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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/super.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * super.c contains code to handle: - mount structures | |
7 | * - super-block tables | |
8 | * - filesystem drivers list | |
9 | * - mount system call | |
10 | * - umount system call | |
11 | * - ustat system call | |
12 | * | |
13 | * GK 2/5/95 - Changed to support mounting the root fs via NFS | |
14 | * | |
15 | * Added kerneld support: Jacques Gelinas and Bjorn Ekwall | |
16 | * Added change_root: Werner Almesberger & Hans Lermen, Feb '96 | |
17 | * Added options to /proc/mounts: | |
96de0e25 | 18 | * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996. |
1da177e4 LT |
19 | * Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998 |
20 | * Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000 | |
21 | */ | |
22 | ||
1da177e4 LT |
23 | #include <linux/module.h> |
24 | #include <linux/slab.h> | |
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> | |
1da177e4 LT |
31 | #include <linux/mount.h> |
32 | #include <linux/security.h> | |
33 | #include <linux/syscalls.h> | |
34 | #include <linux/vfs.h> | |
35 | #include <linux/writeback.h> /* for the emergency remount stuff */ | |
36 | #include <linux/idr.h> | |
37 | #include <linux/kobject.h> | |
353ab6e9 | 38 | #include <linux/mutex.h> |
49e0d02c | 39 | #include <linux/file.h> |
1da177e4 | 40 | #include <asm/uaccess.h> |
6d59e7f5 | 41 | #include "internal.h" |
1da177e4 LT |
42 | |
43 | ||
1da177e4 LT |
44 | LIST_HEAD(super_blocks); |
45 | DEFINE_SPINLOCK(sb_lock); | |
46 | ||
47 | /** | |
48 | * alloc_super - create new superblock | |
fe2bbc48 | 49 | * @type: filesystem type superblock should belong to |
1da177e4 LT |
50 | * |
51 | * Allocates and initializes a new &struct super_block. alloc_super() | |
52 | * returns a pointer new superblock or %NULL if allocation had failed. | |
53 | */ | |
cf516249 | 54 | static struct super_block *alloc_super(struct file_system_type *type) |
1da177e4 | 55 | { |
11b0b5ab | 56 | struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); |
1da177e4 LT |
57 | static struct super_operations default_op; |
58 | ||
59 | if (s) { | |
1da177e4 LT |
60 | if (security_sb_alloc(s)) { |
61 | kfree(s); | |
62 | s = NULL; | |
63 | goto out; | |
64 | } | |
65 | INIT_LIST_HEAD(&s->s_dirty); | |
66 | INIT_LIST_HEAD(&s->s_io); | |
0e0f4fc2 | 67 | INIT_LIST_HEAD(&s->s_more_io); |
1da177e4 LT |
68 | INIT_LIST_HEAD(&s->s_files); |
69 | INIT_LIST_HEAD(&s->s_instances); | |
70 | INIT_HLIST_HEAD(&s->s_anon); | |
71 | INIT_LIST_HEAD(&s->s_inodes); | |
da3bbdd4 | 72 | INIT_LIST_HEAD(&s->s_dentry_lru); |
1da177e4 | 73 | init_rwsem(&s->s_umount); |
7892f2f4 | 74 | mutex_init(&s->s_lock); |
897c6ff9 | 75 | lockdep_set_class(&s->s_umount, &type->s_umount_key); |
cf516249 IM |
76 | /* |
77 | * The locking rules for s_lock are up to the | |
78 | * filesystem. For example ext3fs has different | |
79 | * lock ordering than usbfs: | |
80 | */ | |
81 | lockdep_set_class(&s->s_lock, &type->s_lock_key); | |
ada723dc PZ |
82 | /* |
83 | * sget() can have s_umount recursion. | |
84 | * | |
85 | * When it cannot find a suitable sb, it allocates a new | |
86 | * one (this one), and tries again to find a suitable old | |
87 | * one. | |
88 | * | |
89 | * In case that succeeds, it will acquire the s_umount | |
90 | * lock of the old one. Since these are clearly distrinct | |
91 | * locks, and this object isn't exposed yet, there's no | |
92 | * risk of deadlocks. | |
93 | * | |
94 | * Annotate this by putting this lock in a different | |
95 | * subclass. | |
96 | */ | |
97 | down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); | |
1da177e4 LT |
98 | s->s_count = S_BIAS; |
99 | atomic_set(&s->s_active, 1); | |
a11f3a05 | 100 | mutex_init(&s->s_vfs_rename_mutex); |
d3be915f IM |
101 | mutex_init(&s->s_dquot.dqio_mutex); |
102 | mutex_init(&s->s_dquot.dqonoff_mutex); | |
1da177e4 LT |
103 | init_rwsem(&s->s_dquot.dqptr_sem); |
104 | init_waitqueue_head(&s->s_wait_unfrozen); | |
105 | s->s_maxbytes = MAX_NON_LFS; | |
106 | s->dq_op = sb_dquot_ops; | |
107 | s->s_qcop = sb_quotactl_ops; | |
108 | s->s_op = &default_op; | |
109 | s->s_time_gran = 1000000000; | |
110 | } | |
111 | out: | |
112 | return s; | |
113 | } | |
114 | ||
115 | /** | |
116 | * destroy_super - frees a superblock | |
117 | * @s: superblock to free | |
118 | * | |
119 | * Frees a superblock. | |
120 | */ | |
121 | static inline void destroy_super(struct super_block *s) | |
122 | { | |
123 | security_sb_free(s); | |
79c0b2df | 124 | kfree(s->s_subtype); |
b3b304a2 | 125 | kfree(s->s_options); |
1da177e4 LT |
126 | kfree(s); |
127 | } | |
128 | ||
129 | /* Superblock refcounting */ | |
130 | ||
131 | /* | |
132 | * Drop a superblock's refcount. Returns non-zero if the superblock was | |
133 | * destroyed. The caller must hold sb_lock. | |
134 | */ | |
6b09ae66 | 135 | static int __put_super(struct super_block *sb) |
1da177e4 LT |
136 | { |
137 | int ret = 0; | |
138 | ||
139 | if (!--sb->s_count) { | |
140 | destroy_super(sb); | |
141 | ret = 1; | |
142 | } | |
143 | return ret; | |
144 | } | |
145 | ||
146 | /* | |
147 | * Drop a superblock's refcount. | |
148 | * Returns non-zero if the superblock is about to be destroyed and | |
149 | * at least is already removed from super_blocks list, so if we are | |
150 | * making a loop through super blocks then we need to restart. | |
151 | * The caller must hold sb_lock. | |
152 | */ | |
153 | int __put_super_and_need_restart(struct super_block *sb) | |
154 | { | |
155 | /* check for race with generic_shutdown_super() */ | |
156 | if (list_empty(&sb->s_list)) { | |
157 | /* super block is removed, need to restart... */ | |
158 | __put_super(sb); | |
159 | return 1; | |
160 | } | |
161 | /* can't be the last, since s_list is still in use */ | |
162 | sb->s_count--; | |
163 | BUG_ON(sb->s_count == 0); | |
164 | return 0; | |
165 | } | |
166 | ||
167 | /** | |
168 | * put_super - drop a temporary reference to superblock | |
169 | * @sb: superblock in question | |
170 | * | |
171 | * Drops a temporary reference, frees superblock if there's no | |
172 | * references left. | |
173 | */ | |
174 | static void put_super(struct super_block *sb) | |
175 | { | |
176 | spin_lock(&sb_lock); | |
177 | __put_super(sb); | |
178 | spin_unlock(&sb_lock); | |
179 | } | |
180 | ||
181 | ||
182 | /** | |
183 | * deactivate_super - drop an active reference to superblock | |
184 | * @s: superblock to deactivate | |
185 | * | |
186 | * Drops an active reference to superblock, acquiring a temprory one if | |
187 | * there is no active references left. In that case we lock superblock, | |
188 | * tell fs driver to shut it down and drop the temporary reference we | |
189 | * had just acquired. | |
190 | */ | |
191 | void deactivate_super(struct super_block *s) | |
192 | { | |
193 | struct file_system_type *fs = s->s_type; | |
194 | if (atomic_dec_and_lock(&s->s_active, &sb_lock)) { | |
195 | s->s_count -= S_BIAS-1; | |
196 | spin_unlock(&sb_lock); | |
9e3509e2 | 197 | vfs_dq_off(s, 0); |
1da177e4 LT |
198 | down_write(&s->s_umount); |
199 | fs->kill_sb(s); | |
200 | put_filesystem(fs); | |
201 | put_super(s); | |
202 | } | |
203 | } | |
204 | ||
205 | EXPORT_SYMBOL(deactivate_super); | |
206 | ||
74dbbdd7 AV |
207 | /** |
208 | * deactivate_locked_super - drop an active reference to superblock | |
209 | * @s: superblock to deactivate | |
210 | * | |
211 | * Equivalent of up_write(&s->s_umount); deactivate_super(s);, except that | |
212 | * it does not unlock it until it's all over. As the result, it's safe to | |
213 | * use to dispose of new superblock on ->get_sb() failure exits - nobody | |
214 | * will see the sucker until it's all over. Equivalent using up_write + | |
215 | * deactivate_super is safe for that purpose only if superblock is either | |
216 | * safe to use or has NULL ->s_root when we unlock. | |
217 | */ | |
218 | void deactivate_locked_super(struct super_block *s) | |
219 | { | |
220 | struct file_system_type *fs = s->s_type; | |
221 | if (atomic_dec_and_lock(&s->s_active, &sb_lock)) { | |
222 | s->s_count -= S_BIAS-1; | |
223 | spin_unlock(&sb_lock); | |
224 | vfs_dq_off(s, 0); | |
225 | fs->kill_sb(s); | |
226 | put_filesystem(fs); | |
227 | put_super(s); | |
228 | } else { | |
229 | up_write(&s->s_umount); | |
230 | } | |
231 | } | |
232 | ||
233 | EXPORT_SYMBOL(deactivate_locked_super); | |
234 | ||
1da177e4 LT |
235 | /** |
236 | * grab_super - acquire an active reference | |
237 | * @s: reference we are trying to make active | |
238 | * | |
239 | * Tries to acquire an active reference. grab_super() is used when we | |
240 | * had just found a superblock in super_blocks or fs_type->fs_supers | |
241 | * and want to turn it into a full-blown active reference. grab_super() | |
242 | * is called with sb_lock held and drops it. Returns 1 in case of | |
243 | * success, 0 if we had failed (superblock contents was already dead or | |
244 | * dying when grab_super() had been called). | |
245 | */ | |
9c4dbee7 | 246 | static int grab_super(struct super_block *s) __releases(sb_lock) |
1da177e4 LT |
247 | { |
248 | s->s_count++; | |
249 | spin_unlock(&sb_lock); | |
250 | down_write(&s->s_umount); | |
251 | if (s->s_root) { | |
252 | spin_lock(&sb_lock); | |
253 | if (s->s_count > S_BIAS) { | |
254 | atomic_inc(&s->s_active); | |
255 | s->s_count--; | |
256 | spin_unlock(&sb_lock); | |
257 | return 1; | |
258 | } | |
259 | spin_unlock(&sb_lock); | |
260 | } | |
261 | up_write(&s->s_umount); | |
262 | put_super(s); | |
263 | yield(); | |
264 | return 0; | |
265 | } | |
266 | ||
914e2637 AV |
267 | /* |
268 | * Superblock locking. We really ought to get rid of these two. | |
269 | */ | |
270 | void lock_super(struct super_block * sb) | |
271 | { | |
272 | get_fs_excl(); | |
273 | mutex_lock(&sb->s_lock); | |
274 | } | |
275 | ||
276 | void unlock_super(struct super_block * sb) | |
277 | { | |
278 | put_fs_excl(); | |
279 | mutex_unlock(&sb->s_lock); | |
280 | } | |
281 | ||
282 | EXPORT_SYMBOL(lock_super); | |
283 | EXPORT_SYMBOL(unlock_super); | |
284 | ||
1da177e4 LT |
285 | /** |
286 | * generic_shutdown_super - common helper for ->kill_sb() | |
287 | * @sb: superblock to kill | |
288 | * | |
289 | * generic_shutdown_super() does all fs-independent work on superblock | |
290 | * shutdown. Typical ->kill_sb() should pick all fs-specific objects | |
291 | * that need destruction out of superblock, call generic_shutdown_super() | |
292 | * and release aforementioned objects. Note: dentries and inodes _are_ | |
293 | * taken care of and do not need specific handling. | |
c636ebdb DH |
294 | * |
295 | * Upon calling this function, the filesystem may no longer alter or | |
296 | * rearrange the set of dentries belonging to this super_block, nor may it | |
297 | * change the attachments of dentries to inodes. | |
1da177e4 LT |
298 | */ |
299 | void generic_shutdown_super(struct super_block *sb) | |
300 | { | |
ee9b6d61 | 301 | const struct super_operations *sop = sb->s_op; |
1da177e4 | 302 | |
efaee192 | 303 | |
c636ebdb DH |
304 | if (sb->s_root) { |
305 | shrink_dcache_for_umount(sb); | |
60b0680f | 306 | sync_filesystem(sb); |
1da177e4 LT |
307 | lock_super(sb); |
308 | sb->s_flags &= ~MS_ACTIVE; | |
efaee192 | 309 | |
1da177e4 LT |
310 | /* bad name - it should be evict_inodes() */ |
311 | invalidate_inodes(sb); | |
312 | lock_kernel(); | |
313 | ||
1da177e4 LT |
314 | if (sop->put_super) |
315 | sop->put_super(sb); | |
316 | ||
317 | /* Forget any remaining inodes */ | |
318 | if (invalidate_inodes(sb)) { | |
7b4fe29e DJ |
319 | printk("VFS: Busy inodes after unmount of %s. " |
320 | "Self-destruct in 5 seconds. Have a nice day...\n", | |
321 | sb->s_id); | |
1da177e4 LT |
322 | } |
323 | ||
324 | unlock_kernel(); | |
325 | unlock_super(sb); | |
326 | } | |
327 | spin_lock(&sb_lock); | |
328 | /* should be initialized for __put_super_and_need_restart() */ | |
329 | list_del_init(&sb->s_list); | |
330 | list_del(&sb->s_instances); | |
331 | spin_unlock(&sb_lock); | |
332 | up_write(&sb->s_umount); | |
333 | } | |
334 | ||
335 | EXPORT_SYMBOL(generic_shutdown_super); | |
336 | ||
337 | /** | |
338 | * sget - find or create a superblock | |
339 | * @type: filesystem type superblock should belong to | |
340 | * @test: comparison callback | |
341 | * @set: setup callback | |
342 | * @data: argument to each of them | |
343 | */ | |
344 | struct super_block *sget(struct file_system_type *type, | |
345 | int (*test)(struct super_block *,void *), | |
346 | int (*set)(struct super_block *,void *), | |
347 | void *data) | |
348 | { | |
349 | struct super_block *s = NULL; | |
d4730127 | 350 | struct super_block *old; |
1da177e4 LT |
351 | int err; |
352 | ||
353 | retry: | |
354 | spin_lock(&sb_lock); | |
d4730127 MK |
355 | if (test) { |
356 | list_for_each_entry(old, &type->fs_supers, s_instances) { | |
357 | if (!test(old, data)) | |
358 | continue; | |
359 | if (!grab_super(old)) | |
360 | goto retry; | |
a3cfbb53 LZ |
361 | if (s) { |
362 | up_write(&s->s_umount); | |
d4730127 | 363 | destroy_super(s); |
a3cfbb53 | 364 | } |
d4730127 MK |
365 | return old; |
366 | } | |
1da177e4 LT |
367 | } |
368 | if (!s) { | |
369 | spin_unlock(&sb_lock); | |
cf516249 | 370 | s = alloc_super(type); |
1da177e4 LT |
371 | if (!s) |
372 | return ERR_PTR(-ENOMEM); | |
373 | goto retry; | |
374 | } | |
375 | ||
376 | err = set(s, data); | |
377 | if (err) { | |
378 | spin_unlock(&sb_lock); | |
a3cfbb53 | 379 | up_write(&s->s_umount); |
1da177e4 LT |
380 | destroy_super(s); |
381 | return ERR_PTR(err); | |
382 | } | |
383 | s->s_type = type; | |
384 | strlcpy(s->s_id, type->name, sizeof(s->s_id)); | |
385 | list_add_tail(&s->s_list, &super_blocks); | |
386 | list_add(&s->s_instances, &type->fs_supers); | |
387 | spin_unlock(&sb_lock); | |
388 | get_filesystem(type); | |
389 | return s; | |
390 | } | |
391 | ||
392 | EXPORT_SYMBOL(sget); | |
393 | ||
394 | void drop_super(struct super_block *sb) | |
395 | { | |
396 | up_read(&sb->s_umount); | |
397 | put_super(sb); | |
398 | } | |
399 | ||
400 | EXPORT_SYMBOL(drop_super); | |
401 | ||
402 | static inline void write_super(struct super_block *sb) | |
403 | { | |
404 | lock_super(sb); | |
405 | if (sb->s_root && sb->s_dirt) | |
406 | if (sb->s_op->write_super) | |
407 | sb->s_op->write_super(sb); | |
408 | unlock_super(sb); | |
409 | } | |
410 | ||
411 | /* | |
412 | * Note: check the dirty flag before waiting, so we don't | |
413 | * hold up the sync while mounting a device. (The newly | |
414 | * mounted device won't need syncing.) | |
415 | */ | |
416 | void sync_supers(void) | |
417 | { | |
618f0636 KK |
418 | struct super_block *sb; |
419 | ||
1da177e4 | 420 | spin_lock(&sb_lock); |
618f0636 KK |
421 | restart: |
422 | list_for_each_entry(sb, &super_blocks, s_list) { | |
1da177e4 LT |
423 | if (sb->s_dirt) { |
424 | sb->s_count++; | |
425 | spin_unlock(&sb_lock); | |
426 | down_read(&sb->s_umount); | |
427 | write_super(sb); | |
618f0636 KK |
428 | up_read(&sb->s_umount); |
429 | spin_lock(&sb_lock); | |
430 | if (__put_super_and_need_restart(sb)) | |
431 | goto restart; | |
432 | } | |
433 | } | |
1da177e4 LT |
434 | spin_unlock(&sb_lock); |
435 | } | |
436 | ||
1da177e4 LT |
437 | /** |
438 | * get_super - get the superblock of a device | |
439 | * @bdev: device to get the superblock for | |
440 | * | |
441 | * Scans the superblock list and finds the superblock of the file system | |
442 | * mounted on the device given. %NULL is returned if no match is found. | |
443 | */ | |
444 | ||
445 | struct super_block * get_super(struct block_device *bdev) | |
446 | { | |
618f0636 KK |
447 | struct super_block *sb; |
448 | ||
1da177e4 LT |
449 | if (!bdev) |
450 | return NULL; | |
618f0636 | 451 | |
1da177e4 | 452 | spin_lock(&sb_lock); |
618f0636 KK |
453 | rescan: |
454 | list_for_each_entry(sb, &super_blocks, s_list) { | |
455 | if (sb->s_bdev == bdev) { | |
456 | sb->s_count++; | |
1da177e4 | 457 | spin_unlock(&sb_lock); |
618f0636 KK |
458 | down_read(&sb->s_umount); |
459 | if (sb->s_root) | |
460 | return sb; | |
461 | up_read(&sb->s_umount); | |
462 | /* restart only when sb is no longer on the list */ | |
463 | spin_lock(&sb_lock); | |
464 | if (__put_super_and_need_restart(sb)) | |
465 | goto rescan; | |
1da177e4 LT |
466 | } |
467 | } | |
468 | spin_unlock(&sb_lock); | |
469 | return NULL; | |
470 | } | |
471 | ||
472 | EXPORT_SYMBOL(get_super); | |
473 | ||
474 | struct super_block * user_get_super(dev_t dev) | |
475 | { | |
618f0636 | 476 | struct super_block *sb; |
1da177e4 | 477 | |
1da177e4 | 478 | spin_lock(&sb_lock); |
618f0636 KK |
479 | rescan: |
480 | list_for_each_entry(sb, &super_blocks, s_list) { | |
481 | if (sb->s_dev == dev) { | |
482 | sb->s_count++; | |
1da177e4 | 483 | spin_unlock(&sb_lock); |
618f0636 KK |
484 | down_read(&sb->s_umount); |
485 | if (sb->s_root) | |
486 | return sb; | |
487 | up_read(&sb->s_umount); | |
488 | /* restart only when sb is no longer on the list */ | |
489 | spin_lock(&sb_lock); | |
490 | if (__put_super_and_need_restart(sb)) | |
491 | goto rescan; | |
1da177e4 LT |
492 | } |
493 | } | |
494 | spin_unlock(&sb_lock); | |
495 | return NULL; | |
496 | } | |
497 | ||
257ac264 | 498 | SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf) |
1da177e4 LT |
499 | { |
500 | struct super_block *s; | |
501 | struct ustat tmp; | |
502 | struct kstatfs sbuf; | |
503 | int err = -EINVAL; | |
504 | ||
505 | s = user_get_super(new_decode_dev(dev)); | |
506 | if (s == NULL) | |
507 | goto out; | |
726c3342 | 508 | err = vfs_statfs(s->s_root, &sbuf); |
1da177e4 LT |
509 | drop_super(s); |
510 | if (err) | |
511 | goto out; | |
512 | ||
513 | memset(&tmp,0,sizeof(struct ustat)); | |
514 | tmp.f_tfree = sbuf.f_bfree; | |
515 | tmp.f_tinode = sbuf.f_ffree; | |
516 | ||
517 | err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0; | |
518 | out: | |
519 | return err; | |
520 | } | |
521 | ||
1da177e4 LT |
522 | /** |
523 | * do_remount_sb - asks filesystem to change mount options. | |
524 | * @sb: superblock in question | |
525 | * @flags: numeric part of options | |
526 | * @data: the rest of options | |
527 | * @force: whether or not to force the change | |
528 | * | |
529 | * Alters the mount options of a mounted file system. | |
530 | */ | |
531 | int do_remount_sb(struct super_block *sb, int flags, void *data, int force) | |
532 | { | |
533 | int retval; | |
0ff5af83 | 534 | int remount_rw; |
1da177e4 | 535 | |
9361401e | 536 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
537 | if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) |
538 | return -EACCES; | |
9361401e | 539 | #endif |
1da177e4 LT |
540 | if (flags & MS_RDONLY) |
541 | acct_auto_close(sb); | |
542 | shrink_dcache_sb(sb); | |
60b0680f | 543 | sync_filesystem(sb); |
1da177e4 LT |
544 | |
545 | /* If we are remounting RDONLY and current sb is read/write, | |
546 | make sure there are no rw files opened */ | |
547 | if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) { | |
548 | if (force) | |
549 | mark_files_ro(sb); | |
550 | else if (!fs_may_remount_ro(sb)) | |
551 | return -EBUSY; | |
9e3509e2 | 552 | retval = vfs_dq_off(sb, 1); |
0ff5af83 JK |
553 | if (retval < 0 && retval != -ENOSYS) |
554 | return -EBUSY; | |
1da177e4 | 555 | } |
0ff5af83 | 556 | remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY); |
1da177e4 LT |
557 | |
558 | if (sb->s_op->remount_fs) { | |
559 | lock_super(sb); | |
560 | retval = sb->s_op->remount_fs(sb, &flags, data); | |
561 | unlock_super(sb); | |
562 | if (retval) | |
563 | return retval; | |
564 | } | |
565 | sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); | |
0ff5af83 | 566 | if (remount_rw) |
9e3509e2 | 567 | vfs_dq_quota_on_remount(sb); |
1da177e4 LT |
568 | return 0; |
569 | } | |
570 | ||
a2a9537a | 571 | static void do_emergency_remount(struct work_struct *work) |
1da177e4 LT |
572 | { |
573 | struct super_block *sb; | |
574 | ||
575 | spin_lock(&sb_lock); | |
576 | list_for_each_entry(sb, &super_blocks, s_list) { | |
577 | sb->s_count++; | |
578 | spin_unlock(&sb_lock); | |
579 | down_read(&sb->s_umount); | |
580 | if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) { | |
581 | /* | |
582 | * ->remount_fs needs lock_kernel(). | |
583 | * | |
584 | * What lock protects sb->s_flags?? | |
585 | */ | |
586 | lock_kernel(); | |
587 | do_remount_sb(sb, MS_RDONLY, NULL, 1); | |
588 | unlock_kernel(); | |
589 | } | |
590 | drop_super(sb); | |
591 | spin_lock(&sb_lock); | |
592 | } | |
593 | spin_unlock(&sb_lock); | |
a2a9537a | 594 | kfree(work); |
1da177e4 LT |
595 | printk("Emergency Remount complete\n"); |
596 | } | |
597 | ||
598 | void emergency_remount(void) | |
599 | { | |
a2a9537a JA |
600 | struct work_struct *work; |
601 | ||
602 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
603 | if (work) { | |
604 | INIT_WORK(work, do_emergency_remount); | |
605 | schedule_work(work); | |
606 | } | |
1da177e4 LT |
607 | } |
608 | ||
609 | /* | |
610 | * Unnamed block devices are dummy devices used by virtual | |
611 | * filesystems which don't use real block-devices. -- jrs | |
612 | */ | |
613 | ||
ad76cbc6 | 614 | static DEFINE_IDA(unnamed_dev_ida); |
1da177e4 LT |
615 | static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ |
616 | ||
617 | int set_anon_super(struct super_block *s, void *data) | |
618 | { | |
619 | int dev; | |
620 | int error; | |
621 | ||
622 | retry: | |
ad76cbc6 | 623 | if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) |
1da177e4 LT |
624 | return -ENOMEM; |
625 | spin_lock(&unnamed_dev_lock); | |
ad76cbc6 | 626 | error = ida_get_new(&unnamed_dev_ida, &dev); |
1da177e4 LT |
627 | spin_unlock(&unnamed_dev_lock); |
628 | if (error == -EAGAIN) | |
629 | /* We raced and lost with another CPU. */ | |
630 | goto retry; | |
631 | else if (error) | |
632 | return -EAGAIN; | |
633 | ||
634 | if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { | |
635 | spin_lock(&unnamed_dev_lock); | |
ad76cbc6 | 636 | ida_remove(&unnamed_dev_ida, dev); |
1da177e4 LT |
637 | spin_unlock(&unnamed_dev_lock); |
638 | return -EMFILE; | |
639 | } | |
640 | s->s_dev = MKDEV(0, dev & MINORMASK); | |
641 | return 0; | |
642 | } | |
643 | ||
644 | EXPORT_SYMBOL(set_anon_super); | |
645 | ||
646 | void kill_anon_super(struct super_block *sb) | |
647 | { | |
648 | int slot = MINOR(sb->s_dev); | |
649 | ||
650 | generic_shutdown_super(sb); | |
651 | spin_lock(&unnamed_dev_lock); | |
ad76cbc6 | 652 | ida_remove(&unnamed_dev_ida, slot); |
1da177e4 LT |
653 | spin_unlock(&unnamed_dev_lock); |
654 | } | |
655 | ||
656 | EXPORT_SYMBOL(kill_anon_super); | |
657 | ||
1da177e4 LT |
658 | void kill_litter_super(struct super_block *sb) |
659 | { | |
660 | if (sb->s_root) | |
661 | d_genocide(sb->s_root); | |
662 | kill_anon_super(sb); | |
663 | } | |
664 | ||
665 | EXPORT_SYMBOL(kill_litter_super); | |
666 | ||
909e6d94 SH |
667 | static int ns_test_super(struct super_block *sb, void *data) |
668 | { | |
669 | return sb->s_fs_info == data; | |
670 | } | |
671 | ||
672 | static int ns_set_super(struct super_block *sb, void *data) | |
673 | { | |
674 | sb->s_fs_info = data; | |
675 | return set_anon_super(sb, NULL); | |
676 | } | |
677 | ||
678 | int get_sb_ns(struct file_system_type *fs_type, int flags, void *data, | |
679 | int (*fill_super)(struct super_block *, void *, int), | |
680 | struct vfsmount *mnt) | |
681 | { | |
682 | struct super_block *sb; | |
683 | ||
684 | sb = sget(fs_type, ns_test_super, ns_set_super, data); | |
685 | if (IS_ERR(sb)) | |
686 | return PTR_ERR(sb); | |
687 | ||
688 | if (!sb->s_root) { | |
689 | int err; | |
690 | sb->s_flags = flags; | |
691 | err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); | |
692 | if (err) { | |
74dbbdd7 | 693 | deactivate_locked_super(sb); |
909e6d94 SH |
694 | return err; |
695 | } | |
696 | ||
697 | sb->s_flags |= MS_ACTIVE; | |
698 | } | |
699 | ||
700 | simple_set_mnt(mnt, sb); | |
701 | return 0; | |
702 | } | |
703 | ||
704 | EXPORT_SYMBOL(get_sb_ns); | |
705 | ||
9361401e | 706 | #ifdef CONFIG_BLOCK |
1da177e4 LT |
707 | static int set_bdev_super(struct super_block *s, void *data) |
708 | { | |
709 | s->s_bdev = data; | |
710 | s->s_dev = s->s_bdev->bd_dev; | |
711 | return 0; | |
712 | } | |
713 | ||
714 | static int test_bdev_super(struct super_block *s, void *data) | |
715 | { | |
716 | return (void *)s->s_bdev == data; | |
717 | } | |
718 | ||
454e2398 | 719 | int get_sb_bdev(struct file_system_type *fs_type, |
1da177e4 | 720 | int flags, const char *dev_name, void *data, |
454e2398 DH |
721 | int (*fill_super)(struct super_block *, void *, int), |
722 | struct vfsmount *mnt) | |
1da177e4 LT |
723 | { |
724 | struct block_device *bdev; | |
725 | struct super_block *s; | |
30c40d2c | 726 | fmode_t mode = FMODE_READ; |
1da177e4 LT |
727 | int error = 0; |
728 | ||
30c40d2c AV |
729 | if (!(flags & MS_RDONLY)) |
730 | mode |= FMODE_WRITE; | |
731 | ||
732 | bdev = open_bdev_exclusive(dev_name, mode, fs_type); | |
1da177e4 | 733 | if (IS_ERR(bdev)) |
454e2398 | 734 | return PTR_ERR(bdev); |
1da177e4 LT |
735 | |
736 | /* | |
737 | * once the super is inserted into the list by sget, s_umount | |
738 | * will protect the lockfs code from trying to start a snapshot | |
739 | * while we are mounting | |
740 | */ | |
f73ca1b7 | 741 | down(&bdev->bd_mount_sem); |
1da177e4 | 742 | s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); |
f73ca1b7 | 743 | up(&bdev->bd_mount_sem); |
1da177e4 | 744 | if (IS_ERR(s)) |
454e2398 | 745 | goto error_s; |
1da177e4 LT |
746 | |
747 | if (s->s_root) { | |
748 | if ((flags ^ s->s_flags) & MS_RDONLY) { | |
74dbbdd7 | 749 | deactivate_locked_super(s); |
454e2398 DH |
750 | error = -EBUSY; |
751 | goto error_bdev; | |
1da177e4 | 752 | } |
454e2398 | 753 | |
30c40d2c | 754 | close_bdev_exclusive(bdev, mode); |
1da177e4 LT |
755 | } else { |
756 | char b[BDEVNAME_SIZE]; | |
757 | ||
758 | s->s_flags = flags; | |
30c40d2c | 759 | s->s_mode = mode; |
1da177e4 | 760 | strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); |
e78c9a00 | 761 | sb_set_blocksize(s, block_size(bdev)); |
9b04c997 | 762 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 763 | if (error) { |
74dbbdd7 | 764 | deactivate_locked_super(s); |
454e2398 | 765 | goto error; |
fa675765 | 766 | } |
454e2398 DH |
767 | |
768 | s->s_flags |= MS_ACTIVE; | |
87d8fe1e | 769 | bdev->bd_super = s; |
1da177e4 LT |
770 | } |
771 | ||
a3ec947c SB |
772 | simple_set_mnt(mnt, s); |
773 | return 0; | |
1da177e4 | 774 | |
454e2398 DH |
775 | error_s: |
776 | error = PTR_ERR(s); | |
777 | error_bdev: | |
30c40d2c | 778 | close_bdev_exclusive(bdev, mode); |
454e2398 DH |
779 | error: |
780 | return error; | |
1da177e4 LT |
781 | } |
782 | ||
783 | EXPORT_SYMBOL(get_sb_bdev); | |
784 | ||
785 | void kill_block_super(struct super_block *sb) | |
786 | { | |
787 | struct block_device *bdev = sb->s_bdev; | |
30c40d2c | 788 | fmode_t mode = sb->s_mode; |
1da177e4 | 789 | |
ddbaaf30 | 790 | bdev->bd_super = NULL; |
1da177e4 LT |
791 | generic_shutdown_super(sb); |
792 | sync_blockdev(bdev); | |
30c40d2c | 793 | close_bdev_exclusive(bdev, mode); |
1da177e4 LT |
794 | } |
795 | ||
796 | EXPORT_SYMBOL(kill_block_super); | |
9361401e | 797 | #endif |
1da177e4 | 798 | |
454e2398 | 799 | int get_sb_nodev(struct file_system_type *fs_type, |
1da177e4 | 800 | int flags, void *data, |
454e2398 DH |
801 | int (*fill_super)(struct super_block *, void *, int), |
802 | struct vfsmount *mnt) | |
1da177e4 LT |
803 | { |
804 | int error; | |
805 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); | |
806 | ||
807 | if (IS_ERR(s)) | |
454e2398 | 808 | return PTR_ERR(s); |
1da177e4 LT |
809 | |
810 | s->s_flags = flags; | |
811 | ||
9b04c997 | 812 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 813 | if (error) { |
74dbbdd7 | 814 | deactivate_locked_super(s); |
454e2398 | 815 | return error; |
1da177e4 LT |
816 | } |
817 | s->s_flags |= MS_ACTIVE; | |
a3ec947c SB |
818 | simple_set_mnt(mnt, s); |
819 | return 0; | |
1da177e4 LT |
820 | } |
821 | ||
822 | EXPORT_SYMBOL(get_sb_nodev); | |
823 | ||
824 | static int compare_single(struct super_block *s, void *p) | |
825 | { | |
826 | return 1; | |
827 | } | |
828 | ||
454e2398 | 829 | int get_sb_single(struct file_system_type *fs_type, |
1da177e4 | 830 | int flags, void *data, |
454e2398 DH |
831 | int (*fill_super)(struct super_block *, void *, int), |
832 | struct vfsmount *mnt) | |
1da177e4 LT |
833 | { |
834 | struct super_block *s; | |
835 | int error; | |
836 | ||
837 | s = sget(fs_type, compare_single, set_anon_super, NULL); | |
838 | if (IS_ERR(s)) | |
454e2398 | 839 | return PTR_ERR(s); |
1da177e4 LT |
840 | if (!s->s_root) { |
841 | s->s_flags = flags; | |
9b04c997 | 842 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
1da177e4 | 843 | if (error) { |
74dbbdd7 | 844 | deactivate_locked_super(s); |
454e2398 | 845 | return error; |
1da177e4 LT |
846 | } |
847 | s->s_flags |= MS_ACTIVE; | |
848 | } | |
849 | do_remount_sb(s, flags, data, 0); | |
a3ec947c SB |
850 | simple_set_mnt(mnt, s); |
851 | return 0; | |
1da177e4 LT |
852 | } |
853 | ||
854 | EXPORT_SYMBOL(get_sb_single); | |
855 | ||
856 | struct vfsmount * | |
bb4a58bf | 857 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) |
1da177e4 | 858 | { |
1da177e4 | 859 | struct vfsmount *mnt; |
1da177e4 | 860 | char *secdata = NULL; |
454e2398 | 861 | int error; |
1da177e4 LT |
862 | |
863 | if (!type) | |
864 | return ERR_PTR(-ENODEV); | |
1da177e4 | 865 | |
454e2398 | 866 | error = -ENOMEM; |
1da177e4 LT |
867 | mnt = alloc_vfsmnt(name); |
868 | if (!mnt) | |
869 | goto out; | |
870 | ||
e0007529 | 871 | if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { |
1da177e4 | 872 | secdata = alloc_secdata(); |
454e2398 | 873 | if (!secdata) |
1da177e4 | 874 | goto out_mnt; |
1da177e4 | 875 | |
e0007529 | 876 | error = security_sb_copy_data(data, secdata); |
454e2398 | 877 | if (error) |
1da177e4 | 878 | goto out_free_secdata; |
1da177e4 LT |
879 | } |
880 | ||
454e2398 DH |
881 | error = type->get_sb(type, flags, name, data, mnt); |
882 | if (error < 0) | |
1da177e4 | 883 | goto out_free_secdata; |
b4c07bce | 884 | BUG_ON(!mnt->mnt_sb); |
454e2398 | 885 | |
12204e24 | 886 | error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata); |
1da177e4 LT |
887 | if (error) |
888 | goto out_sb; | |
454e2398 DH |
889 | |
890 | mnt->mnt_mountpoint = mnt->mnt_root; | |
1da177e4 | 891 | mnt->mnt_parent = mnt; |
454e2398 | 892 | up_write(&mnt->mnt_sb->s_umount); |
8680e22f | 893 | free_secdata(secdata); |
1da177e4 LT |
894 | return mnt; |
895 | out_sb: | |
454e2398 | 896 | dput(mnt->mnt_root); |
74dbbdd7 | 897 | deactivate_locked_super(mnt->mnt_sb); |
1da177e4 LT |
898 | out_free_secdata: |
899 | free_secdata(secdata); | |
900 | out_mnt: | |
901 | free_vfsmnt(mnt); | |
902 | out: | |
454e2398 | 903 | return ERR_PTR(error); |
1da177e4 LT |
904 | } |
905 | ||
bb4a58bf TM |
906 | EXPORT_SYMBOL_GPL(vfs_kern_mount); |
907 | ||
79c0b2df MS |
908 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
909 | { | |
910 | int err; | |
911 | const char *subtype = strchr(fstype, '.'); | |
912 | if (subtype) { | |
913 | subtype++; | |
914 | err = -EINVAL; | |
915 | if (!subtype[0]) | |
916 | goto err; | |
917 | } else | |
918 | subtype = ""; | |
919 | ||
920 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); | |
921 | err = -ENOMEM; | |
922 | if (!mnt->mnt_sb->s_subtype) | |
923 | goto err; | |
924 | return mnt; | |
925 | ||
926 | err: | |
927 | mntput(mnt); | |
928 | return ERR_PTR(err); | |
929 | } | |
930 | ||
bb4a58bf TM |
931 | struct vfsmount * |
932 | do_kern_mount(const char *fstype, int flags, const char *name, void *data) | |
933 | { | |
934 | struct file_system_type *type = get_fs_type(fstype); | |
935 | struct vfsmount *mnt; | |
936 | if (!type) | |
937 | return ERR_PTR(-ENODEV); | |
938 | mnt = vfs_kern_mount(type, flags, name, data); | |
79c0b2df MS |
939 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && |
940 | !mnt->mnt_sb->s_subtype) | |
941 | mnt = fs_set_subtype(mnt, fstype); | |
bb4a58bf TM |
942 | put_filesystem(type); |
943 | return mnt; | |
944 | } | |
8a4e98d9 | 945 | EXPORT_SYMBOL_GPL(do_kern_mount); |
bb4a58bf | 946 | |
8bf9725c | 947 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) |
1da177e4 | 948 | { |
8bf9725c | 949 | return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); |
1da177e4 LT |
950 | } |
951 | ||
8bf9725c | 952 | EXPORT_SYMBOL_GPL(kern_mount_data); |