blob: 9674ab2c8718c3f1061f3556e6ec3e9b479cb8a9 [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);
Al Viro7a4dec52010-08-09 12:05:43 -0400308 s = NULL;
Li Zefana3cfbb52009-03-12 14:31:29 -0700309 }
Al Virod3f21472010-03-23 11:11:05 -0400310 down_write(&old->s_umount);
Al Viro7a4dec52010-08-09 12:05:43 -0400311 if (unlikely(!(old->s_flags & MS_BORN))) {
312 deactivate_locked_super(old);
313 goto retry;
314 }
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700315 return old;
316 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 }
318 if (!s) {
319 spin_unlock(&sb_lock);
Ingo Molnarcf516242006-07-03 00:25:27 -0700320 s = alloc_super(type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321 if (!s)
322 return ERR_PTR(-ENOMEM);
323 goto retry;
324 }
325
326 err = set(s, data);
327 if (err) {
328 spin_unlock(&sb_lock);
Li Zefana3cfbb52009-03-12 14:31:29 -0700329 up_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 destroy_super(s);
331 return ERR_PTR(err);
332 }
333 s->s_type = type;
334 strlcpy(s->s_id, type->name, sizeof(s->s_id));
335 list_add_tail(&s->s_list, &super_blocks);
336 list_add(&s->s_instances, &type->fs_supers);
337 spin_unlock(&sb_lock);
338 get_filesystem(type);
339 return s;
340}
341
342EXPORT_SYMBOL(sget);
343
344void drop_super(struct super_block *sb)
345{
346 up_read(&sb->s_umount);
347 put_super(sb);
348}
349
350EXPORT_SYMBOL(drop_super);
351
Christoph Hellwige5004752009-05-05 16:08:56 +0200352/**
353 * sync_supers - helper for periodic superblock writeback
354 *
355 * Call the write_super method if present on all dirty superblocks in
356 * the system. This is for the periodic writeback used by most older
357 * filesystems. For data integrity superblock writeback use
358 * sync_filesystems() instead.
359 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 * Note: check the dirty flag before waiting, so we don't
361 * hold up the sync while mounting a device. (The newly
362 * mounted device won't need syncing.)
363 */
364void sync_supers(void)
365{
Al Virodca33252010-07-25 02:31:46 +0400366 struct super_block *sb, *p = NULL;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700367
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400369 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400370 if (list_empty(&sb->s_instances))
371 continue;
Christoph Hellwige5004752009-05-05 16:08:56 +0200372 if (sb->s_op->write_super && sb->s_dirt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 sb->s_count++;
374 spin_unlock(&sb_lock);
Christoph Hellwige5004752009-05-05 16:08:56 +0200375
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 down_read(&sb->s_umount);
Christoph Hellwige5004752009-05-05 16:08:56 +0200377 if (sb->s_root && sb->s_dirt)
378 sb->s_op->write_super(sb);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700379 up_read(&sb->s_umount);
Christoph Hellwige5004752009-05-05 16:08:56 +0200380
Kirill Korotaev618f0632005-06-23 00:09:54 -0700381 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400382 if (p)
383 __put_super(p);
384 p = sb;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700385 }
386 }
Al Virodca33252010-07-25 02:31:46 +0400387 if (p)
388 __put_super(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 spin_unlock(&sb_lock);
390}
391
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392/**
Al Viro01a05b32010-03-23 06:06:58 -0400393 * iterate_supers - call function for all active superblocks
394 * @f: function to call
395 * @arg: argument to pass to it
396 *
397 * Scans the superblock list and calls given function, passing it
398 * locked superblock and given argument.
399 */
400void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
401{
Al Virodca33252010-07-25 02:31:46 +0400402 struct super_block *sb, *p = NULL;
Al Viro01a05b32010-03-23 06:06:58 -0400403
404 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400405 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro01a05b32010-03-23 06:06:58 -0400406 if (list_empty(&sb->s_instances))
407 continue;
408 sb->s_count++;
409 spin_unlock(&sb_lock);
410
411 down_read(&sb->s_umount);
412 if (sb->s_root)
413 f(sb, arg);
414 up_read(&sb->s_umount);
415
416 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400417 if (p)
418 __put_super(p);
419 p = sb;
Al Viro01a05b32010-03-23 06:06:58 -0400420 }
Al Virodca33252010-07-25 02:31:46 +0400421 if (p)
422 __put_super(p);
Al Viro01a05b32010-03-23 06:06:58 -0400423 spin_unlock(&sb_lock);
424}
425
426/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 * get_super - get the superblock of a device
428 * @bdev: device to get the superblock for
429 *
430 * Scans the superblock list and finds the superblock of the file system
431 * mounted on the device given. %NULL is returned if no match is found.
432 */
433
Al Virodf40c012010-03-22 20:23:25 -0400434struct super_block *get_super(struct block_device *bdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700436 struct super_block *sb;
437
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 if (!bdev)
439 return NULL;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700440
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700442rescan:
443 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400444 if (list_empty(&sb->s_instances))
445 continue;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700446 if (sb->s_bdev == bdev) {
447 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700449 down_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400450 /* still alive? */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700451 if (sb->s_root)
452 return sb;
453 up_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400454 /* nope, got unmounted */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700455 spin_lock(&sb_lock);
Al Virodf40c012010-03-22 20:23:25 -0400456 __put_super(sb);
457 goto rescan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458 }
459 }
460 spin_unlock(&sb_lock);
461 return NULL;
462}
463
464EXPORT_SYMBOL(get_super);
Christoph Hellwig45042302009-08-03 23:28:35 +0200465
466/**
467 * get_active_super - get an active reference to the superblock of a device
468 * @bdev: device to get the superblock for
469 *
470 * Scans the superblock list and finds the superblock of the file system
471 * mounted on the device given. Returns the superblock with an active
Al Virod3f21472010-03-23 11:11:05 -0400472 * reference or %NULL if none was found.
Christoph Hellwig45042302009-08-03 23:28:35 +0200473 */
474struct super_block *get_active_super(struct block_device *bdev)
475{
476 struct super_block *sb;
477
478 if (!bdev)
479 return NULL;
480
Al Viro14945832010-03-22 20:15:33 -0400481restart:
Christoph Hellwig45042302009-08-03 23:28:35 +0200482 spin_lock(&sb_lock);
483 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400484 if (list_empty(&sb->s_instances))
485 continue;
Al Viro14945832010-03-22 20:15:33 -0400486 if (sb->s_bdev == bdev) {
487 if (grab_super(sb)) /* drops sb_lock */
488 return sb;
489 else
490 goto restart;
491 }
Christoph Hellwig45042302009-08-03 23:28:35 +0200492 }
493 spin_unlock(&sb_lock);
494 return NULL;
495}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496
Al Virodf40c012010-03-22 20:23:25 -0400497struct super_block *user_get_super(dev_t dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700499 struct super_block *sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700502rescan:
503 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400504 if (list_empty(&sb->s_instances))
505 continue;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700506 if (sb->s_dev == dev) {
507 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700509 down_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400510 /* still alive? */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700511 if (sb->s_root)
512 return sb;
513 up_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400514 /* nope, got unmounted */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700515 spin_lock(&sb_lock);
Al Virodf40c012010-03-22 20:23:25 -0400516 __put_super(sb);
517 goto rescan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 }
519 }
520 spin_unlock(&sb_lock);
521 return NULL;
522}
523
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 * do_remount_sb - asks filesystem to change mount options.
526 * @sb: superblock in question
527 * @flags: numeric part of options
528 * @data: the rest of options
529 * @force: whether or not to force the change
530 *
531 * Alters the mount options of a mounted file system.
532 */
533int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
534{
535 int retval;
Christoph Hellwigc79d9672010-05-19 07:16:40 -0400536 int remount_ro;
Christoph Hellwig45042302009-08-03 23:28:35 +0200537
538 if (sb->s_frozen != SB_UNFROZEN)
539 return -EBUSY;
540
David Howells93614012006-09-30 20:45:40 +0200541#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
543 return -EACCES;
David Howells93614012006-09-30 20:45:40 +0200544#endif
Christoph Hellwig45042302009-08-03 23:28:35 +0200545
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 if (flags & MS_RDONLY)
547 acct_auto_close(sb);
548 shrink_dcache_sb(sb);
Jan Kara60b06802009-04-27 16:43:53 +0200549 sync_filesystem(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550
Nick Piggind208bbd2009-12-21 16:28:53 -0800551 remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
Nick Piggind208bbd2009-12-21 16:28:53 -0800552
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 /* If we are remounting RDONLY and current sb is read/write,
554 make sure there are no rw files opened */
Nick Piggind208bbd2009-12-21 16:28:53 -0800555 if (remount_ro) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 if (force)
557 mark_files_ro(sb);
J. R. Okajimab0895512009-06-17 01:16:50 +0900558 else if (!fs_may_remount_ro(sb))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559 return -EBUSY;
560 }
561
562 if (sb->s_op->remount_fs) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 retval = sb->s_op->remount_fs(sb, &flags, data);
J. R. Okajimab0895512009-06-17 01:16:50 +0900564 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 return retval;
566 }
567 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
Christoph Hellwigc79d9672010-05-19 07:16:40 -0400568
Nick Piggind208bbd2009-12-21 16:28:53 -0800569 /*
570 * Some filesystems modify their metadata via some other path than the
571 * bdev buffer cache (eg. use a private mapping, or directories in
572 * pagecache, etc). Also file data modifications go via their own
573 * mappings. So If we try to mount readonly then copy the filesystem
574 * from bdev, we could get stale data, so invalidate it to give a best
575 * effort at coherency.
576 */
577 if (remount_ro && sb->s_bdev)
578 invalidate_bdev(sb->s_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 return 0;
580}
581
Jens Axboea2a95372009-03-17 09:38:40 +0100582static void do_emergency_remount(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583{
Al Virodca33252010-07-25 02:31:46 +0400584 struct super_block *sb, *p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585
586 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400587 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400588 if (list_empty(&sb->s_instances))
589 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 sb->s_count++;
591 spin_unlock(&sb_lock);
Al Viro443b94b2009-05-05 23:48:50 -0400592 down_write(&sb->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
594 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 * What lock protects sb->s_flags??
596 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 do_remount_sb(sb, MS_RDONLY, NULL, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 }
Al Viro443b94b2009-05-05 23:48:50 -0400599 up_write(&sb->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400601 if (p)
602 __put_super(p);
603 p = sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 }
Al Virodca33252010-07-25 02:31:46 +0400605 if (p)
606 __put_super(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 spin_unlock(&sb_lock);
Jens Axboea2a95372009-03-17 09:38:40 +0100608 kfree(work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 printk("Emergency Remount complete\n");
610}
611
612void emergency_remount(void)
613{
Jens Axboea2a95372009-03-17 09:38:40 +0100614 struct work_struct *work;
615
616 work = kmalloc(sizeof(*work), GFP_ATOMIC);
617 if (work) {
618 INIT_WORK(work, do_emergency_remount);
619 schedule_work(work);
620 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621}
622
623/*
624 * Unnamed block devices are dummy devices used by virtual
625 * filesystems which don't use real block-devices. -- jrs
626 */
627
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400628static DEFINE_IDA(unnamed_dev_ida);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
Al Viroc63e09e2009-06-24 02:05:18 -0400630static int unnamed_dev_start = 0; /* don't bother trying below it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631
632int set_anon_super(struct super_block *s, void *data)
633{
634 int dev;
635 int error;
636
637 retry:
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400638 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 return -ENOMEM;
640 spin_lock(&unnamed_dev_lock);
Al Viroc63e09e2009-06-24 02:05:18 -0400641 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
Al Virof21f6222009-06-24 03:12:00 -0400642 if (!error)
643 unnamed_dev_start = dev + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 spin_unlock(&unnamed_dev_lock);
645 if (error == -EAGAIN)
646 /* We raced and lost with another CPU. */
647 goto retry;
648 else if (error)
649 return -EAGAIN;
650
651 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
652 spin_lock(&unnamed_dev_lock);
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400653 ida_remove(&unnamed_dev_ida, dev);
Al Virof21f6222009-06-24 03:12:00 -0400654 if (unnamed_dev_start > dev)
655 unnamed_dev_start = dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 spin_unlock(&unnamed_dev_lock);
657 return -EMFILE;
658 }
659 s->s_dev = MKDEV(0, dev & MINORMASK);
Jörn Engel5129a462010-04-25 08:54:42 +0200660 s->s_bdi = &noop_backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 return 0;
662}
663
664EXPORT_SYMBOL(set_anon_super);
665
666void kill_anon_super(struct super_block *sb)
667{
668 int slot = MINOR(sb->s_dev);
669
670 generic_shutdown_super(sb);
671 spin_lock(&unnamed_dev_lock);
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400672 ida_remove(&unnamed_dev_ida, slot);
Al Viroc63e09e2009-06-24 02:05:18 -0400673 if (slot < unnamed_dev_start)
674 unnamed_dev_start = slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 spin_unlock(&unnamed_dev_lock);
676}
677
678EXPORT_SYMBOL(kill_anon_super);
679
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680void kill_litter_super(struct super_block *sb)
681{
682 if (sb->s_root)
683 d_genocide(sb->s_root);
684 kill_anon_super(sb);
685}
686
687EXPORT_SYMBOL(kill_litter_super);
688
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700689static int ns_test_super(struct super_block *sb, void *data)
690{
691 return sb->s_fs_info == data;
692}
693
694static int ns_set_super(struct super_block *sb, void *data)
695{
696 sb->s_fs_info = data;
697 return set_anon_super(sb, NULL);
698}
699
700int get_sb_ns(struct file_system_type *fs_type, int flags, void *data,
701 int (*fill_super)(struct super_block *, void *, int),
702 struct vfsmount *mnt)
703{
704 struct super_block *sb;
705
706 sb = sget(fs_type, ns_test_super, ns_set_super, data);
707 if (IS_ERR(sb))
708 return PTR_ERR(sb);
709
710 if (!sb->s_root) {
711 int err;
712 sb->s_flags = flags;
713 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
714 if (err) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400715 deactivate_locked_super(sb);
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700716 return err;
717 }
718
719 sb->s_flags |= MS_ACTIVE;
720 }
721
722 simple_set_mnt(mnt, sb);
723 return 0;
724}
725
726EXPORT_SYMBOL(get_sb_ns);
727
David Howells93614012006-09-30 20:45:40 +0200728#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729static int set_bdev_super(struct super_block *s, void *data)
730{
731 s->s_bdev = data;
732 s->s_dev = s->s_bdev->bd_dev;
Jens Axboe32a88aa2009-09-16 15:02:33 +0200733
734 /*
735 * We set the bdi here to the queue backing, file systems can
736 * overwrite this in ->fill_super()
737 */
738 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 return 0;
740}
741
742static int test_bdev_super(struct super_block *s, void *data)
743{
744 return (void *)s->s_bdev == data;
745}
746
David Howells454e2392006-06-23 02:02:57 -0700747int get_sb_bdev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 int flags, const char *dev_name, void *data,
David Howells454e2392006-06-23 02:02:57 -0700749 int (*fill_super)(struct super_block *, void *, int),
750 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751{
752 struct block_device *bdev;
753 struct super_block *s;
Al Viro30c40d22008-02-22 19:50:45 -0500754 fmode_t mode = FMODE_READ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 int error = 0;
756
Al Viro30c40d22008-02-22 19:50:45 -0500757 if (!(flags & MS_RDONLY))
758 mode |= FMODE_WRITE;
759
760 bdev = open_bdev_exclusive(dev_name, mode, fs_type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 if (IS_ERR(bdev))
David Howells454e2392006-06-23 02:02:57 -0700762 return PTR_ERR(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763
764 /*
765 * once the super is inserted into the list by sget, s_umount
766 * will protect the lockfs code from trying to start a snapshot
767 * while we are mounting
768 */
Christoph Hellwig4fadd7b2009-08-03 23:28:06 +0200769 mutex_lock(&bdev->bd_fsfreeze_mutex);
770 if (bdev->bd_fsfreeze_count > 0) {
771 mutex_unlock(&bdev->bd_fsfreeze_mutex);
772 error = -EBUSY;
773 goto error_bdev;
774 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
Christoph Hellwig4fadd7b2009-08-03 23:28:06 +0200776 mutex_unlock(&bdev->bd_fsfreeze_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700778 goto error_s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779
780 if (s->s_root) {
781 if ((flags ^ s->s_flags) & MS_RDONLY) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400782 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700783 error = -EBUSY;
784 goto error_bdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 }
David Howells454e2392006-06-23 02:02:57 -0700786
Tejun Heo4f331f02010-07-20 15:18:07 -0700787 /*
788 * s_umount nests inside bd_mutex during
789 * __invalidate_device(). close_bdev_exclusive()
790 * acquires bd_mutex and can't be called under
791 * s_umount. Drop s_umount temporarily. This is safe
792 * as we're holding an active reference.
793 */
794 up_write(&s->s_umount);
Al Viro30c40d22008-02-22 19:50:45 -0500795 close_bdev_exclusive(bdev, mode);
Tejun Heo4f331f02010-07-20 15:18:07 -0700796 down_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 } else {
798 char b[BDEVNAME_SIZE];
799
800 s->s_flags = flags;
Al Viro30c40d22008-02-22 19:50:45 -0500801 s->s_mode = mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
Pekka Enberge78c9a02006-01-08 01:03:39 -0800803 sb_set_blocksize(s, block_size(bdev));
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800804 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400806 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700807 goto error;
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800808 }
David Howells454e2392006-06-23 02:02:57 -0700809
810 s->s_flags |= MS_ACTIVE;
Theodore Ts'o87d8fe12009-01-03 09:47:09 -0500811 bdev->bd_super = s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 }
813
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800814 simple_set_mnt(mnt, s);
815 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816
David Howells454e2392006-06-23 02:02:57 -0700817error_s:
818 error = PTR_ERR(s);
819error_bdev:
Al Viro30c40d22008-02-22 19:50:45 -0500820 close_bdev_exclusive(bdev, mode);
David Howells454e2392006-06-23 02:02:57 -0700821error:
822 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823}
824
825EXPORT_SYMBOL(get_sb_bdev);
826
827void kill_block_super(struct super_block *sb)
828{
829 struct block_device *bdev = sb->s_bdev;
Al Viro30c40d22008-02-22 19:50:45 -0500830 fmode_t mode = sb->s_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831
H Hartley Sweetenddbaaf32009-04-29 20:14:57 -0400832 bdev->bd_super = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 generic_shutdown_super(sb);
834 sync_blockdev(bdev);
Al Viro30c40d22008-02-22 19:50:45 -0500835 close_bdev_exclusive(bdev, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836}
837
838EXPORT_SYMBOL(kill_block_super);
David Howells93614012006-09-30 20:45:40 +0200839#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840
David Howells454e2392006-06-23 02:02:57 -0700841int get_sb_nodev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842 int flags, void *data,
David Howells454e2392006-06-23 02:02:57 -0700843 int (*fill_super)(struct super_block *, void *, int),
844 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845{
846 int error;
847 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
848
849 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700850 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851
852 s->s_flags = flags;
853
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800854 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400856 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700857 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858 }
859 s->s_flags |= MS_ACTIVE;
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800860 simple_set_mnt(mnt, s);
861 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862}
863
864EXPORT_SYMBOL(get_sb_nodev);
865
866static int compare_single(struct super_block *s, void *p)
867{
868 return 1;
869}
870
David Howells454e2392006-06-23 02:02:57 -0700871int get_sb_single(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 int flags, void *data,
David Howells454e2392006-06-23 02:02:57 -0700873 int (*fill_super)(struct super_block *, void *, int),
874 struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875{
876 struct super_block *s;
877 int error;
878
879 s = sget(fs_type, compare_single, set_anon_super, NULL);
880 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700881 return PTR_ERR(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 if (!s->s_root) {
883 s->s_flags = flags;
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800884 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400886 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700887 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888 }
889 s->s_flags |= MS_ACTIVE;
Kay Sievers9329d1b2009-12-18 21:18:15 +0100890 } else {
891 do_remount_sb(s, flags, data, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 }
Sukadev Bhattiprolua3ec9472009-03-04 12:06:34 -0800893 simple_set_mnt(mnt, s);
894 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895}
896
897EXPORT_SYMBOL(get_sb_single);
898
899struct vfsmount *
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400900vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902 struct vfsmount *mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 char *secdata = NULL;
David Howells454e2392006-06-23 02:02:57 -0700904 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905
906 if (!type)
907 return ERR_PTR(-ENODEV);
908
David Howells454e2392006-06-23 02:02:57 -0700909 error = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 mnt = alloc_vfsmnt(name);
911 if (!mnt)
912 goto out;
913
Al Viro80893522010-02-05 09:30:46 -0500914 if (flags & MS_KERNMOUNT)
915 mnt->mnt_flags = MNT_INTERNAL;
916
Eric Parise0007522008-03-05 10:31:54 -0500917 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700918 secdata = alloc_secdata();
David Howells454e2392006-06-23 02:02:57 -0700919 if (!secdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 goto out_mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
Eric Parise0007522008-03-05 10:31:54 -0500922 error = security_sb_copy_data(data, secdata);
David Howells454e2392006-06-23 02:02:57 -0700923 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 goto out_free_secdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 }
926
David Howells454e2392006-06-23 02:02:57 -0700927 error = type->get_sb(type, flags, name, data, mnt);
928 if (error < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 goto out_free_secdata;
Lee Schermerhornb4c07bc2007-07-15 23:40:54 -0700930 BUG_ON(!mnt->mnt_sb);
Jörn Engel5129a462010-04-25 08:54:42 +0200931 WARN_ON(!mnt->mnt_sb->s_bdi);
Al Viro7a4dec52010-08-09 12:05:43 -0400932 mnt->mnt_sb->s_flags |= MS_BORN;
David Howells454e2392006-06-23 02:02:57 -0700933
Jörn Engel5129a462010-04-25 08:54:42 +0200934 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
935 if (error)
936 goto out_sb;
David Howells454e2392006-06-23 02:02:57 -0700937
Jeff Layton42cb56a2009-09-18 13:05:53 -0700938 /*
939 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
940 * but s_maxbytes was an unsigned long long for many releases. Throw
941 * this warning for a little while to try and catch filesystems that
942 * violate this rule. This warning should be either removed or
943 * converted to a BUG() in 2.6.34.
944 */
945 WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
946 "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
947
David Howells454e2392006-06-23 02:02:57 -0700948 mnt->mnt_mountpoint = mnt->mnt_root;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700949 mnt->mnt_parent = mnt;
David Howells454e2392006-06-23 02:02:57 -0700950 up_write(&mnt->mnt_sb->s_umount);
Gerald Schaefer8680e222005-06-21 17:15:16 -0700951 free_secdata(secdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 return mnt;
953out_sb:
David Howells454e2392006-06-23 02:02:57 -0700954 dput(mnt->mnt_root);
Al Viro74dbbdd2009-05-06 01:07:50 -0400955 deactivate_locked_super(mnt->mnt_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956out_free_secdata:
957 free_secdata(secdata);
958out_mnt:
959 free_vfsmnt(mnt);
960out:
David Howells454e2392006-06-23 02:02:57 -0700961 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962}
963
Trond Myklebustbb4a58b2006-06-09 09:34:15 -0400964EXPORT_SYMBOL_GPL(vfs_kern_mount);
965
Josef Bacik18e9e512010-03-23 10:34:56 -0400966/**
Randy Dunlap7000d3c2010-05-24 22:22:34 -0700967 * freeze_super - lock the filesystem and force it into a consistent state
968 * @sb: the super to lock
Josef Bacik18e9e512010-03-23 10:34:56 -0400969 *
970 * Syncs the super to make sure the filesystem is consistent and calls the fs's
971 * freeze_fs. Subsequent calls to this without first thawing the fs will return
972 * -EBUSY.
973 */
974int freeze_super(struct super_block *sb)
975{
976 int ret;
977
978 atomic_inc(&sb->s_active);
979 down_write(&sb->s_umount);
980 if (sb->s_frozen) {
981 deactivate_locked_super(sb);
982 return -EBUSY;
983 }
984
985 if (sb->s_flags & MS_RDONLY) {
986 sb->s_frozen = SB_FREEZE_TRANS;
987 smp_wmb();
988 up_write(&sb->s_umount);
989 return 0;
990 }
991
992 sb->s_frozen = SB_FREEZE_WRITE;
993 smp_wmb();
994
995 sync_filesystem(sb);
996
997 sb->s_frozen = SB_FREEZE_TRANS;
998 smp_wmb();
999
1000 sync_blockdev(sb->s_bdev);
1001 if (sb->s_op->freeze_fs) {
1002 ret = sb->s_op->freeze_fs(sb);
1003 if (ret) {
1004 printk(KERN_ERR
1005 "VFS:Filesystem freeze failed\n");
1006 sb->s_frozen = SB_UNFROZEN;
1007 deactivate_locked_super(sb);
1008 return ret;
1009 }
1010 }
1011 up_write(&sb->s_umount);
1012 return 0;
1013}
1014EXPORT_SYMBOL(freeze_super);
1015
1016/**
1017 * thaw_super -- unlock filesystem
1018 * @sb: the super to thaw
1019 *
1020 * Unlocks the filesystem and marks it writeable again after freeze_super().
1021 */
1022int thaw_super(struct super_block *sb)
1023{
1024 int error;
1025
1026 down_write(&sb->s_umount);
1027 if (sb->s_frozen == SB_UNFROZEN) {
1028 up_write(&sb->s_umount);
1029 return -EINVAL;
1030 }
1031
1032 if (sb->s_flags & MS_RDONLY)
1033 goto out;
1034
1035 if (sb->s_op->unfreeze_fs) {
1036 error = sb->s_op->unfreeze_fs(sb);
1037 if (error) {
1038 printk(KERN_ERR
1039 "VFS:Filesystem thaw failed\n");
1040 sb->s_frozen = SB_FREEZE_TRANS;
1041 up_write(&sb->s_umount);
1042 return error;
1043 }
1044 }
1045
1046out:
1047 sb->s_frozen = SB_UNFROZEN;
1048 smp_wmb();
1049 wake_up(&sb->s_wait_unfrozen);
1050 deactivate_locked_super(sb);
1051
1052 return 0;
1053}
1054EXPORT_SYMBOL(thaw_super);
1055
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -07001056static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
1057{
1058 int err;
1059 const char *subtype = strchr(fstype, '.');
1060 if (subtype) {
1061 subtype++;
1062 err = -EINVAL;
1063 if (!subtype[0])
1064 goto err;
1065 } else
1066 subtype = "";
1067
1068 mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
1069 err = -ENOMEM;
1070 if (!mnt->mnt_sb->s_subtype)
1071 goto err;
1072 return mnt;
1073
1074 err:
1075 mntput(mnt);
1076 return ERR_PTR(err);
1077}
1078
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001079struct vfsmount *
1080do_kern_mount(const char *fstype, int flags, const char *name, void *data)
1081{
1082 struct file_system_type *type = get_fs_type(fstype);
1083 struct vfsmount *mnt;
1084 if (!type)
1085 return ERR_PTR(-ENODEV);
1086 mnt = vfs_kern_mount(type, flags, name, data);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -07001087 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
1088 !mnt->mnt_sb->s_subtype)
1089 mnt = fs_set_subtype(mnt, fstype);
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001090 put_filesystem(type);
1091 return mnt;
1092}
Al Viro8a4e98d2008-02-24 01:43:03 -05001093EXPORT_SYMBOL_GPL(do_kern_mount);
Trond Myklebustbb4a58b2006-06-09 09:34:15 -04001094
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001095struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096{
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001097 return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098}
1099
Pavel Emelyanov8bf97252007-10-18 23:40:02 -07001100EXPORT_SYMBOL_GPL(kern_mount_data);