Root/
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: |
18 | * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996. |
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 | |
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/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> |
38 | #include <linux/mutex.h> |
39 | #include <linux/file.h> |
40 | #include <linux/backing-dev.h> |
41 | #include <asm/uaccess.h> |
42 | #include "internal.h" |
43 | |
44 | |
45 | LIST_HEAD(super_blocks); |
46 | DEFINE_SPINLOCK(sb_lock); |
47 | |
48 | /** |
49 | * alloc_super - create new superblock |
50 | * @type: filesystem type superblock should belong to |
51 | * |
52 | * Allocates and initializes a new &struct super_block. alloc_super() |
53 | * returns a pointer new superblock or %NULL if allocation had failed. |
54 | */ |
55 | static struct super_block *alloc_super(struct file_system_type *type) |
56 | { |
57 | struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); |
58 | static const struct super_operations default_op; |
59 | |
60 | if (s) { |
61 | if (security_sb_alloc(s)) { |
62 | kfree(s); |
63 | s = NULL; |
64 | goto out; |
65 | } |
66 | INIT_LIST_HEAD(&s->s_files); |
67 | INIT_LIST_HEAD(&s->s_instances); |
68 | INIT_HLIST_HEAD(&s->s_anon); |
69 | INIT_LIST_HEAD(&s->s_inodes); |
70 | INIT_LIST_HEAD(&s->s_dentry_lru); |
71 | init_rwsem(&s->s_umount); |
72 | mutex_init(&s->s_lock); |
73 | lockdep_set_class(&s->s_umount, &type->s_umount_key); |
74 | /* |
75 | * The locking rules for s_lock are up to the |
76 | * filesystem. For example ext3fs has different |
77 | * lock ordering than usbfs: |
78 | */ |
79 | lockdep_set_class(&s->s_lock, &type->s_lock_key); |
80 | /* |
81 | * sget() can have s_umount recursion. |
82 | * |
83 | * When it cannot find a suitable sb, it allocates a new |
84 | * one (this one), and tries again to find a suitable old |
85 | * one. |
86 | * |
87 | * In case that succeeds, it will acquire the s_umount |
88 | * lock of the old one. Since these are clearly distrinct |
89 | * locks, and this object isn't exposed yet, there's no |
90 | * risk of deadlocks. |
91 | * |
92 | * Annotate this by putting this lock in a different |
93 | * subclass. |
94 | */ |
95 | down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); |
96 | s->s_count = S_BIAS; |
97 | atomic_set(&s->s_active, 1); |
98 | mutex_init(&s->s_vfs_rename_mutex); |
99 | mutex_init(&s->s_dquot.dqio_mutex); |
100 | mutex_init(&s->s_dquot.dqonoff_mutex); |
101 | init_rwsem(&s->s_dquot.dqptr_sem); |
102 | init_waitqueue_head(&s->s_wait_unfrozen); |
103 | s->s_maxbytes = MAX_NON_LFS; |
104 | s->dq_op = sb_dquot_ops; |
105 | s->s_qcop = sb_quotactl_ops; |
106 | s->s_op = &default_op; |
107 | s->s_time_gran = 1000000000; |
108 | } |
109 | out: |
110 | return s; |
111 | } |
112 | |
113 | /** |
114 | * destroy_super - frees a superblock |
115 | * @s: superblock to free |
116 | * |
117 | * Frees a superblock. |
118 | */ |
119 | static inline void destroy_super(struct super_block *s) |
120 | { |
121 | security_sb_free(s); |
122 | kfree(s->s_subtype); |
123 | kfree(s->s_options); |
124 | kfree(s); |
125 | } |
126 | |
127 | /* Superblock refcounting */ |
128 | |
129 | /* |
130 | * Drop a superblock's refcount. Returns non-zero if the superblock was |
131 | * destroyed. The caller must hold sb_lock. |
132 | */ |
133 | static int __put_super(struct super_block *sb) |
134 | { |
135 | int ret = 0; |
136 | |
137 | if (!--sb->s_count) { |
138 | destroy_super(sb); |
139 | ret = 1; |
140 | } |
141 | return ret; |
142 | } |
143 | |
144 | /* |
145 | * Drop a superblock's refcount. |
146 | * Returns non-zero if the superblock is about to be destroyed and |
147 | * at least is already removed from super_blocks list, so if we are |
148 | * making a loop through super blocks then we need to restart. |
149 | * The caller must hold sb_lock. |
150 | */ |
151 | int __put_super_and_need_restart(struct super_block *sb) |
152 | { |
153 | /* check for race with generic_shutdown_super() */ |
154 | if (list_empty(&sb->s_list)) { |
155 | /* super block is removed, need to restart... */ |
156 | __put_super(sb); |
157 | return 1; |
158 | } |
159 | /* can't be the last, since s_list is still in use */ |
160 | sb->s_count--; |
161 | BUG_ON(sb->s_count == 0); |
162 | return 0; |
163 | } |
164 | |
165 | /** |
166 | * put_super - drop a temporary reference to superblock |
167 | * @sb: superblock in question |
168 | * |
169 | * Drops a temporary reference, frees superblock if there's no |
170 | * references left. |
171 | */ |
172 | void put_super(struct super_block *sb) |
173 | { |
174 | spin_lock(&sb_lock); |
175 | __put_super(sb); |
176 | spin_unlock(&sb_lock); |
177 | } |
178 | |
179 | |
180 | /** |
181 | * deactivate_super - drop an active reference to superblock |
182 | * @s: superblock to deactivate |
183 | * |
184 | * Drops an active reference to superblock, acquiring a temprory one if |
185 | * there is no active references left. In that case we lock superblock, |
186 | * tell fs driver to shut it down and drop the temporary reference we |
187 | * had just acquired. |
188 | */ |
189 | void deactivate_super(struct super_block *s) |
190 | { |
191 | struct file_system_type *fs = s->s_type; |
192 | if (atomic_dec_and_lock(&s->s_active, &sb_lock)) { |
193 | s->s_count -= S_BIAS-1; |
194 | spin_unlock(&sb_lock); |
195 | vfs_dq_off(s, 0); |
196 | down_write(&s->s_umount); |
197 | fs->kill_sb(s); |
198 | put_filesystem(fs); |
199 | put_super(s); |
200 | } |
201 | } |
202 | |
203 | EXPORT_SYMBOL(deactivate_super); |
204 | |
205 | /** |
206 | * deactivate_locked_super - drop an active reference to superblock |
207 | * @s: superblock to deactivate |
208 | * |
209 | * Equivalent of up_write(&s->s_umount); deactivate_super(s);, except that |
210 | * it does not unlock it until it's all over. As the result, it's safe to |
211 | * use to dispose of new superblock on ->get_sb() failure exits - nobody |
212 | * will see the sucker until it's all over. Equivalent using up_write + |
213 | * deactivate_super is safe for that purpose only if superblock is either |
214 | * safe to use or has NULL ->s_root when we unlock. |
215 | */ |
216 | void deactivate_locked_super(struct super_block *s) |
217 | { |
218 | struct file_system_type *fs = s->s_type; |
219 | if (atomic_dec_and_lock(&s->s_active, &sb_lock)) { |
220 | s->s_count -= S_BIAS-1; |
221 | spin_unlock(&sb_lock); |
222 | vfs_dq_off(s, 0); |
223 | fs->kill_sb(s); |
224 | put_filesystem(fs); |
225 | put_super(s); |
226 | } else { |
227 | up_write(&s->s_umount); |
228 | } |
229 | } |
230 | |
231 | EXPORT_SYMBOL(deactivate_locked_super); |
232 | |
233 | /** |
234 | * grab_super - acquire an active reference |
235 | * @s: reference we are trying to make active |
236 | * |
237 | * Tries to acquire an active reference. grab_super() is used when we |
238 | * had just found a superblock in super_blocks or fs_type->fs_supers |
239 | * and want to turn it into a full-blown active reference. grab_super() |
240 | * is called with sb_lock held and drops it. Returns 1 in case of |
241 | * success, 0 if we had failed (superblock contents was already dead or |
242 | * dying when grab_super() had been called). |
243 | */ |
244 | static int grab_super(struct super_block *s) __releases(sb_lock) |
245 | { |
246 | s->s_count++; |
247 | spin_unlock(&sb_lock); |
248 | down_write(&s->s_umount); |
249 | if (s->s_root) { |
250 | spin_lock(&sb_lock); |
251 | if (s->s_count > S_BIAS) { |
252 | atomic_inc(&s->s_active); |
253 | s->s_count--; |
254 | spin_unlock(&sb_lock); |
255 | return 1; |
256 | } |
257 | spin_unlock(&sb_lock); |
258 | } |
259 | up_write(&s->s_umount); |
260 | put_super(s); |
261 | yield(); |
262 | return 0; |
263 | } |
264 | |
265 | /* |
266 | * Superblock locking. We really ought to get rid of these two. |
267 | */ |
268 | void lock_super(struct super_block * sb) |
269 | { |
270 | get_fs_excl(); |
271 | mutex_lock(&sb->s_lock); |
272 | } |
273 | |
274 | void unlock_super(struct super_block * sb) |
275 | { |
276 | put_fs_excl(); |
277 | mutex_unlock(&sb->s_lock); |
278 | } |
279 | |
280 | EXPORT_SYMBOL(lock_super); |
281 | EXPORT_SYMBOL(unlock_super); |
282 | |
283 | /** |
284 | * generic_shutdown_super - common helper for ->kill_sb() |
285 | * @sb: superblock to kill |
286 | * |
287 | * generic_shutdown_super() does all fs-independent work on superblock |
288 | * shutdown. Typical ->kill_sb() should pick all fs-specific objects |
289 | * that need destruction out of superblock, call generic_shutdown_super() |
290 | * and release aforementioned objects. Note: dentries and inodes _are_ |
291 | * taken care of and do not need specific handling. |
292 | * |
293 | * Upon calling this function, the filesystem may no longer alter or |
294 | * rearrange the set of dentries belonging to this super_block, nor may it |
295 | * change the attachments of dentries to inodes. |
296 | */ |
297 | void generic_shutdown_super(struct super_block *sb) |
298 | { |
299 | const struct super_operations *sop = sb->s_op; |
300 | |
301 | |
302 | if (sb->s_root) { |
303 | shrink_dcache_for_umount(sb); |
304 | sync_filesystem(sb); |
305 | get_fs_excl(); |
306 | sb->s_flags &= ~MS_ACTIVE; |
307 | |
308 | /* bad name - it should be evict_inodes() */ |
309 | invalidate_inodes(sb); |
310 | |
311 | if (sop->put_super) |
312 | sop->put_super(sb); |
313 | |
314 | /* Forget any remaining inodes */ |
315 | if (invalidate_inodes(sb)) { |
316 | printk("VFS: Busy inodes after unmount of %s. " |
317 | "Self-destruct in 5 seconds. Have a nice day...\n", |
318 | sb->s_id); |
319 | } |
320 | put_fs_excl(); |
321 | } |
322 | spin_lock(&sb_lock); |
323 | /* should be initialized for __put_super_and_need_restart() */ |
324 | list_del_init(&sb->s_list); |
325 | list_del(&sb->s_instances); |
326 | spin_unlock(&sb_lock); |
327 | up_write(&sb->s_umount); |
328 | } |
329 | |
330 | EXPORT_SYMBOL(generic_shutdown_super); |
331 | |
332 | /** |
333 | * sget - find or create a superblock |
334 | * @type: filesystem type superblock should belong to |
335 | * @test: comparison callback |
336 | * @set: setup callback |
337 | * @data: argument to each of them |
338 | */ |
339 | struct super_block *sget(struct file_system_type *type, |
340 | int (*test)(struct super_block *,void *), |
341 | int (*set)(struct super_block *,void *), |
342 | void *data) |
343 | { |
344 | struct super_block *s = NULL; |
345 | struct super_block *old; |
346 | int err; |
347 | |
348 | retry: |
349 | spin_lock(&sb_lock); |
350 | if (test) { |
351 | list_for_each_entry(old, &type->fs_supers, s_instances) { |
352 | if (!test(old, data)) |
353 | continue; |
354 | if (!grab_super(old)) |
355 | goto retry; |
356 | if (s) { |
357 | up_write(&s->s_umount); |
358 | destroy_super(s); |
359 | } |
360 | return old; |
361 | } |
362 | } |
363 | if (!s) { |
364 | spin_unlock(&sb_lock); |
365 | s = alloc_super(type); |
366 | if (!s) |
367 | return ERR_PTR(-ENOMEM); |
368 | goto retry; |
369 | } |
370 | |
371 | err = set(s, data); |
372 | if (err) { |
373 | spin_unlock(&sb_lock); |
374 | up_write(&s->s_umount); |
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 | /** |
398 | * sync_supers - helper for periodic superblock writeback |
399 | * |
400 | * Call the write_super method if present on all dirty superblocks in |
401 | * the system. This is for the periodic writeback used by most older |
402 | * filesystems. For data integrity superblock writeback use |
403 | * sync_filesystems() instead. |
404 | * |
405 | * Note: check the dirty flag before waiting, so we don't |
406 | * hold up the sync while mounting a device. (The newly |
407 | * mounted device won't need syncing.) |
408 | */ |
409 | void sync_supers(void) |
410 | { |
411 | struct super_block *sb; |
412 | |
413 | spin_lock(&sb_lock); |
414 | restart: |
415 | list_for_each_entry(sb, &super_blocks, s_list) { |
416 | if (sb->s_op->write_super && sb->s_dirt) { |
417 | sb->s_count++; |
418 | spin_unlock(&sb_lock); |
419 | |
420 | down_read(&sb->s_umount); |
421 | if (sb->s_root && sb->s_dirt) |
422 | sb->s_op->write_super(sb); |
423 | up_read(&sb->s_umount); |
424 | |
425 | spin_lock(&sb_lock); |
426 | if (__put_super_and_need_restart(sb)) |
427 | goto restart; |
428 | } |
429 | } |
430 | spin_unlock(&sb_lock); |
431 | } |
432 | |
433 | /** |
434 | * get_super - get the superblock of a device |
435 | * @bdev: device to get the superblock for |
436 | * |
437 | * Scans the superblock list and finds the superblock of the file system |
438 | * mounted on the device given. %NULL is returned if no match is found. |
439 | */ |
440 | |
441 | struct super_block * get_super(struct block_device *bdev) |
442 | { |
443 | struct super_block *sb; |
444 | |
445 | if (!bdev) |
446 | return NULL; |
447 | |
448 | spin_lock(&sb_lock); |
449 | rescan: |
450 | list_for_each_entry(sb, &super_blocks, s_list) { |
451 | if (sb->s_bdev == bdev) { |
452 | sb->s_count++; |
453 | spin_unlock(&sb_lock); |
454 | down_read(&sb->s_umount); |
455 | if (sb->s_root) |
456 | return sb; |
457 | up_read(&sb->s_umount); |
458 | /* restart only when sb is no longer on the list */ |
459 | spin_lock(&sb_lock); |
460 | if (__put_super_and_need_restart(sb)) |
461 | goto rescan; |
462 | } |
463 | } |
464 | spin_unlock(&sb_lock); |
465 | return NULL; |
466 | } |
467 | |
468 | EXPORT_SYMBOL(get_super); |
469 | |
470 | /** |
471 | * get_active_super - get an active reference to the superblock of a device |
472 | * @bdev: device to get the superblock for |
473 | * |
474 | * Scans the superblock list and finds the superblock of the file system |
475 | * mounted on the device given. Returns the superblock with an active |
476 | * reference and s_umount held exclusively or %NULL if none was found. |
477 | */ |
478 | struct super_block *get_active_super(struct block_device *bdev) |
479 | { |
480 | struct super_block *sb; |
481 | |
482 | if (!bdev) |
483 | return NULL; |
484 | |
485 | spin_lock(&sb_lock); |
486 | list_for_each_entry(sb, &super_blocks, s_list) { |
487 | if (sb->s_bdev != bdev) |
488 | continue; |
489 | |
490 | sb->s_count++; |
491 | spin_unlock(&sb_lock); |
492 | down_write(&sb->s_umount); |
493 | if (sb->s_root) { |
494 | spin_lock(&sb_lock); |
495 | if (sb->s_count > S_BIAS) { |
496 | atomic_inc(&sb->s_active); |
497 | sb->s_count--; |
498 | spin_unlock(&sb_lock); |
499 | return sb; |
500 | } |
501 | spin_unlock(&sb_lock); |
502 | } |
503 | up_write(&sb->s_umount); |
504 | put_super(sb); |
505 | yield(); |
506 | spin_lock(&sb_lock); |
507 | } |
508 | spin_unlock(&sb_lock); |
509 | return NULL; |
510 | } |
511 | |
512 | struct super_block * user_get_super(dev_t dev) |
513 | { |
514 | struct super_block *sb; |
515 | |
516 | spin_lock(&sb_lock); |
517 | rescan: |
518 | list_for_each_entry(sb, &super_blocks, s_list) { |
519 | if (sb->s_dev == dev) { |
520 | sb->s_count++; |
521 | spin_unlock(&sb_lock); |
522 | down_read(&sb->s_umount); |
523 | if (sb->s_root) |
524 | return sb; |
525 | up_read(&sb->s_umount); |
526 | /* restart only when sb is no longer on the list */ |
527 | spin_lock(&sb_lock); |
528 | if (__put_super_and_need_restart(sb)) |
529 | goto rescan; |
530 | } |
531 | } |
532 | spin_unlock(&sb_lock); |
533 | return NULL; |
534 | } |
535 | |
536 | SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf) |
537 | { |
538 | struct super_block *s; |
539 | struct ustat tmp; |
540 | struct kstatfs sbuf; |
541 | int err = -EINVAL; |
542 | |
543 | s = user_get_super(new_decode_dev(dev)); |
544 | if (s == NULL) |
545 | goto out; |
546 | err = vfs_statfs(s->s_root, &sbuf); |
547 | drop_super(s); |
548 | if (err) |
549 | goto out; |
550 | |
551 | memset(&tmp,0,sizeof(struct ustat)); |
552 | tmp.f_tfree = sbuf.f_bfree; |
553 | tmp.f_tinode = sbuf.f_ffree; |
554 | |
555 | err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0; |
556 | out: |
557 | return err; |
558 | } |
559 | |
560 | /** |
561 | * do_remount_sb - asks filesystem to change mount options. |
562 | * @sb: superblock in question |
563 | * @flags: numeric part of options |
564 | * @data: the rest of options |
565 | * @force: whether or not to force the change |
566 | * |
567 | * Alters the mount options of a mounted file system. |
568 | */ |
569 | int do_remount_sb(struct super_block *sb, int flags, void *data, int force) |
570 | { |
571 | int retval; |
572 | int remount_rw, remount_ro; |
573 | |
574 | if (sb->s_frozen != SB_UNFROZEN) |
575 | return -EBUSY; |
576 | |
577 | #ifdef CONFIG_BLOCK |
578 | if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) |
579 | return -EACCES; |
580 | #endif |
581 | |
582 | if (flags & MS_RDONLY) |
583 | acct_auto_close(sb); |
584 | shrink_dcache_sb(sb); |
585 | sync_filesystem(sb); |
586 | |
587 | remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); |
588 | remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY); |
589 | |
590 | /* If we are remounting RDONLY and current sb is read/write, |
591 | make sure there are no rw files opened */ |
592 | if (remount_ro) { |
593 | if (force) |
594 | mark_files_ro(sb); |
595 | else if (!fs_may_remount_ro(sb)) |
596 | return -EBUSY; |
597 | retval = vfs_dq_off(sb, 1); |
598 | if (retval < 0 && retval != -ENOSYS) |
599 | return -EBUSY; |
600 | } |
601 | |
602 | if (sb->s_op->remount_fs) { |
603 | retval = sb->s_op->remount_fs(sb, &flags, data); |
604 | if (retval) |
605 | return retval; |
606 | } |
607 | sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); |
608 | if (remount_rw) |
609 | vfs_dq_quota_on_remount(sb); |
610 | /* |
611 | * Some filesystems modify their metadata via some other path than the |
612 | * bdev buffer cache (eg. use a private mapping, or directories in |
613 | * pagecache, etc). Also file data modifications go via their own |
614 | * mappings. So If we try to mount readonly then copy the filesystem |
615 | * from bdev, we could get stale data, so invalidate it to give a best |
616 | * effort at coherency. |
617 | */ |
618 | if (remount_ro && sb->s_bdev) |
619 | invalidate_bdev(sb->s_bdev); |
620 | return 0; |
621 | } |
622 | |
623 | static void do_emergency_remount(struct work_struct *work) |
624 | { |
625 | struct super_block *sb; |
626 | |
627 | spin_lock(&sb_lock); |
628 | list_for_each_entry(sb, &super_blocks, s_list) { |
629 | sb->s_count++; |
630 | spin_unlock(&sb_lock); |
631 | down_write(&sb->s_umount); |
632 | if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) { |
633 | /* |
634 | * ->remount_fs needs lock_kernel(). |
635 | * |
636 | * What lock protects sb->s_flags?? |
637 | */ |
638 | do_remount_sb(sb, MS_RDONLY, NULL, 1); |
639 | } |
640 | up_write(&sb->s_umount); |
641 | put_super(sb); |
642 | spin_lock(&sb_lock); |
643 | } |
644 | spin_unlock(&sb_lock); |
645 | kfree(work); |
646 | printk("Emergency Remount complete\n"); |
647 | } |
648 | |
649 | void emergency_remount(void) |
650 | { |
651 | struct work_struct *work; |
652 | |
653 | work = kmalloc(sizeof(*work), GFP_ATOMIC); |
654 | if (work) { |
655 | INIT_WORK(work, do_emergency_remount); |
656 | schedule_work(work); |
657 | } |
658 | } |
659 | |
660 | /* |
661 | * Unnamed block devices are dummy devices used by virtual |
662 | * filesystems which don't use real block-devices. -- jrs |
663 | */ |
664 | |
665 | static DEFINE_IDA(unnamed_dev_ida); |
666 | static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ |
667 | static int unnamed_dev_start = 0; /* don't bother trying below it */ |
668 | |
669 | int set_anon_super(struct super_block *s, void *data) |
670 | { |
671 | int dev; |
672 | int error; |
673 | |
674 | retry: |
675 | if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) |
676 | return -ENOMEM; |
677 | spin_lock(&unnamed_dev_lock); |
678 | error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev); |
679 | if (!error) |
680 | unnamed_dev_start = dev + 1; |
681 | spin_unlock(&unnamed_dev_lock); |
682 | if (error == -EAGAIN) |
683 | /* We raced and lost with another CPU. */ |
684 | goto retry; |
685 | else if (error) |
686 | return -EAGAIN; |
687 | |
688 | if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { |
689 | spin_lock(&unnamed_dev_lock); |
690 | ida_remove(&unnamed_dev_ida, dev); |
691 | if (unnamed_dev_start > dev) |
692 | unnamed_dev_start = dev; |
693 | spin_unlock(&unnamed_dev_lock); |
694 | return -EMFILE; |
695 | } |
696 | s->s_dev = MKDEV(0, dev & MINORMASK); |
697 | s->s_bdi = &noop_backing_dev_info; |
698 | return 0; |
699 | } |
700 | |
701 | EXPORT_SYMBOL(set_anon_super); |
702 | |
703 | void kill_anon_super(struct super_block *sb) |
704 | { |
705 | int slot = MINOR(sb->s_dev); |
706 | |
707 | generic_shutdown_super(sb); |
708 | spin_lock(&unnamed_dev_lock); |
709 | ida_remove(&unnamed_dev_ida, slot); |
710 | if (slot < unnamed_dev_start) |
711 | unnamed_dev_start = slot; |
712 | spin_unlock(&unnamed_dev_lock); |
713 | } |
714 | |
715 | EXPORT_SYMBOL(kill_anon_super); |
716 | |
717 | void kill_litter_super(struct super_block *sb) |
718 | { |
719 | if (sb->s_root) |
720 | d_genocide(sb->s_root); |
721 | kill_anon_super(sb); |
722 | } |
723 | |
724 | EXPORT_SYMBOL(kill_litter_super); |
725 | |
726 | static int ns_test_super(struct super_block *sb, void *data) |
727 | { |
728 | return sb->s_fs_info == data; |
729 | } |
730 | |
731 | static int ns_set_super(struct super_block *sb, void *data) |
732 | { |
733 | sb->s_fs_info = data; |
734 | return set_anon_super(sb, NULL); |
735 | } |
736 | |
737 | int get_sb_ns(struct file_system_type *fs_type, int flags, void *data, |
738 | int (*fill_super)(struct super_block *, void *, int), |
739 | struct vfsmount *mnt) |
740 | { |
741 | struct super_block *sb; |
742 | |
743 | sb = sget(fs_type, ns_test_super, ns_set_super, data); |
744 | if (IS_ERR(sb)) |
745 | return PTR_ERR(sb); |
746 | |
747 | if (!sb->s_root) { |
748 | int err; |
749 | sb->s_flags = flags; |
750 | err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); |
751 | if (err) { |
752 | deactivate_locked_super(sb); |
753 | return err; |
754 | } |
755 | |
756 | sb->s_flags |= MS_ACTIVE; |
757 | } |
758 | |
759 | simple_set_mnt(mnt, sb); |
760 | return 0; |
761 | } |
762 | |
763 | EXPORT_SYMBOL(get_sb_ns); |
764 | |
765 | #ifdef CONFIG_BLOCK |
766 | static int set_bdev_super(struct super_block *s, void *data) |
767 | { |
768 | s->s_bdev = data; |
769 | s->s_dev = s->s_bdev->bd_dev; |
770 | |
771 | /* |
772 | * We set the bdi here to the queue backing, file systems can |
773 | * overwrite this in ->fill_super() |
774 | */ |
775 | s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info; |
776 | return 0; |
777 | } |
778 | |
779 | static int test_bdev_super(struct super_block *s, void *data) |
780 | { |
781 | return (void *)s->s_bdev == data; |
782 | } |
783 | |
784 | int get_sb_bdev(struct file_system_type *fs_type, |
785 | int flags, const char *dev_name, void *data, |
786 | int (*fill_super)(struct super_block *, void *, int), |
787 | struct vfsmount *mnt) |
788 | { |
789 | struct block_device *bdev; |
790 | struct super_block *s; |
791 | fmode_t mode = FMODE_READ; |
792 | int error = 0; |
793 | |
794 | if (!(flags & MS_RDONLY)) |
795 | mode |= FMODE_WRITE; |
796 | |
797 | bdev = open_bdev_exclusive(dev_name, mode, fs_type); |
798 | if (IS_ERR(bdev)) |
799 | return PTR_ERR(bdev); |
800 | |
801 | /* |
802 | * once the super is inserted into the list by sget, s_umount |
803 | * will protect the lockfs code from trying to start a snapshot |
804 | * while we are mounting |
805 | */ |
806 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
807 | if (bdev->bd_fsfreeze_count > 0) { |
808 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
809 | error = -EBUSY; |
810 | goto error_bdev; |
811 | } |
812 | s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); |
813 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
814 | if (IS_ERR(s)) |
815 | goto error_s; |
816 | |
817 | if (s->s_root) { |
818 | if ((flags ^ s->s_flags) & MS_RDONLY) { |
819 | deactivate_locked_super(s); |
820 | error = -EBUSY; |
821 | goto error_bdev; |
822 | } |
823 | |
824 | close_bdev_exclusive(bdev, mode); |
825 | } else { |
826 | char b[BDEVNAME_SIZE]; |
827 | |
828 | s->s_flags = flags; |
829 | s->s_mode = mode; |
830 | strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); |
831 | sb_set_blocksize(s, block_size(bdev)); |
832 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
833 | if (error) { |
834 | deactivate_locked_super(s); |
835 | goto error; |
836 | } |
837 | |
838 | s->s_flags |= MS_ACTIVE; |
839 | bdev->bd_super = s; |
840 | } |
841 | |
842 | simple_set_mnt(mnt, s); |
843 | return 0; |
844 | |
845 | error_s: |
846 | error = PTR_ERR(s); |
847 | error_bdev: |
848 | close_bdev_exclusive(bdev, mode); |
849 | error: |
850 | return error; |
851 | } |
852 | |
853 | EXPORT_SYMBOL(get_sb_bdev); |
854 | |
855 | void kill_block_super(struct super_block *sb) |
856 | { |
857 | struct block_device *bdev = sb->s_bdev; |
858 | fmode_t mode = sb->s_mode; |
859 | |
860 | bdev->bd_super = NULL; |
861 | generic_shutdown_super(sb); |
862 | sync_blockdev(bdev); |
863 | close_bdev_exclusive(bdev, mode); |
864 | } |
865 | |
866 | EXPORT_SYMBOL(kill_block_super); |
867 | #endif |
868 | |
869 | int get_sb_nodev(struct file_system_type *fs_type, |
870 | int flags, void *data, |
871 | int (*fill_super)(struct super_block *, void *, int), |
872 | struct vfsmount *mnt) |
873 | { |
874 | int error; |
875 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); |
876 | |
877 | if (IS_ERR(s)) |
878 | return PTR_ERR(s); |
879 | |
880 | s->s_flags = flags; |
881 | |
882 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
883 | if (error) { |
884 | deactivate_locked_super(s); |
885 | return error; |
886 | } |
887 | s->s_flags |= MS_ACTIVE; |
888 | simple_set_mnt(mnt, s); |
889 | return 0; |
890 | } |
891 | |
892 | EXPORT_SYMBOL(get_sb_nodev); |
893 | |
894 | static int compare_single(struct super_block *s, void *p) |
895 | { |
896 | return 1; |
897 | } |
898 | |
899 | int get_sb_single(struct file_system_type *fs_type, |
900 | int flags, void *data, |
901 | int (*fill_super)(struct super_block *, void *, int), |
902 | struct vfsmount *mnt) |
903 | { |
904 | struct super_block *s; |
905 | int error; |
906 | |
907 | s = sget(fs_type, compare_single, set_anon_super, NULL); |
908 | if (IS_ERR(s)) |
909 | return PTR_ERR(s); |
910 | if (!s->s_root) { |
911 | s->s_flags = flags; |
912 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
913 | if (error) { |
914 | deactivate_locked_super(s); |
915 | return error; |
916 | } |
917 | s->s_flags |= MS_ACTIVE; |
918 | } else { |
919 | do_remount_sb(s, flags, data, 0); |
920 | } |
921 | simple_set_mnt(mnt, s); |
922 | return 0; |
923 | } |
924 | |
925 | EXPORT_SYMBOL(get_sb_single); |
926 | |
927 | struct vfsmount * |
928 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) |
929 | { |
930 | struct vfsmount *mnt; |
931 | char *secdata = NULL; |
932 | int error; |
933 | |
934 | if (!type) |
935 | return ERR_PTR(-ENODEV); |
936 | |
937 | error = -ENOMEM; |
938 | mnt = alloc_vfsmnt(name); |
939 | if (!mnt) |
940 | goto out; |
941 | |
942 | if (flags & MS_KERNMOUNT) |
943 | mnt->mnt_flags = MNT_INTERNAL; |
944 | |
945 | if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { |
946 | secdata = alloc_secdata(); |
947 | if (!secdata) |
948 | goto out_mnt; |
949 | |
950 | error = security_sb_copy_data(data, secdata); |
951 | if (error) |
952 | goto out_free_secdata; |
953 | } |
954 | |
955 | error = type->get_sb(type, flags, name, data, mnt); |
956 | if (error < 0) |
957 | goto out_free_secdata; |
958 | BUG_ON(!mnt->mnt_sb); |
959 | WARN_ON(!mnt->mnt_sb->s_bdi); |
960 | |
961 | error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata); |
962 | if (error) |
963 | goto out_sb; |
964 | |
965 | /* |
966 | * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE |
967 | * but s_maxbytes was an unsigned long long for many releases. Throw |
968 | * this warning for a little while to try and catch filesystems that |
969 | * violate this rule. This warning should be either removed or |
970 | * converted to a BUG() in 2.6.34. |
971 | */ |
972 | WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " |
973 | "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes); |
974 | |
975 | mnt->mnt_mountpoint = mnt->mnt_root; |
976 | mnt->mnt_parent = mnt; |
977 | up_write(&mnt->mnt_sb->s_umount); |
978 | free_secdata(secdata); |
979 | return mnt; |
980 | out_sb: |
981 | dput(mnt->mnt_root); |
982 | deactivate_locked_super(mnt->mnt_sb); |
983 | out_free_secdata: |
984 | free_secdata(secdata); |
985 | out_mnt: |
986 | free_vfsmnt(mnt); |
987 | out: |
988 | return ERR_PTR(error); |
989 | } |
990 | |
991 | EXPORT_SYMBOL_GPL(vfs_kern_mount); |
992 | |
993 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
994 | { |
995 | int err; |
996 | const char *subtype = strchr(fstype, '.'); |
997 | if (subtype) { |
998 | subtype++; |
999 | err = -EINVAL; |
1000 | if (!subtype[0]) |
1001 | goto err; |
1002 | } else |
1003 | subtype = ""; |
1004 | |
1005 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); |
1006 | err = -ENOMEM; |
1007 | if (!mnt->mnt_sb->s_subtype) |
1008 | goto err; |
1009 | return mnt; |
1010 | |
1011 | err: |
1012 | mntput(mnt); |
1013 | return ERR_PTR(err); |
1014 | } |
1015 | |
1016 | struct vfsmount * |
1017 | do_kern_mount(const char *fstype, int flags, const char *name, void *data) |
1018 | { |
1019 | struct file_system_type *type = get_fs_type(fstype); |
1020 | struct vfsmount *mnt; |
1021 | if (!type) |
1022 | return ERR_PTR(-ENODEV); |
1023 | mnt = vfs_kern_mount(type, flags, name, data); |
1024 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && |
1025 | !mnt->mnt_sb->s_subtype) |
1026 | mnt = fs_set_subtype(mnt, fstype); |
1027 | put_filesystem(type); |
1028 | return mnt; |
1029 | } |
1030 | EXPORT_SYMBOL_GPL(do_kern_mount); |
1031 | |
1032 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) |
1033 | { |
1034 | return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); |
1035 | } |
1036 | |
1037 | EXPORT_SYMBOL_GPL(kern_mount_data); |
1038 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9