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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 <asm/uaccess.h> |
41 | #include "internal.h" |
42 | |
43 | |
44 | LIST_HEAD(super_blocks); |
45 | DEFINE_SPINLOCK(sb_lock); |
46 | |
47 | /** |
48 | * alloc_super - create new superblock |
49 | * @type: filesystem type superblock should belong to |
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 | */ |
54 | static struct super_block *alloc_super(struct file_system_type *type) |
55 | { |
56 | struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); |
57 | static struct super_operations default_op; |
58 | |
59 | if (s) { |
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); |
67 | INIT_LIST_HEAD(&s->s_more_io); |
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); |
72 | INIT_LIST_HEAD(&s->s_dentry_lru); |
73 | init_rwsem(&s->s_umount); |
74 | mutex_init(&s->s_lock); |
75 | lockdep_set_class(&s->s_umount, &type->s_umount_key); |
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); |
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); |
98 | s->s_count = S_BIAS; |
99 | atomic_set(&s->s_active, 1); |
100 | mutex_init(&s->s_vfs_rename_mutex); |
101 | mutex_init(&s->s_dquot.dqio_mutex); |
102 | mutex_init(&s->s_dquot.dqonoff_mutex); |
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); |
124 | kfree(s->s_subtype); |
125 | kfree(s->s_options); |
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 | */ |
135 | static int __put_super(struct super_block *sb) |
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); |
197 | vfs_dq_off(s, 0); |
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 | |
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 | |
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 | */ |
246 | static int grab_super(struct super_block *s) __releases(sb_lock) |
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 | |
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 | |
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. |
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. |
298 | */ |
299 | void generic_shutdown_super(struct super_block *sb) |
300 | { |
301 | const struct super_operations *sop = sb->s_op; |
302 | |
303 | |
304 | if (sb->s_root) { |
305 | shrink_dcache_for_umount(sb); |
306 | sync_filesystem(sb); |
307 | get_fs_excl(); |
308 | sb->s_flags &= ~MS_ACTIVE; |
309 | |
310 | /* bad name - it should be evict_inodes() */ |
311 | invalidate_inodes(sb); |
312 | |
313 | if (sop->put_super) |
314 | sop->put_super(sb); |
315 | |
316 | /* Forget any remaining inodes */ |
317 | if (invalidate_inodes(sb)) { |
318 | printk("VFS: Busy inodes after unmount of %s. " |
319 | "Self-destruct in 5 seconds. Have a nice day...\n", |
320 | sb->s_id); |
321 | } |
322 | put_fs_excl(); |
323 | } |
324 | spin_lock(&sb_lock); |
325 | /* should be initialized for __put_super_and_need_restart() */ |
326 | list_del_init(&sb->s_list); |
327 | list_del(&sb->s_instances); |
328 | spin_unlock(&sb_lock); |
329 | up_write(&sb->s_umount); |
330 | } |
331 | |
332 | EXPORT_SYMBOL(generic_shutdown_super); |
333 | |
334 | /** |
335 | * sget - find or create a superblock |
336 | * @type: filesystem type superblock should belong to |
337 | * @test: comparison callback |
338 | * @set: setup callback |
339 | * @data: argument to each of them |
340 | */ |
341 | struct super_block *sget(struct file_system_type *type, |
342 | int (*test)(struct super_block *,void *), |
343 | int (*set)(struct super_block *,void *), |
344 | void *data) |
345 | { |
346 | struct super_block *s = NULL; |
347 | struct super_block *old; |
348 | int err; |
349 | |
350 | retry: |
351 | spin_lock(&sb_lock); |
352 | if (test) { |
353 | list_for_each_entry(old, &type->fs_supers, s_instances) { |
354 | if (!test(old, data)) |
355 | continue; |
356 | if (!grab_super(old)) |
357 | goto retry; |
358 | if (s) { |
359 | up_write(&s->s_umount); |
360 | destroy_super(s); |
361 | } |
362 | return old; |
363 | } |
364 | } |
365 | if (!s) { |
366 | spin_unlock(&sb_lock); |
367 | s = alloc_super(type); |
368 | if (!s) |
369 | return ERR_PTR(-ENOMEM); |
370 | goto retry; |
371 | } |
372 | |
373 | err = set(s, data); |
374 | if (err) { |
375 | spin_unlock(&sb_lock); |
376 | up_write(&s->s_umount); |
377 | destroy_super(s); |
378 | return ERR_PTR(err); |
379 | } |
380 | s->s_type = type; |
381 | strlcpy(s->s_id, type->name, sizeof(s->s_id)); |
382 | list_add_tail(&s->s_list, &super_blocks); |
383 | list_add(&s->s_instances, &type->fs_supers); |
384 | spin_unlock(&sb_lock); |
385 | get_filesystem(type); |
386 | return s; |
387 | } |
388 | |
389 | EXPORT_SYMBOL(sget); |
390 | |
391 | void drop_super(struct super_block *sb) |
392 | { |
393 | up_read(&sb->s_umount); |
394 | put_super(sb); |
395 | } |
396 | |
397 | EXPORT_SYMBOL(drop_super); |
398 | |
399 | /** |
400 | * sync_supers - helper for periodic superblock writeback |
401 | * |
402 | * Call the write_super method if present on all dirty superblocks in |
403 | * the system. This is for the periodic writeback used by most older |
404 | * filesystems. For data integrity superblock writeback use |
405 | * sync_filesystems() instead. |
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 | { |
413 | struct super_block *sb; |
414 | |
415 | spin_lock(&sb_lock); |
416 | restart: |
417 | list_for_each_entry(sb, &super_blocks, s_list) { |
418 | if (sb->s_op->write_super && sb->s_dirt) { |
419 | sb->s_count++; |
420 | spin_unlock(&sb_lock); |
421 | |
422 | down_read(&sb->s_umount); |
423 | if (sb->s_root && sb->s_dirt) |
424 | sb->s_op->write_super(sb); |
425 | up_read(&sb->s_umount); |
426 | |
427 | spin_lock(&sb_lock); |
428 | if (__put_super_and_need_restart(sb)) |
429 | goto restart; |
430 | } |
431 | } |
432 | spin_unlock(&sb_lock); |
433 | } |
434 | |
435 | /** |
436 | * get_super - get the superblock of a device |
437 | * @bdev: device to get the superblock for |
438 | * |
439 | * Scans the superblock list and finds the superblock of the file system |
440 | * mounted on the device given. %NULL is returned if no match is found. |
441 | */ |
442 | |
443 | struct super_block * get_super(struct block_device *bdev) |
444 | { |
445 | struct super_block *sb; |
446 | |
447 | if (!bdev) |
448 | return NULL; |
449 | |
450 | spin_lock(&sb_lock); |
451 | rescan: |
452 | list_for_each_entry(sb, &super_blocks, s_list) { |
453 | if (sb->s_bdev == bdev) { |
454 | sb->s_count++; |
455 | spin_unlock(&sb_lock); |
456 | down_read(&sb->s_umount); |
457 | if (sb->s_root) |
458 | return sb; |
459 | up_read(&sb->s_umount); |
460 | /* restart only when sb is no longer on the list */ |
461 | spin_lock(&sb_lock); |
462 | if (__put_super_and_need_restart(sb)) |
463 | goto rescan; |
464 | } |
465 | } |
466 | spin_unlock(&sb_lock); |
467 | return NULL; |
468 | } |
469 | |
470 | EXPORT_SYMBOL(get_super); |
471 | |
472 | struct super_block * user_get_super(dev_t dev) |
473 | { |
474 | struct super_block *sb; |
475 | |
476 | spin_lock(&sb_lock); |
477 | rescan: |
478 | list_for_each_entry(sb, &super_blocks, s_list) { |
479 | if (sb->s_dev == dev) { |
480 | sb->s_count++; |
481 | spin_unlock(&sb_lock); |
482 | down_read(&sb->s_umount); |
483 | if (sb->s_root) |
484 | return sb; |
485 | up_read(&sb->s_umount); |
486 | /* restart only when sb is no longer on the list */ |
487 | spin_lock(&sb_lock); |
488 | if (__put_super_and_need_restart(sb)) |
489 | goto rescan; |
490 | } |
491 | } |
492 | spin_unlock(&sb_lock); |
493 | return NULL; |
494 | } |
495 | |
496 | SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf) |
497 | { |
498 | struct super_block *s; |
499 | struct ustat tmp; |
500 | struct kstatfs sbuf; |
501 | int err = -EINVAL; |
502 | |
503 | s = user_get_super(new_decode_dev(dev)); |
504 | if (s == NULL) |
505 | goto out; |
506 | err = vfs_statfs(s->s_root, &sbuf); |
507 | drop_super(s); |
508 | if (err) |
509 | goto out; |
510 | |
511 | memset(&tmp,0,sizeof(struct ustat)); |
512 | tmp.f_tfree = sbuf.f_bfree; |
513 | tmp.f_tinode = sbuf.f_ffree; |
514 | |
515 | err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0; |
516 | out: |
517 | return err; |
518 | } |
519 | |
520 | /** |
521 | * do_remount_sb - asks filesystem to change mount options. |
522 | * @sb: superblock in question |
523 | * @flags: numeric part of options |
524 | * @data: the rest of options |
525 | * @force: whether or not to force the change |
526 | * |
527 | * Alters the mount options of a mounted file system. |
528 | */ |
529 | int do_remount_sb(struct super_block *sb, int flags, void *data, int force) |
530 | { |
531 | int retval; |
532 | int remount_rw; |
533 | |
534 | #ifdef CONFIG_BLOCK |
535 | if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) |
536 | return -EACCES; |
537 | #endif |
538 | if (flags & MS_RDONLY) |
539 | acct_auto_close(sb); |
540 | shrink_dcache_sb(sb); |
541 | sync_filesystem(sb); |
542 | |
543 | /* If we are remounting RDONLY and current sb is read/write, |
544 | make sure there are no rw files opened */ |
545 | if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) { |
546 | if (force) |
547 | mark_files_ro(sb); |
548 | else if (!fs_may_remount_ro(sb)) |
549 | return -EBUSY; |
550 | retval = vfs_dq_off(sb, 1); |
551 | if (retval < 0 && retval != -ENOSYS) |
552 | return -EBUSY; |
553 | } |
554 | remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY); |
555 | |
556 | if (sb->s_op->remount_fs) { |
557 | retval = sb->s_op->remount_fs(sb, &flags, data); |
558 | if (retval) |
559 | return retval; |
560 | } |
561 | sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); |
562 | if (remount_rw) |
563 | vfs_dq_quota_on_remount(sb); |
564 | return 0; |
565 | } |
566 | |
567 | static void do_emergency_remount(struct work_struct *work) |
568 | { |
569 | struct super_block *sb; |
570 | |
571 | spin_lock(&sb_lock); |
572 | list_for_each_entry(sb, &super_blocks, s_list) { |
573 | sb->s_count++; |
574 | spin_unlock(&sb_lock); |
575 | down_write(&sb->s_umount); |
576 | if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) { |
577 | /* |
578 | * ->remount_fs needs lock_kernel(). |
579 | * |
580 | * What lock protects sb->s_flags?? |
581 | */ |
582 | do_remount_sb(sb, MS_RDONLY, NULL, 1); |
583 | } |
584 | up_write(&sb->s_umount); |
585 | put_super(sb); |
586 | spin_lock(&sb_lock); |
587 | } |
588 | spin_unlock(&sb_lock); |
589 | kfree(work); |
590 | printk("Emergency Remount complete\n"); |
591 | } |
592 | |
593 | void emergency_remount(void) |
594 | { |
595 | struct work_struct *work; |
596 | |
597 | work = kmalloc(sizeof(*work), GFP_ATOMIC); |
598 | if (work) { |
599 | INIT_WORK(work, do_emergency_remount); |
600 | schedule_work(work); |
601 | } |
602 | } |
603 | |
604 | /* |
605 | * Unnamed block devices are dummy devices used by virtual |
606 | * filesystems which don't use real block-devices. -- jrs |
607 | */ |
608 | |
609 | static DEFINE_IDA(unnamed_dev_ida); |
610 | static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ |
611 | static int unnamed_dev_start = 0; /* don't bother trying below it */ |
612 | |
613 | int set_anon_super(struct super_block *s, void *data) |
614 | { |
615 | int dev; |
616 | int error; |
617 | |
618 | retry: |
619 | if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) |
620 | return -ENOMEM; |
621 | spin_lock(&unnamed_dev_lock); |
622 | error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev); |
623 | if (!error) |
624 | unnamed_dev_start = dev + 1; |
625 | spin_unlock(&unnamed_dev_lock); |
626 | if (error == -EAGAIN) |
627 | /* We raced and lost with another CPU. */ |
628 | goto retry; |
629 | else if (error) |
630 | return -EAGAIN; |
631 | |
632 | if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { |
633 | spin_lock(&unnamed_dev_lock); |
634 | ida_remove(&unnamed_dev_ida, dev); |
635 | if (unnamed_dev_start > dev) |
636 | unnamed_dev_start = dev; |
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); |
652 | ida_remove(&unnamed_dev_ida, slot); |
653 | if (slot < unnamed_dev_start) |
654 | unnamed_dev_start = slot; |
655 | spin_unlock(&unnamed_dev_lock); |
656 | } |
657 | |
658 | EXPORT_SYMBOL(kill_anon_super); |
659 | |
660 | void kill_litter_super(struct super_block *sb) |
661 | { |
662 | if (sb->s_root) |
663 | d_genocide(sb->s_root); |
664 | kill_anon_super(sb); |
665 | } |
666 | |
667 | EXPORT_SYMBOL(kill_litter_super); |
668 | |
669 | static int ns_test_super(struct super_block *sb, void *data) |
670 | { |
671 | return sb->s_fs_info == data; |
672 | } |
673 | |
674 | static int ns_set_super(struct super_block *sb, void *data) |
675 | { |
676 | sb->s_fs_info = data; |
677 | return set_anon_super(sb, NULL); |
678 | } |
679 | |
680 | int get_sb_ns(struct file_system_type *fs_type, int flags, void *data, |
681 | int (*fill_super)(struct super_block *, void *, int), |
682 | struct vfsmount *mnt) |
683 | { |
684 | struct super_block *sb; |
685 | |
686 | sb = sget(fs_type, ns_test_super, ns_set_super, data); |
687 | if (IS_ERR(sb)) |
688 | return PTR_ERR(sb); |
689 | |
690 | if (!sb->s_root) { |
691 | int err; |
692 | sb->s_flags = flags; |
693 | err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); |
694 | if (err) { |
695 | deactivate_locked_super(sb); |
696 | return err; |
697 | } |
698 | |
699 | sb->s_flags |= MS_ACTIVE; |
700 | } |
701 | |
702 | simple_set_mnt(mnt, sb); |
703 | return 0; |
704 | } |
705 | |
706 | EXPORT_SYMBOL(get_sb_ns); |
707 | |
708 | #ifdef CONFIG_BLOCK |
709 | static int set_bdev_super(struct super_block *s, void *data) |
710 | { |
711 | s->s_bdev = data; |
712 | s->s_dev = s->s_bdev->bd_dev; |
713 | return 0; |
714 | } |
715 | |
716 | static int test_bdev_super(struct super_block *s, void *data) |
717 | { |
718 | return (void *)s->s_bdev == data; |
719 | } |
720 | |
721 | int get_sb_bdev(struct file_system_type *fs_type, |
722 | int flags, const char *dev_name, void *data, |
723 | int (*fill_super)(struct super_block *, void *, int), |
724 | struct vfsmount *mnt) |
725 | { |
726 | struct block_device *bdev; |
727 | struct super_block *s; |
728 | fmode_t mode = FMODE_READ; |
729 | int error = 0; |
730 | |
731 | if (!(flags & MS_RDONLY)) |
732 | mode |= FMODE_WRITE; |
733 | |
734 | bdev = open_bdev_exclusive(dev_name, mode, fs_type); |
735 | if (IS_ERR(bdev)) |
736 | return PTR_ERR(bdev); |
737 | |
738 | /* |
739 | * once the super is inserted into the list by sget, s_umount |
740 | * will protect the lockfs code from trying to start a snapshot |
741 | * while we are mounting |
742 | */ |
743 | down(&bdev->bd_mount_sem); |
744 | s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); |
745 | up(&bdev->bd_mount_sem); |
746 | if (IS_ERR(s)) |
747 | goto error_s; |
748 | |
749 | if (s->s_root) { |
750 | if ((flags ^ s->s_flags) & MS_RDONLY) { |
751 | deactivate_locked_super(s); |
752 | error = -EBUSY; |
753 | goto error_bdev; |
754 | } |
755 | |
756 | close_bdev_exclusive(bdev, mode); |
757 | } else { |
758 | char b[BDEVNAME_SIZE]; |
759 | |
760 | s->s_flags = flags; |
761 | s->s_mode = mode; |
762 | strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); |
763 | sb_set_blocksize(s, block_size(bdev)); |
764 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
765 | if (error) { |
766 | deactivate_locked_super(s); |
767 | goto error; |
768 | } |
769 | |
770 | s->s_flags |= MS_ACTIVE; |
771 | bdev->bd_super = s; |
772 | } |
773 | |
774 | simple_set_mnt(mnt, s); |
775 | return 0; |
776 | |
777 | error_s: |
778 | error = PTR_ERR(s); |
779 | error_bdev: |
780 | close_bdev_exclusive(bdev, mode); |
781 | error: |
782 | return error; |
783 | } |
784 | |
785 | EXPORT_SYMBOL(get_sb_bdev); |
786 | |
787 | void kill_block_super(struct super_block *sb) |
788 | { |
789 | struct block_device *bdev = sb->s_bdev; |
790 | fmode_t mode = sb->s_mode; |
791 | |
792 | bdev->bd_super = NULL; |
793 | generic_shutdown_super(sb); |
794 | sync_blockdev(bdev); |
795 | close_bdev_exclusive(bdev, mode); |
796 | } |
797 | |
798 | EXPORT_SYMBOL(kill_block_super); |
799 | #endif |
800 | |
801 | int get_sb_nodev(struct file_system_type *fs_type, |
802 | int flags, void *data, |
803 | int (*fill_super)(struct super_block *, void *, int), |
804 | struct vfsmount *mnt) |
805 | { |
806 | int error; |
807 | struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); |
808 | |
809 | if (IS_ERR(s)) |
810 | return PTR_ERR(s); |
811 | |
812 | s->s_flags = flags; |
813 | |
814 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
815 | if (error) { |
816 | deactivate_locked_super(s); |
817 | return error; |
818 | } |
819 | s->s_flags |= MS_ACTIVE; |
820 | simple_set_mnt(mnt, s); |
821 | return 0; |
822 | } |
823 | |
824 | EXPORT_SYMBOL(get_sb_nodev); |
825 | |
826 | static int compare_single(struct super_block *s, void *p) |
827 | { |
828 | return 1; |
829 | } |
830 | |
831 | int get_sb_single(struct file_system_type *fs_type, |
832 | int flags, void *data, |
833 | int (*fill_super)(struct super_block *, void *, int), |
834 | struct vfsmount *mnt) |
835 | { |
836 | struct super_block *s; |
837 | int error; |
838 | |
839 | s = sget(fs_type, compare_single, set_anon_super, NULL); |
840 | if (IS_ERR(s)) |
841 | return PTR_ERR(s); |
842 | if (!s->s_root) { |
843 | s->s_flags = flags; |
844 | error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); |
845 | if (error) { |
846 | deactivate_locked_super(s); |
847 | return error; |
848 | } |
849 | s->s_flags |= MS_ACTIVE; |
850 | } |
851 | do_remount_sb(s, flags, data, 0); |
852 | simple_set_mnt(mnt, s); |
853 | return 0; |
854 | } |
855 | |
856 | EXPORT_SYMBOL(get_sb_single); |
857 | |
858 | struct vfsmount * |
859 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) |
860 | { |
861 | struct vfsmount *mnt; |
862 | char *secdata = NULL; |
863 | int error; |
864 | |
865 | if (!type) |
866 | return ERR_PTR(-ENODEV); |
867 | |
868 | error = -ENOMEM; |
869 | mnt = alloc_vfsmnt(name); |
870 | if (!mnt) |
871 | goto out; |
872 | |
873 | if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { |
874 | secdata = alloc_secdata(); |
875 | if (!secdata) |
876 | goto out_mnt; |
877 | |
878 | error = security_sb_copy_data(data, secdata); |
879 | if (error) |
880 | goto out_free_secdata; |
881 | } |
882 | |
883 | error = type->get_sb(type, flags, name, data, mnt); |
884 | if (error < 0) |
885 | goto out_free_secdata; |
886 | BUG_ON(!mnt->mnt_sb); |
887 | |
888 | error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata); |
889 | if (error) |
890 | goto out_sb; |
891 | |
892 | mnt->mnt_mountpoint = mnt->mnt_root; |
893 | mnt->mnt_parent = mnt; |
894 | up_write(&mnt->mnt_sb->s_umount); |
895 | free_secdata(secdata); |
896 | return mnt; |
897 | out_sb: |
898 | dput(mnt->mnt_root); |
899 | deactivate_locked_super(mnt->mnt_sb); |
900 | out_free_secdata: |
901 | free_secdata(secdata); |
902 | out_mnt: |
903 | free_vfsmnt(mnt); |
904 | out: |
905 | return ERR_PTR(error); |
906 | } |
907 | |
908 | EXPORT_SYMBOL_GPL(vfs_kern_mount); |
909 | |
910 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
911 | { |
912 | int err; |
913 | const char *subtype = strchr(fstype, '.'); |
914 | if (subtype) { |
915 | subtype++; |
916 | err = -EINVAL; |
917 | if (!subtype[0]) |
918 | goto err; |
919 | } else |
920 | subtype = ""; |
921 | |
922 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); |
923 | err = -ENOMEM; |
924 | if (!mnt->mnt_sb->s_subtype) |
925 | goto err; |
926 | return mnt; |
927 | |
928 | err: |
929 | mntput(mnt); |
930 | return ERR_PTR(err); |
931 | } |
932 | |
933 | struct vfsmount * |
934 | do_kern_mount(const char *fstype, int flags, const char *name, void *data) |
935 | { |
936 | struct file_system_type *type = get_fs_type(fstype); |
937 | struct vfsmount *mnt; |
938 | if (!type) |
939 | return ERR_PTR(-ENODEV); |
940 | mnt = vfs_kern_mount(type, flags, name, data); |
941 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && |
942 | !mnt->mnt_sb->s_subtype) |
943 | mnt = fs_set_subtype(mnt, fstype); |
944 | put_filesystem(type); |
945 | return mnt; |
946 | } |
947 | EXPORT_SYMBOL_GPL(do_kern_mount); |
948 | |
949 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) |
950 | { |
951 | return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); |
952 | } |
953 | |
954 | EXPORT_SYMBOL_GPL(kern_mount_data); |
955 |
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v2.6.34-rc5
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