blob: 938119ab8dcbc28f3f9853bc0808d6d70cd51d55 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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:
Jan Engelhardt96de0e22007-10-19 23:21:04 +020018 * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
Linus Torvalds1da177e2005-04-16 15:20:36 -070019 * 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/module.h>
24#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/acct.h>
26#include <linux/blkdev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/mount.h>
28#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/writeback.h> /* for the emergency remount stuff */
30#include <linux/idr.h>
Ingo Molnar353ab6e2006-03-26 01:37:12 -080031#include <linux/mutex.h>
Jens Axboe5477d0f2010-04-29 20:33:35 +020032#include <linux/backing-dev.h>
Al Viro6d59e7f2008-03-22 15:48:17 -040033#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
35
Linus Torvalds1da177e2005-04-16 15:20:36 -070036LIST_HEAD(super_blocks);
37DEFINE_SPINLOCK(sb_lock);
38
39/**
40 * alloc_super - create new superblock
Henrik Kretzschmarfe2bbc42006-09-06 00:03:41 -070041 * @type: filesystem type superblock should belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -070042 *
43 * Allocates and initializes a new &struct super_block. alloc_super()
44 * returns a pointer new superblock or %NULL if allocation had failed.
45 */
Ingo Molnarcf516242006-07-03 00:25:27 -070046static struct super_block *alloc_super(struct file_system_type *type)
Linus Torvalds1da177e2005-04-16 15:20:36 -070047{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -080048 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
Alexey Dobriyanb87221d2009-09-21 17:01:09 -070049 static const struct super_operations default_op;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
51 if (s) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 if (security_sb_alloc(s)) {
53 kfree(s);
54 s = NULL;
55 goto out;
56 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 INIT_LIST_HEAD(&s->s_files);
58 INIT_LIST_HEAD(&s->s_instances);
59 INIT_HLIST_HEAD(&s->s_anon);
60 INIT_LIST_HEAD(&s->s_inodes);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -070061 INIT_LIST_HEAD(&s->s_dentry_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 init_rwsem(&s->s_umount);
Ingo Molnar7892f2f2006-01-09 15:59:25 -080063 mutex_init(&s->s_lock);
Arjan van de Ven897c6ff2006-07-03 00:25:28 -070064 lockdep_set_class(&s->s_umount, &type->s_umount_key);
Ingo Molnarcf516242006-07-03 00:25:27 -070065 /*
66 * The locking rules for s_lock are up to the
67 * filesystem. For example ext3fs has different
68 * lock ordering than usbfs:
69 */
70 lockdep_set_class(&s->s_lock, &type->s_lock_key);
Peter Zijlstraada723d2009-02-18 14:48:30 -080071 /*
72 * sget() can have s_umount recursion.
73 *
74 * When it cannot find a suitable sb, it allocates a new
75 * one (this one), and tries again to find a suitable old
76 * one.
77 *
78 * In case that succeeds, it will acquire the s_umount
79 * lock of the old one. Since these are clearly distrinct
80 * locks, and this object isn't exposed yet, there's no
81 * risk of deadlocks.
82 *
83 * Annotate this by putting this lock in a different
84 * subclass.
85 */
86 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
Al Virob20bd1a2010-03-22 08:53:19 -040087 s->s_count = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 atomic_set(&s->s_active, 1);
Arjan van de Vena11f3a02006-03-23 03:00:33 -080089 mutex_init(&s->s_vfs_rename_mutex);
Roland Dreier51ee0492010-04-27 14:23:57 -070090 lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
Ingo Molnard3be9152006-03-23 03:00:29 -080091 mutex_init(&s->s_dquot.dqio_mutex);
92 mutex_init(&s->s_dquot.dqonoff_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 init_rwsem(&s->s_dquot.dqptr_sem);
94 init_waitqueue_head(&s->s_wait_unfrozen);
95 s->s_maxbytes = MAX_NON_LFS;
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 s->s_op = &default_op;
97 s->s_time_gran = 1000000000;
98 }
99out:
100 return s;
101}
102
103/**
104 * destroy_super - frees a superblock
105 * @s: superblock to free
106 *
107 * Frees a superblock.
108 */
109static inline void destroy_super(struct super_block *s)
110{
111 security_sb_free(s);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -0700112 kfree(s->s_subtype);
Miklos Szeredib3b304a2008-02-08 04:21:35 -0800113 kfree(s->s_options);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 kfree(s);
115}
116
117/* Superblock refcounting */
118
119/*
Al Viro35cf7ba2010-03-22 21:13:53 -0400120 * Drop a superblock's refcount. The caller must hold sb_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 */
Al Viro35cf7ba2010-03-22 21:13:53 -0400122void __put_super(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 if (!--sb->s_count) {
Al Viro551de6f2010-03-22 19:36:35 -0400125 list_del_init(&sb->s_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 destroy_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128}
129
130/**
131 * put_super - drop a temporary reference to superblock
132 * @sb: superblock in question
133 *
134 * Drops a temporary reference, frees superblock if there's no
135 * references left.
136 */
Jens Axboe03ba3782009-09-09 09:08:54 +0200137void put_super(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138{
139 spin_lock(&sb_lock);
140 __put_super(sb);
141 spin_unlock(&sb_lock);
142}
143
144
145/**
Al Viro74dbbdd2009-05-06 01:07:50 -0400146 * deactivate_locked_super - drop an active reference to superblock
147 * @s: superblock to deactivate
148 *
Al Viro1712ac82010-03-22 15:22:31 -0400149 * Drops an active reference to superblock, converting it into a temprory
150 * one if there is no other active references left. In that case we
151 * tell fs driver to shut it down and drop the temporary reference we
152 * had just acquired.
153 *
154 * Caller holds exclusive lock on superblock; that lock is released.
Al Viro74dbbdd2009-05-06 01:07:50 -0400155 */
156void deactivate_locked_super(struct super_block *s)
157{
158 struct file_system_type *fs = s->s_type;
Al Virob20bd1a2010-03-22 08:53:19 -0400159 if (atomic_dec_and_test(&s->s_active)) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400160 fs->kill_sb(s);
161 put_filesystem(fs);
162 put_super(s);
163 } else {
164 up_write(&s->s_umount);
165 }
166}
167
168EXPORT_SYMBOL(deactivate_locked_super);
169
170/**
Al Viro1712ac82010-03-22 15:22:31 -0400171 * deactivate_super - drop an active reference to superblock
172 * @s: superblock to deactivate
173 *
174 * Variant of deactivate_locked_super(), except that superblock is *not*
175 * locked by caller. If we are going to drop the final active reference,
176 * lock will be acquired prior to that.
177 */
178void deactivate_super(struct super_block *s)
179{
180 if (!atomic_add_unless(&s->s_active, -1, 1)) {
181 down_write(&s->s_umount);
182 deactivate_locked_super(s);
183 }
184}
185
186EXPORT_SYMBOL(deactivate_super);
187
188/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 * grab_super - acquire an active reference
190 * @s: reference we are trying to make active
191 *
192 * Tries to acquire an active reference. grab_super() is used when we
193 * had just found a superblock in super_blocks or fs_type->fs_supers
194 * and want to turn it into a full-blown active reference. grab_super()
195 * is called with sb_lock held and drops it. Returns 1 in case of
196 * success, 0 if we had failed (superblock contents was already dead or
197 * dying when grab_super() had been called).
198 */
Josh Triplett9c4dbee2006-09-29 01:59:29 -0700199static int grab_super(struct super_block *s) __releases(sb_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200{
Al Virob20bd1a2010-03-22 08:53:19 -0400201 if (atomic_inc_not_zero(&s->s_active)) {
202 spin_unlock(&sb_lock);
Al Virob20bd1a2010-03-22 08:53:19 -0400203 return 1;
204 }
205 /* it's going away */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 s->s_count++;
207 spin_unlock(&sb_lock);
Al Viro1712ac82010-03-22 15:22:31 -0400208 /* wait for it to die */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 down_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 up_write(&s->s_umount);
211 put_super(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 return 0;
213}
214
David Howellscf9a2ae2006-08-29 19:05:54 +0100215/*
Al Viro914e2632006-10-18 13:55:46 -0400216 * Superblock locking. We really ought to get rid of these two.
217 */
218void lock_super(struct super_block * sb)
219{
220 get_fs_excl();
221 mutex_lock(&sb->s_lock);
222}
223
224void unlock_super(struct super_block * sb)
225{
226 put_fs_excl();
227 mutex_unlock(&sb->s_lock);
228}
229
230EXPORT_SYMBOL(lock_super);
231EXPORT_SYMBOL(unlock_super);
232
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233/**
234 * generic_shutdown_super - common helper for ->kill_sb()
235 * @sb: superblock to kill
236 *
237 * generic_shutdown_super() does all fs-independent work on superblock
238 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
239 * that need destruction out of superblock, call generic_shutdown_super()
240 * and release aforementioned objects. Note: dentries and inodes _are_
241 * taken care of and do not need specific handling.
David Howellsc636ebd2006-10-11 01:22:19 -0700242 *
243 * Upon calling this function, the filesystem may no longer alter or
244 * rearrange the set of dentries belonging to this super_block, nor may it
245 * change the attachments of dentries to inodes.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 */
247void generic_shutdown_super(struct super_block *sb)
248{
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800249 const struct super_operations *sop = sb->s_op;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250
Arjan van de Venefaee192009-01-06 07:20:54 -0800251
David Howellsc636ebd2006-10-11 01:22:19 -0700252 if (sb->s_root) {
253 shrink_dcache_for_umount(sb);
Jan Kara60b06802009-04-27 16:43:53 +0200254 sync_filesystem(sb);
Al Viroa9e220f2009-05-05 22:10:44 -0400255 get_fs_excl();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 sb->s_flags &= ~MS_ACTIVE;
Arjan van de Venefaee192009-01-06 07:20:54 -0800257
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 /* bad name - it should be evict_inodes() */
259 invalidate_inodes(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 if (sop->put_super)
262 sop->put_super(sb);
263
264 /* Forget any remaining inodes */
265 if (invalidate_inodes(sb)) {
Dave Jones7b4fe292006-02-07 12:58:48 -0800266 printk("VFS: Busy inodes after unmount of %s. "
267 "Self-destruct in 5 seconds. Have a nice day...\n",
268 sb->s_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 }
Al Viroa9e220f2009-05-05 22:10:44 -0400270 put_fs_excl();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 }
272 spin_lock(&sb_lock);
273 /* should be initialized for __put_super_and_need_restart() */
Al Viro551de6f2010-03-22 19:36:35 -0400274 list_del_init(&sb->s_instances);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 spin_unlock(&sb_lock);
276 up_write(&sb->s_umount);
277}
278
279EXPORT_SYMBOL(generic_shutdown_super);
280
281/**
282 * sget - find or create a superblock
283 * @type: filesystem type superblock should belong to
284 * @test: comparison callback
285 * @set: setup callback
286 * @data: argument to each of them
287 */
288struct super_block *sget(struct file_system_type *type,
289 int (*test)(struct super_block *,void *),
290 int (*set)(struct super_block *,void *),
291 void *data)
292{
293 struct super_block *s = NULL;
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700294 struct super_block *old;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 int err;
296
297retry:
298 spin_lock(&sb_lock);
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700299 if (test) {
300 list_for_each_entry(old, &type->fs_supers, s_instances) {
301 if (!test(old, data))
302 continue;
303 if (!grab_super(old))
304 goto retry;
Li Zefana3cfbb52009-03-12 14:31:29 -0700305 if (s) {
306 up_write(&s->s_umount);
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700307 destroy_super(s);
Li Zefana3cfbb52009-03-12 14:31:29 -0700308 }
Al Virod3f21472010-03-23 11:11:05 -0400309 down_write(&old->s_umount);
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700310 return old;
311 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 }
313 if (!s) {
314 spin_unlock(&sb_lock);
Ingo Molnarcf516242006-07-03 00:25:27 -0700315 s = alloc_super(type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 if (!s)
317 return ERR_PTR(-ENOMEM);
318 goto retry;
319 }
320
321 err = set(s, data);
322 if (err) {
323 spin_unlock(&sb_lock);
Li Zefana3cfbb52009-03-12 14:31:29 -0700324 up_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 destroy_super(s);
326 return ERR_PTR(err);
327 }
328 s->s_type = type;
329 strlcpy(s->s_id, type->name, sizeof(s->s_id));
330 list_add_tail(&s->s_list, &super_blocks);
331 list_add(&s->s_instances, &type->fs_supers);
332 spin_unlock(&sb_lock);
333 get_filesystem(type);
334 return s;
335}
336
337EXPORT_SYMBOL(sget);
338
339void drop_super(struct super_block *sb)
340{
341 up_read(&sb->s_umount);
342 put_super(sb);
343}
344
345EXPORT_SYMBOL(drop_super);
346
Christoph Hellwige5004752009-05-05 16:08:56 +0200347/**
348 * sync_supers - helper for periodic superblock writeback
349 *
350 * Call the write_super method if present on all dirty superblocks in
351 * the system. This is for the periodic writeback used by most older
352 * filesystems. For data integrity superblock writeback use
353 * sync_filesystems() instead.
354 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 * Note: check the dirty flag before waiting, so we don't
356 * hold up the sync while mounting a device. (The newly
357 * mounted device won't need syncing.)
358 */
359void sync_supers(void)
360{
Al Viro6754af62010-03-22 20:09:33 -0400361 struct super_block *sb, *n;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700362
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 spin_lock(&sb_lock);
Al Viro6754af62010-03-22 20:09:33 -0400364 list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400365 if (list_empty(&sb->s_instances))
366 continue;
Christoph Hellwige5004752009-05-05 16:08:56 +0200367 if (sb->s_op->write_super && sb->s_dirt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 sb->s_count++;
369 spin_unlock(&sb_lock);
Christoph Hellwige5004752009-05-05 16:08:56 +0200370
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 down_read(&sb->s_umount);
Christoph Hellwige5004752009-05-05 16:08:56 +0200372 if (sb->s_root && sb->s_dirt)
373 sb->s_op->write_super(sb);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700374 up_read(&sb->s_umount);
Christoph Hellwige5004752009-05-05 16:08:56 +0200375
Kirill Korotaev618f0632005-06-23 00:09:54 -0700376 spin_lock(&sb_lock);
npiggin@suse.de57439f82010-06-24 13:02:14 +1000377 /* lock was dropped, must reset next */
378 list_safe_reset_next(sb, n, s_list);
Al Viro6754af62010-03-22 20:09:33 -0400379 __put_super(sb);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700380 }
381 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 spin_unlock(&sb_lock);
383}
384
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385/**
Al Viro01a05b32010-03-23 06:06:58 -0400386 * iterate_supers - call function for all active superblocks
387 * @f: function to call
388 * @arg: argument to pass to it
389 *
390 * Scans the superblock list and calls given function, passing it
391 * locked superblock and given argument.
392 */
393void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
394{
395 struct super_block *sb, *n;
396
397 spin_lock(&sb_lock);
398 list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
399 if (list_empty(&sb->s_instances))
400 continue;
401 sb->s_count++;
402 spin_unlock(&sb_lock);
403
404 down_read(&sb->s_umount);
405 if (sb->s_root)
406 f(sb, arg);
407 up_read(&sb->s_umount);
408
409 spin_lock(&sb_lock);
npiggin@suse.de57439f82010-06-24 13:02:14 +1000410 /* lock was dropped, must reset next */
411 list_safe_reset_next(sb, n, s_list);
Al Viro01a05b32010-03-23 06:06:58 -0400412 __put_super(sb);
413 }
414 spin_unlock(&sb_lock);
415}
416
417/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 * get_super - get the superblock of a device
419 * @bdev: device to get the superblock for
420 *
421 * Scans the superblock list and finds the superblock of the file system
422 * mounted on the device given. %NULL is returned if no match is found.
423 */
424
Al Virodf40c012010-03-22 20:23:25 -0400425struct super_block *get_super(struct block_device *bdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700427 struct super_block *sb;
428
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 if (!bdev)
430 return NULL;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700431
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700433rescan:
434 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400435 if (list_empty(&sb->s_instances))
436 continue;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700437 if (sb->s_bdev == bdev) {
438 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700440 down_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400441 /* still alive? */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700442 if (sb->s_root)
443 return sb;
444 up_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400445 /* nope, got unmounted */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700446 spin_lock(&sb_lock);
Al Virodf40c012010-03-22 20:23:25 -0400447 __put_super(sb);
448 goto rescan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 }
450 }
451 spin_unlock(&sb_lock);
452 return NULL;
453}
454
455EXPORT_SYMBOL(get_super);
Christoph Hellwig45042302009-08-03 23:28:35 +0200456
457/**
458 * get_active_super - get an active reference to the superblock of a device
459 * @bdev: device to get the superblock for
460 *
461 * Scans the superblock list and finds the superblock of the file system
462 * mounted on the device given. Returns the superblock with an active
Al Virod3f21472010-03-23 11:11:05 -0400463 * reference or %NULL if none was found.
Christoph Hellwig45042302009-08-03 23:28:35 +0200464 */
465struct super_block *get_active_super(struct block_device *bdev)
466{
467 struct super_block *sb;
468
469 if (!bdev)
470 return NULL;
471
Al Viro14945832010-03-22 20:15:33 -0400472restart:
Christoph Hellwig45042302009-08-03 23:28:35 +0200473 spin_lock(&sb_lock);
474 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400475 if (list_empty(&sb->s_instances))
476 continue;
Al Viro14945832010-03-22 20:15:33 -0400477 if (sb->s_bdev == bdev) {
478 if (grab_super(sb)) /* drops sb_lock */
479 return sb;
480 else
481 goto restart;
482 }
Christoph Hellwig45042302009-08-03 23:28:35 +0200483 }
484 spin_unlock(&sb_lock);
485 return NULL;
486}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487
Al Virodf40c012010-03-22 20:23:25 -0400488struct super_block *user_get_super(dev_t dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700490 struct super_block *sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700493rescan:
494 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400495 if (list_empty(&sb->s_instances))
496 continue;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700497 if (sb->s_dev == dev) {
498 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700500 down_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400501 /* still alive? */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700502 if (sb->s_root)
503 return sb;
504 up_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400505 /* nope, got unmounted */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700506 spin_lock(&sb_lock);
Al Virodf40c012010-03-22 20:23:25 -0400507 __put_super(sb);
508 goto rescan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 }
510 }
511 spin_unlock(&sb_lock);
512 return NULL;
513}
514
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 * do_remount_sb - asks filesystem to change mount options.
517 * @sb: superblock in question
518 * @flags: numeric part of options
519 * @data: the rest of options
520 * @force: whether or not to force the change
521 *
522 * Alters the mount options of a mounted file system.
523 */
524int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
525{
526 int retval;
Christoph Hellwigc79d9672010-05-19 07:16:40 -0400527 int remount_ro;
Christoph Hellwig45042302009-08-03 23:28:35 +0200528
529 if (sb->s_frozen != SB_UNFROZEN)
530 return -EBUSY;
531
David Howells93614012006-09-30 20:45:40 +0200532#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
534 return -EACCES;
David Howells93614012006-09-30 20:45:40 +0200535#endif
Christoph Hellwig45042302009-08-03 23:28:35 +0200536
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 if (flags & MS_RDONLY)
538 acct_auto_close(sb);
539 shrink_dcache_sb(sb);
Jan Kara60b06802009-04-27 16:43:53 +0200540 sync_filesystem(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541
Nick Piggind208bbd2009-12-21 16:28:53 -0800542 remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
Nick Piggind208bbd2009-12-21 16:28:53 -0800543
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 /* If we are remounting RDONLY and current sb is read/write,
545 make sure there are no rw files opened */
Nick Piggind208bbd2009-12-21 16:28:53 -0800546 if (remount_ro) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 if (force)
548 mark_files_ro(sb);
J. R. Okajimab0895512009-06-17 01:16:50 +0900549 else if (!fs_may_remount_ro(sb))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 return -EBUSY;
551 }
552
553 if (sb->s_op->remount_fs) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 retval = sb->s_op->remount_fs(sb, &flags, data);
J. R. Okajimab0895512009-06-17 01:16:50 +0900555 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 return retval;
557 }
558 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
Christoph Hellwigc79d9672010-05-19 07:16:40 -0400559
Nick Piggind208bbd2009-12-21 16:28:53 -0800560 /*
561 * Some filesystems modify their metadata via some other path than the
562 * bdev buffer cache (eg. use a private mapping, or directories in
563 * pagecache, etc). Also file data modifications go via their own
564 * mappings. So If we try to mount readonly then copy the filesystem
565 * from bdev, we could get stale data, so invalidate it to give a best
566 * effort at coherency.
567 */
568 if (remount_ro && sb->s_bdev)
569 invalidate_bdev(sb->s_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 return 0;
571}
572
Jens Axboea2a95372009-03-17 09:38:40 +0100573static void do_emergency_remount(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574{
Al Viroe7fe0582010-03-22 20:11:53 -0400575 struct super_block *sb, *n;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576
577 spin_lock(&sb_lock);
Al Viroe7fe0582010-03-22 20:11:53 -0400578 list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400579 if (list_empty(&sb->s_instances))
580 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 sb->s_count++;
582 spin_unlock(&sb_lock);
Al Viro443b94b2009-05-05 23:48:50 -0400583 down_write(&sb->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
585 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 * What lock protects sb->s_flags??
587 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588 do_remount_sb(sb, MS_RDONLY, NULL, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 }
Al Viro443b94b2009-05-05 23:48:50 -0400590 up_write(&sb->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 spin_lock(&sb_lock);
npiggin@suse.de57439f82010-06-24 13:02:14 +1000592 /* lock was dropped, must reset next */
593 list_safe_reset_next(sb, n, s_list);
Al Viroe7fe0582010-03-22 20:11:53 -0400594 __put_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 }
596 spin_unlock(&sb_lock);
Jens Axboea2a95372009-03-17 09:38:40 +0100597 kfree(work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 printk("Emergency Remount complete\n");
599}
600
601void emergency_remount(void)
602{
Jens Axboea2a95372009-03-17 09:38:40 +0100603 struct work_struct *work;
604
605 work = kmalloc(sizeof(*work), GFP_ATOMIC);
606 if (work) {
607 INIT_WORK(work, do_emergency_remount);
608 schedule_work(work);
609 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610}
611
612/*
613 * Unnamed block devices are dummy devices used by virtual
614 * filesystems which don't use real block-devices. -- jrs
615 */
616
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400617static DEFINE_IDA(unnamed_dev_ida);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
Al Viroc63e09e2009-06-24 02:05:18 -0400619static int unnamed_dev_start = 0; /* don't bother trying below it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620
621int set_anon_super(struct super_block *s, void *data)
622{
623 int dev;
624 int error;
625
626 retry:
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400627 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 return -ENOMEM;
629 spin_lock(&unnamed_dev_lock);
Al Viroc63e09e2009-06-24 02:05:18 -0400630 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
Al Virof21f6222009-06-24 03:12:00 -0400631 if (!error)
632 unnamed_dev_start = dev + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 spin_unlock(&unnamed_dev_lock);
634 if (error == -EAGAIN)
635 /* We raced and lost with another CPU. */
636 goto retry;
637 else if (error)
638 return -EAGAIN;
639
640 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
641 spin_lock(&unnamed_dev_lock);
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400642 ida_remove(&unnamed_dev_ida, dev);
Al Virof21f6222009-06-24 03:12:00 -0400643 if (unnamed_dev_start > dev)
644 unnamed_dev_start = dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 spin_unlock(&unnamed_dev_lock);
646 return -EMFILE;
647 }
648 s->s_dev = MKDEV(0, dev & MINORMASK);
Jörn Engel5129a462010-04-25 08:54:42 +0200649 s->s_bdi = &noop_backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 return 0;
651}
652
653EXPORT_SYMBOL(set_anon_super);
654
655void kill_anon_super(struct super_block *sb)
656{
657 int slot = MINOR(sb->s_dev);
658
659 generic_shutdown_super(sb);
660 spin_lock(&unnamed_dev_lock);
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400661 ida_remove(&unnamed_dev_ida, slot);
Al Viroc63e09e2009-06-24 02:05:18 -0400662 if (slot < unnamed_dev_start)
663 unnamed_dev_start = slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 spin_unlock(&unnamed_dev_lock);
665}
666
667EXPORT_SYMBOL(kill_anon_super);
668
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669void kill_litter_super(struct super_block *sb)
670{
671 if (sb->s_root)
672 d_genocide(sb->s_root);
673 kill_anon_super(sb);
674}
675
676EXPORT_SYMBOL(kill_litter_super);
677
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700678static int ns_test_super(struct super_block *sb, void *data)
679{
680 return sb->s_fs_info == data;
681}
682
683static int ns_set_super(struct super_block *sb, void *data)
684{
685 sb->s_fs_info = data;
686 return set_anon_super(sb, NULL);
687}
688
689int get_sb_ns(struct file_system_type *fs_type, int flags, void *data,
690 int (*fill_super)(struct super_block *, void *, int),
691 struct vfsmount *mnt)
692{
693 struct super_block *sb;
694
695 sb = sget(fs_type, ns_test_super, ns_set_super, data);
696 if (IS_ERR(sb))
697 return PTR_ERR(sb);
698
699 if (!sb->s_root) {
700 int err;
701 sb->s_flags = flags;
702 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
703 if (err) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400704 deactivate_locked_super(sb);
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700705 return err;
706 }
707
708 sb->s_flags |= MS_ACTIVE;
709 }
710
711 simple_set_mnt(mnt, sb);
712 return 0;
713}
714
715EXPORT_SYMBOL(get_sb_ns);
716
David Howells93614012006-09-30 20:45:40 +0200717#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718static int set_bdev_super(struct super_block *s, void *data)
719{
720 s->s_bdev = data;
721 s->s_dev = s->s_bdev->bd_dev;
Jens Axboe32a88aa2009-09-16 15:02:33 +0200722
723 /*
724 * We set the bdi here to the queue backing, file systems can
725 * overwrite this in ->fill_super()
726 */
727 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 return 0;
729}
730
731static int test_bdev_super(struct super_block *s, void *data)
732{
733 return (void *)s->s_bdev == data;
734}
735
David Howells454e2392006-06-23 02:02:57 -0700736int get_sb_bdev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 int flags, const char *dev_name, void *data,
David Howells454e2392006-06-23 02:02:57 -0700738 int (*fill_super)(struct super_block *, void *, int),
739 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740{
741 struct block_device *bdev;
742 struct super_block *s;
Al Viro30c40d22008-02-22 19:50:45 -0500743 fmode_t mode = FMODE_READ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 int error = 0;
745
Al Viro30c40d22008-02-22 19:50:45 -0500746 if (!(flags & MS_RDONLY))
747 mode |= FMODE_WRITE;
748
749 bdev = open_bdev_exclusive(dev_name, mode, fs_type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 if (IS_ERR(bdev))
David Howells454e2392006-06-23 02:02:57 -0700751 return PTR_ERR(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752
753 /*
754 * once the super is inserted into the list by sget, s_umount
755 * will protect the lockfs code from trying to start a snapshot
756 * while we are mounting
757 */
Christoph Hellwig4fadd7b2009-08-03 23:28:06 +0200758 mutex_lock(&bdev->bd_fsfreeze_mutex);
759 if (bdev->bd_fsfreeze_count > 0) {
760 mutex_unlock(&bdev->bd_fsfreeze_mutex);
761 error = -EBUSY;
762 goto error_bdev;
763 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
Christoph Hellwig4fadd7b2009-08-03 23:28:06 +0200765 mutex_unlock(&bdev->bd_fsfreeze_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700767 goto error_s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768
769 if (s->s_root) {
770 if ((flags ^ s->s_flags) & MS_RDONLY) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400771 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700772 error = -EBUSY;
773 goto error_bdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 }
David Howells454e2392006-06-23 02:02:57 -0700775
Al Viro30c40d22008-02-22 19:50:45 -0500776 close_bdev_exclusive(bdev, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 } else {
778 char b[BDEVNAME_SIZE];
779
780 s->s_flags = flags;
Al Viro30c40d22008-02-22 19:50:45 -0500781 s->s_mode = mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
Pekka Enberge78c9a02006-01-08 01:03:39 -0800783 sb_set_blocksize(s, block_size(bdev));
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800784 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400786 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700787 goto error;
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800788 }
David Howells454e2392006-06-23 02:02:57 -0700789
790 s->s_flags |= MS_ACTIVE;
Theodore Ts'o87d8fe12009-01-03 09:47:09 -0500791 bdev->bd_super = s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 }
793
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800794 simple_set_mnt(mnt, s);
795 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796
David Howells454e2392006-06-23 02:02:57 -0700797error_s:
798 error = PTR_ERR(s);
799error_bdev:
Al Viro30c40d22008-02-22 19:50:45 -0500800 close_bdev_exclusive(bdev, mode);
David Howells454e2392006-06-23 02:02:57 -0700801error:
802 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803}
804
805EXPORT_SYMBOL(get_sb_bdev);
806
807void kill_block_super(struct super_block *sb)
808{
809 struct block_device *bdev = sb->s_bdev;
Al Viro30c40d22008-02-22 19:50:45 -0500810 fmode_t mode = sb->s_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811
H Hartley Sweetenddbaaf32009-04-29 20:14:57 -0400812 bdev->bd_super = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813 generic_shutdown_super(sb);
814 sync_blockdev(bdev);
Al Viro30c40d22008-02-22 19:50:45 -0500815 close_bdev_exclusive(bdev, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816}
817
818EXPORT_SYMBOL(kill_block_super);
David Howells93614012006-09-30 20:45:40 +0200819#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820
David Howells454e2392006-06-23 02:02:57 -0700821int get_sb_nodev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 int flags, void *data,
David Howells454e2392006-06-23 02:02:57 -0700823 int (*fill_super)(struct super_block *, void *, int),
824 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825{
826 int error;
827 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
828
829 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700830 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831
832 s->s_flags = flags;
833
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800834 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400836 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700837 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 }
839 s->s_flags |= MS_ACTIVE;
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800840 simple_set_mnt(mnt, s);
841 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842}
843
844EXPORT_SYMBOL(get_sb_nodev);
845
846static int compare_single(struct super_block *s, void *p)
847{
848 return 1;
849}
850
David Howells454e2392006-06-23 02:02:57 -0700851int get_sb_single(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852 int flags, void *data,
David Howells454e2392006-06-23 02:02:57 -0700853 int (*fill_super)(struct super_block *, void *, int),
854 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855{
856 struct super_block *s;
857 int error;
858
859 s = sget(fs_type, compare_single, set_anon_super, NULL);
860 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700861 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 if (!s->s_root) {
863 s->s_flags = flags;
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800864 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400866 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700867 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 }
869 s->s_flags |= MS_ACTIVE;
Kay Sievers9329d1b2009-12-18 21:18:15 +0100870 } else {
871 do_remount_sb(s, flags, data, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 }
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800873 simple_set_mnt(mnt, s);
874 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875}
876
877EXPORT_SYMBOL(get_sb_single);
878
879struct vfsmount *
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400880vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 struct vfsmount *mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883 char *secdata = NULL;
David Howells454e2392006-06-23 02:02:57 -0700884 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885
886 if (!type)
887 return ERR_PTR(-ENODEV);
888
David Howells454e2392006-06-23 02:02:57 -0700889 error = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890 mnt = alloc_vfsmnt(name);
891 if (!mnt)
892 goto out;
893
Al Viro80893522010-02-05 09:30:46 -0500894 if (flags & MS_KERNMOUNT)
895 mnt->mnt_flags = MNT_INTERNAL;
896
Eric Parise0007522008-03-05 10:31:54 -0500897 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700898 secdata = alloc_secdata();
David Howells454e2392006-06-23 02:02:57 -0700899 if (!secdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 goto out_mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901
Eric Parise0007522008-03-05 10:31:54 -0500902 error = security_sb_copy_data(data, secdata);
David Howells454e2392006-06-23 02:02:57 -0700903 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 goto out_free_secdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 }
906
David Howells454e2392006-06-23 02:02:57 -0700907 error = type->get_sb(type, flags, name, data, mnt);
908 if (error < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 goto out_free_secdata;
Lee Schermerhornb4c07bc2007-07-15 23:40:54 -0700910 BUG_ON(!mnt->mnt_sb);
Jörn Engel5129a462010-04-25 08:54:42 +0200911 WARN_ON(!mnt->mnt_sb->s_bdi);
David Howells454e2392006-06-23 02:02:57 -0700912
Jörn Engel5129a462010-04-25 08:54:42 +0200913 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
914 if (error)
915 goto out_sb;
David Howells454e2392006-06-23 02:02:57 -0700916
Jeff Layton42cb56a2009-09-18 13:05:53 -0700917 /*
918 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
919 * but s_maxbytes was an unsigned long long for many releases. Throw
920 * this warning for a little while to try and catch filesystems that
921 * violate this rule. This warning should be either removed or
922 * converted to a BUG() in 2.6.34.
923 */
924 WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
925 "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
926
David Howells454e2392006-06-23 02:02:57 -0700927 mnt->mnt_mountpoint = mnt->mnt_root;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928 mnt->mnt_parent = mnt;
David Howells454e2392006-06-23 02:02:57 -0700929 up_write(&mnt->mnt_sb->s_umount);
Gerald Schaefer8680e222005-06-21 17:15:16 -0700930 free_secdata(secdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 return mnt;
932out_sb:
David Howells454e2392006-06-23 02:02:57 -0700933 dput(mnt->mnt_root);
Al Viro74dbbdd2009-05-06 01:07:50 -0400934 deactivate_locked_super(mnt->mnt_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935out_free_secdata:
936 free_secdata(secdata);
937out_mnt:
938 free_vfsmnt(mnt);
939out:
David Howells454e2392006-06-23 02:02:57 -0700940 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941}
942
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400943EXPORT_SYMBOL_GPL(vfs_kern_mount);
944
Josef Bacik18e9e512010-03-23 10:34:56 -0400945/**
Randy Dunlap7000d3c2010-05-24 22:22:34 -0700946 * freeze_super - lock the filesystem and force it into a consistent state
947 * @sb: the super to lock
Josef Bacik18e9e512010-03-23 10:34:56 -0400948 *
949 * Syncs the super to make sure the filesystem is consistent and calls the fs's
950 * freeze_fs. Subsequent calls to this without first thawing the fs will return
951 * -EBUSY.
952 */
953int freeze_super(struct super_block *sb)
954{
955 int ret;
956
957 atomic_inc(&sb->s_active);
958 down_write(&sb->s_umount);
959 if (sb->s_frozen) {
960 deactivate_locked_super(sb);
961 return -EBUSY;
962 }
963
964 if (sb->s_flags & MS_RDONLY) {
965 sb->s_frozen = SB_FREEZE_TRANS;
966 smp_wmb();
967 up_write(&sb->s_umount);
968 return 0;
969 }
970
971 sb->s_frozen = SB_FREEZE_WRITE;
972 smp_wmb();
973
974 sync_filesystem(sb);
975
976 sb->s_frozen = SB_FREEZE_TRANS;
977 smp_wmb();
978
979 sync_blockdev(sb->s_bdev);
980 if (sb->s_op->freeze_fs) {
981 ret = sb->s_op->freeze_fs(sb);
982 if (ret) {
983 printk(KERN_ERR
984 "VFS:Filesystem freeze failed\n");
985 sb->s_frozen = SB_UNFROZEN;
986 deactivate_locked_super(sb);
987 return ret;
988 }
989 }
990 up_write(&sb->s_umount);
991 return 0;
992}
993EXPORT_SYMBOL(freeze_super);
994
995/**
996 * thaw_super -- unlock filesystem
997 * @sb: the super to thaw
998 *
999 * Unlocks the filesystem and marks it writeable again after freeze_super().
1000 */
1001int thaw_super(struct super_block *sb)
1002{
1003 int error;
1004
1005 down_write(&sb->s_umount);
1006 if (sb->s_frozen == SB_UNFROZEN) {
1007 up_write(&sb->s_umount);
1008 return -EINVAL;
1009 }
1010
1011 if (sb->s_flags & MS_RDONLY)
1012 goto out;
1013
1014 if (sb->s_op->unfreeze_fs) {
1015 error = sb->s_op->unfreeze_fs(sb);
1016 if (error) {
1017 printk(KERN_ERR
1018 "VFS:Filesystem thaw failed\n");
1019 sb->s_frozen = SB_FREEZE_TRANS;
1020 up_write(&sb->s_umount);
1021 return error;
1022 }
1023 }
1024
1025out:
1026 sb->s_frozen = SB_UNFROZEN;
1027 smp_wmb();
1028 wake_up(&sb->s_wait_unfrozen);
1029 deactivate_locked_super(sb);
1030
1031 return 0;
1032}
1033EXPORT_SYMBOL(thaw_super);
1034
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -07001035static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
1036{
1037 int err;
1038 const char *subtype = strchr(fstype, '.');
1039 if (subtype) {
1040 subtype++;
1041 err = -EINVAL;
1042 if (!subtype[0])
1043 goto err;
1044 } else
1045 subtype = "";
1046
1047 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
1048 err = -ENOMEM;
1049 if (!mnt->mnt_sb->s_subtype)
1050 goto err;
1051 return mnt;
1052
1053 err:
1054 mntput(mnt);
1055 return ERR_PTR(err);
1056}
1057
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001058struct vfsmount *
1059do_kern_mount(const char *fstype, int flags, const char *name, void *data)
1060{
1061 struct file_system_type *type = get_fs_type(fstype);
1062 struct vfsmount *mnt;
1063 if (!type)
1064 return ERR_PTR(-ENODEV);
1065 mnt = vfs_kern_mount(type, flags, name, data);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -07001066 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
1067 !mnt->mnt_sb->s_subtype)
1068 mnt = fs_set_subtype(mnt, fstype);
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001069 put_filesystem(type);
1070 return mnt;
1071}
Al Viro8a4e98d2008-02-24 01:43:03 -05001072EXPORT_SYMBOL_GPL(do_kern_mount);
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001073
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001074struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075{
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001076 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077}
1078
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001079EXPORT_SYMBOL_GPL(kern_mount_data);