Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/fs/super.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | * | |
7 | * super.c contains code to handle: - mount structures | |
8 | * - super-block tables | |
9 | * - filesystem drivers list | |
10 | * - mount system call | |
11 | * - umount system call | |
12 | * - ustat system call | |
13 | * | |
14 | * GK 2/5/95 - Changed to support mounting the root fs via NFS | |
15 | * | |
16 | * Added kerneld support: Jacques Gelinas and Bjorn Ekwall | |
17 | * Added change_root: Werner Almesberger & Hans Lermen, Feb '96 | |
18 | * Added options to /proc/mounts: | |
96de0e25 | 19 | * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996. |
1da177e4 LT |
20 | * Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998 |
21 | * Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000 | |
22 | */ | |
23 | ||
630d9c47 | 24 | #include <linux/export.h> |
1da177e4 | 25 | #include <linux/slab.h> |
1da177e4 | 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> |
22d94f49 | 34 | #include <linux/fscrypt.h> |
40401530 | 35 | #include <linux/fsnotify.h> |
5accdf82 | 36 | #include <linux/lockdep.h> |
6e4eab57 | 37 | #include <linux/user_namespace.h> |
9bc61ab1 | 38 | #include <linux/fs_context.h> |
e262e32d | 39 | #include <uapi/linux/mount.h> |
6d59e7f5 | 40 | #include "internal.h" |
1da177e4 | 41 | |
880b9577 | 42 | static int thaw_super_locked(struct super_block *sb, enum freeze_holder who); |
1da177e4 | 43 | |
15d0f5ea AV |
44 | static LIST_HEAD(super_blocks); |
45 | static DEFINE_SPINLOCK(sb_lock); | |
1da177e4 | 46 | |
5accdf82 JK |
47 | static char *sb_writers_name[SB_FREEZE_LEVELS] = { |
48 | "sb_writers", | |
49 | "sb_pagefaults", | |
50 | "sb_internal", | |
51 | }; | |
52 | ||
5e874914 | 53 | static inline void __super_lock(struct super_block *sb, bool excl) |
0ed33598 CB |
54 | { |
55 | if (excl) | |
56 | down_write(&sb->s_umount); | |
57 | else | |
58 | down_read(&sb->s_umount); | |
59 | } | |
60 | ||
61 | static inline void super_unlock(struct super_block *sb, bool excl) | |
62 | { | |
63 | if (excl) | |
64 | up_write(&sb->s_umount); | |
65 | else | |
66 | up_read(&sb->s_umount); | |
67 | } | |
68 | ||
5e874914 | 69 | static inline void __super_lock_excl(struct super_block *sb) |
0ed33598 | 70 | { |
5e874914 | 71 | __super_lock(sb, true); |
0ed33598 CB |
72 | } |
73 | ||
74 | static inline void super_unlock_excl(struct super_block *sb) | |
75 | { | |
76 | super_unlock(sb, true); | |
77 | } | |
78 | ||
79 | static inline void super_unlock_shared(struct super_block *sb) | |
80 | { | |
81 | super_unlock(sb, false); | |
82 | } | |
83 | ||
5e874914 CB |
84 | static inline bool wait_born(struct super_block *sb) |
85 | { | |
86 | unsigned int flags; | |
87 | ||
88 | /* | |
89 | * Pairs with smp_store_release() in super_wake() and ensures | |
90 | * that we see SB_BORN or SB_DYING after we're woken. | |
91 | */ | |
92 | flags = smp_load_acquire(&sb->s_flags); | |
93 | return flags & (SB_BORN | SB_DYING); | |
94 | } | |
95 | ||
96 | /** | |
97 | * super_lock - wait for superblock to become ready and lock it | |
98 | * @sb: superblock to wait for | |
99 | * @excl: whether exclusive access is required | |
100 | * | |
101 | * If the superblock has neither passed through vfs_get_tree() or | |
102 | * generic_shutdown_super() yet wait for it to happen. Either superblock | |
103 | * creation will succeed and SB_BORN is set by vfs_get_tree() or we're | |
104 | * woken and we'll see SB_DYING. | |
105 | * | |
106 | * The caller must have acquired a temporary reference on @sb->s_count. | |
107 | * | |
108 | * Return: This returns true if SB_BORN was set, false if SB_DYING was | |
109 | * set. The function acquires s_umount and returns with it held. | |
110 | */ | |
111 | static __must_check bool super_lock(struct super_block *sb, bool excl) | |
112 | { | |
113 | ||
114 | lockdep_assert_not_held(&sb->s_umount); | |
115 | ||
116 | relock: | |
117 | __super_lock(sb, excl); | |
118 | ||
119 | /* | |
120 | * Has gone through generic_shutdown_super() in the meantime. | |
121 | * @sb->s_root is NULL and @sb->s_active is 0. No one needs to | |
122 | * grab a reference to this. Tell them so. | |
123 | */ | |
124 | if (sb->s_flags & SB_DYING) | |
125 | return false; | |
126 | ||
127 | /* Has called ->get_tree() successfully. */ | |
128 | if (sb->s_flags & SB_BORN) | |
129 | return true; | |
130 | ||
131 | super_unlock(sb, excl); | |
132 | ||
133 | /* wait until the superblock is ready or dying */ | |
134 | wait_var_event(&sb->s_flags, wait_born(sb)); | |
135 | ||
136 | /* | |
137 | * Neither SB_BORN nor SB_DYING are ever unset so we never loop. | |
138 | * Just reacquire @sb->s_umount for the caller. | |
139 | */ | |
140 | goto relock; | |
141 | } | |
142 | ||
143 | /* wait and acquire read-side of @sb->s_umount */ | |
144 | static inline bool super_lock_shared(struct super_block *sb) | |
145 | { | |
146 | return super_lock(sb, false); | |
147 | } | |
148 | ||
149 | /* wait and acquire write-side of @sb->s_umount */ | |
150 | static inline bool super_lock_excl(struct super_block *sb) | |
151 | { | |
152 | return super_lock(sb, true); | |
153 | } | |
154 | ||
155 | /* wake waiters */ | |
2c18a63b | 156 | #define SUPER_WAKE_FLAGS (SB_BORN | SB_DYING | SB_DEAD) |
5e874914 CB |
157 | static void super_wake(struct super_block *sb, unsigned int flag) |
158 | { | |
159 | WARN_ON_ONCE((flag & ~SUPER_WAKE_FLAGS)); | |
160 | WARN_ON_ONCE(hweight32(flag & SUPER_WAKE_FLAGS) > 1); | |
161 | ||
162 | /* | |
163 | * Pairs with smp_load_acquire() in super_lock() to make sure | |
164 | * all initializations in the superblock are seen by the user | |
165 | * seeing SB_BORN sent. | |
166 | */ | |
167 | smp_store_release(&sb->s_flags, sb->s_flags | flag); | |
168 | /* | |
169 | * Pairs with the barrier in prepare_to_wait_event() to make sure | |
170 | * ___wait_var_event() either sees SB_BORN set or | |
171 | * waitqueue_active() check in wake_up_var() sees the waiter. | |
172 | */ | |
173 | smp_mb(); | |
174 | wake_up_var(&sb->s_flags); | |
175 | } | |
176 | ||
b0d40c92 DC |
177 | /* |
178 | * One thing we have to be careful of with a per-sb shrinker is that we don't | |
179 | * drop the last active reference to the superblock from within the shrinker. | |
180 | * If that happens we could trigger unregistering the shrinker from within the | |
8a0e8bb1 | 181 | * shrinker path and that leads to deadlock on the shrinker_mutex. Hence we |
b0d40c92 DC |
182 | * take a passive reference to the superblock to avoid this from occurring. |
183 | */ | |
0a234c6d DC |
184 | static unsigned long super_cache_scan(struct shrinker *shrink, |
185 | struct shrink_control *sc) | |
b0d40c92 DC |
186 | { |
187 | struct super_block *sb; | |
0a234c6d DC |
188 | long fs_objects = 0; |
189 | long total_objects; | |
190 | long freed = 0; | |
191 | long dentries; | |
192 | long inodes; | |
b0d40c92 | 193 | |
1720f5dd | 194 | sb = shrink->private_data; |
b0d40c92 DC |
195 | |
196 | /* | |
197 | * Deadlock avoidance. We may hold various FS locks, and we don't want | |
198 | * to recurse into the FS that called us in clear_inode() and friends.. | |
199 | */ | |
0a234c6d DC |
200 | if (!(sc->gfp_mask & __GFP_FS)) |
201 | return SHRINK_STOP; | |
b0d40c92 | 202 | |
d8ce82ef | 203 | if (!super_trylock_shared(sb)) |
0a234c6d | 204 | return SHRINK_STOP; |
b0d40c92 | 205 | |
d0407903 | 206 | if (sb->s_op->nr_cached_objects) |
4101b624 | 207 | fs_objects = sb->s_op->nr_cached_objects(sb, sc); |
0e1fdafd | 208 | |
503c358c VD |
209 | inodes = list_lru_shrink_count(&sb->s_inode_lru, sc); |
210 | dentries = list_lru_shrink_count(&sb->s_dentry_lru, sc); | |
f6041567 | 211 | total_objects = dentries + inodes + fs_objects + 1; |
475d0db7 TH |
212 | if (!total_objects) |
213 | total_objects = 1; | |
0e1fdafd | 214 | |
0a234c6d | 215 | /* proportion the scan between the caches */ |
f6041567 | 216 | dentries = mult_frac(sc->nr_to_scan, dentries, total_objects); |
bc3b14cb | 217 | inodes = mult_frac(sc->nr_to_scan, inodes, total_objects); |
503c358c | 218 | fs_objects = mult_frac(sc->nr_to_scan, fs_objects, total_objects); |
b0d40c92 | 219 | |
0a234c6d DC |
220 | /* |
221 | * prune the dcache first as the icache is pinned by it, then | |
222 | * prune the icache, followed by the filesystem specific caches | |
49e7e7ff VD |
223 | * |
224 | * Ensure that we always scan at least one object - memcg kmem | |
225 | * accounting uses this to fully empty the caches. | |
0a234c6d | 226 | */ |
49e7e7ff | 227 | sc->nr_to_scan = dentries + 1; |
503c358c | 228 | freed = prune_dcache_sb(sb, sc); |
49e7e7ff | 229 | sc->nr_to_scan = inodes + 1; |
503c358c | 230 | freed += prune_icache_sb(sb, sc); |
0a234c6d DC |
231 | |
232 | if (fs_objects) { | |
49e7e7ff | 233 | sc->nr_to_scan = fs_objects + 1; |
4101b624 | 234 | freed += sb->s_op->free_cached_objects(sb, sc); |
b0d40c92 DC |
235 | } |
236 | ||
0ed33598 | 237 | super_unlock_shared(sb); |
0a234c6d DC |
238 | return freed; |
239 | } | |
240 | ||
241 | static unsigned long super_cache_count(struct shrinker *shrink, | |
242 | struct shrink_control *sc) | |
243 | { | |
244 | struct super_block *sb; | |
245 | long total_objects = 0; | |
246 | ||
1720f5dd | 247 | sb = shrink->private_data; |
0a234c6d | 248 | |
d23da150 | 249 | /* |
d8ce82ef CB |
250 | * We don't call super_trylock_shared() here as it is a scalability |
251 | * bottleneck, so we're exposed to partial setup state. The shrinker | |
252 | * rwsem does not protect filesystem operations backing | |
253 | * list_lru_shrink_count() or s_op->nr_cached_objects(). Counts can | |
254 | * change between super_cache_count and super_cache_scan, so we really | |
255 | * don't need locks here. | |
79f546a6 DC |
256 | * |
257 | * However, if we are currently mounting the superblock, the underlying | |
258 | * filesystem might be in a state of partial construction and hence it | |
d8ce82ef CB |
259 | * is dangerous to access it. super_trylock_shared() uses a SB_BORN check |
260 | * to avoid this situation, so do the same here. The memory barrier is | |
79f546a6 | 261 | * matched with the one in mount_fs() as we don't hold locks here. |
d23da150 | 262 | */ |
79f546a6 DC |
263 | if (!(sb->s_flags & SB_BORN)) |
264 | return 0; | |
265 | smp_rmb(); | |
266 | ||
0a234c6d | 267 | if (sb->s_op && sb->s_op->nr_cached_objects) |
4101b624 | 268 | total_objects = sb->s_op->nr_cached_objects(sb, sc); |
0a234c6d | 269 | |
503c358c VD |
270 | total_objects += list_lru_shrink_count(&sb->s_dentry_lru, sc); |
271 | total_objects += list_lru_shrink_count(&sb->s_inode_lru, sc); | |
0a234c6d | 272 | |
9b996468 KT |
273 | if (!total_objects) |
274 | return SHRINK_EMPTY; | |
275 | ||
55f841ce | 276 | total_objects = vfs_pressure_ratio(total_objects); |
0e1fdafd | 277 | return total_objects; |
b0d40c92 DC |
278 | } |
279 | ||
853b39a7 ON |
280 | static void destroy_super_work(struct work_struct *work) |
281 | { | |
282 | struct super_block *s = container_of(work, struct super_block, | |
283 | destroy_work); | |
284 | int i; | |
285 | ||
286 | for (i = 0; i < SB_FREEZE_LEVELS; i++) | |
8129ed29 | 287 | percpu_free_rwsem(&s->s_writers.rw_sem[i]); |
853b39a7 ON |
288 | kfree(s); |
289 | } | |
290 | ||
291 | static void destroy_super_rcu(struct rcu_head *head) | |
292 | { | |
293 | struct super_block *s = container_of(head, struct super_block, rcu); | |
294 | INIT_WORK(&s->destroy_work, destroy_super_work); | |
295 | schedule_work(&s->destroy_work); | |
296 | } | |
297 | ||
0200894d AV |
298 | /* Free a superblock that has never been seen by anyone */ |
299 | static void destroy_unused_super(struct super_block *s) | |
5accdf82 | 300 | { |
0200894d AV |
301 | if (!s) |
302 | return; | |
0ed33598 | 303 | super_unlock_excl(s); |
7eb5e882 AV |
304 | list_lru_destroy(&s->s_dentry_lru); |
305 | list_lru_destroy(&s->s_inode_lru); | |
7eb5e882 | 306 | security_sb_free(s); |
6e4eab57 | 307 | put_user_ns(s->s_user_ns); |
7eb5e882 | 308 | kfree(s->s_subtype); |
1720f5dd | 309 | shrinker_free(s->s_shrink); |
0200894d AV |
310 | /* no delays needed */ |
311 | destroy_super_work(&s->destroy_work); | |
5accdf82 JK |
312 | } |
313 | ||
1da177e4 LT |
314 | /** |
315 | * alloc_super - create new superblock | |
fe2bbc48 | 316 | * @type: filesystem type superblock should belong to |
9249e17f | 317 | * @flags: the mount flags |
6e4eab57 | 318 | * @user_ns: User namespace for the super_block |
1da177e4 LT |
319 | * |
320 | * Allocates and initializes a new &struct super_block. alloc_super() | |
321 | * returns a pointer new superblock or %NULL if allocation had failed. | |
322 | */ | |
6e4eab57 EB |
323 | static struct super_block *alloc_super(struct file_system_type *type, int flags, |
324 | struct user_namespace *user_ns) | |
1da177e4 | 325 | { |
11b0b5ab | 326 | struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); |
b87221de | 327 | static const struct super_operations default_op; |
7eb5e882 AV |
328 | int i; |
329 | ||
330 | if (!s) | |
331 | return NULL; | |
1da177e4 | 332 | |
b5bd856a | 333 | INIT_LIST_HEAD(&s->s_mounts); |
6e4eab57 | 334 | s->s_user_ns = get_user_ns(user_ns); |
ca0168e8 AV |
335 | init_rwsem(&s->s_umount); |
336 | lockdep_set_class(&s->s_umount, &type->s_umount_key); | |
337 | /* | |
338 | * sget() can have s_umount recursion. | |
339 | * | |
340 | * When it cannot find a suitable sb, it allocates a new | |
341 | * one (this one), and tries again to find a suitable old | |
342 | * one. | |
343 | * | |
344 | * In case that succeeds, it will acquire the s_umount | |
345 | * lock of the old one. Since these are clearly distrinct | |
346 | * locks, and this object isn't exposed yet, there's no | |
347 | * risk of deadlocks. | |
348 | * | |
349 | * Annotate this by putting this lock in a different | |
350 | * subclass. | |
351 | */ | |
352 | down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); | |
b5bd856a | 353 | |
7eb5e882 AV |
354 | if (security_sb_alloc(s)) |
355 | goto fail; | |
7b7a8665 | 356 | |
7eb5e882 | 357 | for (i = 0; i < SB_FREEZE_LEVELS; i++) { |
8129ed29 ON |
358 | if (__percpu_init_rwsem(&s->s_writers.rw_sem[i], |
359 | sb_writers_name[i], | |
360 | &type->s_writers_key[i])) | |
7eb5e882 | 361 | goto fail; |
1da177e4 | 362 | } |
df0ce26c | 363 | s->s_bdi = &noop_backing_dev_info; |
7eb5e882 | 364 | s->s_flags = flags; |
cc50a07a | 365 | if (s->s_user_ns != &init_user_ns) |
67690f93 | 366 | s->s_iflags |= SB_I_NODEV; |
7eb5e882 | 367 | INIT_HLIST_NODE(&s->s_instances); |
f1ee6162 | 368 | INIT_HLIST_BL_HEAD(&s->s_roots); |
e97fedb9 | 369 | mutex_init(&s->s_sync_lock); |
7eb5e882 | 370 | INIT_LIST_HEAD(&s->s_inodes); |
74278da9 | 371 | spin_lock_init(&s->s_inode_list_lock); |
6c60d2b5 DC |
372 | INIT_LIST_HEAD(&s->s_inodes_wb); |
373 | spin_lock_init(&s->s_inode_wblist_lock); | |
7eb5e882 | 374 | |
7eb5e882 AV |
375 | s->s_count = 1; |
376 | atomic_set(&s->s_active, 1); | |
377 | mutex_init(&s->s_vfs_rename_mutex); | |
378 | lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key); | |
bc8230ee | 379 | init_rwsem(&s->s_dquot.dqio_sem); |
7eb5e882 AV |
380 | s->s_maxbytes = MAX_NON_LFS; |
381 | s->s_op = &default_op; | |
382 | s->s_time_gran = 1000000000; | |
188d20bc DD |
383 | s->s_time_min = TIME64_MIN; |
384 | s->s_time_max = TIME64_MAX; | |
7eb5e882 | 385 | |
1720f5dd QZ |
386 | s->s_shrink = shrinker_alloc(SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE, |
387 | "sb-%s", type->name); | |
388 | if (!s->s_shrink) | |
8e04944f | 389 | goto fail; |
1720f5dd QZ |
390 | |
391 | s->s_shrink->scan_objects = super_cache_scan; | |
392 | s->s_shrink->count_objects = super_cache_count; | |
393 | s->s_shrink->batch = 1024; | |
394 | s->s_shrink->private_data = s; | |
395 | ||
396 | if (list_lru_init_memcg(&s->s_dentry_lru, s->s_shrink)) | |
2b3648a6 | 397 | goto fail; |
1720f5dd | 398 | if (list_lru_init_memcg(&s->s_inode_lru, s->s_shrink)) |
2b3648a6 | 399 | goto fail; |
1da177e4 | 400 | return s; |
5ca302c8 | 401 | |
7eb5e882 | 402 | fail: |
0200894d | 403 | destroy_unused_super(s); |
7eb5e882 | 404 | return NULL; |
1da177e4 LT |
405 | } |
406 | ||
407 | /* Superblock refcounting */ | |
408 | ||
409 | /* | |
35cf7ba0 | 410 | * Drop a superblock's refcount. The caller must hold sb_lock. |
1da177e4 | 411 | */ |
c645b930 | 412 | static void __put_super(struct super_block *s) |
1da177e4 | 413 | { |
c645b930 AV |
414 | if (!--s->s_count) { |
415 | list_del_init(&s->s_list); | |
416 | WARN_ON(s->s_dentry_lru.node); | |
417 | WARN_ON(s->s_inode_lru.node); | |
418 | WARN_ON(!list_empty(&s->s_mounts)); | |
419 | security_sb_free(s); | |
420 | put_user_ns(s->s_user_ns); | |
421 | kfree(s->s_subtype); | |
422 | call_rcu(&s->rcu, destroy_super_rcu); | |
1da177e4 | 423 | } |
1da177e4 LT |
424 | } |
425 | ||
426 | /** | |
427 | * put_super - drop a temporary reference to superblock | |
428 | * @sb: superblock in question | |
429 | * | |
430 | * Drops a temporary reference, frees superblock if there's no | |
431 | * references left. | |
432 | */ | |
60b49885 | 433 | void put_super(struct super_block *sb) |
1da177e4 LT |
434 | { |
435 | spin_lock(&sb_lock); | |
436 | __put_super(sb); | |
437 | spin_unlock(&sb_lock); | |
438 | } | |
439 | ||
dc3216b1 CB |
440 | static void kill_super_notify(struct super_block *sb) |
441 | { | |
442 | lockdep_assert_not_held(&sb->s_umount); | |
443 | ||
444 | /* already notified earlier */ | |
445 | if (sb->s_flags & SB_DEAD) | |
446 | return; | |
447 | ||
448 | /* | |
449 | * Remove it from @fs_supers so it isn't found by new | |
450 | * sget{_fc}() walkers anymore. Any concurrent mounter still | |
451 | * managing to grab a temporary reference is guaranteed to | |
452 | * already see SB_DYING and will wait until we notify them about | |
453 | * SB_DEAD. | |
454 | */ | |
455 | spin_lock(&sb_lock); | |
456 | hlist_del_init(&sb->s_instances); | |
457 | spin_unlock(&sb_lock); | |
458 | ||
459 | /* | |
460 | * Let concurrent mounts know that this thing is really dead. | |
461 | * We don't need @sb->s_umount here as every concurrent caller | |
462 | * will see SB_DYING and either discard the superblock or wait | |
463 | * for SB_DEAD. | |
464 | */ | |
465 | super_wake(sb, SB_DEAD); | |
466 | } | |
1da177e4 LT |
467 | |
468 | /** | |
1712ac8f | 469 | * deactivate_locked_super - drop an active reference to superblock |
1da177e4 LT |
470 | * @s: superblock to deactivate |
471 | * | |
bd7ced98 | 472 | * Drops an active reference to superblock, converting it into a temporary |
1712ac8f | 473 | * one if there is no other active references left. In that case we |
1da177e4 LT |
474 | * tell fs driver to shut it down and drop the temporary reference we |
475 | * had just acquired. | |
1712ac8f AV |
476 | * |
477 | * Caller holds exclusive lock on superblock; that lock is released. | |
1da177e4 | 478 | */ |
1712ac8f | 479 | void deactivate_locked_super(struct super_block *s) |
1da177e4 LT |
480 | { |
481 | struct file_system_type *fs = s->s_type; | |
b20bd1a5 | 482 | if (atomic_dec_and_test(&s->s_active)) { |
1720f5dd | 483 | shrinker_free(s->s_shrink); |
28f2cd4f | 484 | fs->kill_sb(s); |
f5e1dd34 | 485 | |
dc3216b1 CB |
486 | kill_super_notify(s); |
487 | ||
c0a5b560 VD |
488 | /* |
489 | * Since list_lru_destroy() may sleep, we cannot call it from | |
490 | * put_super(), where we hold the sb_lock. Therefore we destroy | |
491 | * the lru lists right now. | |
492 | */ | |
493 | list_lru_destroy(&s->s_dentry_lru); | |
494 | list_lru_destroy(&s->s_inode_lru); | |
495 | ||
1da177e4 LT |
496 | put_filesystem(fs); |
497 | put_super(s); | |
1712ac8f | 498 | } else { |
0ed33598 | 499 | super_unlock_excl(s); |
1da177e4 LT |
500 | } |
501 | } | |
502 | ||
1712ac8f | 503 | EXPORT_SYMBOL(deactivate_locked_super); |
1da177e4 | 504 | |
74dbbdd7 | 505 | /** |
1712ac8f | 506 | * deactivate_super - drop an active reference to superblock |
74dbbdd7 AV |
507 | * @s: superblock to deactivate |
508 | * | |
1712ac8f AV |
509 | * Variant of deactivate_locked_super(), except that superblock is *not* |
510 | * locked by caller. If we are going to drop the final active reference, | |
511 | * lock will be acquired prior to that. | |
74dbbdd7 | 512 | */ |
1712ac8f | 513 | void deactivate_super(struct super_block *s) |
74dbbdd7 | 514 | { |
cc23402c | 515 | if (!atomic_add_unless(&s->s_active, -1, 1)) { |
5e874914 | 516 | __super_lock_excl(s); |
1712ac8f | 517 | deactivate_locked_super(s); |
74dbbdd7 AV |
518 | } |
519 | } | |
520 | ||
1712ac8f | 521 | EXPORT_SYMBOL(deactivate_super); |
74dbbdd7 | 522 | |
1da177e4 LT |
523 | /** |
524 | * grab_super - acquire an active reference | |
525 | * @s: reference we are trying to make active | |
526 | * | |
527 | * Tries to acquire an active reference. grab_super() is used when we | |
528 | * had just found a superblock in super_blocks or fs_type->fs_supers | |
529 | * and want to turn it into a full-blown active reference. grab_super() | |
530 | * is called with sb_lock held and drops it. Returns 1 in case of | |
531 | * success, 0 if we had failed (superblock contents was already dead or | |
acfec9a5 AV |
532 | * dying when grab_super() had been called). Note that this is only |
533 | * called for superblocks not in rundown mode (== ones still on ->fs_supers | |
534 | * of their type), so increment of ->s_count is OK here. | |
1da177e4 | 535 | */ |
9c4dbee7 | 536 | static int grab_super(struct super_block *s) __releases(sb_lock) |
1da177e4 | 537 | { |
5e874914 CB |
538 | bool born; |
539 | ||
1da177e4 LT |
540 | s->s_count++; |
541 | spin_unlock(&sb_lock); | |
5e874914 CB |
542 | born = super_lock_excl(s); |
543 | if (born && atomic_inc_not_zero(&s->s_active)) { | |
acfec9a5 AV |
544 | put_super(s); |
545 | return 1; | |
546 | } | |
0ed33598 | 547 | super_unlock_excl(s); |
1da177e4 | 548 | put_super(s); |
1da177e4 LT |
549 | return 0; |
550 | } | |
551 | ||
2c18a63b CB |
552 | static inline bool wait_dead(struct super_block *sb) |
553 | { | |
554 | unsigned int flags; | |
555 | ||
556 | /* | |
557 | * Pairs with memory barrier in super_wake() and ensures | |
558 | * that we see SB_DEAD after we're woken. | |
559 | */ | |
560 | flags = smp_load_acquire(&sb->s_flags); | |
561 | return flags & SB_DEAD; | |
562 | } | |
563 | ||
564 | /** | |
565 | * grab_super_dead - acquire an active reference to a superblock | |
566 | * @sb: superblock to acquire | |
567 | * | |
568 | * Acquire a temporary reference on a superblock and try to trade it for | |
569 | * an active reference. This is used in sget{_fc}() to wait for a | |
570 | * superblock to either become SB_BORN or for it to pass through | |
571 | * sb->kill() and be marked as SB_DEAD. | |
572 | * | |
573 | * Return: This returns true if an active reference could be acquired, | |
574 | * false if not. | |
575 | */ | |
576 | static bool grab_super_dead(struct super_block *sb) | |
577 | { | |
578 | ||
579 | sb->s_count++; | |
580 | if (grab_super(sb)) { | |
581 | put_super(sb); | |
582 | lockdep_assert_held(&sb->s_umount); | |
583 | return true; | |
584 | } | |
585 | wait_var_event(&sb->s_flags, wait_dead(sb)); | |
2c18a63b | 586 | lockdep_assert_not_held(&sb->s_umount); |
345a5c4a | 587 | put_super(sb); |
2c18a63b CB |
588 | return false; |
589 | } | |
590 | ||
12ad3ab6 | 591 | /* |
d8ce82ef | 592 | * super_trylock_shared - try to grab ->s_umount shared |
331cbdee | 593 | * @sb: reference we are trying to grab |
12ad3ab6 | 594 | * |
eb6ef3df | 595 | * Try to prevent fs shutdown. This is used in places where we |
12ad3ab6 | 596 | * cannot take an active reference but we need to ensure that the |
eb6ef3df KK |
597 | * filesystem is not shut down while we are working on it. It returns |
598 | * false if we cannot acquire s_umount or if we lose the race and | |
599 | * filesystem already got into shutdown, and returns true with the s_umount | |
600 | * lock held in read mode in case of success. On successful return, | |
601 | * the caller must drop the s_umount lock when done. | |
602 | * | |
603 | * Note that unlike get_super() et.al. this one does *not* bump ->s_count. | |
604 | * The reason why it's safe is that we are OK with doing trylock instead | |
605 | * of down_read(). There's a couple of places that are OK with that, but | |
606 | * it's very much not a general-purpose interface. | |
12ad3ab6 | 607 | */ |
d8ce82ef | 608 | bool super_trylock_shared(struct super_block *sb) |
12ad3ab6 | 609 | { |
12ad3ab6 | 610 | if (down_read_trylock(&sb->s_umount)) { |
5e874914 CB |
611 | if (!(sb->s_flags & SB_DYING) && sb->s_root && |
612 | (sb->s_flags & SB_BORN)) | |
12ad3ab6 | 613 | return true; |
0ed33598 | 614 | super_unlock_shared(sb); |
12ad3ab6 DC |
615 | } |
616 | ||
12ad3ab6 DC |
617 | return false; |
618 | } | |
619 | ||
04b94071 DL |
620 | /** |
621 | * retire_super - prevents superblock from being reused | |
622 | * @sb: superblock to retire | |
623 | * | |
624 | * The function marks superblock to be ignored in superblock test, which | |
625 | * prevents it from being reused for any new mounts. If the superblock has | |
626 | * a private bdi, it also unregisters it, but doesn't reduce the refcount | |
627 | * of the superblock to prevent potential races. The refcount is reduced | |
628 | * by generic_shutdown_super(). The function can not be called | |
629 | * concurrently with generic_shutdown_super(). It is safe to call the | |
630 | * function multiple times, subsequent calls have no effect. | |
631 | * | |
632 | * The marker will affect the re-use only for block-device-based | |
633 | * superblocks. Other superblocks will still get marked if this function | |
634 | * is used, but that will not affect their reusability. | |
635 | */ | |
636 | void retire_super(struct super_block *sb) | |
637 | { | |
638 | WARN_ON(!sb->s_bdev); | |
5e874914 | 639 | __super_lock_excl(sb); |
04b94071 DL |
640 | if (sb->s_iflags & SB_I_PERSB_BDI) { |
641 | bdi_unregister(sb->s_bdi); | |
642 | sb->s_iflags &= ~SB_I_PERSB_BDI; | |
643 | } | |
644 | sb->s_iflags |= SB_I_RETIRED; | |
0ed33598 | 645 | super_unlock_excl(sb); |
04b94071 DL |
646 | } |
647 | EXPORT_SYMBOL(retire_super); | |
648 | ||
1da177e4 LT |
649 | /** |
650 | * generic_shutdown_super - common helper for ->kill_sb() | |
651 | * @sb: superblock to kill | |
652 | * | |
653 | * generic_shutdown_super() does all fs-independent work on superblock | |
654 | * shutdown. Typical ->kill_sb() should pick all fs-specific objects | |
655 | * that need destruction out of superblock, call generic_shutdown_super() | |
656 | * and release aforementioned objects. Note: dentries and inodes _are_ | |
657 | * taken care of and do not need specific handling. | |
c636ebdb DH |
658 | * |
659 | * Upon calling this function, the filesystem may no longer alter or | |
660 | * rearrange the set of dentries belonging to this super_block, nor may it | |
661 | * change the attachments of dentries to inodes. | |
1da177e4 LT |
662 | */ |
663 | void generic_shutdown_super(struct super_block *sb) | |
664 | { | |
ee9b6d61 | 665 | const struct super_operations *sop = sb->s_op; |
1da177e4 | 666 | |
c636ebdb DH |
667 | if (sb->s_root) { |
668 | shrink_dcache_for_umount(sb); | |
60b0680f | 669 | sync_filesystem(sb); |
e462ec50 | 670 | sb->s_flags &= ~SB_ACTIVE; |
efaee192 | 671 | |
a1a0e23e | 672 | cgroup_writeback_umount(); |
63997e98 | 673 | |
ccb820dc | 674 | /* Evict all inodes with zero refcount. */ |
63997e98 | 675 | evict_inodes(sb); |
ccb820dc EB |
676 | |
677 | /* | |
678 | * Clean up and evict any inodes that still have references due | |
679 | * to fsnotify or the security policy. | |
680 | */ | |
1edc8eb2 | 681 | fsnotify_sb_delete(sb); |
83e804f0 | 682 | security_sb_delete(sb); |
1da177e4 | 683 | |
ccb820dc EB |
684 | /* |
685 | * Now that all potentially-encrypted inodes have been evicted, | |
686 | * the fscrypt keyring can be destroyed. | |
687 | */ | |
688 | fscrypt_destroy_keyring(sb); | |
689 | ||
7b7a8665 CH |
690 | if (sb->s_dio_done_wq) { |
691 | destroy_workqueue(sb->s_dio_done_wq); | |
692 | sb->s_dio_done_wq = NULL; | |
693 | } | |
694 | ||
1da177e4 LT |
695 | if (sop->put_super) |
696 | sop->put_super(sb); | |
697 | ||
47d58691 JH |
698 | if (CHECK_DATA_CORRUPTION(!list_empty(&sb->s_inodes), |
699 | "VFS: Busy inodes after unmount of %s (%s)", | |
700 | sb->s_id, sb->s_type->name)) { | |
701 | /* | |
702 | * Adding a proper bailout path here would be hard, but | |
703 | * we can at least make it more likely that a later | |
704 | * iput_final() or such crashes cleanly. | |
705 | */ | |
706 | struct inode *inode; | |
707 | ||
708 | spin_lock(&sb->s_inode_list_lock); | |
709 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { | |
710 | inode->i_op = VFS_PTR_POISON; | |
711 | inode->i_sb = VFS_PTR_POISON; | |
712 | inode->i_mapping = VFS_PTR_POISON; | |
713 | } | |
714 | spin_unlock(&sb->s_inode_list_lock); | |
1da177e4 | 715 | } |
1da177e4 | 716 | } |
5e874914 CB |
717 | /* |
718 | * Broadcast to everyone that grabbed a temporary reference to this | |
719 | * superblock before we removed it from @fs_supers that the superblock | |
720 | * is dying. Every walker of @fs_supers outside of sget{_fc}() will now | |
721 | * discard this superblock and treat it as dead. | |
2c18a63b CB |
722 | * |
723 | * We leave the superblock on @fs_supers so it can be found by | |
724 | * sget{_fc}() until we passed sb->kill_sb(). | |
5e874914 CB |
725 | */ |
726 | super_wake(sb, SB_DYING); | |
0ed33598 | 727 | super_unlock_excl(sb); |
c1844d53 | 728 | if (sb->s_bdi != &noop_backing_dev_info) { |
0b3ea092 CH |
729 | if (sb->s_iflags & SB_I_PERSB_BDI) |
730 | bdi_unregister(sb->s_bdi); | |
fca39346 JK |
731 | bdi_put(sb->s_bdi); |
732 | sb->s_bdi = &noop_backing_dev_info; | |
fca39346 | 733 | } |
1da177e4 LT |
734 | } |
735 | ||
736 | EXPORT_SYMBOL(generic_shutdown_super); | |
737 | ||
20284ab7 | 738 | bool mount_capable(struct fs_context *fc) |
0ce0cf12 | 739 | { |
20284ab7 | 740 | if (!(fc->fs_type->fs_flags & FS_USERNS_MOUNT)) |
0ce0cf12 AV |
741 | return capable(CAP_SYS_ADMIN); |
742 | else | |
c2c44ec2 | 743 | return ns_capable(fc->user_ns, CAP_SYS_ADMIN); |
0ce0cf12 AV |
744 | } |
745 | ||
cb50b348 AV |
746 | /** |
747 | * sget_fc - Find or create a superblock | |
748 | * @fc: Filesystem context. | |
749 | * @test: Comparison callback | |
750 | * @set: Setup callback | |
751 | * | |
22ed7ecd | 752 | * Create a new superblock or find an existing one. |
cb50b348 | 753 | * |
22ed7ecd CB |
754 | * The @test callback is used to find a matching existing superblock. |
755 | * Whether or not the requested parameters in @fc are taken into account | |
756 | * is specific to the @test callback that is used. They may even be | |
757 | * completely ignored. | |
758 | * | |
759 | * If an extant superblock is matched, it will be returned unless: | |
760 | * | |
761 | * (1) the namespace the filesystem context @fc and the extant | |
762 | * superblock's namespace differ | |
763 | * | |
764 | * (2) the filesystem context @fc has requested that reusing an extant | |
765 | * superblock is not allowed | |
766 | * | |
767 | * In both cases EBUSY will be returned. | |
cb50b348 AV |
768 | * |
769 | * If no match is made, a new superblock will be allocated and basic | |
22ed7ecd CB |
770 | * initialisation will be performed (s_type, s_fs_info and s_id will be |
771 | * set and the @set callback will be invoked), the superblock will be | |
772 | * published and it will be returned in a partially constructed state | |
773 | * with SB_BORN and SB_ACTIVE as yet unset. | |
774 | * | |
775 | * Return: On success, an extant or newly created superblock is | |
776 | * returned. On failure an error pointer is returned. | |
cb50b348 AV |
777 | */ |
778 | struct super_block *sget_fc(struct fs_context *fc, | |
779 | int (*test)(struct super_block *, struct fs_context *), | |
780 | int (*set)(struct super_block *, struct fs_context *)) | |
781 | { | |
782 | struct super_block *s = NULL; | |
783 | struct super_block *old; | |
784 | struct user_namespace *user_ns = fc->global ? &init_user_ns : fc->user_ns; | |
785 | int err; | |
786 | ||
cb50b348 AV |
787 | retry: |
788 | spin_lock(&sb_lock); | |
789 | if (test) { | |
790 | hlist_for_each_entry(old, &fc->fs_type->fs_supers, s_instances) { | |
791 | if (test(old, fc)) | |
792 | goto share_extant_sb; | |
793 | } | |
794 | } | |
795 | if (!s) { | |
796 | spin_unlock(&sb_lock); | |
797 | s = alloc_super(fc->fs_type, fc->sb_flags, user_ns); | |
798 | if (!s) | |
799 | return ERR_PTR(-ENOMEM); | |
800 | goto retry; | |
801 | } | |
802 | ||
803 | s->s_fs_info = fc->s_fs_info; | |
804 | err = set(s, fc); | |
805 | if (err) { | |
806 | s->s_fs_info = NULL; | |
807 | spin_unlock(&sb_lock); | |
808 | destroy_unused_super(s); | |
809 | return ERR_PTR(err); | |
810 | } | |
811 | fc->s_fs_info = NULL; | |
812 | s->s_type = fc->fs_type; | |
c80fa7c8 | 813 | s->s_iflags |= fc->s_iflags; |
c642256b | 814 | strscpy(s->s_id, s->s_type->name, sizeof(s->s_id)); |
5e874914 CB |
815 | /* |
816 | * Make the superblock visible on @super_blocks and @fs_supers. | |
817 | * It's in a nascent state and users should wait on SB_BORN or | |
818 | * SB_DYING to be set. | |
819 | */ | |
cb50b348 AV |
820 | list_add_tail(&s->s_list, &super_blocks); |
821 | hlist_add_head(&s->s_instances, &s->s_type->fs_supers); | |
822 | spin_unlock(&sb_lock); | |
823 | get_filesystem(s->s_type); | |
1720f5dd | 824 | shrinker_register(s->s_shrink); |
cb50b348 AV |
825 | return s; |
826 | ||
827 | share_extant_sb: | |
22ed7ecd | 828 | if (user_ns != old->s_user_ns || fc->exclusive) { |
cb50b348 AV |
829 | spin_unlock(&sb_lock); |
830 | destroy_unused_super(s); | |
22ed7ecd CB |
831 | if (fc->exclusive) |
832 | warnfc(fc, "reusing existing filesystem not allowed"); | |
833 | else | |
834 | warnfc(fc, "reusing existing filesystem in another namespace not allowed"); | |
cb50b348 AV |
835 | return ERR_PTR(-EBUSY); |
836 | } | |
2c18a63b | 837 | if (!grab_super_dead(old)) |
cb50b348 AV |
838 | goto retry; |
839 | destroy_unused_super(s); | |
840 | return old; | |
841 | } | |
842 | EXPORT_SYMBOL(sget_fc); | |
843 | ||
1da177e4 | 844 | /** |
023d066a DH |
845 | * sget - find or create a superblock |
846 | * @type: filesystem type superblock should belong to | |
847 | * @test: comparison callback | |
848 | * @set: setup callback | |
849 | * @flags: mount flags | |
850 | * @data: argument to each of them | |
1da177e4 | 851 | */ |
023d066a | 852 | struct super_block *sget(struct file_system_type *type, |
1da177e4 LT |
853 | int (*test)(struct super_block *,void *), |
854 | int (*set)(struct super_block *,void *), | |
023d066a | 855 | int flags, |
1da177e4 LT |
856 | void *data) |
857 | { | |
023d066a | 858 | struct user_namespace *user_ns = current_user_ns(); |
1da177e4 | 859 | struct super_block *s = NULL; |
d4730127 | 860 | struct super_block *old; |
1da177e4 LT |
861 | int err; |
862 | ||
023d066a DH |
863 | /* We don't yet pass the user namespace of the parent |
864 | * mount through to here so always use &init_user_ns | |
865 | * until that changes. | |
866 | */ | |
867 | if (flags & SB_SUBMOUNT) | |
868 | user_ns = &init_user_ns; | |
869 | ||
1da177e4 LT |
870 | retry: |
871 | spin_lock(&sb_lock); | |
d4730127 | 872 | if (test) { |
b67bfe0d | 873 | hlist_for_each_entry(old, &type->fs_supers, s_instances) { |
d4730127 MK |
874 | if (!test(old, data)) |
875 | continue; | |
6e4eab57 EB |
876 | if (user_ns != old->s_user_ns) { |
877 | spin_unlock(&sb_lock); | |
0200894d | 878 | destroy_unused_super(s); |
6e4eab57 EB |
879 | return ERR_PTR(-EBUSY); |
880 | } | |
2c18a63b | 881 | if (!grab_super_dead(old)) |
d4730127 | 882 | goto retry; |
0200894d | 883 | destroy_unused_super(s); |
d4730127 MK |
884 | return old; |
885 | } | |
1da177e4 LT |
886 | } |
887 | if (!s) { | |
888 | spin_unlock(&sb_lock); | |
e462ec50 | 889 | s = alloc_super(type, (flags & ~SB_SUBMOUNT), user_ns); |
1da177e4 LT |
890 | if (!s) |
891 | return ERR_PTR(-ENOMEM); | |
892 | goto retry; | |
893 | } | |
dd111b31 | 894 | |
1da177e4 LT |
895 | err = set(s, data); |
896 | if (err) { | |
897 | spin_unlock(&sb_lock); | |
0200894d | 898 | destroy_unused_super(s); |
1da177e4 LT |
899 | return ERR_PTR(err); |
900 | } | |
901 | s->s_type = type; | |
c642256b | 902 | strscpy(s->s_id, type->name, sizeof(s->s_id)); |
1da177e4 | 903 | list_add_tail(&s->s_list, &super_blocks); |
a5166169 | 904 | hlist_add_head(&s->s_instances, &type->fs_supers); |
1da177e4 LT |
905 | spin_unlock(&sb_lock); |
906 | get_filesystem(type); | |
1720f5dd | 907 | shrinker_register(s->s_shrink); |
1da177e4 LT |
908 | return s; |
909 | } | |
1da177e4 LT |
910 | EXPORT_SYMBOL(sget); |
911 | ||
912 | void drop_super(struct super_block *sb) | |
913 | { | |
0ed33598 | 914 | super_unlock_shared(sb); |
1da177e4 LT |
915 | put_super(sb); |
916 | } | |
917 | ||
918 | EXPORT_SYMBOL(drop_super); | |
919 | ||
ba6379f7 JK |
920 | void drop_super_exclusive(struct super_block *sb) |
921 | { | |
0ed33598 | 922 | super_unlock_excl(sb); |
ba6379f7 JK |
923 | put_super(sb); |
924 | } | |
925 | EXPORT_SYMBOL(drop_super_exclusive); | |
926 | ||
fa7c1d50 MG |
927 | static void __iterate_supers(void (*f)(struct super_block *)) |
928 | { | |
929 | struct super_block *sb, *p = NULL; | |
930 | ||
931 | spin_lock(&sb_lock); | |
932 | list_for_each_entry(sb, &super_blocks, s_list) { | |
5e874914 CB |
933 | /* Pairs with memory marrier in super_wake(). */ |
934 | if (smp_load_acquire(&sb->s_flags) & SB_DYING) | |
fa7c1d50 MG |
935 | continue; |
936 | sb->s_count++; | |
937 | spin_unlock(&sb_lock); | |
938 | ||
939 | f(sb); | |
940 | ||
941 | spin_lock(&sb_lock); | |
942 | if (p) | |
943 | __put_super(p); | |
944 | p = sb; | |
945 | } | |
946 | if (p) | |
947 | __put_super(p); | |
948 | spin_unlock(&sb_lock); | |
949 | } | |
01a05b33 AV |
950 | /** |
951 | * iterate_supers - call function for all active superblocks | |
952 | * @f: function to call | |
953 | * @arg: argument to pass to it | |
954 | * | |
955 | * Scans the superblock list and calls given function, passing it | |
956 | * locked superblock and given argument. | |
957 | */ | |
958 | void iterate_supers(void (*f)(struct super_block *, void *), void *arg) | |
959 | { | |
dca33252 | 960 | struct super_block *sb, *p = NULL; |
01a05b33 AV |
961 | |
962 | spin_lock(&sb_lock); | |
dca33252 | 963 | list_for_each_entry(sb, &super_blocks, s_list) { |
5e874914 CB |
964 | bool born; |
965 | ||
01a05b33 AV |
966 | sb->s_count++; |
967 | spin_unlock(&sb_lock); | |
968 | ||
5e874914 CB |
969 | born = super_lock_shared(sb); |
970 | if (born && sb->s_root) | |
01a05b33 | 971 | f(sb, arg); |
0ed33598 | 972 | super_unlock_shared(sb); |
01a05b33 AV |
973 | |
974 | spin_lock(&sb_lock); | |
dca33252 AV |
975 | if (p) |
976 | __put_super(p); | |
977 | p = sb; | |
01a05b33 | 978 | } |
dca33252 AV |
979 | if (p) |
980 | __put_super(p); | |
01a05b33 AV |
981 | spin_unlock(&sb_lock); |
982 | } | |
983 | ||
43e15cdb AV |
984 | /** |
985 | * iterate_supers_type - call function for superblocks of given type | |
986 | * @type: fs type | |
987 | * @f: function to call | |
988 | * @arg: argument to pass to it | |
989 | * | |
990 | * Scans the superblock list and calls given function, passing it | |
991 | * locked superblock and given argument. | |
992 | */ | |
993 | void iterate_supers_type(struct file_system_type *type, | |
994 | void (*f)(struct super_block *, void *), void *arg) | |
995 | { | |
996 | struct super_block *sb, *p = NULL; | |
997 | ||
998 | spin_lock(&sb_lock); | |
b67bfe0d | 999 | hlist_for_each_entry(sb, &type->fs_supers, s_instances) { |
5e874914 CB |
1000 | bool born; |
1001 | ||
43e15cdb AV |
1002 | sb->s_count++; |
1003 | spin_unlock(&sb_lock); | |
1004 | ||
5e874914 CB |
1005 | born = super_lock_shared(sb); |
1006 | if (born && sb->s_root) | |
43e15cdb | 1007 | f(sb, arg); |
0ed33598 | 1008 | super_unlock_shared(sb); |
43e15cdb AV |
1009 | |
1010 | spin_lock(&sb_lock); | |
1011 | if (p) | |
1012 | __put_super(p); | |
1013 | p = sb; | |
1014 | } | |
1015 | if (p) | |
1016 | __put_super(p); | |
1017 | spin_unlock(&sb_lock); | |
1018 | } | |
1019 | ||
1020 | EXPORT_SYMBOL(iterate_supers_type); | |
1021 | ||
4504230a CH |
1022 | /** |
1023 | * get_active_super - get an active reference to the superblock of a device | |
1024 | * @bdev: device to get the superblock for | |
1025 | * | |
1026 | * Scans the superblock list and finds the superblock of the file system | |
1027 | * mounted on the device given. Returns the superblock with an active | |
d3f21473 | 1028 | * reference or %NULL if none was found. |
4504230a CH |
1029 | */ |
1030 | struct super_block *get_active_super(struct block_device *bdev) | |
1031 | { | |
1032 | struct super_block *sb; | |
1033 | ||
1034 | if (!bdev) | |
1035 | return NULL; | |
1036 | ||
1037 | spin_lock(&sb_lock); | |
1038 | list_for_each_entry(sb, &super_blocks, s_list) { | |
1494583d | 1039 | if (sb->s_bdev == bdev) { |
acfec9a5 | 1040 | if (!grab_super(sb)) |
5e874914 | 1041 | return NULL; |
0ed33598 | 1042 | super_unlock_excl(sb); |
acfec9a5 | 1043 | return sb; |
1494583d | 1044 | } |
4504230a CH |
1045 | } |
1046 | spin_unlock(&sb_lock); | |
1047 | return NULL; | |
1048 | } | |
dd111b31 | 1049 | |
4e7b5671 | 1050 | struct super_block *user_get_super(dev_t dev, bool excl) |
1da177e4 | 1051 | { |
618f0636 | 1052 | struct super_block *sb; |
1da177e4 | 1053 | |
1da177e4 | 1054 | spin_lock(&sb_lock); |
618f0636 KK |
1055 | list_for_each_entry(sb, &super_blocks, s_list) { |
1056 | if (sb->s_dev == dev) { | |
5e874914 CB |
1057 | bool born; |
1058 | ||
618f0636 | 1059 | sb->s_count++; |
1da177e4 | 1060 | spin_unlock(&sb_lock); |
df40c01a | 1061 | /* still alive? */ |
5e874914 CB |
1062 | born = super_lock(sb, excl); |
1063 | if (born && sb->s_root) | |
618f0636 | 1064 | return sb; |
0ed33598 | 1065 | super_unlock(sb, excl); |
df40c01a | 1066 | /* nope, got unmounted */ |
618f0636 | 1067 | spin_lock(&sb_lock); |
df40c01a | 1068 | __put_super(sb); |
5e874914 | 1069 | break; |
1da177e4 LT |
1070 | } |
1071 | } | |
1072 | spin_unlock(&sb_lock); | |
1073 | return NULL; | |
1074 | } | |
1075 | ||
1da177e4 | 1076 | /** |
8d0347f6 DH |
1077 | * reconfigure_super - asks filesystem to change superblock parameters |
1078 | * @fc: The superblock and configuration | |
1da177e4 | 1079 | * |
8d0347f6 | 1080 | * Alters the configuration parameters of a live superblock. |
1da177e4 | 1081 | */ |
8d0347f6 | 1082 | int reconfigure_super(struct fs_context *fc) |
1da177e4 | 1083 | { |
8d0347f6 | 1084 | struct super_block *sb = fc->root->d_sb; |
1da177e4 | 1085 | int retval; |
8d0347f6 | 1086 | bool remount_ro = false; |
c541dce8 | 1087 | bool remount_rw = false; |
8d0347f6 | 1088 | bool force = fc->sb_flags & SB_FORCE; |
4504230a | 1089 | |
8d0347f6 DH |
1090 | if (fc->sb_flags_mask & ~MS_RMT_MASK) |
1091 | return -EINVAL; | |
5accdf82 | 1092 | if (sb->s_writers.frozen != SB_UNFROZEN) |
4504230a CH |
1093 | return -EBUSY; |
1094 | ||
8d0347f6 DH |
1095 | retval = security_sb_remount(sb, fc->security); |
1096 | if (retval) | |
1097 | return retval; | |
1098 | ||
1099 | if (fc->sb_flags_mask & SB_RDONLY) { | |
9361401e | 1100 | #ifdef CONFIG_BLOCK |
6f0d9689 CH |
1101 | if (!(fc->sb_flags & SB_RDONLY) && sb->s_bdev && |
1102 | bdev_read_only(sb->s_bdev)) | |
8d0347f6 | 1103 | return -EACCES; |
9361401e | 1104 | #endif |
c541dce8 | 1105 | remount_rw = !(fc->sb_flags & SB_RDONLY) && sb_rdonly(sb); |
8d0347f6 DH |
1106 | remount_ro = (fc->sb_flags & SB_RDONLY) && !sb_rdonly(sb); |
1107 | } | |
d208bbdd | 1108 | |
0aec09d0 | 1109 | if (remount_ro) { |
fdab684d | 1110 | if (!hlist_empty(&sb->s_pins)) { |
0ed33598 | 1111 | super_unlock_excl(sb); |
fdab684d | 1112 | group_pin_kill(&sb->s_pins); |
5e874914 | 1113 | __super_lock_excl(sb); |
0aec09d0 AV |
1114 | if (!sb->s_root) |
1115 | return 0; | |
1116 | if (sb->s_writers.frozen != SB_UNFROZEN) | |
1117 | return -EBUSY; | |
8d0347f6 | 1118 | remount_ro = !sb_rdonly(sb); |
0aec09d0 AV |
1119 | } |
1120 | } | |
1121 | shrink_dcache_sb(sb); | |
1122 | ||
8d0347f6 DH |
1123 | /* If we are reconfiguring to RDONLY and current sb is read/write, |
1124 | * make sure there are no files open for writing. | |
1125 | */ | |
d208bbdd | 1126 | if (remount_ro) { |
4ed5e82f | 1127 | if (force) { |
d7439fb1 | 1128 | sb_start_ro_state_change(sb); |
4ed5e82f MS |
1129 | } else { |
1130 | retval = sb_prepare_remount_readonly(sb); | |
1131 | if (retval) | |
1132 | return retval; | |
4ed5e82f | 1133 | } |
c541dce8 JK |
1134 | } else if (remount_rw) { |
1135 | /* | |
d7439fb1 JK |
1136 | * Protect filesystem's reconfigure code from writes from |
1137 | * userspace until reconfigure finishes. | |
c541dce8 | 1138 | */ |
d7439fb1 | 1139 | sb_start_ro_state_change(sb); |
1da177e4 LT |
1140 | } |
1141 | ||
f3a09c92 AV |
1142 | if (fc->ops->reconfigure) { |
1143 | retval = fc->ops->reconfigure(fc); | |
1144 | if (retval) { | |
1145 | if (!force) | |
1146 | goto cancel_readonly; | |
1147 | /* If forced remount, go ahead despite any errors */ | |
1148 | WARN(1, "forced remount of a %s fs returned %i\n", | |
1149 | sb->s_type->name, retval); | |
1150 | } | |
1da177e4 | 1151 | } |
8d0347f6 DH |
1152 | |
1153 | WRITE_ONCE(sb->s_flags, ((sb->s_flags & ~fc->sb_flags_mask) | | |
1154 | (fc->sb_flags & fc->sb_flags_mask))); | |
d7439fb1 | 1155 | sb_end_ro_state_change(sb); |
c79d967d | 1156 | |
d208bbdd NP |
1157 | /* |
1158 | * Some filesystems modify their metadata via some other path than the | |
1159 | * bdev buffer cache (eg. use a private mapping, or directories in | |
1160 | * pagecache, etc). Also file data modifications go via their own | |
1161 | * mappings. So If we try to mount readonly then copy the filesystem | |
1162 | * from bdev, we could get stale data, so invalidate it to give a best | |
1163 | * effort at coherency. | |
1164 | */ | |
1165 | if (remount_ro && sb->s_bdev) | |
1166 | invalidate_bdev(sb->s_bdev); | |
1da177e4 | 1167 | return 0; |
4ed5e82f MS |
1168 | |
1169 | cancel_readonly: | |
d7439fb1 | 1170 | sb_end_ro_state_change(sb); |
4ed5e82f | 1171 | return retval; |
1da177e4 LT |
1172 | } |
1173 | ||
fa7c1d50 | 1174 | static void do_emergency_remount_callback(struct super_block *sb) |
1da177e4 | 1175 | { |
5e874914 CB |
1176 | bool born = super_lock_excl(sb); |
1177 | ||
1178 | if (born && sb->s_root && sb->s_bdev && !sb_rdonly(sb)) { | |
8d0347f6 DH |
1179 | struct fs_context *fc; |
1180 | ||
1181 | fc = fs_context_for_reconfigure(sb->s_root, | |
1182 | SB_RDONLY | SB_FORCE, SB_RDONLY); | |
1183 | if (!IS_ERR(fc)) { | |
1184 | if (parse_monolithic_mount_data(fc, NULL) == 0) | |
1185 | (void)reconfigure_super(fc); | |
1186 | put_fs_context(fc); | |
1187 | } | |
1da177e4 | 1188 | } |
0ed33598 | 1189 | super_unlock_excl(sb); |
fa7c1d50 MG |
1190 | } |
1191 | ||
1192 | static void do_emergency_remount(struct work_struct *work) | |
1193 | { | |
1194 | __iterate_supers(do_emergency_remount_callback); | |
a2a9537a | 1195 | kfree(work); |
1da177e4 LT |
1196 | printk("Emergency Remount complete\n"); |
1197 | } | |
1198 | ||
1199 | void emergency_remount(void) | |
1200 | { | |
a2a9537a JA |
1201 | struct work_struct *work; |
1202 | ||
1203 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
1204 | if (work) { | |
1205 | INIT_WORK(work, do_emergency_remount); | |
1206 | schedule_work(work); | |
1207 | } | |
1da177e4 LT |
1208 | } |
1209 | ||
08fdc8a0 MG |
1210 | static void do_thaw_all_callback(struct super_block *sb) |
1211 | { | |
5e874914 CB |
1212 | bool born = super_lock_excl(sb); |
1213 | ||
1214 | if (born && sb->s_root) { | |
4a8b719f CH |
1215 | if (IS_ENABLED(CONFIG_BLOCK)) |
1216 | while (sb->s_bdev && !thaw_bdev(sb->s_bdev)) | |
1217 | pr_warn("Emergency Thaw on %pg\n", sb->s_bdev); | |
880b9577 | 1218 | thaw_super_locked(sb, FREEZE_HOLDER_USERSPACE); |
08fdc8a0 | 1219 | } else { |
0ed33598 | 1220 | super_unlock_excl(sb); |
08fdc8a0 MG |
1221 | } |
1222 | } | |
1223 | ||
1224 | static void do_thaw_all(struct work_struct *work) | |
1225 | { | |
1226 | __iterate_supers(do_thaw_all_callback); | |
1227 | kfree(work); | |
1228 | printk(KERN_WARNING "Emergency Thaw complete\n"); | |
1229 | } | |
1230 | ||
1231 | /** | |
1232 | * emergency_thaw_all -- forcibly thaw every frozen filesystem | |
1233 | * | |
1234 | * Used for emergency unfreeze of all filesystems via SysRq | |
1235 | */ | |
1236 | void emergency_thaw_all(void) | |
1237 | { | |
1238 | struct work_struct *work; | |
1239 | ||
1240 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
1241 | if (work) { | |
1242 | INIT_WORK(work, do_thaw_all); | |
1243 | schedule_work(work); | |
1244 | } | |
1245 | } | |
1246 | ||
ad76cbc6 | 1247 | static DEFINE_IDA(unnamed_dev_ida); |
1da177e4 | 1248 | |
5a66847e MW |
1249 | /** |
1250 | * get_anon_bdev - Allocate a block device for filesystems which don't have one. | |
1251 | * @p: Pointer to a dev_t. | |
1252 | * | |
1253 | * Filesystems which don't use real block devices can call this function | |
1254 | * to allocate a virtual block device. | |
1255 | * | |
1256 | * Context: Any context. Frequently called while holding sb_lock. | |
1257 | * Return: 0 on success, -EMFILE if there are no anonymous bdevs left | |
1258 | * or -ENOMEM if memory allocation failed. | |
1259 | */ | |
0ee5dc67 | 1260 | int get_anon_bdev(dev_t *p) |
1da177e4 LT |
1261 | { |
1262 | int dev; | |
5a66847e MW |
1263 | |
1264 | /* | |
1265 | * Many userspace utilities consider an FSID of 0 invalid. | |
1266 | * Always return at least 1 from get_anon_bdev. | |
1267 | */ | |
1268 | dev = ida_alloc_range(&unnamed_dev_ida, 1, (1 << MINORBITS) - 1, | |
1269 | GFP_ATOMIC); | |
1270 | if (dev == -ENOSPC) | |
1271 | dev = -EMFILE; | |
1272 | if (dev < 0) | |
1273 | return dev; | |
1274 | ||
1275 | *p = MKDEV(0, dev); | |
1da177e4 LT |
1276 | return 0; |
1277 | } | |
0ee5dc67 | 1278 | EXPORT_SYMBOL(get_anon_bdev); |
1da177e4 | 1279 | |
0ee5dc67 | 1280 | void free_anon_bdev(dev_t dev) |
1da177e4 | 1281 | { |
5a66847e | 1282 | ida_free(&unnamed_dev_ida, MINOR(dev)); |
1da177e4 | 1283 | } |
0ee5dc67 AV |
1284 | EXPORT_SYMBOL(free_anon_bdev); |
1285 | ||
1286 | int set_anon_super(struct super_block *s, void *data) | |
1287 | { | |
df0ce26c | 1288 | return get_anon_bdev(&s->s_dev); |
0ee5dc67 | 1289 | } |
0ee5dc67 AV |
1290 | EXPORT_SYMBOL(set_anon_super); |
1291 | ||
1292 | void kill_anon_super(struct super_block *sb) | |
1293 | { | |
1294 | dev_t dev = sb->s_dev; | |
1295 | generic_shutdown_super(sb); | |
dc3216b1 | 1296 | kill_super_notify(sb); |
0ee5dc67 AV |
1297 | free_anon_bdev(dev); |
1298 | } | |
1da177e4 LT |
1299 | EXPORT_SYMBOL(kill_anon_super); |
1300 | ||
1da177e4 LT |
1301 | void kill_litter_super(struct super_block *sb) |
1302 | { | |
1303 | if (sb->s_root) | |
1304 | d_genocide(sb->s_root); | |
1305 | kill_anon_super(sb); | |
1306 | } | |
1da177e4 LT |
1307 | EXPORT_SYMBOL(kill_litter_super); |
1308 | ||
cb50b348 AV |
1309 | int set_anon_super_fc(struct super_block *sb, struct fs_context *fc) |
1310 | { | |
1311 | return set_anon_super(sb, NULL); | |
1312 | } | |
1313 | EXPORT_SYMBOL(set_anon_super_fc); | |
1314 | ||
1315 | static int test_keyed_super(struct super_block *sb, struct fs_context *fc) | |
1316 | { | |
1317 | return sb->s_fs_info == fc->s_fs_info; | |
1318 | } | |
1319 | ||
1320 | static int test_single_super(struct super_block *s, struct fs_context *fc) | |
1321 | { | |
1322 | return 1; | |
1323 | } | |
1324 | ||
e062abae | 1325 | static int vfs_get_super(struct fs_context *fc, |
cda2ed05 CH |
1326 | int (*test)(struct super_block *, struct fs_context *), |
1327 | int (*fill_super)(struct super_block *sb, | |
1328 | struct fs_context *fc)) | |
cb50b348 | 1329 | { |
cb50b348 | 1330 | struct super_block *sb; |
43ce4c1f | 1331 | int err; |
cb50b348 | 1332 | |
cb50b348 AV |
1333 | sb = sget_fc(fc, test, set_anon_super_fc); |
1334 | if (IS_ERR(sb)) | |
1335 | return PTR_ERR(sb); | |
1336 | ||
1337 | if (!sb->s_root) { | |
43ce4c1f DH |
1338 | err = fill_super(sb, fc); |
1339 | if (err) | |
1340 | goto error; | |
cb50b348 AV |
1341 | |
1342 | sb->s_flags |= SB_ACTIVE; | |
1343 | } | |
1344 | ||
e062abae | 1345 | fc->root = dget(sb->s_root); |
cb50b348 | 1346 | return 0; |
43ce4c1f DH |
1347 | |
1348 | error: | |
1349 | deactivate_locked_super(sb); | |
1350 | return err; | |
cb50b348 | 1351 | } |
cb50b348 | 1352 | |
2ac295d4 AV |
1353 | int get_tree_nodev(struct fs_context *fc, |
1354 | int (*fill_super)(struct super_block *sb, | |
1355 | struct fs_context *fc)) | |
1356 | { | |
e062abae | 1357 | return vfs_get_super(fc, NULL, fill_super); |
2ac295d4 AV |
1358 | } |
1359 | EXPORT_SYMBOL(get_tree_nodev); | |
1360 | ||
c23a0bba AV |
1361 | int get_tree_single(struct fs_context *fc, |
1362 | int (*fill_super)(struct super_block *sb, | |
1363 | struct fs_context *fc)) | |
1364 | { | |
e062abae | 1365 | return vfs_get_super(fc, test_single_super, fill_super); |
c23a0bba AV |
1366 | } |
1367 | EXPORT_SYMBOL(get_tree_single); | |
1368 | ||
533770cc AV |
1369 | int get_tree_keyed(struct fs_context *fc, |
1370 | int (*fill_super)(struct super_block *sb, | |
1371 | struct fs_context *fc), | |
1372 | void *key) | |
1373 | { | |
1374 | fc->s_fs_info = key; | |
e062abae | 1375 | return vfs_get_super(fc, test_keyed_super, fill_super); |
533770cc AV |
1376 | } |
1377 | EXPORT_SYMBOL(get_tree_keyed); | |
1378 | ||
69881be3 CB |
1379 | static int set_bdev_super(struct super_block *s, void *data) |
1380 | { | |
1381 | s->s_dev = *(dev_t *)data; | |
1382 | return 0; | |
1383 | } | |
1384 | ||
1385 | static int super_s_dev_set(struct super_block *s, struct fs_context *fc) | |
1386 | { | |
1387 | return set_bdev_super(s, fc->sget_key); | |
1388 | } | |
1389 | ||
1390 | static int super_s_dev_test(struct super_block *s, struct fs_context *fc) | |
1391 | { | |
1392 | return !(s->s_iflags & SB_I_RETIRED) && | |
1393 | s->s_dev == *(dev_t *)fc->sget_key; | |
1394 | } | |
1395 | ||
1396 | /** | |
1397 | * sget_dev - Find or create a superblock by device number | |
1398 | * @fc: Filesystem context. | |
1399 | * @dev: device number | |
1400 | * | |
1401 | * Find or create a superblock using the provided device number that | |
1402 | * will be stored in fc->sget_key. | |
1403 | * | |
1404 | * If an extant superblock is matched, then that will be returned with | |
1405 | * an elevated reference count that the caller must transfer or discard. | |
1406 | * | |
1407 | * If no match is made, a new superblock will be allocated and basic | |
1408 | * initialisation will be performed (s_type, s_fs_info, s_id, s_dev will | |
1409 | * be set). The superblock will be published and it will be returned in | |
1410 | * a partially constructed state with SB_BORN and SB_ACTIVE as yet | |
1411 | * unset. | |
1412 | * | |
1413 | * Return: an existing or newly created superblock on success, an error | |
1414 | * pointer on failure. | |
1415 | */ | |
1416 | struct super_block *sget_dev(struct fs_context *fc, dev_t dev) | |
1417 | { | |
1418 | fc->sget_key = &dev; | |
1419 | return sget_fc(fc, super_s_dev_test, super_s_dev_set); | |
1420 | } | |
1421 | EXPORT_SYMBOL(sget_dev); | |
1422 | ||
9361401e | 1423 | #ifdef CONFIG_BLOCK |
9c09a7cf | 1424 | /* |
fd146410 JK |
1425 | * Lock the superblock that is holder of the bdev. Returns the superblock |
1426 | * pointer if we successfully locked the superblock and it is alive. Otherwise | |
1427 | * we return NULL and just unlock bdev->bd_holder_lock. | |
9c09a7cf | 1428 | * |
fd146410 | 1429 | * The function must be called with bdev->bd_holder_lock and releases it. |
9c09a7cf | 1430 | */ |
fd146410 JK |
1431 | static struct super_block *bdev_super_lock_shared(struct block_device *bdev) |
1432 | __releases(&bdev->bd_holder_lock) | |
87efb390 | 1433 | { |
fd146410 JK |
1434 | struct super_block *sb = bdev->bd_holder; |
1435 | bool born; | |
1436 | ||
1437 | lockdep_assert_held(&bdev->bd_holder_lock); | |
1438 | lockdep_assert_not_held(&sb->s_umount); | |
3b224e1d | 1439 | lockdep_assert_not_held(&bdev->bd_disk->open_mutex); |
fd146410 JK |
1440 | |
1441 | /* Make sure sb doesn't go away from under us */ | |
1442 | spin_lock(&sb_lock); | |
1443 | sb->s_count++; | |
1444 | spin_unlock(&sb_lock); | |
1445 | mutex_unlock(&bdev->bd_holder_lock); | |
87efb390 | 1446 | |
fd146410 | 1447 | born = super_lock_shared(sb); |
5e874914 | 1448 | if (!born || !sb->s_root || !(sb->s_flags & SB_ACTIVE)) { |
0ed33598 | 1449 | super_unlock_shared(sb); |
fd146410 JK |
1450 | put_super(sb); |
1451 | return NULL; | |
9c09a7cf | 1452 | } |
fd146410 JK |
1453 | /* |
1454 | * The superblock is active and we hold s_umount, we can drop our | |
1455 | * temporary reference now. | |
1456 | */ | |
1457 | put_super(sb); | |
1458 | return sb; | |
9c09a7cf CH |
1459 | } |
1460 | ||
d8530de5 | 1461 | static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise) |
87efb390 | 1462 | { |
fd146410 | 1463 | struct super_block *sb; |
9c09a7cf | 1464 | |
fd146410 JK |
1465 | sb = bdev_super_lock_shared(bdev); |
1466 | if (!sb) | |
87efb390 CH |
1467 | return; |
1468 | ||
d8530de5 CH |
1469 | if (!surprise) |
1470 | sync_filesystem(sb); | |
1471 | shrink_dcache_sb(sb); | |
e127b9bc | 1472 | invalidate_inodes(sb); |
87efb390 CH |
1473 | if (sb->s_op->shutdown) |
1474 | sb->s_op->shutdown(sb); | |
9c09a7cf | 1475 | |
0ed33598 | 1476 | super_unlock_shared(sb); |
87efb390 CH |
1477 | } |
1478 | ||
2142b88c CH |
1479 | static void fs_bdev_sync(struct block_device *bdev) |
1480 | { | |
fd146410 | 1481 | struct super_block *sb; |
2142b88c | 1482 | |
fd146410 JK |
1483 | sb = bdev_super_lock_shared(bdev); |
1484 | if (!sb) | |
2142b88c CH |
1485 | return; |
1486 | sync_filesystem(sb); | |
0ed33598 | 1487 | super_unlock_shared(sb); |
2142b88c CH |
1488 | } |
1489 | ||
7ecd0b6f | 1490 | const struct blk_holder_ops fs_holder_ops = { |
d8530de5 | 1491 | .mark_dead = fs_bdev_mark_dead, |
2142b88c | 1492 | .sync = fs_bdev_sync, |
87efb390 | 1493 | }; |
7ecd0b6f | 1494 | EXPORT_SYMBOL_GPL(fs_holder_ops); |
fe62c3a4 | 1495 | |
cf6da236 | 1496 | int setup_bdev_super(struct super_block *sb, int sb_flags, |
aca740ce JK |
1497 | struct fs_context *fc) |
1498 | { | |
1499 | blk_mode_t mode = sb_open_mode(sb_flags); | |
f4a48bc3 | 1500 | struct bdev_handle *bdev_handle; |
aca740ce JK |
1501 | struct block_device *bdev; |
1502 | ||
f4a48bc3 JK |
1503 | bdev_handle = bdev_open_by_dev(sb->s_dev, mode, sb, &fs_holder_ops); |
1504 | if (IS_ERR(bdev_handle)) { | |
aca740ce JK |
1505 | if (fc) |
1506 | errorf(fc, "%s: Can't open blockdev", fc->source); | |
f4a48bc3 | 1507 | return PTR_ERR(bdev_handle); |
aca740ce | 1508 | } |
f4a48bc3 | 1509 | bdev = bdev_handle->bdev; |
aca740ce JK |
1510 | |
1511 | /* | |
1512 | * This really should be in blkdev_get_by_dev, but right now can't due | |
1513 | * to legacy issues that require us to allow opening a block device node | |
1514 | * writable from userspace even for a read-only block device. | |
1515 | */ | |
1516 | if ((mode & BLK_OPEN_WRITE) && bdev_read_only(bdev)) { | |
f4a48bc3 | 1517 | bdev_release(bdev_handle); |
aca740ce JK |
1518 | return -EACCES; |
1519 | } | |
1520 | ||
1521 | /* | |
1522 | * Until SB_BORN flag is set, there can be no active superblock | |
1523 | * references and thus no filesystem freezing. get_active_super() will | |
1524 | * just loop waiting for SB_BORN so even freeze_bdev() cannot proceed. | |
1525 | * | |
1526 | * It is enough to check bdev was not frozen before we set s_bdev. | |
1527 | */ | |
1528 | mutex_lock(&bdev->bd_fsfreeze_mutex); | |
1529 | if (bdev->bd_fsfreeze_count > 0) { | |
1530 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
1531 | if (fc) | |
1532 | warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); | |
f4a48bc3 | 1533 | bdev_release(bdev_handle); |
aca740ce JK |
1534 | return -EBUSY; |
1535 | } | |
1536 | spin_lock(&sb_lock); | |
f4a48bc3 | 1537 | sb->s_bdev_handle = bdev_handle; |
aca740ce JK |
1538 | sb->s_bdev = bdev; |
1539 | sb->s_bdi = bdi_get(bdev->bd_disk->bdi); | |
1540 | if (bdev_stable_writes(bdev)) | |
1541 | sb->s_iflags |= SB_I_STABLE_WRITES; | |
1542 | spin_unlock(&sb_lock); | |
1543 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
1544 | ||
1545 | snprintf(sb->s_id, sizeof(sb->s_id), "%pg", bdev); | |
1720f5dd | 1546 | shrinker_debugfs_rename(sb->s_shrink, "sb-%s:%s", sb->s_type->name, |
aca740ce JK |
1547 | sb->s_id); |
1548 | sb_set_blocksize(sb, block_size(bdev)); | |
1549 | return 0; | |
fe62c3a4 | 1550 | } |
cf6da236 | 1551 | EXPORT_SYMBOL_GPL(setup_bdev_super); |
fe62c3a4 DH |
1552 | |
1553 | /** | |
1554 | * get_tree_bdev - Get a superblock based on a single block device | |
1555 | * @fc: The filesystem context holding the parameters | |
1556 | * @fill_super: Helper to initialise a new superblock | |
1557 | */ | |
1558 | int get_tree_bdev(struct fs_context *fc, | |
1559 | int (*fill_super)(struct super_block *, | |
1560 | struct fs_context *)) | |
1561 | { | |
fe62c3a4 | 1562 | struct super_block *s; |
fe62c3a4 | 1563 | int error = 0; |
aca740ce | 1564 | dev_t dev; |
fe62c3a4 | 1565 | |
fe62c3a4 DH |
1566 | if (!fc->source) |
1567 | return invalf(fc, "No source specified"); | |
1568 | ||
aca740ce JK |
1569 | error = lookup_bdev(fc->source, &dev); |
1570 | if (error) { | |
1571 | errorf(fc, "%s: Can't lookup blockdev", fc->source); | |
1572 | return error; | |
fe62c3a4 DH |
1573 | } |
1574 | ||
1575 | fc->sb_flags |= SB_NOSEC; | |
69881be3 | 1576 | s = sget_dev(fc, dev); |
aca740ce | 1577 | if (IS_ERR(s)) |
fe62c3a4 DH |
1578 | return PTR_ERR(s); |
1579 | ||
1580 | if (s->s_root) { | |
1581 | /* Don't summarily change the RO/RW state. */ | |
1582 | if ((fc->sb_flags ^ s->s_flags) & SB_RDONLY) { | |
aca740ce | 1583 | warnf(fc, "%pg: Can't mount, would change RO state", s->s_bdev); |
fe62c3a4 | 1584 | deactivate_locked_super(s); |
fe62c3a4 DH |
1585 | return -EBUSY; |
1586 | } | |
aca740ce | 1587 | } else { |
fe62c3a4 | 1588 | /* |
aca740ce JK |
1589 | * We drop s_umount here because we need to open the bdev and |
1590 | * bdev->open_mutex ranks above s_umount (blkdev_put() -> | |
560e20e4 | 1591 | * bdev_mark_dead()). It is safe because we have active sb |
aca740ce | 1592 | * reference and SB_BORN is not set yet. |
fe62c3a4 | 1593 | */ |
0ed33598 | 1594 | super_unlock_excl(s); |
aca740ce | 1595 | error = setup_bdev_super(s, fc->sb_flags, fc); |
5e874914 | 1596 | __super_lock_excl(s); |
aca740ce JK |
1597 | if (!error) |
1598 | error = fill_super(s, fc); | |
fe62c3a4 DH |
1599 | if (error) { |
1600 | deactivate_locked_super(s); | |
1601 | return error; | |
1602 | } | |
fe62c3a4 | 1603 | s->s_flags |= SB_ACTIVE; |
fe62c3a4 DH |
1604 | } |
1605 | ||
1606 | BUG_ON(fc->root); | |
1607 | fc->root = dget(s->s_root); | |
1608 | return 0; | |
1609 | } | |
1610 | EXPORT_SYMBOL(get_tree_bdev); | |
1611 | ||
1da177e4 LT |
1612 | static int test_bdev_super(struct super_block *s, void *data) |
1613 | { | |
aca740ce | 1614 | return !(s->s_iflags & SB_I_RETIRED) && s->s_dev == *(dev_t *)data; |
1da177e4 LT |
1615 | } |
1616 | ||
152a0836 | 1617 | struct dentry *mount_bdev(struct file_system_type *fs_type, |
1da177e4 | 1618 | int flags, const char *dev_name, void *data, |
152a0836 | 1619 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 | 1620 | { |
1da177e4 | 1621 | struct super_block *s; |
aca740ce JK |
1622 | int error; |
1623 | dev_t dev; | |
1da177e4 | 1624 | |
aca740ce JK |
1625 | error = lookup_bdev(dev_name, &dev); |
1626 | if (error) | |
1627 | return ERR_PTR(error); | |
1da177e4 | 1628 | |
aca740ce JK |
1629 | flags |= SB_NOSEC; |
1630 | s = sget(fs_type, test_bdev_super, set_bdev_super, flags, &dev); | |
1da177e4 | 1631 | if (IS_ERR(s)) |
aca740ce | 1632 | return ERR_CAST(s); |
1da177e4 LT |
1633 | |
1634 | if (s->s_root) { | |
e462ec50 | 1635 | if ((flags ^ s->s_flags) & SB_RDONLY) { |
74dbbdd7 | 1636 | deactivate_locked_super(s); |
aca740ce | 1637 | return ERR_PTR(-EBUSY); |
1da177e4 | 1638 | } |
aca740ce | 1639 | } else { |
4f331f01 | 1640 | /* |
aca740ce JK |
1641 | * We drop s_umount here because we need to open the bdev and |
1642 | * bdev->open_mutex ranks above s_umount (blkdev_put() -> | |
560e20e4 | 1643 | * bdev_mark_dead()). It is safe because we have active sb |
aca740ce | 1644 | * reference and SB_BORN is not set yet. |
4f331f01 | 1645 | */ |
0ed33598 | 1646 | super_unlock_excl(s); |
aca740ce | 1647 | error = setup_bdev_super(s, flags, NULL); |
5e874914 | 1648 | __super_lock_excl(s); |
aca740ce JK |
1649 | if (!error) |
1650 | error = fill_super(s, data, flags & SB_SILENT ? 1 : 0); | |
1da177e4 | 1651 | if (error) { |
74dbbdd7 | 1652 | deactivate_locked_super(s); |
aca740ce | 1653 | return ERR_PTR(error); |
fa675765 | 1654 | } |
454e2398 | 1655 | |
e462ec50 | 1656 | s->s_flags |= SB_ACTIVE; |
1da177e4 LT |
1657 | } |
1658 | ||
152a0836 | 1659 | return dget(s->s_root); |
152a0836 AV |
1660 | } |
1661 | EXPORT_SYMBOL(mount_bdev); | |
1662 | ||
1da177e4 LT |
1663 | void kill_block_super(struct super_block *sb) |
1664 | { | |
1665 | struct block_device *bdev = sb->s_bdev; | |
1666 | ||
1da177e4 | 1667 | generic_shutdown_super(sb); |
aca740ce JK |
1668 | if (bdev) { |
1669 | sync_blockdev(bdev); | |
f4a48bc3 | 1670 | bdev_release(sb->s_bdev_handle); |
aca740ce | 1671 | } |
1da177e4 LT |
1672 | } |
1673 | ||
1674 | EXPORT_SYMBOL(kill_block_super); | |
9361401e | 1675 | #endif |
1da177e4 | 1676 | |
3c26ff6e | 1677 | struct dentry *mount_nodev(struct file_system_type *fs_type, |
1da177e4 | 1678 | int flags, void *data, |
3c26ff6e | 1679 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
1680 | { |
1681 | int error; | |
9249e17f | 1682 | struct super_block *s = sget(fs_type, NULL, set_anon_super, flags, NULL); |
1da177e4 LT |
1683 | |
1684 | if (IS_ERR(s)) | |
3c26ff6e | 1685 | return ERR_CAST(s); |
1da177e4 | 1686 | |
e462ec50 | 1687 | error = fill_super(s, data, flags & SB_SILENT ? 1 : 0); |
1da177e4 | 1688 | if (error) { |
74dbbdd7 | 1689 | deactivate_locked_super(s); |
3c26ff6e | 1690 | return ERR_PTR(error); |
1da177e4 | 1691 | } |
e462ec50 | 1692 | s->s_flags |= SB_ACTIVE; |
3c26ff6e | 1693 | return dget(s->s_root); |
1da177e4 | 1694 | } |
3c26ff6e AV |
1695 | EXPORT_SYMBOL(mount_nodev); |
1696 | ||
a6097180 N |
1697 | int reconfigure_single(struct super_block *s, |
1698 | int flags, void *data) | |
8d0347f6 DH |
1699 | { |
1700 | struct fs_context *fc; | |
1701 | int ret; | |
1702 | ||
1703 | /* The caller really need to be passing fc down into mount_single(), | |
1704 | * then a chunk of this can be removed. [Bollocks -- AV] | |
1705 | * Better yet, reconfiguration shouldn't happen, but rather the second | |
1706 | * mount should be rejected if the parameters are not compatible. | |
1707 | */ | |
1708 | fc = fs_context_for_reconfigure(s->s_root, flags, MS_RMT_MASK); | |
1709 | if (IS_ERR(fc)) | |
1710 | return PTR_ERR(fc); | |
1711 | ||
1712 | ret = parse_monolithic_mount_data(fc, data); | |
1713 | if (ret < 0) | |
1714 | goto out; | |
1715 | ||
1716 | ret = reconfigure_super(fc); | |
1717 | out: | |
1718 | put_fs_context(fc); | |
1719 | return ret; | |
1720 | } | |
1721 | ||
1da177e4 LT |
1722 | static int compare_single(struct super_block *s, void *p) |
1723 | { | |
1724 | return 1; | |
1725 | } | |
1726 | ||
fc14f2fe | 1727 | struct dentry *mount_single(struct file_system_type *fs_type, |
1da177e4 | 1728 | int flags, void *data, |
fc14f2fe | 1729 | int (*fill_super)(struct super_block *, void *, int)) |
1da177e4 LT |
1730 | { |
1731 | struct super_block *s; | |
1732 | int error; | |
1733 | ||
9249e17f | 1734 | s = sget(fs_type, compare_single, set_anon_super, flags, NULL); |
1da177e4 | 1735 | if (IS_ERR(s)) |
fc14f2fe | 1736 | return ERR_CAST(s); |
1da177e4 | 1737 | if (!s->s_root) { |
e462ec50 | 1738 | error = fill_super(s, data, flags & SB_SILENT ? 1 : 0); |
8d0347f6 DH |
1739 | if (!error) |
1740 | s->s_flags |= SB_ACTIVE; | |
9329d1be | 1741 | } else { |
8d0347f6 DH |
1742 | error = reconfigure_single(s, flags, data); |
1743 | } | |
1744 | if (unlikely(error)) { | |
1745 | deactivate_locked_super(s); | |
1746 | return ERR_PTR(error); | |
1da177e4 | 1747 | } |
fc14f2fe AV |
1748 | return dget(s->s_root); |
1749 | } | |
1750 | EXPORT_SYMBOL(mount_single); | |
1751 | ||
9bc61ab1 DH |
1752 | /** |
1753 | * vfs_get_tree - Get the mountable root | |
1754 | * @fc: The superblock configuration context. | |
1755 | * | |
1756 | * The filesystem is invoked to get or create a superblock which can then later | |
1757 | * be used for mounting. The filesystem places a pointer to the root to be | |
1758 | * used for mounting in @fc->root. | |
1759 | */ | |
1760 | int vfs_get_tree(struct fs_context *fc) | |
1da177e4 | 1761 | { |
9d412a43 | 1762 | struct super_block *sb; |
9bc61ab1 | 1763 | int error; |
8089352a | 1764 | |
f3a09c92 AV |
1765 | if (fc->root) |
1766 | return -EBUSY; | |
1767 | ||
1768 | /* Get the mountable root in fc->root, with a ref on the root and a ref | |
1769 | * on the superblock. | |
1770 | */ | |
1771 | error = fc->ops->get_tree(fc); | |
9bc61ab1 DH |
1772 | if (error < 0) |
1773 | return error; | |
1da177e4 | 1774 | |
f3a09c92 AV |
1775 | if (!fc->root) { |
1776 | pr_err("Filesystem %s get_tree() didn't set fc->root\n", | |
1777 | fc->fs_type->name); | |
1778 | /* We don't know what the locking state of the superblock is - | |
1779 | * if there is a superblock. | |
1780 | */ | |
1781 | BUG(); | |
1782 | } | |
1783 | ||
9bc61ab1 | 1784 | sb = fc->root->d_sb; |
9d412a43 | 1785 | WARN_ON(!sb->s_bdi); |
79f546a6 DC |
1786 | |
1787 | /* | |
5e874914 CB |
1788 | * super_wake() contains a memory barrier which also care of |
1789 | * ordering for super_cache_count(). We place it before setting | |
1790 | * SB_BORN as the data dependency between the two functions is | |
1791 | * the superblock structure contents that we just set up, not | |
1792 | * the SB_BORN flag. | |
79f546a6 | 1793 | */ |
5e874914 | 1794 | super_wake(sb, SB_BORN); |
454e2398 | 1795 | |
9bc61ab1 | 1796 | error = security_sb_set_mnt_opts(sb, fc->security, 0, NULL); |
c9ce29ed AV |
1797 | if (unlikely(error)) { |
1798 | fc_drop_locked(fc); | |
1799 | return error; | |
a10d7c22 AV |
1800 | } |
1801 | ||
42cb56ae JL |
1802 | /* |
1803 | * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE | |
1804 | * but s_maxbytes was an unsigned long long for many releases. Throw | |
1805 | * this warning for a little while to try and catch filesystems that | |
4358b567 | 1806 | * violate this rule. |
42cb56ae | 1807 | */ |
9d412a43 | 1808 | WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " |
9bc61ab1 | 1809 | "negative value (%lld)\n", fc->fs_type->name, sb->s_maxbytes); |
42cb56ae | 1810 | |
9bc61ab1 | 1811 | return 0; |
1da177e4 | 1812 | } |
9bc61ab1 | 1813 | EXPORT_SYMBOL(vfs_get_tree); |
1da177e4 | 1814 | |
fca39346 JK |
1815 | /* |
1816 | * Setup private BDI for given superblock. It gets automatically cleaned up | |
1817 | * in generic_shutdown_super(). | |
1818 | */ | |
1819 | int super_setup_bdi_name(struct super_block *sb, char *fmt, ...) | |
1820 | { | |
1821 | struct backing_dev_info *bdi; | |
1822 | int err; | |
1823 | va_list args; | |
1824 | ||
aef33c2f | 1825 | bdi = bdi_alloc(NUMA_NO_NODE); |
fca39346 JK |
1826 | if (!bdi) |
1827 | return -ENOMEM; | |
1828 | ||
fca39346 | 1829 | va_start(args, fmt); |
7c4cc300 | 1830 | err = bdi_register_va(bdi, fmt, args); |
fca39346 JK |
1831 | va_end(args); |
1832 | if (err) { | |
1833 | bdi_put(bdi); | |
1834 | return err; | |
1835 | } | |
1836 | WARN_ON(sb->s_bdi != &noop_backing_dev_info); | |
1837 | sb->s_bdi = bdi; | |
0b3ea092 | 1838 | sb->s_iflags |= SB_I_PERSB_BDI; |
fca39346 JK |
1839 | |
1840 | return 0; | |
1841 | } | |
1842 | EXPORT_SYMBOL(super_setup_bdi_name); | |
1843 | ||
1844 | /* | |
1845 | * Setup private BDI for given superblock. I gets automatically cleaned up | |
1846 | * in generic_shutdown_super(). | |
1847 | */ | |
1848 | int super_setup_bdi(struct super_block *sb) | |
1849 | { | |
1850 | static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0); | |
1851 | ||
1852 | return super_setup_bdi_name(sb, "%.28s-%ld", sb->s_type->name, | |
1853 | atomic_long_inc_return(&bdi_seq)); | |
1854 | } | |
1855 | EXPORT_SYMBOL(super_setup_bdi); | |
1856 | ||
5accdf82 JK |
1857 | /** |
1858 | * sb_wait_write - wait until all writers to given file system finish | |
1859 | * @sb: the super for which we wait | |
1860 | * @level: type of writers we wait for (normal vs page fault) | |
1861 | * | |
1862 | * This function waits until there are no writers of given type to given file | |
8129ed29 | 1863 | * system. |
5accdf82 JK |
1864 | */ |
1865 | static void sb_wait_write(struct super_block *sb, int level) | |
1866 | { | |
8129ed29 | 1867 | percpu_down_write(sb->s_writers.rw_sem + level-1); |
8129ed29 | 1868 | } |
5accdf82 | 1869 | |
f1a96220 ON |
1870 | /* |
1871 | * We are going to return to userspace and forget about these locks, the | |
1872 | * ownership goes to the caller of thaw_super() which does unlock(). | |
1873 | */ | |
1874 | static void lockdep_sb_freeze_release(struct super_block *sb) | |
1875 | { | |
1876 | int level; | |
1877 | ||
1878 | for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--) | |
1879 | percpu_rwsem_release(sb->s_writers.rw_sem + level, 0, _THIS_IP_); | |
1880 | } | |
1881 | ||
1882 | /* | |
1883 | * Tell lockdep we are holding these locks before we call ->unfreeze_fs(sb). | |
1884 | */ | |
1885 | static void lockdep_sb_freeze_acquire(struct super_block *sb) | |
8129ed29 ON |
1886 | { |
1887 | int level; | |
5accdf82 | 1888 | |
8129ed29 ON |
1889 | for (level = 0; level < SB_FREEZE_LEVELS; ++level) |
1890 | percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_); | |
f1a96220 ON |
1891 | } |
1892 | ||
2719c716 | 1893 | static void sb_freeze_unlock(struct super_block *sb, int level) |
f1a96220 | 1894 | { |
2719c716 | 1895 | for (level--; level >= 0; level--) |
8129ed29 | 1896 | percpu_up_write(sb->s_writers.rw_sem + level); |
5accdf82 JK |
1897 | } |
1898 | ||
59ba4fdd DW |
1899 | static int wait_for_partially_frozen(struct super_block *sb) |
1900 | { | |
1901 | int ret = 0; | |
1902 | ||
1903 | do { | |
1904 | unsigned short old = sb->s_writers.frozen; | |
1905 | ||
1906 | up_write(&sb->s_umount); | |
1907 | ret = wait_var_event_killable(&sb->s_writers.frozen, | |
1908 | sb->s_writers.frozen != old); | |
1909 | down_write(&sb->s_umount); | |
1910 | } while (ret == 0 && | |
1911 | sb->s_writers.frozen != SB_UNFROZEN && | |
1912 | sb->s_writers.frozen != SB_FREEZE_COMPLETE); | |
1913 | ||
1914 | return ret; | |
1915 | } | |
1916 | ||
18e9e510 | 1917 | /** |
7000d3c4 RD |
1918 | * freeze_super - lock the filesystem and force it into a consistent state |
1919 | * @sb: the super to lock | |
880b9577 | 1920 | * @who: context that wants to freeze |
18e9e510 JB |
1921 | * |
1922 | * Syncs the super to make sure the filesystem is consistent and calls the fs's | |
880b9577 | 1923 | * freeze_fs. Subsequent calls to this without first thawing the fs may return |
18e9e510 | 1924 | * -EBUSY. |
5accdf82 | 1925 | * |
880b9577 DW |
1926 | * @who should be: |
1927 | * * %FREEZE_HOLDER_USERSPACE if userspace wants to freeze the fs; | |
1928 | * * %FREEZE_HOLDER_KERNEL if the kernel wants to freeze the fs. | |
1929 | * | |
1930 | * The @who argument distinguishes between the kernel and userspace trying to | |
1931 | * freeze the filesystem. Although there cannot be multiple kernel freezes or | |
1932 | * multiple userspace freezes in effect at any given time, the kernel and | |
1933 | * userspace can both hold a filesystem frozen. The filesystem remains frozen | |
1934 | * until there are no kernel or userspace freezes in effect. | |
1935 | * | |
5accdf82 JK |
1936 | * During this function, sb->s_writers.frozen goes through these values: |
1937 | * | |
1938 | * SB_UNFROZEN: File system is normal, all writes progress as usual. | |
1939 | * | |
1940 | * SB_FREEZE_WRITE: The file system is in the process of being frozen. New | |
1941 | * writes should be blocked, though page faults are still allowed. We wait for | |
1942 | * all writes to complete and then proceed to the next stage. | |
1943 | * | |
1944 | * SB_FREEZE_PAGEFAULT: Freezing continues. Now also page faults are blocked | |
1945 | * but internal fs threads can still modify the filesystem (although they | |
1946 | * should not dirty new pages or inodes), writeback can run etc. After waiting | |
1947 | * for all running page faults we sync the filesystem which will clean all | |
1948 | * dirty pages and inodes (no new dirty pages or inodes can be created when | |
1949 | * sync is running). | |
1950 | * | |
1951 | * SB_FREEZE_FS: The file system is frozen. Now all internal sources of fs | |
1952 | * modification are blocked (e.g. XFS preallocation truncation on inode | |
1953 | * reclaim). This is usually implemented by blocking new transactions for | |
1954 | * filesystems that have them and need this additional guard. After all | |
1955 | * internal writers are finished we call ->freeze_fs() to finish filesystem | |
1956 | * freezing. Then we transition to SB_FREEZE_COMPLETE state. This state is | |
1957 | * mostly auxiliary for filesystems to verify they do not modify frozen fs. | |
1958 | * | |
1959 | * sb->s_writers.frozen is protected by sb->s_umount. | |
18e9e510 | 1960 | */ |
880b9577 | 1961 | int freeze_super(struct super_block *sb, enum freeze_holder who) |
18e9e510 JB |
1962 | { |
1963 | int ret; | |
1964 | ||
1965 | atomic_inc(&sb->s_active); | |
051178c3 CB |
1966 | if (!super_lock_excl(sb)) |
1967 | WARN(1, "Dying superblock while freezing!"); | |
1968 | ||
59ba4fdd | 1969 | retry: |
880b9577 DW |
1970 | if (sb->s_writers.frozen == SB_FREEZE_COMPLETE) { |
1971 | if (sb->s_writers.freeze_holders & who) { | |
1972 | deactivate_locked_super(sb); | |
1973 | return -EBUSY; | |
1974 | } | |
1975 | ||
1976 | WARN_ON(sb->s_writers.freeze_holders == 0); | |
1977 | ||
1978 | /* | |
1979 | * Someone else already holds this type of freeze; share the | |
1980 | * freeze and assign the active ref to the freeze. | |
1981 | */ | |
1982 | sb->s_writers.freeze_holders |= who; | |
3fb5a656 | 1983 | super_unlock_excl(sb); |
880b9577 DW |
1984 | return 0; |
1985 | } | |
1986 | ||
5accdf82 | 1987 | if (sb->s_writers.frozen != SB_UNFROZEN) { |
59ba4fdd DW |
1988 | ret = wait_for_partially_frozen(sb); |
1989 | if (ret) { | |
1990 | deactivate_locked_super(sb); | |
1991 | return ret; | |
1992 | } | |
1993 | ||
1994 | goto retry; | |
18e9e510 JB |
1995 | } |
1996 | ||
e462ec50 | 1997 | if (!(sb->s_flags & SB_BORN)) { |
0ed33598 | 1998 | super_unlock_excl(sb); |
dabe0dc1 AV |
1999 | return 0; /* sic - it's "nothing to do" */ |
2000 | } | |
2001 | ||
bc98a42c | 2002 | if (sb_rdonly(sb)) { |
5accdf82 | 2003 | /* Nothing to do really... */ |
880b9577 | 2004 | sb->s_writers.freeze_holders |= who; |
5accdf82 | 2005 | sb->s_writers.frozen = SB_FREEZE_COMPLETE; |
59ba4fdd | 2006 | wake_up_var(&sb->s_writers.frozen); |
0ed33598 | 2007 | super_unlock_excl(sb); |
18e9e510 JB |
2008 | return 0; |
2009 | } | |
2010 | ||
5accdf82 | 2011 | sb->s_writers.frozen = SB_FREEZE_WRITE; |
5accdf82 | 2012 | /* Release s_umount to preserve sb_start_write -> s_umount ordering */ |
0ed33598 | 2013 | super_unlock_excl(sb); |
5accdf82 | 2014 | sb_wait_write(sb, SB_FREEZE_WRITE); |
051178c3 CB |
2015 | if (!super_lock_excl(sb)) |
2016 | WARN(1, "Dying superblock while freezing!"); | |
5accdf82 JK |
2017 | |
2018 | /* Now we go and block page faults... */ | |
5accdf82 | 2019 | sb->s_writers.frozen = SB_FREEZE_PAGEFAULT; |
5accdf82 JK |
2020 | sb_wait_write(sb, SB_FREEZE_PAGEFAULT); |
2021 | ||
2022 | /* All writers are done so after syncing there won't be dirty data */ | |
2719c716 DW |
2023 | ret = sync_filesystem(sb); |
2024 | if (ret) { | |
2025 | sb->s_writers.frozen = SB_UNFROZEN; | |
2026 | sb_freeze_unlock(sb, SB_FREEZE_PAGEFAULT); | |
59ba4fdd | 2027 | wake_up_var(&sb->s_writers.frozen); |
2719c716 DW |
2028 | deactivate_locked_super(sb); |
2029 | return ret; | |
2030 | } | |
18e9e510 | 2031 | |
5accdf82 JK |
2032 | /* Now wait for internal filesystem counter */ |
2033 | sb->s_writers.frozen = SB_FREEZE_FS; | |
5accdf82 | 2034 | sb_wait_write(sb, SB_FREEZE_FS); |
18e9e510 | 2035 | |
18e9e510 JB |
2036 | if (sb->s_op->freeze_fs) { |
2037 | ret = sb->s_op->freeze_fs(sb); | |
2038 | if (ret) { | |
2039 | printk(KERN_ERR | |
2040 | "VFS:Filesystem freeze failed\n"); | |
5accdf82 | 2041 | sb->s_writers.frozen = SB_UNFROZEN; |
2719c716 | 2042 | sb_freeze_unlock(sb, SB_FREEZE_FS); |
59ba4fdd | 2043 | wake_up_var(&sb->s_writers.frozen); |
18e9e510 JB |
2044 | deactivate_locked_super(sb); |
2045 | return ret; | |
2046 | } | |
2047 | } | |
5accdf82 | 2048 | /* |
89f39af1 ON |
2049 | * For debugging purposes so that fs can warn if it sees write activity |
2050 | * when frozen is set to SB_FREEZE_COMPLETE, and for thaw_super(). | |
5accdf82 | 2051 | */ |
880b9577 | 2052 | sb->s_writers.freeze_holders |= who; |
5accdf82 | 2053 | sb->s_writers.frozen = SB_FREEZE_COMPLETE; |
59ba4fdd | 2054 | wake_up_var(&sb->s_writers.frozen); |
f1a96220 | 2055 | lockdep_sb_freeze_release(sb); |
0ed33598 | 2056 | super_unlock_excl(sb); |
18e9e510 JB |
2057 | return 0; |
2058 | } | |
2059 | EXPORT_SYMBOL(freeze_super); | |
2060 | ||
880b9577 DW |
2061 | /* |
2062 | * Undoes the effect of a freeze_super_locked call. If the filesystem is | |
2063 | * frozen both by userspace and the kernel, a thaw call from either source | |
2064 | * removes that state without releasing the other state or unlocking the | |
2065 | * filesystem. | |
2066 | */ | |
2067 | static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) | |
18e9e510 JB |
2068 | { |
2069 | int error; | |
2070 | ||
880b9577 DW |
2071 | if (sb->s_writers.frozen == SB_FREEZE_COMPLETE) { |
2072 | if (!(sb->s_writers.freeze_holders & who)) { | |
3fb5a656 | 2073 | super_unlock_excl(sb); |
880b9577 DW |
2074 | return -EINVAL; |
2075 | } | |
2076 | ||
2077 | /* | |
2078 | * Freeze is shared with someone else. Release our hold and | |
2079 | * drop the active ref that freeze_super assigned to the | |
2080 | * freezer. | |
2081 | */ | |
2082 | if (sb->s_writers.freeze_holders & ~who) { | |
2083 | sb->s_writers.freeze_holders &= ~who; | |
2084 | deactivate_locked_super(sb); | |
2085 | return 0; | |
2086 | } | |
2087 | } else { | |
0ed33598 | 2088 | super_unlock_excl(sb); |
18e9e510 JB |
2089 | return -EINVAL; |
2090 | } | |
2091 | ||
bc98a42c | 2092 | if (sb_rdonly(sb)) { |
880b9577 | 2093 | sb->s_writers.freeze_holders &= ~who; |
8129ed29 | 2094 | sb->s_writers.frozen = SB_UNFROZEN; |
59ba4fdd | 2095 | wake_up_var(&sb->s_writers.frozen); |
18e9e510 | 2096 | goto out; |
8129ed29 | 2097 | } |
18e9e510 | 2098 | |
f1a96220 ON |
2099 | lockdep_sb_freeze_acquire(sb); |
2100 | ||
18e9e510 JB |
2101 | if (sb->s_op->unfreeze_fs) { |
2102 | error = sb->s_op->unfreeze_fs(sb); | |
2103 | if (error) { | |
3fb5a656 | 2104 | printk(KERN_ERR "VFS:Filesystem thaw failed\n"); |
f1a96220 | 2105 | lockdep_sb_freeze_release(sb); |
0ed33598 | 2106 | super_unlock_excl(sb); |
18e9e510 JB |
2107 | return error; |
2108 | } | |
2109 | } | |
2110 | ||
880b9577 | 2111 | sb->s_writers.freeze_holders &= ~who; |
5accdf82 | 2112 | sb->s_writers.frozen = SB_UNFROZEN; |
59ba4fdd | 2113 | wake_up_var(&sb->s_writers.frozen); |
2719c716 | 2114 | sb_freeze_unlock(sb, SB_FREEZE_FS); |
8129ed29 | 2115 | out: |
18e9e510 | 2116 | deactivate_locked_super(sb); |
18e9e510 JB |
2117 | return 0; |
2118 | } | |
08fdc8a0 | 2119 | |
961f3c89 MCC |
2120 | /** |
2121 | * thaw_super -- unlock filesystem | |
2122 | * @sb: the super to thaw | |
880b9577 DW |
2123 | * @who: context that wants to freeze |
2124 | * | |
2125 | * Unlocks the filesystem and marks it writeable again after freeze_super() | |
2126 | * if there are no remaining freezes on the filesystem. | |
961f3c89 | 2127 | * |
880b9577 DW |
2128 | * @who should be: |
2129 | * * %FREEZE_HOLDER_USERSPACE if userspace wants to thaw the fs; | |
2130 | * * %FREEZE_HOLDER_KERNEL if the kernel wants to thaw the fs. | |
961f3c89 | 2131 | */ |
880b9577 | 2132 | int thaw_super(struct super_block *sb, enum freeze_holder who) |
08fdc8a0 | 2133 | { |
051178c3 CB |
2134 | if (!super_lock_excl(sb)) |
2135 | WARN(1, "Dying superblock while thawing!"); | |
880b9577 | 2136 | return thaw_super_locked(sb, who); |
08fdc8a0 | 2137 | } |
18e9e510 | 2138 | EXPORT_SYMBOL(thaw_super); |
439bc39b CH |
2139 | |
2140 | /* | |
2141 | * Create workqueue for deferred direct IO completions. We allocate the | |
2142 | * workqueue when it's first needed. This avoids creating workqueue for | |
2143 | * filesystems that don't need it and also allows us to create the workqueue | |
2144 | * late enough so the we can include s_id in the name of the workqueue. | |
2145 | */ | |
2146 | int sb_init_dio_done_wq(struct super_block *sb) | |
2147 | { | |
2148 | struct workqueue_struct *old; | |
2149 | struct workqueue_struct *wq = alloc_workqueue("dio/%s", | |
2150 | WQ_MEM_RECLAIM, 0, | |
2151 | sb->s_id); | |
2152 | if (!wq) | |
2153 | return -ENOMEM; | |
2154 | /* | |
2155 | * This has to be atomic as more DIOs can race to create the workqueue | |
2156 | */ | |
2157 | old = cmpxchg(&sb->s_dio_done_wq, NULL, wq); | |
2158 | /* Someone created workqueue before us? Free ours... */ | |
2159 | if (old) | |
2160 | destroy_workqueue(wq); | |
2161 | return 0; | |
2162 | } | |
389a4a4a | 2163 | EXPORT_SYMBOL_GPL(sb_init_dio_done_wq); |