Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/super.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * super.c contains code to handle: - mount structures | |
7 | * - super-block tables | |
8 | * - filesystem drivers list | |
9 | * - mount system call | |
10 | * - umount system call | |
11 | * - ustat system call | |
12 | * | |
13 | * GK 2/5/95 - Changed to support mounting the root fs via NFS | |
14 | * | |
15 | * Added kerneld support: Jacques Gelinas and Bjorn Ekwall | |
16 | * Added change_root: Werner Almesberger & Hans Lermen, Feb '96 | |
17 | * Added options to /proc/mounts: | |
96de0e25 | 18 | * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996. |
1da177e4 LT |
19 | * Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998 |
20 | * Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000 | |
21 | */ | |
22 | ||
1da177e4 LT |
23 | #include <linux/module.h> |
24 | #include <linux/slab.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/smp_lock.h> | |
27 | #include <linux/acct.h> | |
28 | #include <linux/blkdev.h> | |
29 | #include <linux/quotaops.h> | |
30 | #include <linux/namei.h> | |
31 | #include <linux/buffer_head.h> /* for fsync_super() */ | |
32 | #include <linux/mount.h> | |
33 | #include <linux/security.h> | |
34 | #include <linux/syscalls.h> | |
35 | #include <linux/vfs.h> | |
36 | #include <linux/writeback.h> /* for the emergency remount stuff */ | |
37 | #include <linux/idr.h> | |
38 | #include <linux/kobject.h> | |
353ab6e9 | 39 | #include <linux/mutex.h> |
49e0d02c | 40 | #include <linux/file.h> |
efaee192 | 41 | #include <linux/async.h> |
1da177e4 | 42 | #include <asm/uaccess.h> |
6d59e7f5 | 43 | #include "internal.h" |
1da177e4 LT |
44 | |
45 | ||
1da177e4 LT |
46 | LIST_HEAD(super_blocks); |
47 | DEFINE_SPINLOCK(sb_lock); | |
48 | ||
49 | /** | |
50 | * alloc_super - create new superblock | |
fe2bbc48 | 51 | * @type: filesystem type superblock should belong to |
1da177e4 LT |
52 | * |
53 | * Allocates and initializes a new &struct super_block. alloc_super() | |
54 | * returns a pointer new superblock or %NULL if allocation had failed. | |
55 | */ | |
cf516249 | 56 | static struct super_block *alloc_super(struct file_system_type *type) |
1da177e4 | 57 | { |
11b0b5ab | 58 | struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); |
1da177e4 LT |
59 | static struct super_operations default_op; |
60 | ||
61 | if (s) { | |
1da177e4 LT |
62 | if (security_sb_alloc(s)) { |
63 | kfree(s); | |
64 | s = NULL; | |
65 | goto out; | |
66 | } | |
67 | INIT_LIST_HEAD(&s->s_dirty); | |
68 | INIT_LIST_HEAD(&s->s_io); | |
0e0f4fc2 | 69 | INIT_LIST_HEAD(&s->s_more_io); |
1da177e4 LT |
70 | INIT_LIST_HEAD(&s->s_files); |
71 | INIT_LIST_HEAD(&s->s_instances); | |
72 | INIT_HLIST_HEAD(&s->s_anon); | |
73 | INIT_LIST_HEAD(&s->s_inodes); | |
da3bbdd4 | 74 | INIT_LIST_HEAD(&s->s_dentry_lru); |
efaee192 | 75 | INIT_LIST_HEAD(&s->s_async_list); |
1da177e4 | 76 | init_rwsem(&s->s_umount); |
7892f2f4 | 77 | mutex_init(&s->s_lock); |
897c6ff9 | 78 | lockdep_set_class(&s->s_umount, &type->s_umount_key); |
cf516249 IM |
79 | /* |
80 | * The locking rules for s_lock are up to the | |
81 | * filesystem. For example ext3fs has different | |
82 | * lock ordering than usbfs: | |
83 | */ | |
84 | lockdep_set_class(&s->s_lock, &type->s_lock_key); | |
1da177e4 LT |
85 | down_write(&s->s_umount); |
86 | s->s_count = S_BIAS; | |
87 | atomic_set(&s->s_active, 1); | |
a11f3a05 | 88 | mutex_init(&s->s_vfs_rename_mutex); |
d3be915f IM |
89 | mutex_init(&s->s_dquot.dqio_mutex); |
90 | mutex_init(&s->s_dquot.dqonoff_mutex); | |
1da177e4 LT |
91 | init_rwsem(&s->s_dquot.dqptr_sem); |
92 | init_waitqueue_head(&s->s_wait_unfrozen); | |
93 | s->s_maxbytes = MAX_NON_LFS; | |
94 | s->dq_op = sb_dquot_ops; | |
95 | s->s_qcop = sb_quotactl_ops; | |
96 | s->s_op = &default_op; | |
97 | s->s_time_gran = 1000000000; | |
98 | } | |
99 | out: | |
100 | return s; | |
101 | } | |
102 | ||
103 | /** | |
104 | * destroy_super - frees a superblock | |
105 | * @s: superblock to free | |
106 | * | |
107 | * Frees a superblock. | |
108 | */ | |
109 | static inline void destroy_super(struct super_block *s) | |
110 | { | |
111 | security_sb_free(s); | |
79c0b2df | 112 | kfree(s->s_subtype); |
b3b304a2 | 113 | kfree(s->s_options); |
1da177e4 LT |
114 | kfree(s); |
115 | } | |
116 | ||
117 | /* Superblock refcounting */ | |
118 | ||
119 | /* | |
120 | * Drop a superblock's refcount. Returns non-zero if the superblock was | |
121 | * destroyed. The caller must hold sb_lock. | |
122 | */ | |
6b09ae66 | 123 | static int __put_super(struct super_block *sb) |
1da177e4 LT |
124 | { |
125 | int ret = 0; | |
126 | ||
127 | if (!--sb->s_count) { | |
128 | destroy_super(sb); | |
129 | ret = 1; | |
130 | } | |
131 | return ret; | |
132 | } | |
133 | ||
134 | /* | |
135 | * Drop a superblock's refcount. | |
136 | * Returns non-zero if the superblock is about to be destroyed and | |
137 | * at least is already removed from super_blocks list, so if we are | |
138 | * making a loop through super blocks then we need to restart. | |
139 | * The caller must hold sb_lock. | |
140 | */ | |
141 | int __put_super_and_need_restart(struct super_block *sb) | |
142 | { | |
143 | /* check for race with generic_shutdown_super() */ | |
144 | if (list_empty(&sb->s_list)) { | |
145 | /* super block is removed, need to restart... */ | |
146 | __put_super(sb); | |
147 | return 1; | |
148 | } | |
149 | /* can't be the last, since s_list is still in use */ | |
150 | sb->s_count--; | |
151 | BUG_ON(sb->s_count == 0); | |
152 | return 0; | |
153 | } | |
154 | ||
155 | /** | |
156 | * put_super - drop a temporary reference to superblock | |
157 | * @sb: superblock in question | |
158 | * | |
159 | * Drops a temporary reference, frees superblock if there's no | |
160 | * references left. | |
161 | */ | |
162 | static void put_super(struct super_block *sb) | |
163 | { | |
164 | spin_lock(&sb_lock); | |
165 | __put_super(sb); | |
166 | spin_unlock(&sb_lock); | |
167 | } | |
168 | ||
169 | ||
170 | /** | |
171 | * deactivate_super - drop an active reference to superblock | |
172 | * @s: superblock to deactivate | |
173 | * | |
174 | * Drops an active reference to superblock, acquiring a temprory one if | |
175 | * there is no active references left. In that case we lock superblock, | |
176 | * tell fs driver to shut it down and drop the temporary reference we | |
177 | * had just acquired. | |
178 | */ | |
179 | void deactivate_super(struct super_block *s) | |
180 | { | |
181 | struct file_system_type *fs = s->s_type; | |
182 | if (atomic_dec_and_lock(&s->s_active, &sb_lock)) { | |
183 | s->s_count -= S_BIAS-1; | |
184 | spin_unlock(&sb_lock); | |
0ff5af83 | 185 | DQUOT_OFF(s, 0); |
1da177e4 LT |
186 | down_write(&s->s_umount); |
187 | fs->kill_sb(s); | |
188 | put_filesystem(fs); | |
189 | put_super(s); | |
190 | } | |
191 | } | |
192 | ||
193 | EXPORT_SYMBOL(deactivate_super); | |
194 | ||
195 | /** | |
196 | * grab_super - acquire an active reference | |
197 | * @s: reference we are trying to make active | |
198 | * | |
199 | * Tries to acquire an active reference. grab_super() is used when we | |
200 | * had just found a superblock in super_blocks or fs_type->fs_supers | |
201 | * and want to turn it into a full-blown active reference. grab_super() | |
202 | * is called with sb_lock held and drops it. Returns 1 in case of | |
203 | * success, 0 if we had failed (superblock contents was already dead or | |
204 | * dying when grab_super() had been called). | |
205 | */ | |
9c4dbee7 | 206 | static int grab_super(struct super_block *s) __releases(sb_lock) |
1da177e4 LT |
207 | { |
208 | s->s_count++; | |
209 | spin_unlock(&sb_lock); | |
210 | down_write(&s->s_umount); | |
211 | if (s->s_root) { | |
212 | spin_lock(&sb_lock); | |
213 | if (s->s_count > S_BIAS) { | |
214 | atomic_inc(&s->s_active); | |
215 | s->s_count--; | |
216 | spin_unlock(&sb_lock); | |
217 | return 1; | |
218 | } | |
219 | spin_unlock(&sb_lock); | |
220 | } | |
221 | up_write(&s->s_umount); | |
222 | put_super(s); | |
223 | yield(); | |
224 | return 0; | |
225 | } | |
226 | ||
914e2637 AV |
227 | /* |
228 | * Superblock locking. We really ought to get rid of these two. | |
229 | */ | |
230 | void lock_super(struct super_block * sb) | |
231 | { | |
232 | get_fs_excl(); | |
233 | mutex_lock(&sb->s_lock); | |
234 | } | |
235 | ||
236 | void unlock_super(struct super_block * sb) | |
237 | { | |
238 | put_fs_excl(); | |
239 | mutex_unlock(&sb->s_lock); | |
240 | } | |
241 | ||
242 | EXPORT_SYMBOL(lock_super); | |
243 | EXPORT_SYMBOL(unlock_super); | |
244 | ||
cf9a2ae8 DH |
245 | /* |
246 | * Write out and wait upon all dirty data associated with this | |
247 | * superblock. Filesystem data as well as the underlying block | |
248 | * device. Takes the superblock lock. Requires a second blkdev | |
249 | * flush by the caller to complete the operation. | |
250 | */ | |
251 | void __fsync_super(struct super_block *sb) | |
252 | { | |
253 | sync_inodes_sb(sb, 0); | |
254 | DQUOT_SYNC(sb); | |
255 | lock_super(sb); | |
256 | if (sb->s_dirt && sb->s_op->write_super) | |
257 | sb->s_op->write_super(sb); | |
258 | unlock_super(sb); | |
259 | if (sb->s_op->sync_fs) | |
260 | sb->s_op->sync_fs(sb, 1); | |
261 | sync_blockdev(sb->s_bdev); | |
262 | sync_inodes_sb(sb, 1); | |
263 | } | |
264 | ||
265 | /* | |
266 | * Write out and wait upon all dirty data associated with this | |
267 | * superblock. Filesystem data as well as the underlying block | |
268 | * device. Takes the superblock lock. | |
269 | */ | |
270 | int fsync_super(struct super_block *sb) | |
271 | { | |
272 | __fsync_super(sb); | |
273 | return sync_blockdev(sb->s_bdev); | |
274 | } | |
275 | ||
1da177e4 LT |
276 | /** |
277 | * generic_shutdown_super - common helper for ->kill_sb() | |
278 | * @sb: superblock to kill | |
279 | * | |
280 | * generic_shutdown_super() does all fs-independent work on superblock | |
281 | * shutdown. Typical ->kill_sb() should pick all fs-specific objects | |
282 | * that need destruction out of superblock, call generic_shutdown_super() | |
283 | * and release aforementioned objects. Note: dentries and inodes _are_ | |
284 | * taken care of and do not need specific handling. | |
c636ebdb DH |
285 | * |
286 | * Upon calling this function, the filesystem may no longer alter or | |
287 | * rearrange the set of dentries belonging to this super_block, nor may it | |
288 | * change the attachments of dentries to inodes. | |
1da177e4 LT |
289 | */ |
290 | void generic_shutdown_super(struct super_block *sb) | |
291 | { | |
ee9b6d61 | 292 | const struct super_operations *sop = sb->s_op; |
1da177e4 | 293 | |
efaee192 | 294 | |
c636ebdb DH |
295 | if (sb->s_root) { |
296 | shrink_dcache_for_umount(sb); | |
1da177e4 LT |
297 | fsync_super(sb); |
298 | lock_super(sb); | |
299 | sb->s_flags &= ~MS_ACTIVE; | |
efaee192 AV |
300 | |
301 | /* | |
302 | * wait for asynchronous fs operations to finish before going further | |
303 | */ | |
304 | async_synchronize_full_special(&sb->s_async_list); | |
305 | ||
1da177e4 LT |
306 | /* bad name - it should be evict_inodes() */ |
307 | invalidate_inodes(sb); | |
308 | lock_kernel(); | |
309 | ||
310 | if (sop->write_super && sb->s_dirt) | |
311 | sop->write_super(sb); | |
312 | if (sop->put_super) | |
313 | sop->put_super(sb); | |
314 | ||
315 | /* Forget any remaining inodes */ | |
316 | if (invalidate_inodes(sb)) { | |
7b4fe29e DJ |
317 | printk("VFS: Busy inodes after unmount of %s. " |
318 | "Self-destruct in 5 seconds. Have a nice day...\n", | |
319 | sb->s_id); | |
1da177e4 LT |
320 | } |
321 | ||
322 | unlock_kernel(); | |
323 | unlock_super(sb); | |
324 | } | |
325 | spin_lock(&sb_lock); | |
326 | /* should be initialized for __put_super_and_need_restart() */ | |
327 | list_del_init(&sb->s_list); | |
328 | list_del(&sb->s_instances); | |
329 | spin_unlock(&sb_lock); | |
330 | up_write(&sb->s_umount); | |
331 | } | |
332 | ||
333 | EXPORT_SYMBOL(generic_shutdown_super); | |
334 | ||
335 | /** | |
336 | * sget - find or create a superblock | |
337 | * @type: filesystem type superblock should belong to | |
338 | * @test: comparison callback | |
339 | * @set: setup callback | |
340 | * @data: argument to each of them | |
341 | */ | |
342 | struct super_block *sget(struct file_system_type *type, | |
343 | int (*test)(struct super_block *,void *), | |
344 | int (*set)(struct super_block *,void *), | |
345 | void *data) | |
346 | { | |
347 | struct super_block *s = NULL; | |
d4730127 | 348 | struct super_block *old; |
1da177e4 LT |
349 | int err; |
350 | ||
351 | retry: | |
352 | spin_lock(&sb_lock); | |
d4730127 MK |
353 | if (test) { |
354 | list_for_each_entry(old, &type->fs_supers, s_instances) { | |
355 | if (!test(old, data)) | |
356 | continue; | |
357 | if (!grab_super(old)) | |
358 | goto retry; | |
359 | if (s) | |
360 | destroy_super(s); | |
361 | return old; | |
362 | } | |
1da177e4 LT |
363 | } |
364 | if (!s) { | |
365 | spin_unlock(&sb_lock); | |
cf516249 | 366 | s = alloc_super(type); |
1da177e4 LT |
367 | if (!s) |
368 | return ERR_PTR(-ENOMEM); | |
369 | goto retry; | |
370 | } | |
371 | ||
372 | err = set(s, data); | |
373 | if (err) { | |
374 | spin_unlock(&sb_lock); | |
375 | destroy_super(s); | |
376 | return ERR_PTR(err); | |
377 | } | |
378 | s->s_type = type; | |
379 | strlcpy(s->s_id, type->name, sizeof(s->s_id)); | |
380 | list_add_tail(&s->s_list, &super_blocks); | |
381 | list_add(&s->s_instances, &type->fs_supers); | |
382 | spin_unlock(&sb_lock); | |
383 | get_filesystem(type); | |
384 | return s; | |
385 | } | |
386 | ||
387 | EXPORT_SYMBOL(sget); | |
388 | ||
389 | void drop_super(struct super_block *sb) | |
390 | { | |
391 | up_read(&sb->s_umount); | |
392 | put_super(sb); | |
393 | } | |
394 | ||
395 | EXPORT_SYMBOL(drop_super); | |
396 | ||
397 | static inline void write_super(struct super_block *sb) | |
398 | { | |
399 | lock_super(sb); | |
400 | if (sb->s_root && sb->s_dirt) | |
401 | if (sb->s_op->write_super) | |
402 | sb->s_op->write_super(sb); | |
403 | unlock_super(sb); | |
404 | } | |
405 | ||
406 | /* | |
407 | * Note: check the dirty flag before waiting, so we don't | |
408 | * hold up the sync while mounting a device. (The newly | |
409 | * mounted device won't need syncing.) | |
410 | */ | |
411 | void sync_supers(void) | |
412 | { | |
618f0636 KK |
413 | struct super_block *sb; |
414 | ||
1da177e4 | 415 | spin_lock(&sb_lock); |
618f0636 KK |
416 | restart: |
417 | list_for_each_entry(sb, &super_blocks, s_list) { | |
1da177e4 LT |
418 | if (sb->s_dirt) { |
419 | sb->s_count++; | |
420 | spin_unlock(&sb_lock); | |
421 | down_read(&sb->s_umount); | |
422 | write_super(sb); | |
618f0636 KK |
423 | up_read(&sb->s_umount); |
424 | spin_lock(&sb_lock); | |
425 | if (__put_super_and_need_restart(sb)) | |
426 | goto restart; | |
427 | } | |
428 | } | |
1da177e4 LT |
429 | spin_unlock(&sb_lock); |
430 | } | |
431 | ||
432 | /* | |
3a4fa0a2 | 433 | * Call the ->sync_fs super_op against all filesystems which are r/w and |
1da177e4 LT |
434 | * which implement it. |
435 | * | |
436 | * This operation is careful to avoid the livelock which could easily happen | |
437 | * if two or more filesystems are being continuously dirtied. s_need_sync_fs | |
438 | * is used only here. We set it against all filesystems and then clear it as | |
439 | * we sync them. So redirtied filesystems are skipped. | |
440 | * | |
3a4fa0a2 | 441 | * But if process A is currently running sync_filesystems and then process B |
1da177e4 LT |
442 | * calls sync_filesystems as well, process B will set all the s_need_sync_fs |
443 | * flags again, which will cause process A to resync everything. Fix that with | |
444 | * a local mutex. | |
445 | * | |
446 | * (Fabian) Avoid sync_fs with clean fs & wait mode 0 | |
447 | */ | |
448 | void sync_filesystems(int wait) | |
449 | { | |
450 | struct super_block *sb; | |
353ab6e9 | 451 | static DEFINE_MUTEX(mutex); |
1da177e4 | 452 | |
353ab6e9 | 453 | mutex_lock(&mutex); /* Could be down_interruptible */ |
1da177e4 | 454 | spin_lock(&sb_lock); |
618f0636 | 455 | list_for_each_entry(sb, &super_blocks, s_list) { |
1da177e4 LT |
456 | if (!sb->s_op->sync_fs) |
457 | continue; | |
458 | if (sb->s_flags & MS_RDONLY) | |
459 | continue; | |
460 | sb->s_need_sync_fs = 1; | |
461 | } | |
1da177e4 LT |
462 | |
463 | restart: | |
618f0636 | 464 | list_for_each_entry(sb, &super_blocks, s_list) { |
1da177e4 LT |
465 | if (!sb->s_need_sync_fs) |
466 | continue; | |
467 | sb->s_need_sync_fs = 0; | |
468 | if (sb->s_flags & MS_RDONLY) | |
469 | continue; /* hm. Was remounted r/o meanwhile */ | |
470 | sb->s_count++; | |
471 | spin_unlock(&sb_lock); | |
472 | down_read(&sb->s_umount); | |
96777fe7 | 473 | async_synchronize_full_special(&sb->s_async_list); |
1da177e4 LT |
474 | if (sb->s_root && (wait || sb->s_dirt)) |
475 | sb->s_op->sync_fs(sb, wait); | |
618f0636 KK |
476 | up_read(&sb->s_umount); |
477 | /* restart only when sb is no longer on the list */ | |
478 | spin_lock(&sb_lock); | |
479 | if (__put_super_and_need_restart(sb)) | |
480 | goto restart; | |
1da177e4 LT |
481 | } |
482 | spin_unlock(&sb_lock); | |
353ab6e9 | 483 | mutex_unlock(&mutex); |
1da177e4 LT |
484 | } |
485 | ||
486 | /** | |
487 | * get_super - get the superblock of a device | |
488 | * @bdev: device to get the superblock for | |
489 | * | |
490 | * Scans the superblock list and finds the superblock of the file system | |
491 | * mounted on the device given. %NULL is returned if no match is found. | |
492 | */ | |
493 | ||
494 | struct super_block * get_super(struct block_device *bdev) | |
495 | { | |
618f0636 KK |
496 | struct super_block *sb; |
497 | ||
1da177e4 LT |
498 | if (!bdev) |
499 | return NULL; | |
618f0636 | 500 | |
1da177e4 | 501 | spin_lock(&sb_lock); |
618f0636 KK |
502 | rescan: |
503 | list_for_each_entry(sb, &super_blocks, s_list) { | |
504 | if (sb->s_bdev == bdev) { | |
505 | sb->s_count++; | |
1da177e4 | 506 | spin_unlock(&sb_lock); |
618f0636 KK |
507 | down_read(&sb->s_umount); |
508 | if (sb->s_root) | |
509 | return sb; | |
510 | up_read(&sb->s_umount); | |
511 | /* restart only when sb is no longer on the list */ | |
512 | spin_lock(&sb_lock); | |
513 | if (__put_super_and_need_restart(sb)) | |
514 | goto rescan; | |
1da177e4 LT |
515 | } |
516 | } | |
517 | spin_unlock(&sb_lock); | |
518 | return NULL; | |
519 | } | |
520 | ||
521 | EXPORT_SYMBOL(get_super); | |
522 | ||
523 | struct super_block * user_get_super(dev_t dev) | |
524 | { | |
618f0636 | 525 | struct super_block *sb; |
1da177e4 | 526 | |
1da177e4 | 527 | spin_lock(&sb_lock); |
618f0636 KK |
528 | rescan: |
529 | list_for_each_entry(sb, &super_blocks, s_list) { | |
530 | if (sb->s_dev == dev) { | |
531 | sb->s_count++; | |
1da177e4 | 532 | spin_unlock(&sb_lock); |
618f0636 KK |
533 | down_read(&sb->s_umount); |
534 | if (sb->s_root) | |
535 | return sb; | |
536 | up_read(&sb->s_umount); | |
537 | /* restart only when sb is no longer on the list */ | |
538 | spin_lock(&sb_lock); | |
539 | if (__put_super_and_need_restart(sb)) | |
540 | goto rescan; | |
1da177e4 LT |
541 | } |
542 | } | |
543 | spin_unlock(&sb_lock); | |
544 | return NULL; | |
545 | } | |
546 | ||
1da177e4 LT |
547 | asmlinkage long sys_ustat(unsigned dev, struct ustat __user * ubuf) |
548 | { | |
549 | struct super_block *s; | |
550 | struct ustat tmp; | |
551 | struct kstatfs sbuf; | |
552 | int err = -EINVAL; | |
553 | ||
554 | s = user_get_super(new_decode_dev(dev)); | |
555 | if (s == NULL) | |
556 | goto out; | |
726c3342 | 557 | err = vfs_statfs(s->s_root, &sbuf); |
1da177e4 LT |
558 | drop_super(s); |
559 | if (err) | |
560 | goto out; | |
561 | ||
562 | memset(&tmp,0,sizeof(struct ustat)); | |
563 | tmp.f_tfree = sbuf.f_bfree; | |
564 | tmp.f_tinode = sbuf.f_ffree; | |
565 | ||
566 | err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0; | |
567 | out: | |
568 | return err; | |
569 | } | |
570 | ||
571 | /** | |
a6b91919 | 572 | * mark_files_ro - mark all files read-only |
1da177e4 LT |
573 | * @sb: superblock in question |
574 | * | |
a6b91919 RD |
575 | * All files are marked read-only. We don't care about pending |
576 | * delete files so this should be used in 'force' mode only. | |
1da177e4 LT |
577 | */ |
578 | ||
579 | static void mark_files_ro(struct super_block *sb) | |
580 | { | |
581 | struct file *f; | |
582 | ||
49e0d02c | 583 | retry: |
1da177e4 | 584 | file_list_lock(); |
2f512016 | 585 | list_for_each_entry(f, &sb->s_files, f_u.fu_list) { |
49e0d02c DH |
586 | struct vfsmount *mnt; |
587 | if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) | |
588 | continue; | |
589 | if (!file_count(f)) | |
590 | continue; | |
591 | if (!(f->f_mode & FMODE_WRITE)) | |
592 | continue; | |
593 | f->f_mode &= ~FMODE_WRITE; | |
ad775f5a DH |
594 | if (file_check_writeable(f) != 0) |
595 | continue; | |
596 | file_release_write(f); | |
49e0d02c DH |
597 | mnt = mntget(f->f_path.mnt); |
598 | file_list_unlock(); | |
599 | /* | |
600 | * This can sleep, so we can't hold | |
601 | * the file_list_lock() spinlock. | |
602 | */ | |
603 | mnt_drop_write(mnt); | |
604 | mntput(mnt); | |
605 | goto retry; | |
1da177e4 LT |
606 | } |
607 | file_list_unlock(); | |
608 | } | |
609 | ||
610 | /** | |
611 | * do_remount_sb - asks filesystem to change mount options. | |
612 | * @sb: superblock in question | |
613 | * @flags: numeric part of options | |
614 | * @data: the rest of options | |
615 | * @force: whether or not to force the change | |
616 | * | |
617 | * Alters the mount options of a mounted file system. | |
618 | */ | |
619 | int do_remount_sb(struct super_block *sb, int flags, void *data, int force) | |
620 | { | |
621 | int retval; | |
0ff5af83 | 622 | int remount_rw; |
1da177e4 | 623 | |
9361401e | 624 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
625 | if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) |
626 | return -EACCES; | |
9361401e | 627 | #endif |
1da177e4 LT |
628 | if (flags & MS_RDONLY) |
629 | acct_auto_close(sb); | |
630 | shrink_dcache_sb(sb); | |
631 | fsync_super(sb); | |
632 | ||
633 | /* If we are remounting RDONLY and current sb is read/write, | |
634 | make sure there are no rw files opened */ | |
635 | if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) { | |
636 | if (force) | |
637 | mark_files_ro(sb); | |
638 | else if (!fs_may_remount_ro(sb)) | |
639 | return -EBUSY; | |
0ff5af83 JK |
640 | retval = DQUOT_OFF(sb, 1); |
641 | if (retval < 0 && retval != -ENOSYS) | |
642 | return -EBUSY; | |
1da177e4 | 643 | } |
0ff5af83 | 644 | remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY); |
1da177e4 LT |
645 | |
646 | if (sb->s_op->remount_fs) { | |
647 | lock_super(sb); | |
648 | retval = sb->s_op->remount_fs(sb, &flags, data); | |
649 | unlock_super(sb); | |
650 | if (retval) | |
651 | return retval; | |
652 | } | |
653 | sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); | |
0ff5af83 JK |
654 | if (remount_rw) |
655 | DQUOT_ON_REMOUNT(sb); | |
1da177e4 LT |
656 | return 0; |
657 | } | |
658 | ||
659 | static void do_emergency_remount(unsigned long foo) | |
660 | { | |
661 | struct super_block *sb; | |
662 | ||
663 | spin_lock(&sb_lock); | |
664 | list_for_each_entry(sb, &super_blocks, s_list) { | |
665 | sb->s_count++; | |
666 | spin_unlock(&sb_lock); | |
667 | down_read(&sb->s_umount); | |
668 | if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) { | |
669 | /* | |
670 | * ->remount_fs needs lock_kernel(). | |
671 | * | |
672 | * What lock protects sb->s_flags?? | |
673 | */ | |
674 | lock_kernel(); | |
675 | do_remount_sb(sb, MS_RDONLY, NULL, 1); | |
676 | unlock_kernel(); | |
677 | } | |
678 | drop_super(sb); | |
679 | spin_lock(&sb_lock); | |
680 | } | |
681 | spin_unlock(&sb_lock); | |
682 | printk("Emergency Remount complete\n"); | |
683 | } | |
684 | ||
685 | void emergency_remount(void) | |
686 | { | |
687 | pdflush_operation(do_emergency_remount, 0); | |
688 | } | |
689 | ||
690 | /* | |
691 | * Unnamed block devices are dummy devices used by virtual | |
692 | * filesystems which don't use real block-devices. -- jrs | |
693 | */ | |
694 | ||
ad76cbc6 | 695 | static DEFINE_IDA(unnamed_dev_ida); |
1da177e4 LT |
696 | static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ |
697 | ||
698 | int set_anon_super(struct super_block *s, void *data) | |
699 | { | |
700 | int dev; | |
701 | int error; | |
702 | ||
703 | retry: | |
ad76cbc6 | 704 | if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) |
1da177e4 LT |
705 | return -ENOMEM; |
706 | spin_lock(&unnamed_dev_lock); | |
ad76cbc6 | 707 | error = ida_get_new(&unnamed_dev_ida, &dev); |
1da177e4 LT |
708 | spin_unlock(&unnamed_dev_lock); |
709 | if (error == -EAGAIN) | |
710 | /* We raced and lost with another CPU. */ | |
711 | goto retry; | |
712 | else if (error) | |
713 | return -EAGAIN; | |
714 | ||
715 | if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { | |
716 | spin_lock(&unnamed_dev_lock); | |
ad76cbc6 | 717 | ida_remove(&unnamed_dev_ida, dev); |
1da177e4 LT |
718 | spin_unlock(&unnamed_dev_lock); |
719 | return -EMFILE; | |
720 | } | |
721 | s->s_dev = MKDEV(0, dev & MINORMASK); | |
722 | return 0; | |
723 | } | |
724 | ||
725 | EXPORT_SYMBOL(set_anon_super); | |
726 | ||
727 | void kill_anon_super(struct super_block *sb) | |
728 | { | |
729 | int slot = MINOR(sb->s_dev); | |
730 | ||
731 | generic_shutdown_super(sb); | |
732 | spin_lock(&unnamed_dev_lock); | |
ad76cbc6 | 733 | ida_remove(&unnamed_dev_ida, slot); |
1da177e4 LT |
734 | spin_unlock(&unnamed_dev_lock); |
735 | } | |
736 | ||
737 | EXPORT_SYMBOL(kill_anon_super); | |
738 | ||
1da177e4 LT |
739 | void kill_litter_super(struct super_block *sb) |
740 | { | |
741 | if (sb->s_root) | |
742 | d_genocide(sb->s_root); | |
743 | kill_anon_super(sb); | |
744 | } | |
745 | ||
746 | EXPORT_SYMBOL(kill_litter_super); | |
747 | ||
9361401e | 748 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
749 | static int set_bdev_super(struct super_block *s, void *data) |
750 | { | |
751 | s->s_bdev = data; | |
752 | s->s_dev = s->s_bdev->bd_dev; | |
753 | return 0; | |
754 | } | |
755 | ||
756 | static int test_bdev_super(struct super_block *s, void *data) | |
757 | { | |
758 | return (void *)s->s_bdev == data; | |
759 | } | |
760 | ||
454e2398 | 761 | int get_sb_bdev(struct file_system_type *fs_type, |
1da177e4 | 762 | int flags, const char *dev_name, void *data, |
454e2398 DH |
763 | int (*fill_super)(struct super_block *, void *, int), |
764 | struct vfsmount *mnt) | |
1da177e4 LT |
765 | { |
766 | struct block_device *bdev; | |
767 | struct super_block *s; | |
30c40d2c | 768 | fmode_t mode = FMODE_READ; |
1da177e4 LT |
769 | int error = 0; |
770 | ||
30c40d2c AV |
771 | if (!(flags & MS_RDONLY)) |
772 | mode |= FMODE_WRITE; | |
773 | ||
774 | bdev = open_bdev_exclusive(dev_name, mode, fs_type); | |
1da177e4 | 775 | if (IS_ERR(bdev)) |
454e2398 | 776 | return PTR_ERR(bdev); |
1da177e4 LT |
777 | |
778 | /* | |
779 | * once the super is inserted into the list by sget, s_umount | |
780 | * will protect the lockfs code from trying to start a snapshot | |
781 | * while we are mounting | |
782 | */ | |
f73ca1b7 | 783 | down(&bdev->bd_mount_sem); |
1da177e4 | 784 | s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); |
f73ca1b7 | 785 | up(&bdev->bd_mount_sem); |
1da177e4 | 786 | if (IS_ERR(s)) |
454e2398 | 787 | goto error_s; |
1da177e4 LT |
788 | |
789 | if (s->s_root) { | |
790 | if ((flags ^ s->s_flags) & MS_RDONLY) { | |
791 | up_write(&s->s_umount); | |
792 | deactivate_super(s); | |
454e2398 DH |
793 | error = -EBUSY; |
794 | goto error_bdev; | |
1da177e4 | 795 | } |
454e2398 | 796 | |
30c40d2c | 797 | close_bdev_exclusive(bdev, mode); |
1da177e4 LT |
798 | } else { |
799 | char b[BDEVNAME_SIZE]; | |
800 | ||
801 | s->s_flags = flags; | |
30c40d2c | 802 | s->s_mode = mode; |
1da177e4 | 803 | strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); |
e78c9a00 | 804 | sb_set_blocksize(s, block_size(bdev)); |
9b04c997 | 805 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 LT |
806 | if (error) { |
807 | up_write(&s->s_umount); | |
808 | deactivate_super(s); | |
454e2398 | 809 | goto error; |
fa675765 | 810 | } |
454e2398 DH |
811 | |
812 | s->s_flags |= MS_ACTIVE; | |
87d8fe1e | 813 | bdev->bd_super = s; |
1da177e4 LT |
814 | } |
815 | ||
454e2398 | 816 | return simple_set_mnt(mnt, s); |
1da177e4 | 817 | |
454e2398 DH |
818 | error_s: |
819 | error = PTR_ERR(s); | |
820 | error_bdev: | |
30c40d2c | 821 | close_bdev_exclusive(bdev, mode); |
454e2398 DH |
822 | error: |
823 | return error; | |
1da177e4 LT |
824 | } |
825 | ||
826 | EXPORT_SYMBOL(get_sb_bdev); | |
827 | ||
828 | void kill_block_super(struct super_block *sb) | |
829 | { | |
830 | struct block_device *bdev = sb->s_bdev; | |
30c40d2c | 831 | fmode_t mode = sb->s_mode; |
1da177e4 | 832 | |
87d8fe1e | 833 | bdev->bd_super = 0; |
1da177e4 LT |
834 | generic_shutdown_super(sb); |
835 | sync_blockdev(bdev); | |
30c40d2c | 836 | close_bdev_exclusive(bdev, mode); |
1da177e4 LT |
837 | } |
838 | ||
839 | EXPORT_SYMBOL(kill_block_super); | |
9361401e | 840 | #endif |
1da177e4 | 841 | |
454e2398 | 842 | int get_sb_nodev(struct file_system_type *fs_type, |
1da177e4 | 843 | int flags, void *data, |
454e2398 DH |
844 | int (*fill_super)(struct super_block *, void *, int), |
845 | struct vfsmount *mnt) | |
1da177e4 LT |
846 | { |
847 | int error; | |
848 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
849 | ||
850 | if (IS_ERR(s)) | |
454e2398 | 851 | return PTR_ERR(s); |
1da177e4 LT |
852 | |
853 | s->s_flags = flags; | |
854 | ||
9b04c997 | 855 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 LT |
856 | if (error) { |
857 | up_write(&s->s_umount); | |
858 | deactivate_super(s); | |
454e2398 | 859 | return error; |
1da177e4 LT |
860 | } |
861 | s->s_flags |= MS_ACTIVE; | |
454e2398 | 862 | return simple_set_mnt(mnt, s); |
1da177e4 LT |
863 | } |
864 | ||
865 | EXPORT_SYMBOL(get_sb_nodev); | |
866 | ||
867 | static int compare_single(struct super_block *s, void *p) | |
868 | { | |
869 | return 1; | |
870 | } | |
871 | ||
454e2398 | 872 | int get_sb_single(struct file_system_type *fs_type, |
1da177e4 | 873 | int flags, void *data, |
454e2398 DH |
874 | int (*fill_super)(struct super_block *, void *, int), |
875 | struct vfsmount *mnt) | |
1da177e4 LT |
876 | { |
877 | struct super_block *s; | |
878 | int error; | |
879 | ||
880 | s = sget(fs_type, compare_single, set_anon_super, NULL); | |
881 | if (IS_ERR(s)) | |
454e2398 | 882 | return PTR_ERR(s); |
1da177e4 LT |
883 | if (!s->s_root) { |
884 | s->s_flags = flags; | |
9b04c997 | 885 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 LT |
886 | if (error) { |
887 | up_write(&s->s_umount); | |
888 | deactivate_super(s); | |
454e2398 | 889 | return error; |
1da177e4 LT |
890 | } |
891 | s->s_flags |= MS_ACTIVE; | |
892 | } | |
893 | do_remount_sb(s, flags, data, 0); | |
454e2398 | 894 | return simple_set_mnt(mnt, s); |
1da177e4 LT |
895 | } |
896 | ||
897 | EXPORT_SYMBOL(get_sb_single); | |
898 | ||
899 | struct vfsmount * | |
bb4a58bf | 900 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) |
1da177e4 | 901 | { |
1da177e4 | 902 | struct vfsmount *mnt; |
1da177e4 | 903 | char *secdata = NULL; |
454e2398 | 904 | int error; |
1da177e4 LT |
905 | |
906 | if (!type) | |
907 | return ERR_PTR(-ENODEV); | |
1da177e4 | 908 | |
454e2398 | 909 | error = -ENOMEM; |
1da177e4 LT |
910 | mnt = alloc_vfsmnt(name); |
911 | if (!mnt) | |
912 | goto out; | |
913 | ||
e0007529 | 914 | if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { |
1da177e4 | 915 | secdata = alloc_secdata(); |
454e2398 | 916 | if (!secdata) |
1da177e4 | 917 | goto out_mnt; |
1da177e4 | 918 | |
e0007529 | 919 | error = security_sb_copy_data(data, secdata); |
454e2398 | 920 | if (error) |
1da177e4 | 921 | goto out_free_secdata; |
1da177e4 LT |
922 | } |
923 | ||
454e2398 DH |
924 | error = type->get_sb(type, flags, name, data, mnt); |
925 | if (error < 0) | |
1da177e4 | 926 | goto out_free_secdata; |
b4c07bce | 927 | BUG_ON(!mnt->mnt_sb); |
454e2398 | 928 | |
12204e24 | 929 | error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata); |
1da177e4 LT |
930 | if (error) |
931 | goto out_sb; | |
454e2398 DH |
932 | |
933 | mnt->mnt_mountpoint = mnt->mnt_root; | |
1da177e4 | 934 | mnt->mnt_parent = mnt; |
454e2398 | 935 | up_write(&mnt->mnt_sb->s_umount); |
8680e22f | 936 | free_secdata(secdata); |
1da177e4 LT |
937 | return mnt; |
938 | out_sb: | |
454e2398 DH |
939 | dput(mnt->mnt_root); |
940 | up_write(&mnt->mnt_sb->s_umount); | |
941 | deactivate_super(mnt->mnt_sb); | |
1da177e4 LT |
942 | out_free_secdata: |
943 | free_secdata(secdata); | |
944 | out_mnt: | |
945 | free_vfsmnt(mnt); | |
946 | out: | |
454e2398 | 947 | return ERR_PTR(error); |
1da177e4 LT |
948 | } |
949 | ||
bb4a58bf TM |
950 | EXPORT_SYMBOL_GPL(vfs_kern_mount); |
951 | ||
79c0b2df MS |
952 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
953 | { | |
954 | int err; | |
955 | const char *subtype = strchr(fstype, '.'); | |
956 | if (subtype) { | |
957 | subtype++; | |
958 | err = -EINVAL; | |
959 | if (!subtype[0]) | |
960 | goto err; | |
961 | } else | |
962 | subtype = ""; | |
963 | ||
964 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); | |
965 | err = -ENOMEM; | |
966 | if (!mnt->mnt_sb->s_subtype) | |
967 | goto err; | |
968 | return mnt; | |
969 | ||
970 | err: | |
971 | mntput(mnt); | |
972 | return ERR_PTR(err); | |
973 | } | |
974 | ||
bb4a58bf TM |
975 | struct vfsmount * |
976 | do_kern_mount(const char *fstype, int flags, const char *name, void *data) | |
977 | { | |
978 | struct file_system_type *type = get_fs_type(fstype); | |
979 | struct vfsmount *mnt; | |
980 | if (!type) | |
981 | return ERR_PTR(-ENODEV); | |
982 | mnt = vfs_kern_mount(type, flags, name, data); | |
79c0b2df MS |
983 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && |
984 | !mnt->mnt_sb->s_subtype) | |
985 | mnt = fs_set_subtype(mnt, fstype); | |
bb4a58bf TM |
986 | put_filesystem(type); |
987 | return mnt; | |
988 | } | |
8a4e98d9 | 989 | EXPORT_SYMBOL_GPL(do_kern_mount); |
bb4a58bf | 990 | |
8bf9725c | 991 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) |
1da177e4 | 992 | { |
8bf9725c | 993 | return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); |
1da177e4 LT |
994 | } |
995 | ||
8bf9725c | 996 | EXPORT_SYMBOL_GPL(kern_mount_data); |