blob: 69688b15f1fa928002584b1504cfe2146ba3b67f [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>
27#include <linux/quotaops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/mount.h>
29#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/writeback.h> /* for the emergency remount stuff */
31#include <linux/idr.h>
Ingo Molnar353ab6e2006-03-26 01:37:12 -080032#include <linux/mutex.h>
Jens Axboe5477d0f2010-04-29 20:33:35 +020033#include <linux/backing-dev.h>
Al Viro6d59e7f2008-03-22 15:48:17 -040034#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
36
Linus Torvalds1da177e2005-04-16 15:20:36 -070037LIST_HEAD(super_blocks);
38DEFINE_SPINLOCK(sb_lock);
39
40/**
41 * alloc_super - create new superblock
Henrik Kretzschmarfe2bbc42006-09-06 00:03:41 -070042 * @type: filesystem type superblock should belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 *
44 * Allocates and initializes a new &struct super_block. alloc_super()
45 * returns a pointer new superblock or %NULL if allocation had failed.
46 */
Ingo Molnarcf516242006-07-03 00:25:27 -070047static struct super_block *alloc_super(struct file_system_type *type)
Linus Torvalds1da177e2005-04-16 15:20:36 -070048{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -080049 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
Alexey Dobriyanb87221d2009-09-21 17:01:09 -070050 static const struct super_operations default_op;
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52 if (s) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 if (security_sb_alloc(s)) {
54 kfree(s);
55 s = NULL;
56 goto out;
57 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 INIT_LIST_HEAD(&s->s_files);
59 INIT_LIST_HEAD(&s->s_instances);
60 INIT_HLIST_HEAD(&s->s_anon);
61 INIT_LIST_HEAD(&s->s_inodes);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -070062 INIT_LIST_HEAD(&s->s_dentry_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 init_rwsem(&s->s_umount);
Ingo Molnar7892f2f2006-01-09 15:59:25 -080064 mutex_init(&s->s_lock);
Arjan van de Ven897c6ff2006-07-03 00:25:28 -070065 lockdep_set_class(&s->s_umount, &type->s_umount_key);
Ingo Molnarcf516242006-07-03 00:25:27 -070066 /*
67 * The locking rules for s_lock are up to the
68 * filesystem. For example ext3fs has different
69 * lock ordering than usbfs:
70 */
71 lockdep_set_class(&s->s_lock, &type->s_lock_key);
Peter Zijlstraada723d2009-02-18 14:48:30 -080072 /*
73 * sget() can have s_umount recursion.
74 *
75 * When it cannot find a suitable sb, it allocates a new
76 * one (this one), and tries again to find a suitable old
77 * one.
78 *
79 * In case that succeeds, it will acquire the s_umount
80 * lock of the old one. Since these are clearly distrinct
81 * locks, and this object isn't exposed yet, there's no
82 * risk of deadlocks.
83 *
84 * Annotate this by putting this lock in a different
85 * subclass.
86 */
87 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
Al Virob20bd1a2010-03-22 08:53:19 -040088 s->s_count = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 atomic_set(&s->s_active, 1);
Arjan van de Vena11f3a02006-03-23 03:00:33 -080090 mutex_init(&s->s_vfs_rename_mutex);
Roland Dreier51ee0492010-04-27 14:23:57 -070091 lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
Ingo Molnard3be9152006-03-23 03:00:29 -080092 mutex_init(&s->s_dquot.dqio_mutex);
93 mutex_init(&s->s_dquot.dqonoff_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 init_rwsem(&s->s_dquot.dqptr_sem);
95 init_waitqueue_head(&s->s_wait_unfrozen);
96 s->s_maxbytes = MAX_NON_LFS;
97 s->dq_op = sb_dquot_ops;
98 s->s_qcop = sb_quotactl_ops;
99 s->s_op = &default_op;
100 s->s_time_gran = 1000000000;
101 }
102out:
103 return s;
104}
105
106/**
107 * destroy_super - frees a superblock
108 * @s: superblock to free
109 *
110 * Frees a superblock.
111 */
112static inline void destroy_super(struct super_block *s)
113{
114 security_sb_free(s);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -0700115 kfree(s->s_subtype);
Miklos Szeredib3b304a2008-02-08 04:21:35 -0800116 kfree(s->s_options);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 kfree(s);
118}
119
120/* Superblock refcounting */
121
122/*
Al Viro35cf7ba2010-03-22 21:13:53 -0400123 * Drop a superblock's refcount. The caller must hold sb_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 */
Al Viro35cf7ba2010-03-22 21:13:53 -0400125void __put_super(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127 if (!--sb->s_count) {
Al Viro551de6f2010-03-22 19:36:35 -0400128 list_del_init(&sb->s_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 destroy_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131}
132
133/**
134 * put_super - drop a temporary reference to superblock
135 * @sb: superblock in question
136 *
137 * Drops a temporary reference, frees superblock if there's no
138 * references left.
139 */
Jens Axboe03ba3782009-09-09 09:08:54 +0200140void put_super(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141{
142 spin_lock(&sb_lock);
143 __put_super(sb);
144 spin_unlock(&sb_lock);
145}
146
147
148/**
Al Viro74dbbdd2009-05-06 01:07:50 -0400149 * deactivate_locked_super - drop an active reference to superblock
150 * @s: superblock to deactivate
151 *
Al Viro1712ac82010-03-22 15:22:31 -0400152 * Drops an active reference to superblock, converting it into a temprory
153 * one if there is no other active references left. In that case we
154 * tell fs driver to shut it down and drop the temporary reference we
155 * had just acquired.
156 *
157 * Caller holds exclusive lock on superblock; that lock is released.
Al Viro74dbbdd2009-05-06 01:07:50 -0400158 */
159void deactivate_locked_super(struct super_block *s)
160{
161 struct file_system_type *fs = s->s_type;
Al Virob20bd1a2010-03-22 08:53:19 -0400162 if (atomic_dec_and_test(&s->s_active)) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400163 vfs_dq_off(s, 0);
164 fs->kill_sb(s);
165 put_filesystem(fs);
166 put_super(s);
167 } else {
168 up_write(&s->s_umount);
169 }
170}
171
172EXPORT_SYMBOL(deactivate_locked_super);
173
174/**
Al Viro1712ac82010-03-22 15:22:31 -0400175 * deactivate_super - drop an active reference to superblock
176 * @s: superblock to deactivate
177 *
178 * Variant of deactivate_locked_super(), except that superblock is *not*
179 * locked by caller. If we are going to drop the final active reference,
180 * lock will be acquired prior to that.
181 */
182void deactivate_super(struct super_block *s)
183{
184 if (!atomic_add_unless(&s->s_active, -1, 1)) {
185 down_write(&s->s_umount);
186 deactivate_locked_super(s);
187 }
188}
189
190EXPORT_SYMBOL(deactivate_super);
191
192/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 * grab_super - acquire an active reference
194 * @s: reference we are trying to make active
195 *
196 * Tries to acquire an active reference. grab_super() is used when we
197 * had just found a superblock in super_blocks or fs_type->fs_supers
198 * and want to turn it into a full-blown active reference. grab_super()
199 * is called with sb_lock held and drops it. Returns 1 in case of
200 * success, 0 if we had failed (superblock contents was already dead or
201 * dying when grab_super() had been called).
202 */
Josh Triplett9c4dbee2006-09-29 01:59:29 -0700203static int grab_super(struct super_block *s) __releases(sb_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204{
Al Virob20bd1a2010-03-22 08:53:19 -0400205 if (atomic_inc_not_zero(&s->s_active)) {
206 spin_unlock(&sb_lock);
Al Virob20bd1a2010-03-22 08:53:19 -0400207 return 1;
208 }
209 /* it's going away */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 s->s_count++;
211 spin_unlock(&sb_lock);
Al Viro1712ac82010-03-22 15:22:31 -0400212 /* wait for it to die */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 down_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 up_write(&s->s_umount);
215 put_super(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 return 0;
217}
218
David Howellscf9a2ae2006-08-29 19:05:54 +0100219/*
Al Viro914e2632006-10-18 13:55:46 -0400220 * Superblock locking. We really ought to get rid of these two.
221 */
222void lock_super(struct super_block * sb)
223{
224 get_fs_excl();
225 mutex_lock(&sb->s_lock);
226}
227
228void unlock_super(struct super_block * sb)
229{
230 put_fs_excl();
231 mutex_unlock(&sb->s_lock);
232}
233
234EXPORT_SYMBOL(lock_super);
235EXPORT_SYMBOL(unlock_super);
236
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237/**
238 * generic_shutdown_super - common helper for ->kill_sb()
239 * @sb: superblock to kill
240 *
241 * generic_shutdown_super() does all fs-independent work on superblock
242 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
243 * that need destruction out of superblock, call generic_shutdown_super()
244 * and release aforementioned objects. Note: dentries and inodes _are_
245 * taken care of and do not need specific handling.
David Howellsc636ebd2006-10-11 01:22:19 -0700246 *
247 * Upon calling this function, the filesystem may no longer alter or
248 * rearrange the set of dentries belonging to this super_block, nor may it
249 * change the attachments of dentries to inodes.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 */
251void generic_shutdown_super(struct super_block *sb)
252{
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800253 const struct super_operations *sop = sb->s_op;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254
Arjan van de Venefaee192009-01-06 07:20:54 -0800255
David Howellsc636ebd2006-10-11 01:22:19 -0700256 if (sb->s_root) {
257 shrink_dcache_for_umount(sb);
Jan Kara60b06802009-04-27 16:43:53 +0200258 sync_filesystem(sb);
Al Viroa9e220f2009-05-05 22:10:44 -0400259 get_fs_excl();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 sb->s_flags &= ~MS_ACTIVE;
Arjan van de Venefaee192009-01-06 07:20:54 -0800261
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 /* bad name - it should be evict_inodes() */
263 invalidate_inodes(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 if (sop->put_super)
266 sop->put_super(sb);
267
268 /* Forget any remaining inodes */
269 if (invalidate_inodes(sb)) {
Dave Jones7b4fe292006-02-07 12:58:48 -0800270 printk("VFS: Busy inodes after unmount of %s. "
271 "Self-destruct in 5 seconds. Have a nice day...\n",
272 sb->s_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 }
Al Viroa9e220f2009-05-05 22:10:44 -0400274 put_fs_excl();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 }
276 spin_lock(&sb_lock);
277 /* should be initialized for __put_super_and_need_restart() */
Al Viro551de6f2010-03-22 19:36:35 -0400278 list_del_init(&sb->s_instances);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 spin_unlock(&sb_lock);
280 up_write(&sb->s_umount);
281}
282
283EXPORT_SYMBOL(generic_shutdown_super);
284
285/**
286 * sget - find or create a superblock
287 * @type: filesystem type superblock should belong to
288 * @test: comparison callback
289 * @set: setup callback
290 * @data: argument to each of them
291 */
292struct super_block *sget(struct file_system_type *type,
293 int (*test)(struct super_block *,void *),
294 int (*set)(struct super_block *,void *),
295 void *data)
296{
297 struct super_block *s = NULL;
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700298 struct super_block *old;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 int err;
300
301retry:
302 spin_lock(&sb_lock);
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700303 if (test) {
304 list_for_each_entry(old, &type->fs_supers, s_instances) {
305 if (!test(old, data))
306 continue;
307 if (!grab_super(old))
308 goto retry;
Li Zefana3cfbb52009-03-12 14:31:29 -0700309 if (s) {
310 up_write(&s->s_umount);
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700311 destroy_super(s);
Li Zefana3cfbb52009-03-12 14:31:29 -0700312 }
Al Virod3f21472010-03-23 11:11:05 -0400313 down_write(&old->s_umount);
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700314 return old;
315 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 }
317 if (!s) {
318 spin_unlock(&sb_lock);
Ingo Molnarcf516242006-07-03 00:25:27 -0700319 s = alloc_super(type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 if (!s)
321 return ERR_PTR(-ENOMEM);
322 goto retry;
323 }
324
325 err = set(s, data);
326 if (err) {
327 spin_unlock(&sb_lock);
Li Zefana3cfbb52009-03-12 14:31:29 -0700328 up_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 destroy_super(s);
330 return ERR_PTR(err);
331 }
332 s->s_type = type;
333 strlcpy(s->s_id, type->name, sizeof(s->s_id));
334 list_add_tail(&s->s_list, &super_blocks);
335 list_add(&s->s_instances, &type->fs_supers);
336 spin_unlock(&sb_lock);
337 get_filesystem(type);
338 return s;
339}
340
341EXPORT_SYMBOL(sget);
342
343void drop_super(struct super_block *sb)
344{
345 up_read(&sb->s_umount);
346 put_super(sb);
347}
348
349EXPORT_SYMBOL(drop_super);
350
Christoph Hellwige5004752009-05-05 16:08:56 +0200351/**
352 * sync_supers - helper for periodic superblock writeback
353 *
354 * Call the write_super method if present on all dirty superblocks in
355 * the system. This is for the periodic writeback used by most older
356 * filesystems. For data integrity superblock writeback use
357 * sync_filesystems() instead.
358 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 * Note: check the dirty flag before waiting, so we don't
360 * hold up the sync while mounting a device. (The newly
361 * mounted device won't need syncing.)
362 */
363void sync_supers(void)
364{
Al Viro6754af62010-03-22 20:09:33 -0400365 struct super_block *sb, *n;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700366
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 spin_lock(&sb_lock);
Al Viro6754af62010-03-22 20:09:33 -0400368 list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400369 if (list_empty(&sb->s_instances))
370 continue;
Christoph Hellwige5004752009-05-05 16:08:56 +0200371 if (sb->s_op->write_super && sb->s_dirt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 sb->s_count++;
373 spin_unlock(&sb_lock);
Christoph Hellwige5004752009-05-05 16:08:56 +0200374
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 down_read(&sb->s_umount);
Christoph Hellwige5004752009-05-05 16:08:56 +0200376 if (sb->s_root && sb->s_dirt)
377 sb->s_op->write_super(sb);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700378 up_read(&sb->s_umount);
Christoph Hellwige5004752009-05-05 16:08:56 +0200379
Kirill Korotaev618f0632005-06-23 00:09:54 -0700380 spin_lock(&sb_lock);
Al Viro6754af62010-03-22 20:09:33 -0400381 __put_super(sb);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700382 }
383 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 spin_unlock(&sb_lock);
385}
386
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387/**
Al Viro01a05b32010-03-23 06:06:58 -0400388 * iterate_supers - call function for all active superblocks
389 * @f: function to call
390 * @arg: argument to pass to it
391 *
392 * Scans the superblock list and calls given function, passing it
393 * locked superblock and given argument.
394 */
395void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
396{
397 struct super_block *sb, *n;
398
399 spin_lock(&sb_lock);
400 list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
401 if (list_empty(&sb->s_instances))
402 continue;
403 sb->s_count++;
404 spin_unlock(&sb_lock);
405
406 down_read(&sb->s_umount);
407 if (sb->s_root)
408 f(sb, arg);
409 up_read(&sb->s_umount);
410
411 spin_lock(&sb_lock);
412 __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;
Nick Piggind208bbd2009-12-21 16:28:53 -0800527 int remount_rw, 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);
543 remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
544
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 /* If we are remounting RDONLY and current sb is read/write,
546 make sure there are no rw files opened */
Nick Piggind208bbd2009-12-21 16:28:53 -0800547 if (remount_ro) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 if (force)
549 mark_files_ro(sb);
J. R. Okajimab0895512009-06-17 01:16:50 +0900550 else if (!fs_may_remount_ro(sb))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 return -EBUSY;
Jan Kara9e3509e2009-01-26 16:45:12 +0100552 retval = vfs_dq_off(sb, 1);
J. R. Okajimab0895512009-06-17 01:16:50 +0900553 if (retval < 0 && retval != -ENOSYS)
Jan Kara0ff5af82008-04-28 02:14:33 -0700554 return -EBUSY;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 }
556
557 if (sb->s_op->remount_fs) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 retval = sb->s_op->remount_fs(sb, &flags, data);
J. R. Okajimab0895512009-06-17 01:16:50 +0900559 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 return retval;
561 }
562 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
Jan Kara0ff5af82008-04-28 02:14:33 -0700563 if (remount_rw)
Jan Kara9e3509e2009-01-26 16:45:12 +0100564 vfs_dq_quota_on_remount(sb);
Nick Piggind208bbd2009-12-21 16:28:53 -0800565 /*
566 * Some filesystems modify their metadata via some other path than the
567 * bdev buffer cache (eg. use a private mapping, or directories in
568 * pagecache, etc). Also file data modifications go via their own
569 * mappings. So If we try to mount readonly then copy the filesystem
570 * from bdev, we could get stale data, so invalidate it to give a best
571 * effort at coherency.
572 */
573 if (remount_ro && sb->s_bdev)
574 invalidate_bdev(sb->s_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 return 0;
576}
577
Jens Axboea2a95372009-03-17 09:38:40 +0100578static void do_emergency_remount(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579{
Al Viroe7fe0582010-03-22 20:11:53 -0400580 struct super_block *sb, *n;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581
582 spin_lock(&sb_lock);
Al Viroe7fe0582010-03-22 20:11:53 -0400583 list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400584 if (list_empty(&sb->s_instances))
585 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 sb->s_count++;
587 spin_unlock(&sb_lock);
Al Viro443b94b2009-05-05 23:48:50 -0400588 down_write(&sb->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
590 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 * What lock protects sb->s_flags??
592 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 do_remount_sb(sb, MS_RDONLY, NULL, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 }
Al Viro443b94b2009-05-05 23:48:50 -0400595 up_write(&sb->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 spin_lock(&sb_lock);
Al Viroe7fe0582010-03-22 20:11:53 -0400597 __put_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 }
599 spin_unlock(&sb_lock);
Jens Axboea2a95372009-03-17 09:38:40 +0100600 kfree(work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 printk("Emergency Remount complete\n");
602}
603
604void emergency_remount(void)
605{
Jens Axboea2a95372009-03-17 09:38:40 +0100606 struct work_struct *work;
607
608 work = kmalloc(sizeof(*work), GFP_ATOMIC);
609 if (work) {
610 INIT_WORK(work, do_emergency_remount);
611 schedule_work(work);
612 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613}
614
615/*
616 * Unnamed block devices are dummy devices used by virtual
617 * filesystems which don't use real block-devices. -- jrs
618 */
619
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400620static DEFINE_IDA(unnamed_dev_ida);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
Al Viroc63e09e2009-06-24 02:05:18 -0400622static int unnamed_dev_start = 0; /* don't bother trying below it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623
624int set_anon_super(struct super_block *s, void *data)
625{
626 int dev;
627 int error;
628
629 retry:
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400630 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 return -ENOMEM;
632 spin_lock(&unnamed_dev_lock);
Al Viroc63e09e2009-06-24 02:05:18 -0400633 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
Al Virof21f6222009-06-24 03:12:00 -0400634 if (!error)
635 unnamed_dev_start = dev + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 spin_unlock(&unnamed_dev_lock);
637 if (error == -EAGAIN)
638 /* We raced and lost with another CPU. */
639 goto retry;
640 else if (error)
641 return -EAGAIN;
642
643 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
644 spin_lock(&unnamed_dev_lock);
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400645 ida_remove(&unnamed_dev_ida, dev);
Al Virof21f6222009-06-24 03:12:00 -0400646 if (unnamed_dev_start > dev)
647 unnamed_dev_start = dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 spin_unlock(&unnamed_dev_lock);
649 return -EMFILE;
650 }
651 s->s_dev = MKDEV(0, dev & MINORMASK);
Jörn Engel5129a462010-04-25 08:54:42 +0200652 s->s_bdi = &noop_backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 return 0;
654}
655
656EXPORT_SYMBOL(set_anon_super);
657
658void kill_anon_super(struct super_block *sb)
659{
660 int slot = MINOR(sb->s_dev);
661
662 generic_shutdown_super(sb);
663 spin_lock(&unnamed_dev_lock);
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400664 ida_remove(&unnamed_dev_ida, slot);
Al Viroc63e09e2009-06-24 02:05:18 -0400665 if (slot < unnamed_dev_start)
666 unnamed_dev_start = slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 spin_unlock(&unnamed_dev_lock);
668}
669
670EXPORT_SYMBOL(kill_anon_super);
671
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672void kill_litter_super(struct super_block *sb)
673{
674 if (sb->s_root)
675 d_genocide(sb->s_root);
676 kill_anon_super(sb);
677}
678
679EXPORT_SYMBOL(kill_litter_super);
680
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700681static int ns_test_super(struct super_block *sb, void *data)
682{
683 return sb->s_fs_info == data;
684}
685
686static int ns_set_super(struct super_block *sb, void *data)
687{
688 sb->s_fs_info = data;
689 return set_anon_super(sb, NULL);
690}
691
692int get_sb_ns(struct file_system_type *fs_type, int flags, void *data,
693 int (*fill_super)(struct super_block *, void *, int),
694 struct vfsmount *mnt)
695{
696 struct super_block *sb;
697
698 sb = sget(fs_type, ns_test_super, ns_set_super, data);
699 if (IS_ERR(sb))
700 return PTR_ERR(sb);
701
702 if (!sb->s_root) {
703 int err;
704 sb->s_flags = flags;
705 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
706 if (err) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400707 deactivate_locked_super(sb);
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700708 return err;
709 }
710
711 sb->s_flags |= MS_ACTIVE;
712 }
713
714 simple_set_mnt(mnt, sb);
715 return 0;
716}
717
718EXPORT_SYMBOL(get_sb_ns);
719
David Howells93614012006-09-30 20:45:40 +0200720#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721static int set_bdev_super(struct super_block *s, void *data)
722{
723 s->s_bdev = data;
724 s->s_dev = s->s_bdev->bd_dev;
Jens Axboe32a88aa2009-09-16 15:02:33 +0200725
726 /*
727 * We set the bdi here to the queue backing, file systems can
728 * overwrite this in ->fill_super()
729 */
730 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 return 0;
732}
733
734static int test_bdev_super(struct super_block *s, void *data)
735{
736 return (void *)s->s_bdev == data;
737}
738
David Howells454e2392006-06-23 02:02:57 -0700739int get_sb_bdev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 int flags, const char *dev_name, void *data,
David Howells454e2392006-06-23 02:02:57 -0700741 int (*fill_super)(struct super_block *, void *, int),
742 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743{
744 struct block_device *bdev;
745 struct super_block *s;
Al Viro30c40d22008-02-22 19:50:45 -0500746 fmode_t mode = FMODE_READ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 int error = 0;
748
Al Viro30c40d22008-02-22 19:50:45 -0500749 if (!(flags & MS_RDONLY))
750 mode |= FMODE_WRITE;
751
752 bdev = open_bdev_exclusive(dev_name, mode, fs_type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 if (IS_ERR(bdev))
David Howells454e2392006-06-23 02:02:57 -0700754 return PTR_ERR(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755
756 /*
757 * once the super is inserted into the list by sget, s_umount
758 * will protect the lockfs code from trying to start a snapshot
759 * while we are mounting
760 */
Christoph Hellwig4fadd7b2009-08-03 23:28:06 +0200761 mutex_lock(&bdev->bd_fsfreeze_mutex);
762 if (bdev->bd_fsfreeze_count > 0) {
763 mutex_unlock(&bdev->bd_fsfreeze_mutex);
764 error = -EBUSY;
765 goto error_bdev;
766 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
Christoph Hellwig4fadd7b2009-08-03 23:28:06 +0200768 mutex_unlock(&bdev->bd_fsfreeze_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700770 goto error_s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771
772 if (s->s_root) {
773 if ((flags ^ s->s_flags) & MS_RDONLY) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400774 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700775 error = -EBUSY;
776 goto error_bdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 }
David Howells454e2392006-06-23 02:02:57 -0700778
Al Viro30c40d22008-02-22 19:50:45 -0500779 close_bdev_exclusive(bdev, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 } else {
781 char b[BDEVNAME_SIZE];
782
783 s->s_flags = flags;
Al Viro30c40d22008-02-22 19:50:45 -0500784 s->s_mode = mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
Pekka Enberge78c9a02006-01-08 01:03:39 -0800786 sb_set_blocksize(s, block_size(bdev));
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800787 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400789 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700790 goto error;
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800791 }
David Howells454e2392006-06-23 02:02:57 -0700792
793 s->s_flags |= MS_ACTIVE;
Theodore Ts'o87d8fe12009-01-03 09:47:09 -0500794 bdev->bd_super = s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 }
796
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800797 simple_set_mnt(mnt, s);
798 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799
David Howells454e2392006-06-23 02:02:57 -0700800error_s:
801 error = PTR_ERR(s);
802error_bdev:
Al Viro30c40d22008-02-22 19:50:45 -0500803 close_bdev_exclusive(bdev, mode);
David Howells454e2392006-06-23 02:02:57 -0700804error:
805 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806}
807
808EXPORT_SYMBOL(get_sb_bdev);
809
810void kill_block_super(struct super_block *sb)
811{
812 struct block_device *bdev = sb->s_bdev;
Al Viro30c40d22008-02-22 19:50:45 -0500813 fmode_t mode = sb->s_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814
H Hartley Sweetenddbaaf32009-04-29 20:14:57 -0400815 bdev->bd_super = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 generic_shutdown_super(sb);
817 sync_blockdev(bdev);
Al Viro30c40d22008-02-22 19:50:45 -0500818 close_bdev_exclusive(bdev, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819}
820
821EXPORT_SYMBOL(kill_block_super);
David Howells93614012006-09-30 20:45:40 +0200822#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823
David Howells454e2392006-06-23 02:02:57 -0700824int get_sb_nodev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825 int flags, void *data,
David Howells454e2392006-06-23 02:02:57 -0700826 int (*fill_super)(struct super_block *, void *, int),
827 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828{
829 int error;
830 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
831
832 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700833 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834
835 s->s_flags = flags;
836
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800837 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400839 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700840 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 }
842 s->s_flags |= MS_ACTIVE;
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800843 simple_set_mnt(mnt, s);
844 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845}
846
847EXPORT_SYMBOL(get_sb_nodev);
848
849static int compare_single(struct super_block *s, void *p)
850{
851 return 1;
852}
853
David Howells454e2392006-06-23 02:02:57 -0700854int get_sb_single(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 int flags, void *data,
David Howells454e2392006-06-23 02:02:57 -0700856 int (*fill_super)(struct super_block *, void *, int),
857 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858{
859 struct super_block *s;
860 int error;
861
862 s = sget(fs_type, compare_single, set_anon_super, NULL);
863 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700864 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 if (!s->s_root) {
866 s->s_flags = flags;
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800867 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400869 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700870 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871 }
872 s->s_flags |= MS_ACTIVE;
Kay Sievers9329d1b2009-12-18 21:18:15 +0100873 } else {
874 do_remount_sb(s, flags, data, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 }
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800876 simple_set_mnt(mnt, s);
877 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878}
879
880EXPORT_SYMBOL(get_sb_single);
881
882struct vfsmount *
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400883vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 struct vfsmount *mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886 char *secdata = NULL;
David Howells454e2392006-06-23 02:02:57 -0700887 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888
889 if (!type)
890 return ERR_PTR(-ENODEV);
891
David Howells454e2392006-06-23 02:02:57 -0700892 error = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700893 mnt = alloc_vfsmnt(name);
894 if (!mnt)
895 goto out;
896
Al Viro80893522010-02-05 09:30:46 -0500897 if (flags & MS_KERNMOUNT)
898 mnt->mnt_flags = MNT_INTERNAL;
899
Eric Parise0007522008-03-05 10:31:54 -0500900 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 secdata = alloc_secdata();
David Howells454e2392006-06-23 02:02:57 -0700902 if (!secdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 goto out_mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904
Eric Parise0007522008-03-05 10:31:54 -0500905 error = security_sb_copy_data(data, secdata);
David Howells454e2392006-06-23 02:02:57 -0700906 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 goto out_free_secdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 }
909
David Howells454e2392006-06-23 02:02:57 -0700910 error = type->get_sb(type, flags, name, data, mnt);
911 if (error < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 goto out_free_secdata;
Lee Schermerhornb4c07bc2007-07-15 23:40:54 -0700913 BUG_ON(!mnt->mnt_sb);
Jörn Engel5129a462010-04-25 08:54:42 +0200914 WARN_ON(!mnt->mnt_sb->s_bdi);
David Howells454e2392006-06-23 02:02:57 -0700915
Jörn Engel5129a462010-04-25 08:54:42 +0200916 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
917 if (error)
918 goto out_sb;
David Howells454e2392006-06-23 02:02:57 -0700919
Jeff Layton42cb56a2009-09-18 13:05:53 -0700920 /*
921 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
922 * but s_maxbytes was an unsigned long long for many releases. Throw
923 * this warning for a little while to try and catch filesystems that
924 * violate this rule. This warning should be either removed or
925 * converted to a BUG() in 2.6.34.
926 */
927 WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
928 "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
929
David Howells454e2392006-06-23 02:02:57 -0700930 mnt->mnt_mountpoint = mnt->mnt_root;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 mnt->mnt_parent = mnt;
David Howells454e2392006-06-23 02:02:57 -0700932 up_write(&mnt->mnt_sb->s_umount);
Gerald Schaefer8680e222005-06-21 17:15:16 -0700933 free_secdata(secdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934 return mnt;
935out_sb:
David Howells454e2392006-06-23 02:02:57 -0700936 dput(mnt->mnt_root);
Al Viro74dbbdd2009-05-06 01:07:50 -0400937 deactivate_locked_super(mnt->mnt_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938out_free_secdata:
939 free_secdata(secdata);
940out_mnt:
941 free_vfsmnt(mnt);
942out:
David Howells454e2392006-06-23 02:02:57 -0700943 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944}
945
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400946EXPORT_SYMBOL_GPL(vfs_kern_mount);
947
Josef Bacik18e9e512010-03-23 10:34:56 -0400948/**
949 * freeze_super -- lock the filesystem and force it into a consistent state
950 * @super: the super to lock
951 *
952 * Syncs the super to make sure the filesystem is consistent and calls the fs's
953 * freeze_fs. Subsequent calls to this without first thawing the fs will return
954 * -EBUSY.
955 */
956int freeze_super(struct super_block *sb)
957{
958 int ret;
959
960 atomic_inc(&sb->s_active);
961 down_write(&sb->s_umount);
962 if (sb->s_frozen) {
963 deactivate_locked_super(sb);
964 return -EBUSY;
965 }
966
967 if (sb->s_flags & MS_RDONLY) {
968 sb->s_frozen = SB_FREEZE_TRANS;
969 smp_wmb();
970 up_write(&sb->s_umount);
971 return 0;
972 }
973
974 sb->s_frozen = SB_FREEZE_WRITE;
975 smp_wmb();
976
977 sync_filesystem(sb);
978
979 sb->s_frozen = SB_FREEZE_TRANS;
980 smp_wmb();
981
982 sync_blockdev(sb->s_bdev);
983 if (sb->s_op->freeze_fs) {
984 ret = sb->s_op->freeze_fs(sb);
985 if (ret) {
986 printk(KERN_ERR
987 "VFS:Filesystem freeze failed\n");
988 sb->s_frozen = SB_UNFROZEN;
989 deactivate_locked_super(sb);
990 return ret;
991 }
992 }
993 up_write(&sb->s_umount);
994 return 0;
995}
996EXPORT_SYMBOL(freeze_super);
997
998/**
999 * thaw_super -- unlock filesystem
1000 * @sb: the super to thaw
1001 *
1002 * Unlocks the filesystem and marks it writeable again after freeze_super().
1003 */
1004int thaw_super(struct super_block *sb)
1005{
1006 int error;
1007
1008 down_write(&sb->s_umount);
1009 if (sb->s_frozen == SB_UNFROZEN) {
1010 up_write(&sb->s_umount);
1011 return -EINVAL;
1012 }
1013
1014 if (sb->s_flags & MS_RDONLY)
1015 goto out;
1016
1017 if (sb->s_op->unfreeze_fs) {
1018 error = sb->s_op->unfreeze_fs(sb);
1019 if (error) {
1020 printk(KERN_ERR
1021 "VFS:Filesystem thaw failed\n");
1022 sb->s_frozen = SB_FREEZE_TRANS;
1023 up_write(&sb->s_umount);
1024 return error;
1025 }
1026 }
1027
1028out:
1029 sb->s_frozen = SB_UNFROZEN;
1030 smp_wmb();
1031 wake_up(&sb->s_wait_unfrozen);
1032 deactivate_locked_super(sb);
1033
1034 return 0;
1035}
1036EXPORT_SYMBOL(thaw_super);
1037
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -07001038static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
1039{
1040 int err;
1041 const char *subtype = strchr(fstype, '.');
1042 if (subtype) {
1043 subtype++;
1044 err = -EINVAL;
1045 if (!subtype[0])
1046 goto err;
1047 } else
1048 subtype = "";
1049
1050 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
1051 err = -ENOMEM;
1052 if (!mnt->mnt_sb->s_subtype)
1053 goto err;
1054 return mnt;
1055
1056 err:
1057 mntput(mnt);
1058 return ERR_PTR(err);
1059}
1060
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001061struct vfsmount *
1062do_kern_mount(const char *fstype, int flags, const char *name, void *data)
1063{
1064 struct file_system_type *type = get_fs_type(fstype);
1065 struct vfsmount *mnt;
1066 if (!type)
1067 return ERR_PTR(-ENODEV);
1068 mnt = vfs_kern_mount(type, flags, name, data);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -07001069 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
1070 !mnt->mnt_sb->s_subtype)
1071 mnt = fs_set_subtype(mnt, fstype);
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001072 put_filesystem(type);
1073 return mnt;
1074}
Al Viro8a4e98d2008-02-24 01:43:03 -05001075EXPORT_SYMBOL_GPL(do_kern_mount);
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001076
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001077struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078{
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001079 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080}
1081
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001082EXPORT_SYMBOL_GPL(kern_mount_data);