
861 | { |
862 | struct block_device *bdev; | |
863 | struct super_block *s; | |
d4d77629 | 864 | fmode_t mode = FMODE_READ | FMODE_EXCL; |
1da177e4 LT |
865 | int error = 0; |
866 | ||
30c40d2c AV |
867 | if (!(flags & MS_RDONLY)) |
868 | mode |= FMODE_WRITE; | |
869 | ||
d4d77629 | 870 | bdev = blkdev_get_by_path(dev_name, mode, fs_type); |
1da177e4 | 871 | if (IS_ERR(bdev)) |
152a0836 | 872 | return ERR_CAST(bdev); |
1da177e4 LT |
873 | |
874 | /* | |
875 | * once the super is inserted into the list by sget, s_umount | |
876 | * will protect the lockfs code from trying to start a snapshot | |
877 | * while we are mounting | |
878 | */ | |
4fadd7bb CH |
879 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
880 | if (bdev->bd_fsfreeze_count > 0) { | |
881 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
882 | error = -EBUSY; | |
883 | goto error_bdev; | |
884 | } | |
1da177e4 | 885 | s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); |
4fadd7bb | 886 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
1da177e4 | 887 | if (IS_ERR(s)) |
454e2398 | 888 | goto error_s; |
1da177e4 LT |
889 | |
890 | if (s->s_root) { | |
891 | if ((flags ^ s->s_flags) & MS_RDONLY) { | |
74dbbdd7 | 892 | deactivate_locked_super(s); |
454e2398 DH |
893 | error = -EBUSY; |
894 | goto error_bdev; | |
1da177e4 | 895 | } |
454e2398 | 896 | |
4f331f01 TH |
897 | /* |
898 | * s_umount nests inside bd_mutex during | |
e525fd89 TH |
899 | * __invalidate_device(). blkdev_put() acquires |
900 | * bd_mutex and can't be called under s_umount. Drop | |
901 | * s_umount temporarily. This is safe as we're | |
902 | * holding an active reference. | |
4f331f01 TH |
903 | */ |
904 | up_write(&s->s_umount); | |
d4d77629 | 905 | blkdev_put(bdev, mode); |
4f331f01 | 906 | down_write(&s->s_umount); |
1da177e4 LT |
907 | } else { |
908 | char b[BDEVNAME_SIZE]; | |
909 | ||
9e1f1de0 | 910 | s->s_flags = flags | MS_NOSEC; |
30c40d2c | 911 | s->s_mode = mode; |
1da177e4 | 912 | strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); |
e78c9a00 | 913 | sb_set_blocksize(s, block_size(bdev)); |
9b04c997 | 914 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 915 | if (error) { |
74dbbdd7 | 916 | deactivate_locked_super(s); |
454e2398 | 917 | goto error; |
fa675765 | 918 | } |
454e2398 DH |
919 | |
920 | s->s_flags |= MS_ACTIVE; | |
87d8fe1e | 921 | bdev->bd_super = s; |
1da177e4 LT |
922 | } |
923 | ||
152a0836 | 924 | return dget(s->s_root); |
1da177e4 | 925 | |
454e2398 DH |
926 | error_s: |
927 | error = PTR_ERR(s); | |
928 | error_bdev: | |
d4d77629 | 929 | blkdev_put(bdev, mode); |
454e2398 | 930 | error: |
152a0836 AV |
931 | return ERR_PTR(error); |
932 | } | |
933 | EXPORT_SYMBOL(mount_bdev); | |
934 | ||
1da177e4 LT |
935 | void kill_block_super(struct super_block *sb) |
936 | { | |
937 | struct block_device *bdev = sb->s_bdev; | |
30c40d2c | 938 | fmode_t mode = sb->s_mode; |
1da177e4 | 939 | |
ddbaaf30 | 940 | bdev->bd_super = NULL; |
1da177e4 LT |
941 | generic_shutdown_super(sb); |
942 | sync_blockdev(bdev); | |
d4d77629 | 943 | WARN_ON_ONCE(!(mode & FMODE_EXCL)); |
e525fd89 | 944 | blkdev_put(bdev, mode | FMODE_EXCL); |
1da177e4 LT |
945 | } |
946 | ||
947 | EXPORT_SYMBOL(kill_block_super); | |
9361401e | 948 | #endif |
1da177e4 | 949 | |
3c26ff6e | 950 | struct dentry *mount_nodev(struct file_system_type *fs_type, |
1da177e4 | 951 | int flags, void *data, |
3c26ff6e | 952 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
953 | { |
954 | int error; | |
955 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
956 | ||
957 | if (IS_ERR(s)) | |
3c26ff6e | 958 | return ERR_CAST(s); |
1da177e4 LT |
959 | |
960 | s->s_flags = flags; | |
961 | ||
9b04c997 | 962 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 963 | if (error) { |
74dbbdd7 | 964 | deactivate_locked_super(s); |
3c26ff6e | 965 | return ERR_PTR(error); |
1da177e4 LT |
966 | } |
967 | s->s_flags |= MS_ACTIVE; | |
3c26ff6e | 968 | return dget(s->s_root); |
1da177e4 | 969 | } |
3c26ff6e AV |
970 | EXPORT_SYMBOL(mount_nodev); |
971 | ||
1da177e4 LT |
972 | static int compare_single(struct super_block *s, void *p) |
973 | { | |
974 | return 1; | |
975 | } | |
976 | ||
fc14f2fe | 977 | struct dentry *mount_single(struct file_system_type *fs_type, |
1da177e4 | 978 | int flags, void *data, |
fc14f2fe | 979 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
980 | { |
981 | struct super_block *s; | |
982 | int error; | |
983 | ||
984 | s = sget(fs_type, compare_single, set_anon_super, NULL); | |
985 | if (IS_ERR(s)) | |
fc14f2fe | 986 | return ERR_CAST(s); |
1da177e4 LT |
987 | if (!s->s_root) { |
988 | s->s_flags = flags; | |
9b04c997 | 989 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 990 | if (error) { |
74dbbdd7 | 991 | deactivate_locked_super(s); |
fc14f2fe | 992 | return ERR_PTR(error); |
1da177e4 LT |
993 | } |
994 | s->s_flags |= MS_ACTIVE; | |
9329d1be KS |
995 | } else { |
996 | do_remount_sb(s, flags, data, 0); | |
1da177e4 | 997 | } |
fc14f2fe AV |
998 | return dget(s->s_root); |
999 | } | |
1000 | EXPORT_SYMBOL(mount_single); | |
1001 | ||
9d412a43 AV |
1002 | struct dentry * |
1003 | mount_fs(struct file_system_type *type, int flags, const char *name, void *data) | |
1da177e4 | 1004 | { |
c96e41e9 | 1005 | struct dentry *root; |
9d412a43 | 1006 | struct super_block *sb; |
1da177e4 | 1007 | char *secdata = NULL; |
9d412a43 | 1008 | int error = -ENOMEM; |
8089352a | 1009 | |
e0007529 | 1010 | if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { |
1da177e4 | 1011 | secdata = alloc_secdata(); |
454e2398 | 1012 | if (!secdata) |
9d412a43 | 1013 | goto out; |
1da177e4 | 1014 | |
e0007529 | 1015 | error = security_sb_copy_data(data, secdata); |
454e2398 | 1016 | if (error) |
1da177e4 | 1017 | goto out_free_secdata; |
1da177e4 LT |
1018 | } |
1019 | ||
1a102ff9 AV |
1020 | root = type->mount(type, flags, name, data); |
1021 | if (IS_ERR(root)) { | |
1022 | error = PTR_ERR(root); | |
1023 | goto out_free_secdata; | |
c96e41e9 | 1024 | } |
9d412a43 AV |
1025 | sb = root->d_sb; |
1026 | BUG_ON(!sb); | |
1027 | WARN_ON(!sb->s_bdi); | |
6c510389 | 1028 | WARN_ON(sb->s_bdi == &default_backing_dev_info); |
9d412a43 | 1029 | sb->s_flags |= MS_BORN; |
454e2398 | 1030 | |
9d412a43 | 1031 | error = security_sb_kern_mount(sb, flags, secdata); |
5129a469 JE |
1032 | if (error) |
1033 | goto out_sb; | |
454e2398 | 1034 | |
42cb56ae JL |
1035 | /* |
1036 | * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE | |
1037 | * but s_maxbytes was an unsigned long long for many releases. Throw | |
1038 | * this warning for a little while to try and catch filesystems that | |
4358b567 | 1039 | * violate this rule. |
42cb56ae | 1040 | */ |
9d412a43 AV |
1041 | WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " |
1042 | "negative value (%lld)\n", type->name, sb->s_maxbytes); | |
42cb56ae | 1043 | |
9d412a43 | 1044 | up_write(&sb->s_umount); |
8680e22f | 1045 | free_secdata(secdata); |
9d412a43 | 1046 | return root; |
1da177e4 | 1047 | out_sb: |
9d412a43 AV |
1048 | dput(root); |
1049 | deactivate_locked_super(sb); | |
1da177e4 LT |
1050 | out_free_secdata: |
1051 | free_secdata(secdata); | |
1da177e4 | 1052 | out: |
454e2398 | 1053 | return ERR_PTR(error); |
1da177e4 LT |
1054 | } |
1055 | ||
18e9e510 | 1056 | /** |
7000d3c4 RD |
1057 | * freeze_super - lock the filesystem and force it into a consistent state |
1058 | * @sb: the super to lock | |
18e9e510 JB |
1059 | * |
1060 | * Syncs the super to make sure the filesystem is consistent and calls the fs's | |
1061 | * freeze_fs. Subsequent calls to this without first thawing the fs will return | |
1062 | * -EBUSY. | |
1063 | */ | |
1064 | int freeze_super(struct super_block *sb) | |
1065 | { | |
1066 | int ret; | |
1067 | ||
1068 | atomic_inc(&sb->s_active); | |
1069 | down_write(&sb->s_umount); | |
1070 | if (sb->s_frozen) { | |
1071 | deactivate_locked_super(sb); | |
1072 | return -EBUSY; | |
1073 | } | |
1074 | ||
1075 | if (sb->s_flags & MS_RDONLY) { | |
1076 | sb->s_frozen = SB_FREEZE_TRANS; | |
1077 | smp_wmb(); | |
1078 | up_write(&sb->s_umount); | |
1079 | return 0; | |
1080 | } | |
1081 | ||
1082 | sb->s_frozen = SB_FREEZE_WRITE; | |
1083 | smp_wmb(); | |
1084 | ||
1085 | sync_filesystem(sb); | |
1086 | ||
1087 | sb->s_frozen = SB_FREEZE_TRANS; | |
1088 | smp_wmb(); | |
1089 | ||
1090 | sync_blockdev(sb->s_bdev); | |
1091 | if (sb->s_op->freeze_fs) { | |
1092 | ret = sb->s_op->freeze_fs(sb); | |
1093 | if (ret) { | |
1094 | printk(KERN_ERR | |
1095 | "VFS:Filesystem freeze failed\n"); | |
1096 | sb->s_frozen = SB_UNFROZEN; | |
1097 | deactivate_locked_super(sb); | |
1098 | return ret; | |
1099 | } | |
1100 | } | |
1101 | up_write(&sb->s_umount); | |
1102 | return 0; | |
1103 | } | |
1104 | EXPORT_SYMBOL(freeze_super); | |
1105 | ||
1106 | /** | |
1107 | * thaw_super -- unlock filesystem | |
1108 | * @sb: the super to thaw | |
1109 | * | |
1110 | * Unlocks the filesystem and marks it writeable again after freeze_super(). | |
1111 | */ | |
1112 | int thaw_super(struct super_block *sb) | |
1113 | { | |
1114 | int error; | |
1115 | ||
1116 | down_write(&sb->s_umount); | |
1117 | if (sb->s_frozen == SB_UNFROZEN) { | |
1118 | up_write(&sb->s_umount); | |
1119 | return -EINVAL; | |
1120 | } | |
1121 | ||
1122 | if (sb->s_flags & MS_RDONLY) | |
1123 | goto out; | |
1124 | ||
1125 | if (sb->s_op->unfreeze_fs) { | |
1126 | error = sb->s_op->unfreeze_fs(sb); | |
1127 | if (error) { | |
1128 | printk(KERN_ERR | |
1129 | "VFS:Filesystem thaw failed\n"); | |
1130 | sb->s_frozen = SB_FREEZE_TRANS; | |
1131 | up_write(&sb->s_umount); | |
1132 | return error; | |
1133 | } | |
1134 | } | |
1135 | ||
1136 | out: | |
1137 | sb->s_frozen = SB_UNFROZEN; | |
1138 | smp_wmb(); | |
1139 | wake_up(&sb->s_wait_unfrozen); | |
1140 | deactivate_locked_super(sb); | |
1141 | ||
1142 | return 0; | |
1143 | } | |
1144 | EXPORT_SYMBOL(thaw_super); |