blob: ab3d672db0deae0a84a01bc1938cd967cc27e79f [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>
Nick Pigginceb5bdc2011-01-07 17:50:05 +110033#include <linux/rculist_bl.h>
Dan Magenheimerc515e1f2011-05-26 10:01:43 -060034#include <linux/cleancache.h>
Al Viro6d59e7f2008-03-22 15:48:17 -040035#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
37
Linus Torvalds1da177e2005-04-16 15:20:36 -070038LIST_HEAD(super_blocks);
39DEFINE_SPINLOCK(sb_lock);
40
41/**
42 * alloc_super - create new superblock
Henrik Kretzschmarfe2bbc42006-09-06 00:03:41 -070043 * @type: filesystem type superblock should belong to
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 *
45 * Allocates and initializes a new &struct super_block. alloc_super()
46 * returns a pointer new superblock or %NULL if allocation had failed.
47 */
Ingo Molnarcf516242006-07-03 00:25:27 -070048static struct super_block *alloc_super(struct file_system_type *type)
Linus Torvalds1da177e2005-04-16 15:20:36 -070049{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -080050 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
Alexey Dobriyanb87221d2009-09-21 17:01:09 -070051 static const struct super_operations default_op;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53 if (s) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 if (security_sb_alloc(s)) {
55 kfree(s);
56 s = NULL;
57 goto out;
58 }
Nick Piggin6416ccb2010-08-18 04:37:38 +100059#ifdef CONFIG_SMP
60 s->s_files = alloc_percpu(struct list_head);
61 if (!s->s_files) {
62 security_sb_free(s);
63 kfree(s);
64 s = NULL;
65 goto out;
66 } else {
67 int i;
68
69 for_each_possible_cpu(i)
70 INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));
71 }
72#else
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 INIT_LIST_HEAD(&s->s_files);
Nick Piggin6416ccb2010-08-18 04:37:38 +100074#endif
Jens Axboe95f28602011-03-17 11:13:12 +010075 s->s_bdi = &default_backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 INIT_LIST_HEAD(&s->s_instances);
Nick Pigginceb5bdc2011-01-07 17:50:05 +110077 INIT_HLIST_BL_HEAD(&s->s_anon);
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 INIT_LIST_HEAD(&s->s_inodes);
Kentaro Makitada3bbdd2008-07-23 21:27:13 -070079 INIT_LIST_HEAD(&s->s_dentry_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 init_rwsem(&s->s_umount);
Ingo Molnar7892f2f2006-01-09 15:59:25 -080081 mutex_init(&s->s_lock);
Arjan van de Ven897c6ff2006-07-03 00:25:28 -070082 lockdep_set_class(&s->s_umount, &type->s_umount_key);
Ingo Molnarcf516242006-07-03 00:25:27 -070083 /*
84 * The locking rules for s_lock are up to the
85 * filesystem. For example ext3fs has different
86 * lock ordering than usbfs:
87 */
88 lockdep_set_class(&s->s_lock, &type->s_lock_key);
Peter Zijlstraada723d2009-02-18 14:48:30 -080089 /*
90 * sget() can have s_umount recursion.
91 *
92 * When it cannot find a suitable sb, it allocates a new
93 * one (this one), and tries again to find a suitable old
94 * one.
95 *
96 * In case that succeeds, it will acquire the s_umount
97 * lock of the old one. Since these are clearly distrinct
98 * locks, and this object isn't exposed yet, there's no
99 * risk of deadlocks.
100 *
101 * Annotate this by putting this lock in a different
102 * subclass.
103 */
104 down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
Al Virob20bd1a2010-03-22 08:53:19 -0400105 s->s_count = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 atomic_set(&s->s_active, 1);
Arjan van de Vena11f3a02006-03-23 03:00:33 -0800107 mutex_init(&s->s_vfs_rename_mutex);
Roland Dreier51ee0492010-04-27 14:23:57 -0700108 lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
Ingo Molnard3be9152006-03-23 03:00:29 -0800109 mutex_init(&s->s_dquot.dqio_mutex);
110 mutex_init(&s->s_dquot.dqonoff_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 init_rwsem(&s->s_dquot.dqptr_sem);
112 init_waitqueue_head(&s->s_wait_unfrozen);
113 s->s_maxbytes = MAX_NON_LFS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 s->s_op = &default_op;
115 s->s_time_gran = 1000000000;
Dan Magenheimerc515e1f2011-05-26 10:01:43 -0600116 s->cleancache_poolid = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 }
118out:
119 return s;
120}
121
122/**
123 * destroy_super - frees a superblock
124 * @s: superblock to free
125 *
126 * Frees a superblock.
127 */
128static inline void destroy_super(struct super_block *s)
129{
Nick Piggin6416ccb2010-08-18 04:37:38 +1000130#ifdef CONFIG_SMP
131 free_percpu(s->s_files);
132#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 security_sb_free(s);
Miklos Szeredi79c0b2d2007-05-08 00:25:43 -0700134 kfree(s->s_subtype);
Miklos Szeredib3b304a2008-02-08 04:21:35 -0800135 kfree(s->s_options);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 kfree(s);
137}
138
139/* Superblock refcounting */
140
141/*
Al Viro35cf7ba2010-03-22 21:13:53 -0400142 * Drop a superblock's refcount. The caller must hold sb_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 */
Al Viro35cf7ba2010-03-22 21:13:53 -0400144void __put_super(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 if (!--sb->s_count) {
Al Viro551de6f2010-03-22 19:36:35 -0400147 list_del_init(&sb->s_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 destroy_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150}
151
152/**
153 * put_super - drop a temporary reference to superblock
154 * @sb: superblock in question
155 *
156 * Drops a temporary reference, frees superblock if there's no
157 * references left.
158 */
Jens Axboe03ba3782009-09-09 09:08:54 +0200159void put_super(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160{
161 spin_lock(&sb_lock);
162 __put_super(sb);
163 spin_unlock(&sb_lock);
164}
165
166
167/**
Al Viro74dbbdd2009-05-06 01:07:50 -0400168 * deactivate_locked_super - drop an active reference to superblock
169 * @s: superblock to deactivate
170 *
Al Viro1712ac82010-03-22 15:22:31 -0400171 * Drops an active reference to superblock, converting it into a temprory
172 * one if there is no other active references left. In that case we
173 * tell fs driver to shut it down and drop the temporary reference we
174 * had just acquired.
175 *
176 * Caller holds exclusive lock on superblock; that lock is released.
Al Viro74dbbdd2009-05-06 01:07:50 -0400177 */
178void deactivate_locked_super(struct super_block *s)
179{
180 struct file_system_type *fs = s->s_type;
Al Virob20bd1a2010-03-22 08:53:19 -0400181 if (atomic_dec_and_test(&s->s_active)) {
Dan Magenheimerc515e1f2011-05-26 10:01:43 -0600182 cleancache_flush_fs(s);
Al Viro74dbbdd2009-05-06 01:07:50 -0400183 fs->kill_sb(s);
Boaz Harroshd863b502011-02-10 15:01:20 -0800184 /*
185 * We need to call rcu_barrier so all the delayed rcu free
186 * inodes are flushed before we release the fs module.
187 */
188 rcu_barrier();
Al Viro74dbbdd2009-05-06 01:07:50 -0400189 put_filesystem(fs);
190 put_super(s);
191 } else {
192 up_write(&s->s_umount);
193 }
194}
195
196EXPORT_SYMBOL(deactivate_locked_super);
197
198/**
Al Viro1712ac82010-03-22 15:22:31 -0400199 * deactivate_super - drop an active reference to superblock
200 * @s: superblock to deactivate
201 *
202 * Variant of deactivate_locked_super(), except that superblock is *not*
203 * locked by caller. If we are going to drop the final active reference,
204 * lock will be acquired prior to that.
205 */
206void deactivate_super(struct super_block *s)
207{
208 if (!atomic_add_unless(&s->s_active, -1, 1)) {
209 down_write(&s->s_umount);
210 deactivate_locked_super(s);
211 }
212}
213
214EXPORT_SYMBOL(deactivate_super);
215
216/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 * grab_super - acquire an active reference
218 * @s: reference we are trying to make active
219 *
220 * Tries to acquire an active reference. grab_super() is used when we
221 * had just found a superblock in super_blocks or fs_type->fs_supers
222 * and want to turn it into a full-blown active reference. grab_super()
223 * is called with sb_lock held and drops it. Returns 1 in case of
224 * success, 0 if we had failed (superblock contents was already dead or
225 * dying when grab_super() had been called).
226 */
Josh Triplett9c4dbee2006-09-29 01:59:29 -0700227static int grab_super(struct super_block *s) __releases(sb_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228{
Al Virob20bd1a2010-03-22 08:53:19 -0400229 if (atomic_inc_not_zero(&s->s_active)) {
230 spin_unlock(&sb_lock);
Al Virob20bd1a2010-03-22 08:53:19 -0400231 return 1;
232 }
233 /* it's going away */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 s->s_count++;
235 spin_unlock(&sb_lock);
Al Viro1712ac82010-03-22 15:22:31 -0400236 /* wait for it to die */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 down_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 up_write(&s->s_umount);
239 put_super(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 return 0;
241}
242
David Howellscf9a2ae2006-08-29 19:05:54 +0100243/*
Al Viro914e2632006-10-18 13:55:46 -0400244 * Superblock locking. We really ought to get rid of these two.
245 */
246void lock_super(struct super_block * sb)
247{
248 get_fs_excl();
249 mutex_lock(&sb->s_lock);
250}
251
252void unlock_super(struct super_block * sb)
253{
254 put_fs_excl();
255 mutex_unlock(&sb->s_lock);
256}
257
258EXPORT_SYMBOL(lock_super);
259EXPORT_SYMBOL(unlock_super);
260
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261/**
262 * generic_shutdown_super - common helper for ->kill_sb()
263 * @sb: superblock to kill
264 *
265 * generic_shutdown_super() does all fs-independent work on superblock
266 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
267 * that need destruction out of superblock, call generic_shutdown_super()
268 * and release aforementioned objects. Note: dentries and inodes _are_
269 * taken care of and do not need specific handling.
David Howellsc636ebd2006-10-11 01:22:19 -0700270 *
271 * Upon calling this function, the filesystem may no longer alter or
272 * rearrange the set of dentries belonging to this super_block, nor may it
273 * change the attachments of dentries to inodes.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 */
275void generic_shutdown_super(struct super_block *sb)
276{
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800277 const struct super_operations *sop = sb->s_op;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278
Arjan van de Venefaee192009-01-06 07:20:54 -0800279
David Howellsc636ebd2006-10-11 01:22:19 -0700280 if (sb->s_root) {
281 shrink_dcache_for_umount(sb);
Jan Kara60b06802009-04-27 16:43:53 +0200282 sync_filesystem(sb);
Al Viroa9e220f2009-05-05 22:10:44 -0400283 get_fs_excl();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 sb->s_flags &= ~MS_ACTIVE;
Arjan van de Venefaee192009-01-06 07:20:54 -0800285
Al Viro63997e92010-10-25 20:49:35 -0400286 fsnotify_unmount_inodes(&sb->s_inodes);
287
288 evict_inodes(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 if (sop->put_super)
291 sop->put_super(sb);
292
Al Viro63997e92010-10-25 20:49:35 -0400293 if (!list_empty(&sb->s_inodes)) {
Dave Jones7b4fe292006-02-07 12:58:48 -0800294 printk("VFS: Busy inodes after unmount of %s. "
295 "Self-destruct in 5 seconds. Have a nice day...\n",
296 sb->s_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 }
Al Viroa9e220f2009-05-05 22:10:44 -0400298 put_fs_excl();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 }
300 spin_lock(&sb_lock);
301 /* should be initialized for __put_super_and_need_restart() */
Al Viro551de6f2010-03-22 19:36:35 -0400302 list_del_init(&sb->s_instances);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 spin_unlock(&sb_lock);
304 up_write(&sb->s_umount);
305}
306
307EXPORT_SYMBOL(generic_shutdown_super);
308
309/**
310 * sget - find or create a superblock
311 * @type: filesystem type superblock should belong to
312 * @test: comparison callback
313 * @set: setup callback
314 * @data: argument to each of them
315 */
316struct super_block *sget(struct file_system_type *type,
317 int (*test)(struct super_block *,void *),
318 int (*set)(struct super_block *,void *),
319 void *data)
320{
321 struct super_block *s = NULL;
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700322 struct super_block *old;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 int err;
324
325retry:
326 spin_lock(&sb_lock);
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700327 if (test) {
328 list_for_each_entry(old, &type->fs_supers, s_instances) {
329 if (!test(old, data))
330 continue;
331 if (!grab_super(old))
332 goto retry;
Li Zefana3cfbb52009-03-12 14:31:29 -0700333 if (s) {
334 up_write(&s->s_umount);
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700335 destroy_super(s);
Al Viro7a4dec52010-08-09 12:05:43 -0400336 s = NULL;
Li Zefana3cfbb52009-03-12 14:31:29 -0700337 }
Al Virod3f21472010-03-23 11:11:05 -0400338 down_write(&old->s_umount);
Al Viro7a4dec52010-08-09 12:05:43 -0400339 if (unlikely(!(old->s_flags & MS_BORN))) {
340 deactivate_locked_super(old);
341 goto retry;
342 }
Matthias Kaehlcked4730122007-10-18 23:39:57 -0700343 return old;
344 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 }
346 if (!s) {
347 spin_unlock(&sb_lock);
Ingo Molnarcf516242006-07-03 00:25:27 -0700348 s = alloc_super(type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 if (!s)
350 return ERR_PTR(-ENOMEM);
351 goto retry;
352 }
353
354 err = set(s, data);
355 if (err) {
356 spin_unlock(&sb_lock);
Li Zefana3cfbb52009-03-12 14:31:29 -0700357 up_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 destroy_super(s);
359 return ERR_PTR(err);
360 }
361 s->s_type = type;
362 strlcpy(s->s_id, type->name, sizeof(s->s_id));
363 list_add_tail(&s->s_list, &super_blocks);
364 list_add(&s->s_instances, &type->fs_supers);
365 spin_unlock(&sb_lock);
366 get_filesystem(type);
367 return s;
368}
369
370EXPORT_SYMBOL(sget);
371
372void drop_super(struct super_block *sb)
373{
374 up_read(&sb->s_umount);
375 put_super(sb);
376}
377
378EXPORT_SYMBOL(drop_super);
379
Christoph Hellwige5004752009-05-05 16:08:56 +0200380/**
381 * sync_supers - helper for periodic superblock writeback
382 *
383 * Call the write_super method if present on all dirty superblocks in
384 * the system. This is for the periodic writeback used by most older
385 * filesystems. For data integrity superblock writeback use
386 * sync_filesystems() instead.
387 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 * Note: check the dirty flag before waiting, so we don't
389 * hold up the sync while mounting a device. (The newly
390 * mounted device won't need syncing.)
391 */
392void sync_supers(void)
393{
Al Virodca33252010-07-25 02:31:46 +0400394 struct super_block *sb, *p = NULL;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700395
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400397 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400398 if (list_empty(&sb->s_instances))
399 continue;
Christoph Hellwige5004752009-05-05 16:08:56 +0200400 if (sb->s_op->write_super && sb->s_dirt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 sb->s_count++;
402 spin_unlock(&sb_lock);
Christoph Hellwige5004752009-05-05 16:08:56 +0200403
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 down_read(&sb->s_umount);
Christoph Hellwige5004752009-05-05 16:08:56 +0200405 if (sb->s_root && sb->s_dirt)
406 sb->s_op->write_super(sb);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700407 up_read(&sb->s_umount);
Christoph Hellwige5004752009-05-05 16:08:56 +0200408
Kirill Korotaev618f0632005-06-23 00:09:54 -0700409 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400410 if (p)
411 __put_super(p);
412 p = sb;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700413 }
414 }
Al Virodca33252010-07-25 02:31:46 +0400415 if (p)
416 __put_super(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 spin_unlock(&sb_lock);
418}
419
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420/**
Al Viro01a05b32010-03-23 06:06:58 -0400421 * iterate_supers - call function for all active superblocks
422 * @f: function to call
423 * @arg: argument to pass to it
424 *
425 * Scans the superblock list and calls given function, passing it
426 * locked superblock and given argument.
427 */
428void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
429{
Al Virodca33252010-07-25 02:31:46 +0400430 struct super_block *sb, *p = NULL;
Al Viro01a05b32010-03-23 06:06:58 -0400431
432 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400433 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro01a05b32010-03-23 06:06:58 -0400434 if (list_empty(&sb->s_instances))
435 continue;
436 sb->s_count++;
437 spin_unlock(&sb_lock);
438
439 down_read(&sb->s_umount);
440 if (sb->s_root)
441 f(sb, arg);
442 up_read(&sb->s_umount);
443
444 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400445 if (p)
446 __put_super(p);
447 p = sb;
Al Viro01a05b32010-03-23 06:06:58 -0400448 }
Al Virodca33252010-07-25 02:31:46 +0400449 if (p)
450 __put_super(p);
Al Viro01a05b32010-03-23 06:06:58 -0400451 spin_unlock(&sb_lock);
452}
453
454/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 * get_super - get the superblock of a device
456 * @bdev: device to get the superblock for
457 *
458 * Scans the superblock list and finds the superblock of the file system
459 * mounted on the device given. %NULL is returned if no match is found.
460 */
461
Al Virodf40c012010-03-22 20:23:25 -0400462struct super_block *get_super(struct block_device *bdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700464 struct super_block *sb;
465
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 if (!bdev)
467 return NULL;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700468
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700470rescan:
471 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400472 if (list_empty(&sb->s_instances))
473 continue;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700474 if (sb->s_bdev == bdev) {
475 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700477 down_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400478 /* still alive? */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700479 if (sb->s_root)
480 return sb;
481 up_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400482 /* nope, got unmounted */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700483 spin_lock(&sb_lock);
Al Virodf40c012010-03-22 20:23:25 -0400484 __put_super(sb);
485 goto rescan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 }
487 }
488 spin_unlock(&sb_lock);
489 return NULL;
490}
491
492EXPORT_SYMBOL(get_super);
Christoph Hellwig45042302009-08-03 23:28:35 +0200493
494/**
495 * get_active_super - get an active reference to the superblock of a device
496 * @bdev: device to get the superblock for
497 *
498 * Scans the superblock list and finds the superblock of the file system
499 * mounted on the device given. Returns the superblock with an active
Al Virod3f21472010-03-23 11:11:05 -0400500 * reference or %NULL if none was found.
Christoph Hellwig45042302009-08-03 23:28:35 +0200501 */
502struct super_block *get_active_super(struct block_device *bdev)
503{
504 struct super_block *sb;
505
506 if (!bdev)
507 return NULL;
508
Al Viro14945832010-03-22 20:15:33 -0400509restart:
Christoph Hellwig45042302009-08-03 23:28:35 +0200510 spin_lock(&sb_lock);
511 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400512 if (list_empty(&sb->s_instances))
513 continue;
Al Viro14945832010-03-22 20:15:33 -0400514 if (sb->s_bdev == bdev) {
515 if (grab_super(sb)) /* drops sb_lock */
516 return sb;
517 else
518 goto restart;
519 }
Christoph Hellwig45042302009-08-03 23:28:35 +0200520 }
521 spin_unlock(&sb_lock);
522 return NULL;
523}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524
Al Virodf40c012010-03-22 20:23:25 -0400525struct super_block *user_get_super(dev_t dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526{
Kirill Korotaev618f0632005-06-23 00:09:54 -0700527 struct super_block *sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 spin_lock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700530rescan:
531 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400532 if (list_empty(&sb->s_instances))
533 continue;
Kirill Korotaev618f0632005-06-23 00:09:54 -0700534 if (sb->s_dev == dev) {
535 sb->s_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 spin_unlock(&sb_lock);
Kirill Korotaev618f0632005-06-23 00:09:54 -0700537 down_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400538 /* still alive? */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700539 if (sb->s_root)
540 return sb;
541 up_read(&sb->s_umount);
Al Virodf40c012010-03-22 20:23:25 -0400542 /* nope, got unmounted */
Kirill Korotaev618f0632005-06-23 00:09:54 -0700543 spin_lock(&sb_lock);
Al Virodf40c012010-03-22 20:23:25 -0400544 __put_super(sb);
545 goto rescan;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 }
547 }
548 spin_unlock(&sb_lock);
549 return NULL;
550}
551
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 * do_remount_sb - asks filesystem to change mount options.
554 * @sb: superblock in question
555 * @flags: numeric part of options
556 * @data: the rest of options
557 * @force: whether or not to force the change
558 *
559 * Alters the mount options of a mounted file system.
560 */
561int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
562{
563 int retval;
Christoph Hellwigc79d9672010-05-19 07:16:40 -0400564 int remount_ro;
Christoph Hellwig45042302009-08-03 23:28:35 +0200565
566 if (sb->s_frozen != SB_UNFROZEN)
567 return -EBUSY;
568
David Howells93614012006-09-30 20:45:40 +0200569#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
571 return -EACCES;
David Howells93614012006-09-30 20:45:40 +0200572#endif
Christoph Hellwig45042302009-08-03 23:28:35 +0200573
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 if (flags & MS_RDONLY)
575 acct_auto_close(sb);
576 shrink_dcache_sb(sb);
Jan Kara60b06802009-04-27 16:43:53 +0200577 sync_filesystem(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578
Nick Piggind208bbd2009-12-21 16:28:53 -0800579 remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
Nick Piggind208bbd2009-12-21 16:28:53 -0800580
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 /* If we are remounting RDONLY and current sb is read/write,
582 make sure there are no rw files opened */
Nick Piggind208bbd2009-12-21 16:28:53 -0800583 if (remount_ro) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 if (force)
585 mark_files_ro(sb);
J. R. Okajimab0895512009-06-17 01:16:50 +0900586 else if (!fs_may_remount_ro(sb))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 return -EBUSY;
588 }
589
590 if (sb->s_op->remount_fs) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 retval = sb->s_op->remount_fs(sb, &flags, data);
J. R. Okajimab0895512009-06-17 01:16:50 +0900592 if (retval)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 return retval;
594 }
595 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
Christoph Hellwigc79d9672010-05-19 07:16:40 -0400596
Nick Piggind208bbd2009-12-21 16:28:53 -0800597 /*
598 * Some filesystems modify their metadata via some other path than the
599 * bdev buffer cache (eg. use a private mapping, or directories in
600 * pagecache, etc). Also file data modifications go via their own
601 * mappings. So If we try to mount readonly then copy the filesystem
602 * from bdev, we could get stale data, so invalidate it to give a best
603 * effort at coherency.
604 */
605 if (remount_ro && sb->s_bdev)
606 invalidate_bdev(sb->s_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 return 0;
608}
609
Jens Axboea2a95372009-03-17 09:38:40 +0100610static void do_emergency_remount(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611{
Al Virodca33252010-07-25 02:31:46 +0400612 struct super_block *sb, *p = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613
614 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400615 list_for_each_entry(sb, &super_blocks, s_list) {
Al Viro551de6f2010-03-22 19:36:35 -0400616 if (list_empty(&sb->s_instances))
617 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 sb->s_count++;
619 spin_unlock(&sb_lock);
Al Viro443b94b2009-05-05 23:48:50 -0400620 down_write(&sb->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
622 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 * What lock protects sb->s_flags??
624 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 do_remount_sb(sb, MS_RDONLY, NULL, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626 }
Al Viro443b94b2009-05-05 23:48:50 -0400627 up_write(&sb->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 spin_lock(&sb_lock);
Al Virodca33252010-07-25 02:31:46 +0400629 if (p)
630 __put_super(p);
631 p = sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 }
Al Virodca33252010-07-25 02:31:46 +0400633 if (p)
634 __put_super(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 spin_unlock(&sb_lock);
Jens Axboea2a95372009-03-17 09:38:40 +0100636 kfree(work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 printk("Emergency Remount complete\n");
638}
639
640void emergency_remount(void)
641{
Jens Axboea2a95372009-03-17 09:38:40 +0100642 struct work_struct *work;
643
644 work = kmalloc(sizeof(*work), GFP_ATOMIC);
645 if (work) {
646 INIT_WORK(work, do_emergency_remount);
647 schedule_work(work);
648 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649}
650
651/*
652 * Unnamed block devices are dummy devices used by virtual
653 * filesystems which don't use real block-devices. -- jrs
654 */
655
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400656static DEFINE_IDA(unnamed_dev_ida);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
Al Viroc63e09e2009-06-24 02:05:18 -0400658static int unnamed_dev_start = 0; /* don't bother trying below it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659
660int set_anon_super(struct super_block *s, void *data)
661{
662 int dev;
663 int error;
664
665 retry:
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400666 if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 return -ENOMEM;
668 spin_lock(&unnamed_dev_lock);
Al Viroc63e09e2009-06-24 02:05:18 -0400669 error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
Al Virof21f6222009-06-24 03:12:00 -0400670 if (!error)
671 unnamed_dev_start = dev + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 spin_unlock(&unnamed_dev_lock);
673 if (error == -EAGAIN)
674 /* We raced and lost with another CPU. */
675 goto retry;
676 else if (error)
677 return -EAGAIN;
678
679 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
680 spin_lock(&unnamed_dev_lock);
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400681 ida_remove(&unnamed_dev_ida, dev);
Al Virof21f6222009-06-24 03:12:00 -0400682 if (unnamed_dev_start > dev)
683 unnamed_dev_start = dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 spin_unlock(&unnamed_dev_lock);
685 return -EMFILE;
686 }
687 s->s_dev = MKDEV(0, dev & MINORMASK);
Jörn Engel5129a462010-04-25 08:54:42 +0200688 s->s_bdi = &noop_backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 return 0;
690}
691
692EXPORT_SYMBOL(set_anon_super);
693
694void kill_anon_super(struct super_block *sb)
695{
696 int slot = MINOR(sb->s_dev);
697
698 generic_shutdown_super(sb);
699 spin_lock(&unnamed_dev_lock);
Alexey Dobriyanad76cbc2008-08-28 06:26:23 +0400700 ida_remove(&unnamed_dev_ida, slot);
Al Viroc63e09e2009-06-24 02:05:18 -0400701 if (slot < unnamed_dev_start)
702 unnamed_dev_start = slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 spin_unlock(&unnamed_dev_lock);
704}
705
706EXPORT_SYMBOL(kill_anon_super);
707
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708void kill_litter_super(struct super_block *sb)
709{
710 if (sb->s_root)
711 d_genocide(sb->s_root);
712 kill_anon_super(sb);
713}
714
715EXPORT_SYMBOL(kill_litter_super);
716
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700717static int ns_test_super(struct super_block *sb, void *data)
718{
719 return sb->s_fs_info == data;
720}
721
722static int ns_set_super(struct super_block *sb, void *data)
723{
724 sb->s_fs_info = data;
725 return set_anon_super(sb, NULL);
726}
727
Al Viroceefda62010-07-26 13:16:50 +0400728struct dentry *mount_ns(struct file_system_type *fs_type, int flags,
729 void *data, int (*fill_super)(struct super_block *, void *, int))
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700730{
731 struct super_block *sb;
732
733 sb = sget(fs_type, ns_test_super, ns_set_super, data);
734 if (IS_ERR(sb))
Al Viroceefda62010-07-26 13:16:50 +0400735 return ERR_CAST(sb);
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700736
737 if (!sb->s_root) {
738 int err;
739 sb->s_flags = flags;
740 err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
741 if (err) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400742 deactivate_locked_super(sb);
Al Viroceefda62010-07-26 13:16:50 +0400743 return ERR_PTR(err);
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700744 }
745
746 sb->s_flags |= MS_ACTIVE;
747 }
748
Al Viroceefda62010-07-26 13:16:50 +0400749 return dget(sb->s_root);
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700750}
751
Al Viroceefda62010-07-26 13:16:50 +0400752EXPORT_SYMBOL(mount_ns);
Serge E. Hallyn909e6d92009-04-06 19:01:07 -0700753
David Howells93614012006-09-30 20:45:40 +0200754#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755static int set_bdev_super(struct super_block *s, void *data)
756{
757 s->s_bdev = data;
758 s->s_dev = s->s_bdev->bd_dev;
Jens Axboe32a88aa2009-09-16 15:02:33 +0200759
760 /*
761 * We set the bdi here to the queue backing, file systems can
762 * overwrite this in ->fill_super()
763 */
764 s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 return 0;
766}
767
768static int test_bdev_super(struct super_block *s, void *data)
769{
770 return (void *)s->s_bdev == data;
771}
772
Al Viro152a0832010-07-25 00:46:55 +0400773struct dentry *mount_bdev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 int flags, const char *dev_name, void *data,
Al Viro152a0832010-07-25 00:46:55 +0400775 int (*fill_super)(struct super_block *, void *, int))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776{
777 struct block_device *bdev;
778 struct super_block *s;
Tejun Heod4d77622010-11-13 11:55:18 +0100779 fmode_t mode = FMODE_READ | FMODE_EXCL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 int error = 0;
781
Al Viro30c40d22008-02-22 19:50:45 -0500782 if (!(flags & MS_RDONLY))
783 mode |= FMODE_WRITE;
784
Tejun Heod4d77622010-11-13 11:55:18 +0100785 bdev = blkdev_get_by_path(dev_name, mode, fs_type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 if (IS_ERR(bdev))
Al Viro152a0832010-07-25 00:46:55 +0400787 return ERR_CAST(bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788
789 /*
790 * once the super is inserted into the list by sget, s_umount
791 * will protect the lockfs code from trying to start a snapshot
792 * while we are mounting
793 */
Christoph Hellwig4fadd7b2009-08-03 23:28:06 +0200794 mutex_lock(&bdev->bd_fsfreeze_mutex);
795 if (bdev->bd_fsfreeze_count > 0) {
796 mutex_unlock(&bdev->bd_fsfreeze_mutex);
797 error = -EBUSY;
798 goto error_bdev;
799 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
Christoph Hellwig4fadd7b2009-08-03 23:28:06 +0200801 mutex_unlock(&bdev->bd_fsfreeze_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802 if (IS_ERR(s))
David Howells454e2392006-06-23 02:02:57 -0700803 goto error_s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804
805 if (s->s_root) {
806 if ((flags ^ s->s_flags) & MS_RDONLY) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400807 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700808 error = -EBUSY;
809 goto error_bdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 }
David Howells454e2392006-06-23 02:02:57 -0700811
Tejun Heo4f331f02010-07-20 15:18:07 -0700812 /*
813 * s_umount nests inside bd_mutex during
Tejun Heoe525fd82010-11-13 11:55:17 +0100814 * __invalidate_device(). blkdev_put() acquires
815 * bd_mutex and can't be called under s_umount. Drop
816 * s_umount temporarily. This is safe as we're
817 * holding an active reference.
Tejun Heo4f331f02010-07-20 15:18:07 -0700818 */
819 up_write(&s->s_umount);
Tejun Heod4d77622010-11-13 11:55:18 +0100820 blkdev_put(bdev, mode);
Tejun Heo4f331f02010-07-20 15:18:07 -0700821 down_write(&s->s_umount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 } else {
823 char b[BDEVNAME_SIZE];
824
Al Viro9e1f1de2011-06-03 18:24:58 -0400825 s->s_flags = flags | MS_NOSEC;
Al Viro30c40d22008-02-22 19:50:45 -0500826 s->s_mode = mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
Pekka Enberge78c9a02006-01-08 01:03:39 -0800828 sb_set_blocksize(s, block_size(bdev));
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800829 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400831 deactivate_locked_super(s);
David Howells454e2392006-06-23 02:02:57 -0700832 goto error;
Greg Kroah-Hartmanfa675762006-02-22 09:39:02 -0800833 }
David Howells454e2392006-06-23 02:02:57 -0700834
835 s->s_flags |= MS_ACTIVE;
Theodore Ts'o87d8fe12009-01-03 09:47:09 -0500836 bdev->bd_super = s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 }
838
Al Viro152a0832010-07-25 00:46:55 +0400839 return dget(s->s_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840
David Howells454e2392006-06-23 02:02:57 -0700841error_s:
842 error = PTR_ERR(s);
843error_bdev:
Tejun Heod4d77622010-11-13 11:55:18 +0100844 blkdev_put(bdev, mode);
David Howells454e2392006-06-23 02:02:57 -0700845error:
Al Viro152a0832010-07-25 00:46:55 +0400846 return ERR_PTR(error);
847}
848EXPORT_SYMBOL(mount_bdev);
849
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850void kill_block_super(struct super_block *sb)
851{
852 struct block_device *bdev = sb->s_bdev;
Al Viro30c40d22008-02-22 19:50:45 -0500853 fmode_t mode = sb->s_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854
H Hartley Sweetenddbaaf32009-04-29 20:14:57 -0400855 bdev->bd_super = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 generic_shutdown_super(sb);
857 sync_blockdev(bdev);
Tejun Heod4d77622010-11-13 11:55:18 +0100858 WARN_ON_ONCE(!(mode & FMODE_EXCL));
Tejun Heoe525fd82010-11-13 11:55:17 +0100859 blkdev_put(bdev, mode | FMODE_EXCL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860}
861
862EXPORT_SYMBOL(kill_block_super);
David Howells93614012006-09-30 20:45:40 +0200863#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864
Al Viro3c26ff62010-07-25 11:46:36 +0400865struct dentry *mount_nodev(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 int flags, void *data,
Al Viro3c26ff62010-07-25 11:46:36 +0400867 int (*fill_super)(struct super_block *, void *, int))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868{
869 int error;
870 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
871
872 if (IS_ERR(s))
Al Viro3c26ff62010-07-25 11:46:36 +0400873 return ERR_CAST(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874
875 s->s_flags = flags;
876
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800877 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400879 deactivate_locked_super(s);
Al Viro3c26ff62010-07-25 11:46:36 +0400880 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881 }
882 s->s_flags |= MS_ACTIVE;
Al Viro3c26ff62010-07-25 11:46:36 +0400883 return dget(s->s_root);
884}
885EXPORT_SYMBOL(mount_nodev);
886
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887static int compare_single(struct super_block *s, void *p)
888{
889 return 1;
890}
891
Al Virofc14f2f2010-07-25 01:48:30 +0400892struct dentry *mount_single(struct file_system_type *fs_type,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700893 int flags, void *data,
Al Virofc14f2f2010-07-25 01:48:30 +0400894 int (*fill_super)(struct super_block *, void *, int))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895{
896 struct super_block *s;
897 int error;
898
899 s = sget(fs_type, compare_single, set_anon_super, NULL);
900 if (IS_ERR(s))
Al Virofc14f2f2010-07-25 01:48:30 +0400901 return ERR_CAST(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902 if (!s->s_root) {
903 s->s_flags = flags;
Theodore Ts'o9b04c992006-03-24 03:15:10 -0800904 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 if (error) {
Al Viro74dbbdd2009-05-06 01:07:50 -0400906 deactivate_locked_super(s);
Al Virofc14f2f2010-07-25 01:48:30 +0400907 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 }
909 s->s_flags |= MS_ACTIVE;
Kay Sievers9329d1b2009-12-18 21:18:15 +0100910 } else {
911 do_remount_sb(s, flags, data, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 }
Al Virofc14f2f2010-07-25 01:48:30 +0400913 return dget(s->s_root);
914}
915EXPORT_SYMBOL(mount_single);
916
Al Viro9d412a42011-03-17 22:08:28 -0400917struct dentry *
918mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919{
Al Viroc96e41e2010-07-25 00:17:56 +0400920 struct dentry *root;
Al Viro9d412a42011-03-17 22:08:28 -0400921 struct super_block *sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 char *secdata = NULL;
Al Viro9d412a42011-03-17 22:08:28 -0400923 int error = -ENOMEM;
Al Viro80893522010-02-05 09:30:46 -0500924
Eric Parise0007522008-03-05 10:31:54 -0500925 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926 secdata = alloc_secdata();
David Howells454e2392006-06-23 02:02:57 -0700927 if (!secdata)
Al Viro9d412a42011-03-17 22:08:28 -0400928 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929
Eric Parise0007522008-03-05 10:31:54 -0500930 error = security_sb_copy_data(data, secdata);
David Howells454e2392006-06-23 02:02:57 -0700931 if (error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 goto out_free_secdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 }
934
Al Viro1a102ff2011-03-16 09:07:58 -0400935 root = type->mount(type, flags, name, data);
936 if (IS_ERR(root)) {
937 error = PTR_ERR(root);
938 goto out_free_secdata;
Al Viroc96e41e2010-07-25 00:17:56 +0400939 }
Al Viro9d412a42011-03-17 22:08:28 -0400940 sb = root->d_sb;
941 BUG_ON(!sb);
942 WARN_ON(!sb->s_bdi);
Linus Torvalds6c510382011-03-24 10:16:26 -0700943 WARN_ON(sb->s_bdi == &default_backing_dev_info);
Al Viro9d412a42011-03-17 22:08:28 -0400944 sb->s_flags |= MS_BORN;
David Howells454e2392006-06-23 02:02:57 -0700945
Al Viro9d412a42011-03-17 22:08:28 -0400946 error = security_sb_kern_mount(sb, flags, secdata);
Jörn Engel5129a462010-04-25 08:54:42 +0200947 if (error)
948 goto out_sb;
David Howells454e2392006-06-23 02:02:57 -0700949
Jeff Layton42cb56a2009-09-18 13:05:53 -0700950 /*
951 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
952 * but s_maxbytes was an unsigned long long for many releases. Throw
953 * this warning for a little while to try and catch filesystems that
Jeff Layton4358b562011-03-29 09:33:31 -0400954 * violate this rule.
Jeff Layton42cb56a2009-09-18 13:05:53 -0700955 */
Al Viro9d412a42011-03-17 22:08:28 -0400956 WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
957 "negative value (%lld)\n", type->name, sb->s_maxbytes);
Jeff Layton42cb56a2009-09-18 13:05:53 -0700958
Al Viro9d412a42011-03-17 22:08:28 -0400959 up_write(&sb->s_umount);
Gerald Schaefer8680e222005-06-21 17:15:16 -0700960 free_secdata(secdata);
Al Viro9d412a42011-03-17 22:08:28 -0400961 return root;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962out_sb:
Al Viro9d412a42011-03-17 22:08:28 -0400963 dput(root);
964 deactivate_locked_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965out_free_secdata:
966 free_secdata(secdata);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967out:
David Howells454e2392006-06-23 02:02:57 -0700968 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969}
970
Josef Bacik18e9e512010-03-23 10:34:56 -0400971/**
Randy Dunlap7000d3c2010-05-24 22:22:34 -0700972 * freeze_super - lock the filesystem and force it into a consistent state
973 * @sb: the super to lock
Josef Bacik18e9e512010-03-23 10:34:56 -0400974 *
975 * Syncs the super to make sure the filesystem is consistent and calls the fs's
976 * freeze_fs. Subsequent calls to this without first thawing the fs will return
977 * -EBUSY.
978 */
979int freeze_super(struct super_block *sb)
980{
981 int ret;
982
983 atomic_inc(&sb->s_active);
984 down_write(&sb->s_umount);
985 if (sb->s_frozen) {
986 deactivate_locked_super(sb);
987 return -EBUSY;
988 }
989
990 if (sb->s_flags & MS_RDONLY) {
991 sb->s_frozen = SB_FREEZE_TRANS;
992 smp_wmb();
993 up_write(&sb->s_umount);
994 return 0;
995 }
996
997 sb->s_frozen = SB_FREEZE_WRITE;
998 smp_wmb();
999
1000 sync_filesystem(sb);
1001
1002 sb->s_frozen = SB_FREEZE_TRANS;
1003 smp_wmb();
1004
1005 sync_blockdev(sb->s_bdev);
1006 if (sb->s_op->freeze_fs) {
1007 ret = sb->s_op->freeze_fs(sb);
1008 if (ret) {
1009 printk(KERN_ERR
1010 "VFS:Filesystem freeze failed\n");
1011 sb->s_frozen = SB_UNFROZEN;
1012 deactivate_locked_super(sb);
1013 return ret;
1014 }
1015 }
1016 up_write(&sb->s_umount);
1017 return 0;
1018}
1019EXPORT_SYMBOL(freeze_super);
1020
1021/**
1022 * thaw_super -- unlock filesystem
1023 * @sb: the super to thaw
1024 *
1025 * Unlocks the filesystem and marks it writeable again after freeze_super().
1026 */
1027int thaw_super(struct super_block *sb)
1028{
1029 int error;
1030
1031 down_write(&sb->s_umount);
1032 if (sb->s_frozen == SB_UNFROZEN) {
1033 up_write(&sb->s_umount);
1034 return -EINVAL;
1035 }
1036
1037 if (sb->s_flags & MS_RDONLY)
1038 goto out;
1039
1040 if (sb->s_op->unfreeze_fs) {
1041 error = sb->s_op->unfreeze_fs(sb);
1042 if (error) {
1043 printk(KERN_ERR
1044 "VFS:Filesystem thaw failed\n");
1045 sb->s_frozen = SB_FREEZE_TRANS;
1046 up_write(&sb->s_umount);
1047 return error;
1048 }
1049 }
1050
1051out:
1052 sb->s_frozen = SB_UNFROZEN;
1053 smp_wmb();
1054 wake_up(&sb->s_wait_unfrozen);
1055 deactivate_locked_super(sb);
1056
1057 return 0;
1058}
1059EXPORT_SYMBOL(thaw_super);