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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 | ||
630d9c47 | 23 | #include <linux/export.h> |
1da177e4 | 24 | #include <linux/slab.h> |
1da177e4 | 25 | #include <linux/blkdev.h> |
1da177e4 LT |
26 | #include <linux/mount.h> |
27 | #include <linux/security.h> | |
1da177e4 LT |
28 | #include <linux/writeback.h> /* for the emergency remount stuff */ |
29 | #include <linux/idr.h> | |
353ab6e9 | 30 | #include <linux/mutex.h> |
5477d0fa | 31 | #include <linux/backing-dev.h> |
ceb5bdc2 | 32 | #include <linux/rculist_bl.h> |
c515e1fd | 33 | #include <linux/cleancache.h> |
40401530 | 34 | #include <linux/fsnotify.h> |
5accdf82 | 35 | #include <linux/lockdep.h> |
6e4eab57 | 36 | #include <linux/user_namespace.h> |
6d59e7f5 | 37 | #include "internal.h" |
1da177e4 LT |
38 | |
39 | ||
15d0f5ea AV |
40 | static LIST_HEAD(super_blocks); |
41 | static DEFINE_SPINLOCK(sb_lock); | |
1da177e4 | 42 | |
5accdf82 JK |
43 | static char *sb_writers_name[SB_FREEZE_LEVELS] = { |
44 | "sb_writers", | |
45 | "sb_pagefaults", | |
46 | "sb_internal", | |
47 | }; | |
48 | ||
b0d40c92 DC |
49 | /* |
50 | * One thing we have to be careful of with a per-sb shrinker is that we don't | |
51 | * drop the last active reference to the superblock from within the shrinker. | |
52 | * If that happens we could trigger unregistering the shrinker from within the | |
53 | * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we | |
54 | * take a passive reference to the superblock to avoid this from occurring. | |
55 | */ | |
0a234c6d DC |
56 | static unsigned long super_cache_scan(struct shrinker *shrink, |
57 | struct shrink_control *sc) | |
b0d40c92 DC |
58 | { |
59 | struct super_block *sb; | |
0a234c6d DC |
60 | long fs_objects = 0; |
61 | long total_objects; | |
62 | long freed = 0; | |
63 | long dentries; | |
64 | long inodes; | |
b0d40c92 DC |
65 | |
66 | sb = container_of(shrink, struct super_block, s_shrink); | |
67 | ||
68 | /* | |
69 | * Deadlock avoidance. We may hold various FS locks, and we don't want | |
70 | * to recurse into the FS that called us in clear_inode() and friends.. | |
71 | */ | |
0a234c6d DC |
72 | if (!(sc->gfp_mask & __GFP_FS)) |
73 | return SHRINK_STOP; | |
b0d40c92 | 74 | |
eb6ef3df | 75 | if (!trylock_super(sb)) |
0a234c6d | 76 | return SHRINK_STOP; |
b0d40c92 | 77 | |
d0407903 | 78 | if (sb->s_op->nr_cached_objects) |
4101b624 | 79 | fs_objects = sb->s_op->nr_cached_objects(sb, sc); |
0e1fdafd | 80 | |
503c358c VD |
81 | inodes = list_lru_shrink_count(&sb->s_inode_lru, sc); |
82 | dentries = list_lru_shrink_count(&sb->s_dentry_lru, sc); | |
f6041567 | 83 | total_objects = dentries + inodes + fs_objects + 1; |
475d0db7 TH |
84 | if (!total_objects) |
85 | total_objects = 1; | |
0e1fdafd | 86 | |
0a234c6d | 87 | /* proportion the scan between the caches */ |
f6041567 | 88 | dentries = mult_frac(sc->nr_to_scan, dentries, total_objects); |
bc3b14cb | 89 | inodes = mult_frac(sc->nr_to_scan, inodes, total_objects); |
503c358c | 90 | fs_objects = mult_frac(sc->nr_to_scan, fs_objects, total_objects); |
b0d40c92 | 91 | |
0a234c6d DC |
92 | /* |
93 | * prune the dcache first as the icache is pinned by it, then | |
94 | * prune the icache, followed by the filesystem specific caches | |
49e7e7ff VD |
95 | * |
96 | * Ensure that we always scan at least one object - memcg kmem | |
97 | * accounting uses this to fully empty the caches. | |
0a234c6d | 98 | */ |
49e7e7ff | 99 | sc->nr_to_scan = dentries + 1; |
503c358c | 100 | freed = prune_dcache_sb(sb, sc); |
49e7e7ff | 101 | sc->nr_to_scan = inodes + 1; |
503c358c | 102 | freed += prune_icache_sb(sb, sc); |
0a234c6d DC |
103 | |
104 | if (fs_objects) { | |
49e7e7ff | 105 | sc->nr_to_scan = fs_objects + 1; |
4101b624 | 106 | freed += sb->s_op->free_cached_objects(sb, sc); |
b0d40c92 DC |
107 | } |
108 | ||
eb6ef3df | 109 | up_read(&sb->s_umount); |
0a234c6d DC |
110 | return freed; |
111 | } | |
112 | ||
113 | static unsigned long super_cache_count(struct shrinker *shrink, | |
114 | struct shrink_control *sc) | |
115 | { | |
116 | struct super_block *sb; | |
117 | long total_objects = 0; | |
118 | ||
119 | sb = container_of(shrink, struct super_block, s_shrink); | |
120 | ||
d23da150 | 121 | /* |
eb6ef3df | 122 | * Don't call trylock_super as it is a potential |
d23da150 TC |
123 | * scalability bottleneck. The counts could get updated |
124 | * between super_cache_count and super_cache_scan anyway. | |
125 | * Call to super_cache_count with shrinker_rwsem held | |
503c358c | 126 | * ensures the safety of call to list_lru_shrink_count() and |
d23da150 TC |
127 | * s_op->nr_cached_objects(). |
128 | */ | |
0a234c6d | 129 | if (sb->s_op && sb->s_op->nr_cached_objects) |
4101b624 | 130 | total_objects = sb->s_op->nr_cached_objects(sb, sc); |
0a234c6d | 131 | |
503c358c VD |
132 | total_objects += list_lru_shrink_count(&sb->s_dentry_lru, sc); |
133 | total_objects += list_lru_shrink_count(&sb->s_inode_lru, sc); | |
0a234c6d | 134 | |
55f841ce | 135 | total_objects = vfs_pressure_ratio(total_objects); |
0e1fdafd | 136 | return total_objects; |
b0d40c92 DC |
137 | } |
138 | ||
853b39a7 ON |
139 | static void destroy_super_work(struct work_struct *work) |
140 | { | |
141 | struct super_block *s = container_of(work, struct super_block, | |
142 | destroy_work); | |
143 | int i; | |
144 | ||
145 | for (i = 0; i < SB_FREEZE_LEVELS; i++) | |
8129ed29 | 146 | percpu_free_rwsem(&s->s_writers.rw_sem[i]); |
853b39a7 ON |
147 | kfree(s); |
148 | } | |
149 | ||
150 | static void destroy_super_rcu(struct rcu_head *head) | |
151 | { | |
152 | struct super_block *s = container_of(head, struct super_block, rcu); | |
153 | INIT_WORK(&s->destroy_work, destroy_super_work); | |
154 | schedule_work(&s->destroy_work); | |
155 | } | |
156 | ||
7eb5e882 AV |
157 | /** |
158 | * destroy_super - frees a superblock | |
159 | * @s: superblock to free | |
160 | * | |
161 | * Frees a superblock. | |
162 | */ | |
163 | static void destroy_super(struct super_block *s) | |
5accdf82 | 164 | { |
7eb5e882 AV |
165 | list_lru_destroy(&s->s_dentry_lru); |
166 | list_lru_destroy(&s->s_inode_lru); | |
7eb5e882 AV |
167 | security_sb_free(s); |
168 | WARN_ON(!list_empty(&s->s_mounts)); | |
6e4eab57 | 169 | put_user_ns(s->s_user_ns); |
7eb5e882 AV |
170 | kfree(s->s_subtype); |
171 | kfree(s->s_options); | |
853b39a7 | 172 | call_rcu(&s->rcu, destroy_super_rcu); |
5accdf82 JK |
173 | } |
174 | ||
1da177e4 LT |
175 | /** |
176 | * alloc_super - create new superblock | |
fe2bbc48 | 177 | * @type: filesystem type superblock should belong to |
9249e17f | 178 | * @flags: the mount flags |
6e4eab57 | 179 | * @user_ns: User namespace for the super_block |
1da177e4 LT |
180 | * |
181 | * Allocates and initializes a new &struct super_block. alloc_super() | |
182 | * returns a pointer new superblock or %NULL if allocation had failed. | |
183 | */ | |
6e4eab57 EB |
184 | static struct super_block *alloc_super(struct file_system_type *type, int flags, |
185 | struct user_namespace *user_ns) | |
1da177e4 | 186 | { |
11b0b5ab | 187 | struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); |
b87221de | 188 | static const struct super_operations default_op; |
7eb5e882 AV |
189 | int i; |
190 | ||
191 | if (!s) | |
192 | return NULL; | |
1da177e4 | 193 | |
b5bd856a | 194 | INIT_LIST_HEAD(&s->s_mounts); |
6e4eab57 | 195 | s->s_user_ns = get_user_ns(user_ns); |
b5bd856a | 196 | |
7eb5e882 AV |
197 | if (security_sb_alloc(s)) |
198 | goto fail; | |
7b7a8665 | 199 | |
7eb5e882 | 200 | for (i = 0; i < SB_FREEZE_LEVELS; i++) { |
8129ed29 ON |
201 | if (__percpu_init_rwsem(&s->s_writers.rw_sem[i], |
202 | sb_writers_name[i], | |
203 | &type->s_writers_key[i])) | |
7eb5e882 | 204 | goto fail; |
1da177e4 | 205 | } |
7eb5e882 | 206 | init_waitqueue_head(&s->s_writers.wait_unfrozen); |
df0ce26c | 207 | s->s_bdi = &noop_backing_dev_info; |
7eb5e882 | 208 | s->s_flags = flags; |
cc50a07a | 209 | if (s->s_user_ns != &init_user_ns) |
67690f93 | 210 | s->s_iflags |= SB_I_NODEV; |
7eb5e882 AV |
211 | INIT_HLIST_NODE(&s->s_instances); |
212 | INIT_HLIST_BL_HEAD(&s->s_anon); | |
e97fedb9 | 213 | mutex_init(&s->s_sync_lock); |
7eb5e882 | 214 | INIT_LIST_HEAD(&s->s_inodes); |
74278da9 | 215 | spin_lock_init(&s->s_inode_list_lock); |
6c60d2b5 DC |
216 | INIT_LIST_HEAD(&s->s_inodes_wb); |
217 | spin_lock_init(&s->s_inode_wblist_lock); | |
7eb5e882 | 218 | |
2acb60a0 | 219 | if (list_lru_init_memcg(&s->s_dentry_lru)) |
7eb5e882 | 220 | goto fail; |
2acb60a0 | 221 | if (list_lru_init_memcg(&s->s_inode_lru)) |
7eb5e882 AV |
222 | goto fail; |
223 | ||
7eb5e882 AV |
224 | init_rwsem(&s->s_umount); |
225 | lockdep_set_class(&s->s_umount, &type->s_umount_key); | |
226 | /* | |
227 | * sget() can have s_umount recursion. | |
228 | * | |
229 | * When it cannot find a suitable sb, it allocates a new | |
230 | * one (this one), and tries again to find a suitable old | |
231 | * one. | |
232 | * | |
233 | * In case that succeeds, it will acquire the s_umount | |
234 | * lock of the old one. Since these are clearly distrinct | |
235 | * locks, and this object isn't exposed yet, there's no | |
236 | * risk of deadlocks. | |
237 | * | |
238 | * Annotate this by putting this lock in a different | |
239 | * subclass. | |
240 | */ | |
241 | down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); | |
242 | s->s_count = 1; | |
243 | atomic_set(&s->s_active, 1); | |
244 | mutex_init(&s->s_vfs_rename_mutex); | |
245 | lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key); | |
246 | mutex_init(&s->s_dquot.dqio_mutex); | |
7eb5e882 AV |
247 | s->s_maxbytes = MAX_NON_LFS; |
248 | s->s_op = &default_op; | |
249 | s->s_time_gran = 1000000000; | |
3cb29d11 | 250 | s->cleancache_poolid = CLEANCACHE_NO_POOL; |
7eb5e882 AV |
251 | |
252 | s->s_shrink.seeks = DEFAULT_SEEKS; | |
253 | s->s_shrink.scan_objects = super_cache_scan; | |
254 | s->s_shrink.count_objects = super_cache_count; | |
255 | s->s_shrink.batch = 1024; | |
2acb60a0 | 256 | s->s_shrink.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE; |
1da177e4 | 257 | return s; |
5ca302c8 | 258 | |
7eb5e882 AV |
259 | fail: |
260 | destroy_super(s); | |
261 | return NULL; | |
1da177e4 LT |
262 | } |
263 | ||
264 | /* Superblock refcounting */ | |
265 | ||
266 | /* | |
35cf7ba0 | 267 | * Drop a superblock's refcount. The caller must hold sb_lock. |
1da177e4 | 268 | */ |
f47ec3f2 | 269 | static void __put_super(struct super_block *sb) |
1da177e4 | 270 | { |
1da177e4 | 271 | if (!--sb->s_count) { |
551de6f3 | 272 | list_del_init(&sb->s_list); |
1da177e4 | 273 | destroy_super(sb); |
1da177e4 | 274 | } |
1da177e4 LT |
275 | } |
276 | ||
277 | /** | |
278 | * put_super - drop a temporary reference to superblock | |
279 | * @sb: superblock in question | |
280 | * | |
281 | * Drops a temporary reference, frees superblock if there's no | |
282 | * references left. | |
283 | */ | |
f47ec3f2 | 284 | static void put_super(struct super_block *sb) |
1da177e4 LT |
285 | { |
286 | spin_lock(&sb_lock); | |
287 | __put_super(sb); | |
288 | spin_unlock(&sb_lock); | |
289 | } | |
290 | ||
291 | ||
292 | /** | |
1712ac8f | 293 | * deactivate_locked_super - drop an active reference to superblock |
1da177e4 LT |
294 | * @s: superblock to deactivate |
295 | * | |
bd7ced98 | 296 | * Drops an active reference to superblock, converting it into a temporary |
1712ac8f | 297 | * one if there is no other active references left. In that case we |
1da177e4 LT |
298 | * tell fs driver to shut it down and drop the temporary reference we |
299 | * had just acquired. | |
1712ac8f AV |
300 | * |
301 | * Caller holds exclusive lock on superblock; that lock is released. | |
1da177e4 | 302 | */ |
1712ac8f | 303 | void deactivate_locked_super(struct super_block *s) |
1da177e4 LT |
304 | { |
305 | struct file_system_type *fs = s->s_type; | |
b20bd1a5 | 306 | if (atomic_dec_and_test(&s->s_active)) { |
3167760f | 307 | cleancache_invalidate_fs(s); |
b0d40c92 | 308 | unregister_shrinker(&s->s_shrink); |
28f2cd4f | 309 | fs->kill_sb(s); |
f5e1dd34 | 310 | |
c0a5b560 VD |
311 | /* |
312 | * Since list_lru_destroy() may sleep, we cannot call it from | |
313 | * put_super(), where we hold the sb_lock. Therefore we destroy | |
314 | * the lru lists right now. | |
315 | */ | |
316 | list_lru_destroy(&s->s_dentry_lru); | |
317 | list_lru_destroy(&s->s_inode_lru); | |
318 | ||
1da177e4 LT |
319 | put_filesystem(fs); |
320 | put_super(s); | |
1712ac8f AV |
321 | } else { |
322 | up_write(&s->s_umount); | |
1da177e4 LT |
323 | } |
324 | } | |
325 | ||
1712ac8f | 326 | EXPORT_SYMBOL(deactivate_locked_super); |
1da177e4 | 327 | |
74dbbdd7 | 328 | /** |
1712ac8f | 329 | * deactivate_super - drop an active reference to superblock |
74dbbdd7 AV |
330 | * @s: superblock to deactivate |
331 | * | |
1712ac8f AV |
332 | * Variant of deactivate_locked_super(), except that superblock is *not* |
333 | * locked by caller. If we are going to drop the final active reference, | |
334 | * lock will be acquired prior to that. | |
74dbbdd7 | 335 | */ |
1712ac8f | 336 | void deactivate_super(struct super_block *s) |
74dbbdd7 | 337 | { |
1712ac8f AV |
338 | if (!atomic_add_unless(&s->s_active, -1, 1)) { |
339 | down_write(&s->s_umount); | |
340 | deactivate_locked_super(s); | |
74dbbdd7 AV |
341 | } |
342 | } | |
343 | ||
1712ac8f | 344 | EXPORT_SYMBOL(deactivate_super); |
74dbbdd7 | 345 | |
1da177e4 LT |
346 | /** |
347 | * grab_super - acquire an active reference | |
348 | * @s: reference we are trying to make active | |
349 | * | |
350 | * Tries to acquire an active reference. grab_super() is used when we | |
351 | * had just found a superblock in super_blocks or fs_type->fs_supers | |
352 | * and want to turn it into a full-blown active reference. grab_super() | |
353 | * is called with sb_lock held and drops it. Returns 1 in case of | |
354 | * success, 0 if we had failed (superblock contents was already dead or | |
acfec9a5 AV |
355 | * dying when grab_super() had been called). Note that this is only |
356 | * called for superblocks not in rundown mode (== ones still on ->fs_supers | |
357 | * of their type), so increment of ->s_count is OK here. | |
1da177e4 | 358 | */ |
9c4dbee7 | 359 | static int grab_super(struct super_block *s) __releases(sb_lock) |
1da177e4 LT |
360 | { |
361 | s->s_count++; | |
362 | spin_unlock(&sb_lock); | |
363 | down_write(&s->s_umount); | |
acfec9a5 AV |
364 | if ((s->s_flags & MS_BORN) && atomic_inc_not_zero(&s->s_active)) { |
365 | put_super(s); | |
366 | return 1; | |
367 | } | |
1da177e4 LT |
368 | up_write(&s->s_umount); |
369 | put_super(s); | |
1da177e4 LT |
370 | return 0; |
371 | } | |
372 | ||
12ad3ab6 | 373 | /* |
eb6ef3df | 374 | * trylock_super - try to grab ->s_umount shared |
331cbdee | 375 | * @sb: reference we are trying to grab |
12ad3ab6 | 376 | * |
eb6ef3df | 377 | * Try to prevent fs shutdown. This is used in places where we |
12ad3ab6 | 378 | * cannot take an active reference but we need to ensure that the |
eb6ef3df KK |
379 | * filesystem is not shut down while we are working on it. It returns |
380 | * false if we cannot acquire s_umount or if we lose the race and | |
381 | * filesystem already got into shutdown, and returns true with the s_umount | |
382 | * lock held in read mode in case of success. On successful return, | |
383 | * the caller must drop the s_umount lock when done. | |
384 | * | |
385 | * Note that unlike get_super() et.al. this one does *not* bump ->s_count. | |
386 | * The reason why it's safe is that we are OK with doing trylock instead | |
387 | * of down_read(). There's a couple of places that are OK with that, but | |
388 | * it's very much not a general-purpose interface. | |
12ad3ab6 | 389 | */ |
eb6ef3df | 390 | bool trylock_super(struct super_block *sb) |
12ad3ab6 | 391 | { |
12ad3ab6 | 392 | if (down_read_trylock(&sb->s_umount)) { |
eb6ef3df KK |
393 | if (!hlist_unhashed(&sb->s_instances) && |
394 | sb->s_root && (sb->s_flags & MS_BORN)) | |
12ad3ab6 DC |
395 | return true; |
396 | up_read(&sb->s_umount); | |
397 | } | |
398 | ||
12ad3ab6 DC |
399 | return false; |
400 | } | |
401 | ||
1da177e4 LT |
402 | /** |
403 | * generic_shutdown_super - common helper for ->kill_sb() | |
404 | * @sb: superblock to kill | |
405 | * | |
406 | * generic_shutdown_super() does all fs-independent work on superblock | |
407 | * shutdown. Typical ->kill_sb() should pick all fs-specific objects | |
408 | * that need destruction out of superblock, call generic_shutdown_super() | |
409 | * and release aforementioned objects. Note: dentries and inodes _are_ | |
410 | * taken care of and do not need specific handling. | |
c636ebdb DH |
411 | * |
412 | * Upon calling this function, the filesystem may no longer alter or | |
413 | * rearrange the set of dentries belonging to this super_block, nor may it | |
414 | * change the attachments of dentries to inodes. | |
1da177e4 LT |
415 | */ |
416 | void generic_shutdown_super(struct super_block *sb) | |
417 | { | |
ee9b6d61 | 418 | const struct super_operations *sop = sb->s_op; |
1da177e4 | 419 | |
c636ebdb DH |
420 | if (sb->s_root) { |
421 | shrink_dcache_for_umount(sb); | |
60b0680f | 422 | sync_filesystem(sb); |
1da177e4 | 423 | sb->s_flags &= ~MS_ACTIVE; |
efaee192 | 424 | |
74278da9 | 425 | fsnotify_unmount_inodes(sb); |
a1a0e23e | 426 | cgroup_writeback_umount(); |
63997e98 AV |
427 | |
428 | evict_inodes(sb); | |
1da177e4 | 429 | |
7b7a8665 CH |
430 | if (sb->s_dio_done_wq) { |
431 | destroy_workqueue(sb->s_dio_done_wq); | |
432 | sb->s_dio_done_wq = NULL; | |
433 | } | |
434 | ||
1da177e4 LT |
435 | if (sop->put_super) |
436 | sop->put_super(sb); | |
437 | ||
63997e98 | 438 | if (!list_empty(&sb->s_inodes)) { |
7b4fe29e DJ |
439 | printk("VFS: Busy inodes after unmount of %s. " |
440 | "Self-destruct in 5 seconds. Have a nice day...\n", | |
441 | sb->s_id); | |
1da177e4 | 442 | } |
1da177e4 LT |
443 | } |
444 | spin_lock(&sb_lock); | |
445 | /* should be initialized for __put_super_and_need_restart() */ | |
a5166169 | 446 | hlist_del_init(&sb->s_instances); |
1da177e4 LT |
447 | spin_unlock(&sb_lock); |
448 | up_write(&sb->s_umount); | |
fca39346 JK |
449 | if (sb->s_iflags & SB_I_DYNBDI) { |
450 | bdi_put(sb->s_bdi); | |
451 | sb->s_bdi = &noop_backing_dev_info; | |
452 | sb->s_iflags &= ~SB_I_DYNBDI; | |
453 | } | |
1da177e4 LT |
454 | } |
455 | ||
456 | EXPORT_SYMBOL(generic_shutdown_super); | |
457 | ||
458 | /** | |
6e4eab57 | 459 | * sget_userns - find or create a superblock |
1da177e4 LT |
460 | * @type: filesystem type superblock should belong to |
461 | * @test: comparison callback | |
462 | * @set: setup callback | |
9249e17f | 463 | * @flags: mount flags |
6e4eab57 | 464 | * @user_ns: User namespace for the super_block |
1da177e4 LT |
465 | * @data: argument to each of them |
466 | */ | |
6e4eab57 | 467 | struct super_block *sget_userns(struct file_system_type *type, |
1da177e4 LT |
468 | int (*test)(struct super_block *,void *), |
469 | int (*set)(struct super_block *,void *), | |
6e4eab57 | 470 | int flags, struct user_namespace *user_ns, |
1da177e4 LT |
471 | void *data) |
472 | { | |
473 | struct super_block *s = NULL; | |
d4730127 | 474 | struct super_block *old; |
1da177e4 LT |
475 | int err; |
476 | ||
93faccbb | 477 | if (!(flags & (MS_KERNMOUNT|MS_SUBMOUNT)) && |
a001e74c EB |
478 | !(type->fs_flags & FS_USERNS_MOUNT) && |
479 | !capable(CAP_SYS_ADMIN)) | |
480 | return ERR_PTR(-EPERM); | |
1da177e4 LT |
481 | retry: |
482 | spin_lock(&sb_lock); | |
d4730127 | 483 | if (test) { |
b67bfe0d | 484 | hlist_for_each_entry(old, &type->fs_supers, s_instances) { |
d4730127 MK |
485 | if (!test(old, data)) |
486 | continue; | |
6e4eab57 EB |
487 | if (user_ns != old->s_user_ns) { |
488 | spin_unlock(&sb_lock); | |
489 | if (s) { | |
490 | up_write(&s->s_umount); | |
491 | destroy_super(s); | |
492 | } | |
493 | return ERR_PTR(-EBUSY); | |
494 | } | |
d4730127 MK |
495 | if (!grab_super(old)) |
496 | goto retry; | |
a3cfbb53 LZ |
497 | if (s) { |
498 | up_write(&s->s_umount); | |
d4730127 | 499 | destroy_super(s); |
7a4dec53 | 500 | s = NULL; |
a3cfbb53 | 501 | } |
d4730127 MK |
502 | return old; |
503 | } | |
1da177e4 LT |
504 | } |
505 | if (!s) { | |
506 | spin_unlock(&sb_lock); | |
93faccbb | 507 | s = alloc_super(type, (flags & ~MS_SUBMOUNT), user_ns); |
1da177e4 LT |
508 | if (!s) |
509 | return ERR_PTR(-ENOMEM); | |
510 | goto retry; | |
511 | } | |
512 | ||
513 | err = set(s, data); | |
514 | if (err) { | |
515 | spin_unlock(&sb_lock); | |
a3cfbb53 | 516 | up_write(&s->s_umount); |
1da177e4 LT |
517 | destroy_super(s); |
518 | return ERR_PTR(err); | |
519 | } | |
520 | s->s_type = type; | |
521 | strlcpy(s->s_id, type->name, sizeof(s->s_id)); | |
522 | list_add_tail(&s->s_list, &super_blocks); | |
a5166169 | 523 | hlist_add_head(&s->s_instances, &type->fs_supers); |
1da177e4 LT |
524 | spin_unlock(&sb_lock); |
525 | get_filesystem(type); | |
b0d40c92 | 526 | register_shrinker(&s->s_shrink); |
1da177e4 LT |
527 | return s; |
528 | } | |
529 | ||
6e4eab57 EB |
530 | EXPORT_SYMBOL(sget_userns); |
531 | ||
532 | /** | |
533 | * sget - find or create a superblock | |
534 | * @type: filesystem type superblock should belong to | |
535 | * @test: comparison callback | |
536 | * @set: setup callback | |
537 | * @flags: mount flags | |
538 | * @data: argument to each of them | |
539 | */ | |
540 | struct super_block *sget(struct file_system_type *type, | |
541 | int (*test)(struct super_block *,void *), | |
542 | int (*set)(struct super_block *,void *), | |
543 | int flags, | |
544 | void *data) | |
545 | { | |
546 | struct user_namespace *user_ns = current_user_ns(); | |
547 | ||
93faccbb EB |
548 | /* We don't yet pass the user namespace of the parent |
549 | * mount through to here so always use &init_user_ns | |
550 | * until that changes. | |
551 | */ | |
552 | if (flags & MS_SUBMOUNT) | |
553 | user_ns = &init_user_ns; | |
554 | ||
6e4eab57 | 555 | /* Ensure the requestor has permissions over the target filesystem */ |
93faccbb | 556 | if (!(flags & (MS_KERNMOUNT|MS_SUBMOUNT)) && !ns_capable(user_ns, CAP_SYS_ADMIN)) |
6e4eab57 EB |
557 | return ERR_PTR(-EPERM); |
558 | ||
559 | return sget_userns(type, test, set, flags, user_ns, data); | |
560 | } | |
561 | ||
1da177e4 LT |
562 | EXPORT_SYMBOL(sget); |
563 | ||
564 | void drop_super(struct super_block *sb) | |
565 | { | |
566 | up_read(&sb->s_umount); | |
567 | put_super(sb); | |
568 | } | |
569 | ||
570 | EXPORT_SYMBOL(drop_super); | |
571 | ||
ba6379f7 JK |
572 | void drop_super_exclusive(struct super_block *sb) |
573 | { | |
574 | up_write(&sb->s_umount); | |
575 | put_super(sb); | |
576 | } | |
577 | EXPORT_SYMBOL(drop_super_exclusive); | |
578 | ||
01a05b33 AV |
579 | /** |
580 | * iterate_supers - call function for all active superblocks | |
581 | * @f: function to call | |
582 | * @arg: argument to pass to it | |
583 | * | |
584 | * Scans the superblock list and calls given function, passing it | |
585 | * locked superblock and given argument. | |
586 | */ | |
587 | void iterate_supers(void (*f)(struct super_block *, void *), void *arg) | |
588 | { | |
dca33252 | 589 | struct super_block *sb, *p = NULL; |
01a05b33 AV |
590 | |
591 | spin_lock(&sb_lock); | |
dca33252 | 592 | list_for_each_entry(sb, &super_blocks, s_list) { |
a5166169 | 593 | if (hlist_unhashed(&sb->s_instances)) |
01a05b33 AV |
594 | continue; |
595 | sb->s_count++; | |
596 | spin_unlock(&sb_lock); | |
597 | ||
598 | down_read(&sb->s_umount); | |
dabe0dc1 | 599 | if (sb->s_root && (sb->s_flags & MS_BORN)) |
01a05b33 AV |
600 | f(sb, arg); |
601 | up_read(&sb->s_umount); | |
602 | ||
603 | spin_lock(&sb_lock); | |
dca33252 AV |
604 | if (p) |
605 | __put_super(p); | |
606 | p = sb; | |
01a05b33 | 607 | } |
dca33252 AV |
608 | if (p) |
609 | __put_super(p); | |
01a05b33 AV |
610 | spin_unlock(&sb_lock); |
611 | } | |
612 | ||
43e15cdb AV |
613 | /** |
614 | * iterate_supers_type - call function for superblocks of given type | |
615 | * @type: fs type | |
616 | * @f: function to call | |
617 | * @arg: argument to pass to it | |
618 | * | |
619 | * Scans the superblock list and calls given function, passing it | |
620 | * locked superblock and given argument. | |
621 | */ | |
622 | void iterate_supers_type(struct file_system_type *type, | |
623 | void (*f)(struct super_block *, void *), void *arg) | |
624 | { | |
625 | struct super_block *sb, *p = NULL; | |
626 | ||
627 | spin_lock(&sb_lock); | |
b67bfe0d | 628 | hlist_for_each_entry(sb, &type->fs_supers, s_instances) { |
43e15cdb AV |
629 | sb->s_count++; |
630 | spin_unlock(&sb_lock); | |
631 | ||
632 | down_read(&sb->s_umount); | |
dabe0dc1 | 633 | if (sb->s_root && (sb->s_flags & MS_BORN)) |
43e15cdb AV |
634 | f(sb, arg); |
635 | up_read(&sb->s_umount); | |
636 | ||
637 | spin_lock(&sb_lock); | |
638 | if (p) | |
639 | __put_super(p); | |
640 | p = sb; | |
641 | } | |
642 | if (p) | |
643 | __put_super(p); | |
644 | spin_unlock(&sb_lock); | |
645 | } | |
646 | ||
647 | EXPORT_SYMBOL(iterate_supers_type); | |
648 | ||
ba6379f7 | 649 | static struct super_block *__get_super(struct block_device *bdev, bool excl) |
1da177e4 | 650 | { |
618f0636 KK |
651 | struct super_block *sb; |
652 | ||
1da177e4 LT |
653 | if (!bdev) |
654 | return NULL; | |
618f0636 | 655 | |
1da177e4 | 656 | spin_lock(&sb_lock); |
618f0636 KK |
657 | rescan: |
658 | list_for_each_entry(sb, &super_blocks, s_list) { | |
a5166169 | 659 | if (hlist_unhashed(&sb->s_instances)) |
551de6f3 | 660 | continue; |
618f0636 KK |
661 | if (sb->s_bdev == bdev) { |
662 | sb->s_count++; | |
1da177e4 | 663 | spin_unlock(&sb_lock); |
ba6379f7 JK |
664 | if (!excl) |
665 | down_read(&sb->s_umount); | |
666 | else | |
667 | down_write(&sb->s_umount); | |
df40c01a | 668 | /* still alive? */ |
dabe0dc1 | 669 | if (sb->s_root && (sb->s_flags & MS_BORN)) |
618f0636 | 670 | return sb; |
ba6379f7 JK |
671 | if (!excl) |
672 | up_read(&sb->s_umount); | |
673 | else | |
674 | up_write(&sb->s_umount); | |
df40c01a | 675 | /* nope, got unmounted */ |
618f0636 | 676 | spin_lock(&sb_lock); |
df40c01a AV |
677 | __put_super(sb); |
678 | goto rescan; | |
1da177e4 LT |
679 | } |
680 | } | |
681 | spin_unlock(&sb_lock); | |
682 | return NULL; | |
683 | } | |
684 | ||
6b6dc836 | 685 | /** |
ba6379f7 | 686 | * get_super - get the superblock of a device |
6b6dc836 JK |
687 | * @bdev: device to get the superblock for |
688 | * | |
689 | * Scans the superblock list and finds the superblock of the file system | |
ba6379f7 | 690 | * mounted on the device given. %NULL is returned if no match is found. |
6b6dc836 | 691 | */ |
ba6379f7 JK |
692 | struct super_block *get_super(struct block_device *bdev) |
693 | { | |
694 | return __get_super(bdev, false); | |
695 | } | |
696 | EXPORT_SYMBOL(get_super); | |
697 | ||
698 | static struct super_block *__get_super_thawed(struct block_device *bdev, | |
699 | bool excl) | |
6b6dc836 JK |
700 | { |
701 | while (1) { | |
ba6379f7 | 702 | struct super_block *s = __get_super(bdev, excl); |
5accdf82 | 703 | if (!s || s->s_writers.frozen == SB_UNFROZEN) |
6b6dc836 | 704 | return s; |
ba6379f7 JK |
705 | if (!excl) |
706 | up_read(&s->s_umount); | |
707 | else | |
708 | up_write(&s->s_umount); | |
5accdf82 JK |
709 | wait_event(s->s_writers.wait_unfrozen, |
710 | s->s_writers.frozen == SB_UNFROZEN); | |
6b6dc836 JK |
711 | put_super(s); |
712 | } | |
713 | } | |
ba6379f7 JK |
714 | |
715 | /** | |
716 | * get_super_thawed - get thawed superblock of a device | |
717 | * @bdev: device to get the superblock for | |
718 | * | |
719 | * Scans the superblock list and finds the superblock of the file system | |
720 | * mounted on the device. The superblock is returned once it is thawed | |
721 | * (or immediately if it was not frozen). %NULL is returned if no match | |
722 | * is found. | |
723 | */ | |
724 | struct super_block *get_super_thawed(struct block_device *bdev) | |
725 | { | |
726 | return __get_super_thawed(bdev, false); | |
727 | } | |
6b6dc836 JK |
728 | EXPORT_SYMBOL(get_super_thawed); |
729 | ||
ba6379f7 JK |
730 | /** |
731 | * get_super_exclusive_thawed - get thawed superblock of a device | |
732 | * @bdev: device to get the superblock for | |
733 | * | |
734 | * Scans the superblock list and finds the superblock of the file system | |
735 | * mounted on the device. The superblock is returned once it is thawed | |
736 | * (or immediately if it was not frozen) and s_umount semaphore is held | |
737 | * in exclusive mode. %NULL is returned if no match is found. | |
738 | */ | |
739 | struct super_block *get_super_exclusive_thawed(struct block_device *bdev) | |
740 | { | |
741 | return __get_super_thawed(bdev, true); | |
742 | } | |
743 | EXPORT_SYMBOL(get_super_exclusive_thawed); | |
744 | ||
4504230a CH |
745 | /** |
746 | * get_active_super - get an active reference to the superblock of a device | |
747 | * @bdev: device to get the superblock for | |
748 | * | |
749 | * Scans the superblock list and finds the superblock of the file system | |
750 | * mounted on the device given. Returns the superblock with an active | |
d3f21473 | 751 | * reference or %NULL if none was found. |
4504230a CH |
752 | */ |
753 | struct super_block *get_active_super(struct block_device *bdev) | |
754 | { | |
755 | struct super_block *sb; | |
756 | ||
757 | if (!bdev) | |
758 | return NULL; | |
759 | ||
1494583d | 760 | restart: |
4504230a CH |
761 | spin_lock(&sb_lock); |
762 | list_for_each_entry(sb, &super_blocks, s_list) { | |
a5166169 | 763 | if (hlist_unhashed(&sb->s_instances)) |
551de6f3 | 764 | continue; |
1494583d | 765 | if (sb->s_bdev == bdev) { |
acfec9a5 | 766 | if (!grab_super(sb)) |
1494583d | 767 | goto restart; |
acfec9a5 AV |
768 | up_write(&sb->s_umount); |
769 | return sb; | |
1494583d | 770 | } |
4504230a CH |
771 | } |
772 | spin_unlock(&sb_lock); | |
773 | return NULL; | |
774 | } | |
1da177e4 | 775 | |
df40c01a | 776 | struct super_block *user_get_super(dev_t dev) |
1da177e4 | 777 | { |
618f0636 | 778 | struct super_block *sb; |
1da177e4 | 779 | |
1da177e4 | 780 | spin_lock(&sb_lock); |
618f0636 KK |
781 | rescan: |
782 | list_for_each_entry(sb, &super_blocks, s_list) { | |
a5166169 | 783 | if (hlist_unhashed(&sb->s_instances)) |
551de6f3 | 784 | continue; |
618f0636 KK |
785 | if (sb->s_dev == dev) { |
786 | sb->s_count++; | |
1da177e4 | 787 | spin_unlock(&sb_lock); |
618f0636 | 788 | down_read(&sb->s_umount); |
df40c01a | 789 | /* still alive? */ |
dabe0dc1 | 790 | if (sb->s_root && (sb->s_flags & MS_BORN)) |
618f0636 KK |
791 | return sb; |
792 | up_read(&sb->s_umount); | |
df40c01a | 793 | /* nope, got unmounted */ |
618f0636 | 794 | spin_lock(&sb_lock); |
df40c01a AV |
795 | __put_super(sb); |
796 | goto rescan; | |
1da177e4 LT |
797 | } |
798 | } | |
799 | spin_unlock(&sb_lock); | |
800 | return NULL; | |
801 | } | |
802 | ||
1da177e4 LT |
803 | /** |
804 | * do_remount_sb - asks filesystem to change mount options. | |
805 | * @sb: superblock in question | |
806 | * @flags: numeric part of options | |
807 | * @data: the rest of options | |
808 | * @force: whether or not to force the change | |
809 | * | |
810 | * Alters the mount options of a mounted file system. | |
811 | */ | |
812 | int do_remount_sb(struct super_block *sb, int flags, void *data, int force) | |
813 | { | |
814 | int retval; | |
c79d967d | 815 | int remount_ro; |
4504230a | 816 | |
5accdf82 | 817 | if (sb->s_writers.frozen != SB_UNFROZEN) |
4504230a CH |
818 | return -EBUSY; |
819 | ||
9361401e | 820 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
821 | if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) |
822 | return -EACCES; | |
9361401e | 823 | #endif |
4504230a | 824 | |
d208bbdd | 825 | remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); |
d208bbdd | 826 | |
0aec09d0 | 827 | if (remount_ro) { |
fdab684d | 828 | if (!hlist_empty(&sb->s_pins)) { |
0aec09d0 | 829 | up_write(&sb->s_umount); |
fdab684d | 830 | group_pin_kill(&sb->s_pins); |
0aec09d0 AV |
831 | down_write(&sb->s_umount); |
832 | if (!sb->s_root) | |
833 | return 0; | |
834 | if (sb->s_writers.frozen != SB_UNFROZEN) | |
835 | return -EBUSY; | |
836 | remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); | |
837 | } | |
838 | } | |
839 | shrink_dcache_sb(sb); | |
840 | ||
1da177e4 LT |
841 | /* If we are remounting RDONLY and current sb is read/write, |
842 | make sure there are no rw files opened */ | |
d208bbdd | 843 | if (remount_ro) { |
4ed5e82f | 844 | if (force) { |
eee5cc27 AV |
845 | sb->s_readonly_remount = 1; |
846 | smp_wmb(); | |
4ed5e82f MS |
847 | } else { |
848 | retval = sb_prepare_remount_readonly(sb); | |
849 | if (retval) | |
850 | return retval; | |
4ed5e82f | 851 | } |
1da177e4 LT |
852 | } |
853 | ||
854 | if (sb->s_op->remount_fs) { | |
1da177e4 | 855 | retval = sb->s_op->remount_fs(sb, &flags, data); |
2833eb2b MS |
856 | if (retval) { |
857 | if (!force) | |
4ed5e82f | 858 | goto cancel_readonly; |
2833eb2b MS |
859 | /* If forced remount, go ahead despite any errors */ |
860 | WARN(1, "forced remount of a %s fs returned %i\n", | |
861 | sb->s_type->name, retval); | |
862 | } | |
1da177e4 LT |
863 | } |
864 | sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); | |
4ed5e82f MS |
865 | /* Needs to be ordered wrt mnt_is_readonly() */ |
866 | smp_wmb(); | |
867 | sb->s_readonly_remount = 0; | |
c79d967d | 868 | |
d208bbdd NP |
869 | /* |
870 | * Some filesystems modify their metadata via some other path than the | |
871 | * bdev buffer cache (eg. use a private mapping, or directories in | |
872 | * pagecache, etc). Also file data modifications go via their own | |
873 | * mappings. So If we try to mount readonly then copy the filesystem | |
874 | * from bdev, we could get stale data, so invalidate it to give a best | |
875 | * effort at coherency. | |
876 | */ | |
877 | if (remount_ro && sb->s_bdev) | |
878 | invalidate_bdev(sb->s_bdev); | |
1da177e4 | 879 | return 0; |
4ed5e82f MS |
880 | |
881 | cancel_readonly: | |
882 | sb->s_readonly_remount = 0; | |
883 | return retval; | |
1da177e4 LT |
884 | } |
885 | ||
a2a9537a | 886 | static void do_emergency_remount(struct work_struct *work) |
1da177e4 | 887 | { |
dca33252 | 888 | struct super_block *sb, *p = NULL; |
1da177e4 LT |
889 | |
890 | spin_lock(&sb_lock); | |
dca33252 | 891 | list_for_each_entry(sb, &super_blocks, s_list) { |
a5166169 | 892 | if (hlist_unhashed(&sb->s_instances)) |
551de6f3 | 893 | continue; |
1da177e4 LT |
894 | sb->s_count++; |
895 | spin_unlock(&sb_lock); | |
443b94ba | 896 | down_write(&sb->s_umount); |
dabe0dc1 AV |
897 | if (sb->s_root && sb->s_bdev && (sb->s_flags & MS_BORN) && |
898 | !(sb->s_flags & MS_RDONLY)) { | |
1da177e4 | 899 | /* |
1da177e4 LT |
900 | * What lock protects sb->s_flags?? |
901 | */ | |
1da177e4 | 902 | do_remount_sb(sb, MS_RDONLY, NULL, 1); |
1da177e4 | 903 | } |
443b94ba | 904 | up_write(&sb->s_umount); |
1da177e4 | 905 | spin_lock(&sb_lock); |
dca33252 AV |
906 | if (p) |
907 | __put_super(p); | |
908 | p = sb; | |
1da177e4 | 909 | } |
dca33252 AV |
910 | if (p) |
911 | __put_super(p); | |
1da177e4 | 912 | spin_unlock(&sb_lock); |
a2a9537a | 913 | kfree(work); |
1da177e4 LT |
914 | printk("Emergency Remount complete\n"); |
915 | } | |
916 | ||
917 | void emergency_remount(void) | |
918 | { | |
a2a9537a JA |
919 | struct work_struct *work; |
920 | ||
921 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
922 | if (work) { | |
923 | INIT_WORK(work, do_emergency_remount); | |
924 | schedule_work(work); | |
925 | } | |
1da177e4 LT |
926 | } |
927 | ||
928 | /* | |
929 | * Unnamed block devices are dummy devices used by virtual | |
930 | * filesystems which don't use real block-devices. -- jrs | |
931 | */ | |
932 | ||
ad76cbc6 | 933 | static DEFINE_IDA(unnamed_dev_ida); |
1da177e4 | 934 | static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ |
a2a4dc49 TB |
935 | /* Many userspace utilities consider an FSID of 0 invalid. |
936 | * Always return at least 1 from get_anon_bdev. | |
937 | */ | |
938 | static int unnamed_dev_start = 1; | |
1da177e4 | 939 | |
0ee5dc67 | 940 | int get_anon_bdev(dev_t *p) |
1da177e4 LT |
941 | { |
942 | int dev; | |
943 | int error; | |
944 | ||
945 | retry: | |
ad76cbc6 | 946 | if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) |
1da177e4 LT |
947 | return -ENOMEM; |
948 | spin_lock(&unnamed_dev_lock); | |
c63e09ec | 949 | error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev); |
f21f6220 AV |
950 | if (!error) |
951 | unnamed_dev_start = dev + 1; | |
1da177e4 LT |
952 | spin_unlock(&unnamed_dev_lock); |
953 | if (error == -EAGAIN) | |
954 | /* We raced and lost with another CPU. */ | |
955 | goto retry; | |
956 | else if (error) | |
957 | return -EAGAIN; | |
958 | ||
1af95de6 | 959 | if (dev >= (1 << MINORBITS)) { |
1da177e4 | 960 | spin_lock(&unnamed_dev_lock); |
ad76cbc6 | 961 | ida_remove(&unnamed_dev_ida, dev); |
f21f6220 AV |
962 | if (unnamed_dev_start > dev) |
963 | unnamed_dev_start = dev; | |
1da177e4 LT |
964 | spin_unlock(&unnamed_dev_lock); |
965 | return -EMFILE; | |
966 | } | |
0ee5dc67 | 967 | *p = MKDEV(0, dev & MINORMASK); |
1da177e4 LT |
968 | return 0; |
969 | } | |
0ee5dc67 | 970 | EXPORT_SYMBOL(get_anon_bdev); |
1da177e4 | 971 | |
0ee5dc67 | 972 | void free_anon_bdev(dev_t dev) |
1da177e4 | 973 | { |
0ee5dc67 | 974 | int slot = MINOR(dev); |
1da177e4 | 975 | spin_lock(&unnamed_dev_lock); |
ad76cbc6 | 976 | ida_remove(&unnamed_dev_ida, slot); |
c63e09ec AV |
977 | if (slot < unnamed_dev_start) |
978 | unnamed_dev_start = slot; | |
1da177e4 LT |
979 | spin_unlock(&unnamed_dev_lock); |
980 | } | |
0ee5dc67 AV |
981 | EXPORT_SYMBOL(free_anon_bdev); |
982 | ||
983 | int set_anon_super(struct super_block *s, void *data) | |
984 | { | |
df0ce26c | 985 | return get_anon_bdev(&s->s_dev); |
0ee5dc67 AV |
986 | } |
987 | ||
988 | EXPORT_SYMBOL(set_anon_super); | |
989 | ||
990 | void kill_anon_super(struct super_block *sb) | |
991 | { | |
992 | dev_t dev = sb->s_dev; | |
993 | generic_shutdown_super(sb); | |
994 | free_anon_bdev(dev); | |
995 | } | |
1da177e4 LT |
996 | |
997 | EXPORT_SYMBOL(kill_anon_super); | |
998 | ||
1da177e4 LT |
999 | void kill_litter_super(struct super_block *sb) |
1000 | { | |
1001 | if (sb->s_root) | |
1002 | d_genocide(sb->s_root); | |
1003 | kill_anon_super(sb); | |
1004 | } | |
1005 | ||
1006 | EXPORT_SYMBOL(kill_litter_super); | |
1007 | ||
909e6d94 SH |
1008 | static int ns_test_super(struct super_block *sb, void *data) |
1009 | { | |
1010 | return sb->s_fs_info == data; | |
1011 | } | |
1012 | ||
1013 | static int ns_set_super(struct super_block *sb, void *data) | |
1014 | { | |
1015 | sb->s_fs_info = data; | |
1016 | return set_anon_super(sb, NULL); | |
1017 | } | |
1018 | ||
d91ee87d EB |
1019 | struct dentry *mount_ns(struct file_system_type *fs_type, |
1020 | int flags, void *data, void *ns, struct user_namespace *user_ns, | |
1021 | int (*fill_super)(struct super_block *, void *, int)) | |
909e6d94 SH |
1022 | { |
1023 | struct super_block *sb; | |
1024 | ||
d91ee87d EB |
1025 | /* Don't allow mounting unless the caller has CAP_SYS_ADMIN |
1026 | * over the namespace. | |
1027 | */ | |
1028 | if (!(flags & MS_KERNMOUNT) && !ns_capable(user_ns, CAP_SYS_ADMIN)) | |
1029 | return ERR_PTR(-EPERM); | |
1030 | ||
6e4eab57 EB |
1031 | sb = sget_userns(fs_type, ns_test_super, ns_set_super, flags, |
1032 | user_ns, ns); | |
909e6d94 | 1033 | if (IS_ERR(sb)) |
ceefda69 | 1034 | return ERR_CAST(sb); |
909e6d94 SH |
1035 | |
1036 | if (!sb->s_root) { | |
1037 | int err; | |
909e6d94 SH |
1038 | err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); |
1039 | if (err) { | |
74dbbdd7 | 1040 | deactivate_locked_super(sb); |
ceefda69 | 1041 | return ERR_PTR(err); |
909e6d94 SH |
1042 | } |
1043 | ||
1044 | sb->s_flags |= MS_ACTIVE; | |
1045 | } | |
1046 | ||
ceefda69 | 1047 | return dget(sb->s_root); |
909e6d94 SH |
1048 | } |
1049 | ||
ceefda69 | 1050 | EXPORT_SYMBOL(mount_ns); |
909e6d94 | 1051 | |
9361401e | 1052 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
1053 | static int set_bdev_super(struct super_block *s, void *data) |
1054 | { | |
1055 | s->s_bdev = data; | |
1056 | s->s_dev = s->s_bdev->bd_dev; | |
13eec236 JK |
1057 | s->s_bdi = bdi_get(s->s_bdev->bd_bdi); |
1058 | s->s_iflags |= SB_I_DYNBDI; | |
32a88aa1 | 1059 | |
1da177e4 LT |
1060 | return 0; |
1061 | } | |
1062 | ||
1063 | static int test_bdev_super(struct super_block *s, void *data) | |
1064 | { | |
1065 | return (void *)s->s_bdev == data; | |
1066 | } | |
1067 | ||
152a0836 | 1068 | struct dentry *mount_bdev(struct file_system_type *fs_type, |
1da177e4 | 1069 | int flags, const char *dev_name, void *data, |
152a0836 | 1070 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
1071 | { |
1072 | struct block_device *bdev; | |
1073 | struct super_block *s; | |
d4d77629 | 1074 | fmode_t mode = FMODE_READ | FMODE_EXCL; |
1da177e4 LT |
1075 | int error = 0; |
1076 | ||
30c40d2c AV |
1077 | if (!(flags & MS_RDONLY)) |
1078 | mode |= FMODE_WRITE; | |
1079 | ||
d4d77629 | 1080 | bdev = blkdev_get_by_path(dev_name, mode, fs_type); |
1da177e4 | 1081 | if (IS_ERR(bdev)) |
152a0836 | 1082 | return ERR_CAST(bdev); |
1da177e4 LT |
1083 | |
1084 | /* | |
1085 | * once the super is inserted into the list by sget, s_umount | |
1086 | * will protect the lockfs code from trying to start a snapshot | |
1087 | * while we are mounting | |
1088 | */ | |
4fadd7bb CH |
1089 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
1090 | if (bdev->bd_fsfreeze_count > 0) { | |
1091 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
1092 | error = -EBUSY; | |
1093 | goto error_bdev; | |
1094 | } | |
9249e17f DH |
1095 | s = sget(fs_type, test_bdev_super, set_bdev_super, flags | MS_NOSEC, |
1096 | bdev); | |
4fadd7bb | 1097 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
1da177e4 | 1098 | if (IS_ERR(s)) |
454e2398 | 1099 | goto error_s; |
1da177e4 LT |
1100 | |
1101 | if (s->s_root) { | |
1102 | if ((flags ^ s->s_flags) & MS_RDONLY) { | |
74dbbdd7 | 1103 | deactivate_locked_super(s); |
454e2398 DH |
1104 | error = -EBUSY; |
1105 | goto error_bdev; | |
1da177e4 | 1106 | } |
454e2398 | 1107 | |
4f331f01 TH |
1108 | /* |
1109 | * s_umount nests inside bd_mutex during | |
e525fd89 TH |
1110 | * __invalidate_device(). blkdev_put() acquires |
1111 | * bd_mutex and can't be called under s_umount. Drop | |
1112 | * s_umount temporarily. This is safe as we're | |
1113 | * holding an active reference. | |
4f331f01 TH |
1114 | */ |
1115 | up_write(&s->s_umount); | |
d4d77629 | 1116 | blkdev_put(bdev, mode); |
4f331f01 | 1117 | down_write(&s->s_umount); |
1da177e4 | 1118 | } else { |
30c40d2c | 1119 | s->s_mode = mode; |
a1c6f057 | 1120 | snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev); |
e78c9a00 | 1121 | sb_set_blocksize(s, block_size(bdev)); |
9b04c997 | 1122 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 1123 | if (error) { |
74dbbdd7 | 1124 | deactivate_locked_super(s); |
454e2398 | 1125 | goto error; |
fa675765 | 1126 | } |
454e2398 DH |
1127 | |
1128 | s->s_flags |= MS_ACTIVE; | |
87d8fe1e | 1129 | bdev->bd_super = s; |
1da177e4 LT |
1130 | } |
1131 | ||
152a0836 | 1132 | return dget(s->s_root); |
1da177e4 | 1133 | |
454e2398 DH |
1134 | error_s: |
1135 | error = PTR_ERR(s); | |
1136 | error_bdev: | |
d4d77629 | 1137 | blkdev_put(bdev, mode); |
454e2398 | 1138 | error: |
152a0836 AV |
1139 | return ERR_PTR(error); |
1140 | } | |
1141 | EXPORT_SYMBOL(mount_bdev); | |
1142 | ||
1da177e4 LT |
1143 | void kill_block_super(struct super_block *sb) |
1144 | { | |
1145 | struct block_device *bdev = sb->s_bdev; | |
30c40d2c | 1146 | fmode_t mode = sb->s_mode; |
1da177e4 | 1147 | |
ddbaaf30 | 1148 | bdev->bd_super = NULL; |
1da177e4 LT |
1149 | generic_shutdown_super(sb); |
1150 | sync_blockdev(bdev); | |
d4d77629 | 1151 | WARN_ON_ONCE(!(mode & FMODE_EXCL)); |
e525fd89 | 1152 | blkdev_put(bdev, mode | FMODE_EXCL); |
1da177e4 LT |
1153 | } |
1154 | ||
1155 | EXPORT_SYMBOL(kill_block_super); | |
9361401e | 1156 | #endif |
1da177e4 | 1157 | |
3c26ff6e | 1158 | struct dentry *mount_nodev(struct file_system_type *fs_type, |
1da177e4 | 1159 | int flags, void *data, |
3c26ff6e | 1160 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
1161 | { |
1162 | int error; | |
9249e17f | 1163 | struct super_block *s = sget(fs_type, NULL, set_anon_super, flags, NULL); |
1da177e4 LT |
1164 | |
1165 | if (IS_ERR(s)) | |
3c26ff6e | 1166 | return ERR_CAST(s); |
1da177e4 | 1167 | |
9b04c997 | 1168 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 1169 | if (error) { |
74dbbdd7 | 1170 | deactivate_locked_super(s); |
3c26ff6e | 1171 | return ERR_PTR(error); |
1da177e4 LT |
1172 | } |
1173 | s->s_flags |= MS_ACTIVE; | |
3c26ff6e | 1174 | return dget(s->s_root); |
1da177e4 | 1175 | } |
3c26ff6e AV |
1176 | EXPORT_SYMBOL(mount_nodev); |
1177 | ||
1da177e4 LT |
1178 | static int compare_single(struct super_block *s, void *p) |
1179 | { | |
1180 | return 1; | |
1181 | } | |
1182 | ||
fc14f2fe | 1183 | struct dentry *mount_single(struct file_system_type *fs_type, |
1da177e4 | 1184 | int flags, void *data, |
fc14f2fe | 1185 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
1186 | { |
1187 | struct super_block *s; | |
1188 | int error; | |
1189 | ||
9249e17f | 1190 | s = sget(fs_type, compare_single, set_anon_super, flags, NULL); |
1da177e4 | 1191 | if (IS_ERR(s)) |
fc14f2fe | 1192 | return ERR_CAST(s); |
1da177e4 | 1193 | if (!s->s_root) { |
9b04c997 | 1194 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 1195 | if (error) { |
74dbbdd7 | 1196 | deactivate_locked_super(s); |
fc14f2fe | 1197 | return ERR_PTR(error); |
1da177e4 LT |
1198 | } |
1199 | s->s_flags |= MS_ACTIVE; | |
9329d1be KS |
1200 | } else { |
1201 | do_remount_sb(s, flags, data, 0); | |
1da177e4 | 1202 | } |
fc14f2fe AV |
1203 | return dget(s->s_root); |
1204 | } | |
1205 | EXPORT_SYMBOL(mount_single); | |
1206 | ||
9d412a43 AV |
1207 | struct dentry * |
1208 | mount_fs(struct file_system_type *type, int flags, const char *name, void *data) | |
1da177e4 | 1209 | { |
c96e41e9 | 1210 | struct dentry *root; |
9d412a43 | 1211 | struct super_block *sb; |
1da177e4 | 1212 | char *secdata = NULL; |
9d412a43 | 1213 | int error = -ENOMEM; |
8089352a | 1214 | |
e0007529 | 1215 | if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { |
1da177e4 | 1216 | secdata = alloc_secdata(); |
454e2398 | 1217 | if (!secdata) |
9d412a43 | 1218 | goto out; |
1da177e4 | 1219 | |
e0007529 | 1220 | error = security_sb_copy_data(data, secdata); |
454e2398 | 1221 | if (error) |
1da177e4 | 1222 | goto out_free_secdata; |
1da177e4 LT |
1223 | } |
1224 | ||
1a102ff9 AV |
1225 | root = type->mount(type, flags, name, data); |
1226 | if (IS_ERR(root)) { | |
1227 | error = PTR_ERR(root); | |
1228 | goto out_free_secdata; | |
c96e41e9 | 1229 | } |
9d412a43 AV |
1230 | sb = root->d_sb; |
1231 | BUG_ON(!sb); | |
1232 | WARN_ON(!sb->s_bdi); | |
1233 | sb->s_flags |= MS_BORN; | |
454e2398 | 1234 | |
9d412a43 | 1235 | error = security_sb_kern_mount(sb, flags, secdata); |
5129a469 JE |
1236 | if (error) |
1237 | goto out_sb; | |
454e2398 | 1238 | |
42cb56ae JL |
1239 | /* |
1240 | * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE | |
1241 | * but s_maxbytes was an unsigned long long for many releases. Throw | |
1242 | * this warning for a little while to try and catch filesystems that | |
4358b567 | 1243 | * violate this rule. |
42cb56ae | 1244 | */ |
9d412a43 AV |
1245 | WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " |
1246 | "negative value (%lld)\n", type->name, sb->s_maxbytes); | |
42cb56ae | 1247 | |
9d412a43 | 1248 | up_write(&sb->s_umount); |
8680e22f | 1249 | free_secdata(secdata); |
9d412a43 | 1250 | return root; |
1da177e4 | 1251 | out_sb: |
9d412a43 AV |
1252 | dput(root); |
1253 | deactivate_locked_super(sb); | |
1da177e4 LT |
1254 | out_free_secdata: |
1255 | free_secdata(secdata); | |
1da177e4 | 1256 | out: |
454e2398 | 1257 | return ERR_PTR(error); |
1da177e4 LT |
1258 | } |
1259 | ||
fca39346 JK |
1260 | /* |
1261 | * Setup private BDI for given superblock. It gets automatically cleaned up | |
1262 | * in generic_shutdown_super(). | |
1263 | */ | |
1264 | int super_setup_bdi_name(struct super_block *sb, char *fmt, ...) | |
1265 | { | |
1266 | struct backing_dev_info *bdi; | |
1267 | int err; | |
1268 | va_list args; | |
1269 | ||
1270 | bdi = bdi_alloc(GFP_KERNEL); | |
1271 | if (!bdi) | |
1272 | return -ENOMEM; | |
1273 | ||
1274 | bdi->name = sb->s_type->name; | |
1275 | ||
1276 | va_start(args, fmt); | |
1277 | err = bdi_register_va(bdi, NULL, fmt, args); | |
1278 | va_end(args); | |
1279 | if (err) { | |
1280 | bdi_put(bdi); | |
1281 | return err; | |
1282 | } | |
1283 | WARN_ON(sb->s_bdi != &noop_backing_dev_info); | |
1284 | sb->s_bdi = bdi; | |
1285 | sb->s_iflags |= SB_I_DYNBDI; | |
1286 | ||
1287 | return 0; | |
1288 | } | |
1289 | EXPORT_SYMBOL(super_setup_bdi_name); | |
1290 | ||
1291 | /* | |
1292 | * Setup private BDI for given superblock. I gets automatically cleaned up | |
1293 | * in generic_shutdown_super(). | |
1294 | */ | |
1295 | int super_setup_bdi(struct super_block *sb) | |
1296 | { | |
1297 | static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0); | |
1298 | ||
1299 | return super_setup_bdi_name(sb, "%.28s-%ld", sb->s_type->name, | |
1300 | atomic_long_inc_return(&bdi_seq)); | |
1301 | } | |
1302 | EXPORT_SYMBOL(super_setup_bdi); | |
1303 | ||
5accdf82 JK |
1304 | /* |
1305 | * This is an internal function, please use sb_end_{write,pagefault,intwrite} | |
1306 | * instead. | |
1307 | */ | |
1308 | void __sb_end_write(struct super_block *sb, int level) | |
1309 | { | |
8129ed29 | 1310 | percpu_up_read(sb->s_writers.rw_sem + level-1); |
5accdf82 JK |
1311 | } |
1312 | EXPORT_SYMBOL(__sb_end_write); | |
1313 | ||
f4b554af ON |
1314 | /* |
1315 | * This is an internal function, please use sb_start_{write,pagefault,intwrite} | |
1316 | * instead. | |
1317 | */ | |
1318 | int __sb_start_write(struct super_block *sb, int level, bool wait) | |
1319 | { | |
1320 | bool force_trylock = false; | |
8129ed29 | 1321 | int ret = 1; |
f4b554af ON |
1322 | |
1323 | #ifdef CONFIG_LOCKDEP | |
1324 | /* | |
1325 | * We want lockdep to tell us about possible deadlocks with freezing | |
1326 | * but it's it bit tricky to properly instrument it. Getting a freeze | |
1327 | * protection works as getting a read lock but there are subtle | |
1328 | * problems. XFS for example gets freeze protection on internal level | |
1329 | * twice in some cases, which is OK only because we already hold a | |
1330 | * freeze protection also on higher level. Due to these cases we have | |
1331 | * to use wait == F (trylock mode) which must not fail. | |
1332 | */ | |
1333 | if (wait) { | |
1334 | int i; | |
1335 | ||
1336 | for (i = 0; i < level - 1; i++) | |
8129ed29 | 1337 | if (percpu_rwsem_is_held(sb->s_writers.rw_sem + i)) { |
f4b554af ON |
1338 | force_trylock = true; |
1339 | break; | |
1340 | } | |
1341 | } | |
1342 | #endif | |
8129ed29 ON |
1343 | if (wait && !force_trylock) |
1344 | percpu_down_read(sb->s_writers.rw_sem + level-1); | |
1345 | else | |
1346 | ret = percpu_down_read_trylock(sb->s_writers.rw_sem + level-1); | |
1347 | ||
22224a17 | 1348 | WARN_ON(force_trylock && !ret); |
f4b554af ON |
1349 | return ret; |
1350 | } | |
5accdf82 JK |
1351 | EXPORT_SYMBOL(__sb_start_write); |
1352 | ||
1353 | /** | |
1354 | * sb_wait_write - wait until all writers to given file system finish | |
1355 | * @sb: the super for which we wait | |
1356 | * @level: type of writers we wait for (normal vs page fault) | |
1357 | * | |
1358 | * This function waits until there are no writers of given type to given file | |
8129ed29 | 1359 | * system. |
5accdf82 JK |
1360 | */ |
1361 | static void sb_wait_write(struct super_block *sb, int level) | |
1362 | { | |
8129ed29 | 1363 | percpu_down_write(sb->s_writers.rw_sem + level-1); |
8129ed29 | 1364 | } |
5accdf82 | 1365 | |
f1a96220 ON |
1366 | /* |
1367 | * We are going to return to userspace and forget about these locks, the | |
1368 | * ownership goes to the caller of thaw_super() which does unlock(). | |
1369 | */ | |
1370 | static void lockdep_sb_freeze_release(struct super_block *sb) | |
1371 | { | |
1372 | int level; | |
1373 | ||
1374 | for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--) | |
1375 | percpu_rwsem_release(sb->s_writers.rw_sem + level, 0, _THIS_IP_); | |
1376 | } | |
1377 | ||
1378 | /* | |
1379 | * Tell lockdep we are holding these locks before we call ->unfreeze_fs(sb). | |
1380 | */ | |
1381 | static void lockdep_sb_freeze_acquire(struct super_block *sb) | |
8129ed29 ON |
1382 | { |
1383 | int level; | |
5accdf82 | 1384 | |
8129ed29 ON |
1385 | for (level = 0; level < SB_FREEZE_LEVELS; ++level) |
1386 | percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_); | |
f1a96220 ON |
1387 | } |
1388 | ||
1389 | static void sb_freeze_unlock(struct super_block *sb) | |
1390 | { | |
1391 | int level; | |
5accdf82 | 1392 | |
8129ed29 ON |
1393 | for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--) |
1394 | percpu_up_write(sb->s_writers.rw_sem + level); | |
5accdf82 JK |
1395 | } |
1396 | ||
18e9e510 | 1397 | /** |
7000d3c4 RD |
1398 | * freeze_super - lock the filesystem and force it into a consistent state |
1399 | * @sb: the super to lock | |
18e9e510 JB |
1400 | * |
1401 | * Syncs the super to make sure the filesystem is consistent and calls the fs's | |
1402 | * freeze_fs. Subsequent calls to this without first thawing the fs will return | |
1403 | * -EBUSY. | |
5accdf82 JK |
1404 | * |
1405 | * During this function, sb->s_writers.frozen goes through these values: | |
1406 | * | |
1407 | * SB_UNFROZEN: File system is normal, all writes progress as usual. | |
1408 | * | |
1409 | * SB_FREEZE_WRITE: The file system is in the process of being frozen. New | |
1410 | * writes should be blocked, though page faults are still allowed. We wait for | |
1411 | * all writes to complete and then proceed to the next stage. | |
1412 | * | |
1413 | * SB_FREEZE_PAGEFAULT: Freezing continues. Now also page faults are blocked | |
1414 | * but internal fs threads can still modify the filesystem (although they | |
1415 | * should not dirty new pages or inodes), writeback can run etc. After waiting | |
1416 | * for all running page faults we sync the filesystem which will clean all | |
1417 | * dirty pages and inodes (no new dirty pages or inodes can be created when | |
1418 | * sync is running). | |
1419 | * | |
1420 | * SB_FREEZE_FS: The file system is frozen. Now all internal sources of fs | |
1421 | * modification are blocked (e.g. XFS preallocation truncation on inode | |
1422 | * reclaim). This is usually implemented by blocking new transactions for | |
1423 | * filesystems that have them and need this additional guard. After all | |
1424 | * internal writers are finished we call ->freeze_fs() to finish filesystem | |
1425 | * freezing. Then we transition to SB_FREEZE_COMPLETE state. This state is | |
1426 | * mostly auxiliary for filesystems to verify they do not modify frozen fs. | |
1427 | * | |
1428 | * sb->s_writers.frozen is protected by sb->s_umount. | |
18e9e510 JB |
1429 | */ |
1430 | int freeze_super(struct super_block *sb) | |
1431 | { | |
1432 | int ret; | |
1433 | ||
1434 | atomic_inc(&sb->s_active); | |
1435 | down_write(&sb->s_umount); | |
5accdf82 | 1436 | if (sb->s_writers.frozen != SB_UNFROZEN) { |
18e9e510 JB |
1437 | deactivate_locked_super(sb); |
1438 | return -EBUSY; | |
1439 | } | |
1440 | ||
dabe0dc1 AV |
1441 | if (!(sb->s_flags & MS_BORN)) { |
1442 | up_write(&sb->s_umount); | |
1443 | return 0; /* sic - it's "nothing to do" */ | |
1444 | } | |
1445 | ||
18e9e510 | 1446 | if (sb->s_flags & MS_RDONLY) { |
5accdf82 JK |
1447 | /* Nothing to do really... */ |
1448 | sb->s_writers.frozen = SB_FREEZE_COMPLETE; | |
18e9e510 JB |
1449 | up_write(&sb->s_umount); |
1450 | return 0; | |
1451 | } | |
1452 | ||
5accdf82 | 1453 | sb->s_writers.frozen = SB_FREEZE_WRITE; |
5accdf82 JK |
1454 | /* Release s_umount to preserve sb_start_write -> s_umount ordering */ |
1455 | up_write(&sb->s_umount); | |
5accdf82 | 1456 | sb_wait_write(sb, SB_FREEZE_WRITE); |
8129ed29 | 1457 | down_write(&sb->s_umount); |
5accdf82 JK |
1458 | |
1459 | /* Now we go and block page faults... */ | |
5accdf82 | 1460 | sb->s_writers.frozen = SB_FREEZE_PAGEFAULT; |
5accdf82 JK |
1461 | sb_wait_write(sb, SB_FREEZE_PAGEFAULT); |
1462 | ||
1463 | /* All writers are done so after syncing there won't be dirty data */ | |
18e9e510 JB |
1464 | sync_filesystem(sb); |
1465 | ||
5accdf82 JK |
1466 | /* Now wait for internal filesystem counter */ |
1467 | sb->s_writers.frozen = SB_FREEZE_FS; | |
5accdf82 | 1468 | sb_wait_write(sb, SB_FREEZE_FS); |
18e9e510 | 1469 | |
18e9e510 JB |
1470 | if (sb->s_op->freeze_fs) { |
1471 | ret = sb->s_op->freeze_fs(sb); | |
1472 | if (ret) { | |
1473 | printk(KERN_ERR | |
1474 | "VFS:Filesystem freeze failed\n"); | |
5accdf82 | 1475 | sb->s_writers.frozen = SB_UNFROZEN; |
8129ed29 | 1476 | sb_freeze_unlock(sb); |
5accdf82 | 1477 | wake_up(&sb->s_writers.wait_unfrozen); |
18e9e510 JB |
1478 | deactivate_locked_super(sb); |
1479 | return ret; | |
1480 | } | |
1481 | } | |
5accdf82 | 1482 | /* |
89f39af1 ON |
1483 | * For debugging purposes so that fs can warn if it sees write activity |
1484 | * when frozen is set to SB_FREEZE_COMPLETE, and for thaw_super(). | |
5accdf82 JK |
1485 | */ |
1486 | sb->s_writers.frozen = SB_FREEZE_COMPLETE; | |
f1a96220 | 1487 | lockdep_sb_freeze_release(sb); |
18e9e510 JB |
1488 | up_write(&sb->s_umount); |
1489 | return 0; | |
1490 | } | |
1491 | EXPORT_SYMBOL(freeze_super); | |
1492 | ||
1493 | /** | |
1494 | * thaw_super -- unlock filesystem | |
1495 | * @sb: the super to thaw | |
1496 | * | |
1497 | * Unlocks the filesystem and marks it writeable again after freeze_super(). | |
1498 | */ | |
1499 | int thaw_super(struct super_block *sb) | |
1500 | { | |
1501 | int error; | |
1502 | ||
1503 | down_write(&sb->s_umount); | |
89f39af1 | 1504 | if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) { |
18e9e510 JB |
1505 | up_write(&sb->s_umount); |
1506 | return -EINVAL; | |
1507 | } | |
1508 | ||
8129ed29 ON |
1509 | if (sb->s_flags & MS_RDONLY) { |
1510 | sb->s_writers.frozen = SB_UNFROZEN; | |
18e9e510 | 1511 | goto out; |
8129ed29 | 1512 | } |
18e9e510 | 1513 | |
f1a96220 ON |
1514 | lockdep_sb_freeze_acquire(sb); |
1515 | ||
18e9e510 JB |
1516 | if (sb->s_op->unfreeze_fs) { |
1517 | error = sb->s_op->unfreeze_fs(sb); | |
1518 | if (error) { | |
1519 | printk(KERN_ERR | |
1520 | "VFS:Filesystem thaw failed\n"); | |
f1a96220 | 1521 | lockdep_sb_freeze_release(sb); |
18e9e510 JB |
1522 | up_write(&sb->s_umount); |
1523 | return error; | |
1524 | } | |
1525 | } | |
1526 | ||
5accdf82 | 1527 | sb->s_writers.frozen = SB_UNFROZEN; |
8129ed29 ON |
1528 | sb_freeze_unlock(sb); |
1529 | out: | |
5accdf82 | 1530 | wake_up(&sb->s_writers.wait_unfrozen); |
18e9e510 | 1531 | deactivate_locked_super(sb); |
18e9e510 JB |
1532 | return 0; |
1533 | } | |
1534 | EXPORT_SYMBOL(thaw_super); |