ia64/linux-2.6.18-xen.hg

view fs/super.c @ 524:7f8b544237bf

netfront: Allow netfront in domain 0.

This is useful if your physical network device is in a utility domain.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Apr 15 15:18:58 2008 +0100 (2008-04-15)
parents 831230e53067
children cad6f60f0506
line source
1 /*
2 * linux/fs/super.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * super.c contains code to handle: - mount structures
7 * - super-block tables
8 * - filesystem drivers list
9 * - mount system call
10 * - umount system call
11 * - ustat system call
12 *
13 * GK 2/5/95 - Changed to support mounting the root fs via NFS
14 *
15 * Added kerneld support: Jacques Gelinas and Bjorn Ekwall
16 * Added change_root: Werner Almesberger & Hans Lermen, Feb '96
17 * Added options to /proc/mounts:
18 * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
19 * Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998
20 * Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
21 */
23 #include <linux/module.h>
24 #include <linux/slab.h>
25 #include <linux/init.h>
26 #include <linux/smp_lock.h>
27 #include <linux/acct.h>
28 #include <linux/blkdev.h>
29 #include <linux/quotaops.h>
30 #include <linux/namei.h>
31 #include <linux/buffer_head.h> /* for fsync_super() */
32 #include <linux/mount.h>
33 #include <linux/security.h>
34 #include <linux/syscalls.h>
35 #include <linux/vfs.h>
36 #include <linux/writeback.h> /* for the emergency remount stuff */
37 #include <linux/idr.h>
38 #include <linux/kobject.h>
39 #include <linux/mutex.h>
40 #include <asm/uaccess.h>
43 void get_filesystem(struct file_system_type *fs);
44 void put_filesystem(struct file_system_type *fs);
45 struct file_system_type *get_fs_type(const char *name);
47 LIST_HEAD(super_blocks);
48 DEFINE_SPINLOCK(sb_lock);
50 /**
51 * alloc_super - create new superblock
52 * @type: filesystem type superblock should belong to
53 *
54 * Allocates and initializes a new &struct super_block. alloc_super()
55 * returns a pointer new superblock or %NULL if allocation had failed.
56 */
57 static struct super_block *alloc_super(struct file_system_type *type)
58 {
59 struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
60 static struct super_operations default_op;
62 if (s) {
63 if (security_sb_alloc(s)) {
64 kfree(s);
65 s = NULL;
66 goto out;
67 }
68 INIT_LIST_HEAD(&s->s_dirty);
69 INIT_LIST_HEAD(&s->s_io);
70 INIT_LIST_HEAD(&s->s_files);
71 INIT_LIST_HEAD(&s->s_instances);
72 INIT_HLIST_HEAD(&s->s_anon);
73 INIT_LIST_HEAD(&s->s_inodes);
74 init_rwsem(&s->s_umount);
75 mutex_init(&s->s_lock);
76 lockdep_set_class(&s->s_umount, &type->s_umount_key);
77 /*
78 * The locking rules for s_lock are up to the
79 * filesystem. For example ext3fs has different
80 * lock ordering than usbfs:
81 */
82 lockdep_set_class(&s->s_lock, &type->s_lock_key);
83 down_write(&s->s_umount);
84 s->s_count = S_BIAS;
85 atomic_set(&s->s_active, 1);
86 mutex_init(&s->s_vfs_rename_mutex);
87 mutex_init(&s->s_dquot.dqio_mutex);
88 mutex_init(&s->s_dquot.dqonoff_mutex);
89 init_rwsem(&s->s_dquot.dqptr_sem);
90 init_waitqueue_head(&s->s_wait_unfrozen);
91 s->s_maxbytes = MAX_NON_LFS;
92 s->dq_op = sb_dquot_ops;
93 s->s_qcop = sb_quotactl_ops;
94 s->s_op = &default_op;
95 s->s_time_gran = 1000000000;
96 }
97 out:
98 return s;
99 }
101 /**
102 * destroy_super - frees a superblock
103 * @s: superblock to free
104 *
105 * Frees a superblock.
106 */
107 static inline void destroy_super(struct super_block *s)
108 {
109 security_sb_free(s);
110 kfree(s);
111 }
113 /* Superblock refcounting */
115 /*
116 * Drop a superblock's refcount. Returns non-zero if the superblock was
117 * destroyed. The caller must hold sb_lock.
118 */
119 int __put_super(struct super_block *sb)
120 {
121 int ret = 0;
123 if (!--sb->s_count) {
124 destroy_super(sb);
125 ret = 1;
126 }
127 return ret;
128 }
130 /*
131 * Drop a superblock's refcount.
132 * Returns non-zero if the superblock is about to be destroyed and
133 * at least is already removed from super_blocks list, so if we are
134 * making a loop through super blocks then we need to restart.
135 * The caller must hold sb_lock.
136 */
137 int __put_super_and_need_restart(struct super_block *sb)
138 {
139 /* check for race with generic_shutdown_super() */
140 if (list_empty(&sb->s_list)) {
141 /* super block is removed, need to restart... */
142 __put_super(sb);
143 return 1;
144 }
145 /* can't be the last, since s_list is still in use */
146 sb->s_count--;
147 BUG_ON(sb->s_count == 0);
148 return 0;
149 }
151 /**
152 * put_super - drop a temporary reference to superblock
153 * @sb: superblock in question
154 *
155 * Drops a temporary reference, frees superblock if there's no
156 * references left.
157 */
158 static void put_super(struct super_block *sb)
159 {
160 spin_lock(&sb_lock);
161 __put_super(sb);
162 spin_unlock(&sb_lock);
163 }
166 /**
167 * deactivate_super - drop an active reference to superblock
168 * @s: superblock to deactivate
169 *
170 * Drops an active reference to superblock, acquiring a temprory one if
171 * there is no active references left. In that case we lock superblock,
172 * tell fs driver to shut it down and drop the temporary reference we
173 * had just acquired.
174 */
175 void deactivate_super(struct super_block *s)
176 {
177 struct file_system_type *fs = s->s_type;
178 if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
179 s->s_count -= S_BIAS-1;
180 spin_unlock(&sb_lock);
181 DQUOT_OFF(s);
182 down_write(&s->s_umount);
183 fs->kill_sb(s);
184 put_filesystem(fs);
185 put_super(s);
186 }
187 }
189 EXPORT_SYMBOL(deactivate_super);
191 /**
192 * grab_super - acquire an active reference
193 * @s: reference we are trying to make active
194 *
195 * Tries to acquire an active reference. grab_super() is used when we
196 * had just found a superblock in super_blocks or fs_type->fs_supers
197 * and want to turn it into a full-blown active reference. grab_super()
198 * is called with sb_lock held and drops it. Returns 1 in case of
199 * success, 0 if we had failed (superblock contents was already dead or
200 * dying when grab_super() had been called).
201 */
202 static int grab_super(struct super_block *s)
203 {
204 s->s_count++;
205 spin_unlock(&sb_lock);
206 down_write(&s->s_umount);
207 if (s->s_root) {
208 spin_lock(&sb_lock);
209 if (s->s_count > S_BIAS) {
210 atomic_inc(&s->s_active);
211 s->s_count--;
212 spin_unlock(&sb_lock);
213 return 1;
214 }
215 spin_unlock(&sb_lock);
216 }
217 up_write(&s->s_umount);
218 put_super(s);
219 yield();
220 return 0;
221 }
223 /**
224 * generic_shutdown_super - common helper for ->kill_sb()
225 * @sb: superblock to kill
226 *
227 * generic_shutdown_super() does all fs-independent work on superblock
228 * shutdown. Typical ->kill_sb() should pick all fs-specific objects
229 * that need destruction out of superblock, call generic_shutdown_super()
230 * and release aforementioned objects. Note: dentries and inodes _are_
231 * taken care of and do not need specific handling.
232 */
233 void generic_shutdown_super(struct super_block *sb)
234 {
235 struct dentry *root = sb->s_root;
236 struct super_operations *sop = sb->s_op;
238 if (root) {
239 sb->s_root = NULL;
240 shrink_dcache_parent(root);
241 shrink_dcache_sb(sb);
242 dput(root);
243 fsync_super(sb);
244 lock_super(sb);
245 sb->s_flags &= ~MS_ACTIVE;
246 /* bad name - it should be evict_inodes() */
247 invalidate_inodes(sb);
248 lock_kernel();
250 if (sop->write_super && sb->s_dirt)
251 sop->write_super(sb);
252 if (sop->put_super)
253 sop->put_super(sb);
255 /* Forget any remaining inodes */
256 if (invalidate_inodes(sb)) {
257 printk("VFS: Busy inodes after unmount of %s. "
258 "Self-destruct in 5 seconds. Have a nice day...\n",
259 sb->s_id);
260 }
262 unlock_kernel();
263 unlock_super(sb);
264 }
265 spin_lock(&sb_lock);
266 /* should be initialized for __put_super_and_need_restart() */
267 list_del_init(&sb->s_list);
268 list_del(&sb->s_instances);
269 spin_unlock(&sb_lock);
270 up_write(&sb->s_umount);
271 }
273 EXPORT_SYMBOL(generic_shutdown_super);
275 /**
276 * sget - find or create a superblock
277 * @type: filesystem type superblock should belong to
278 * @test: comparison callback
279 * @set: setup callback
280 * @data: argument to each of them
281 */
282 struct super_block *sget(struct file_system_type *type,
283 int (*test)(struct super_block *,void *),
284 int (*set)(struct super_block *,void *),
285 void *data)
286 {
287 struct super_block *s = NULL;
288 struct list_head *p;
289 int err;
291 retry:
292 spin_lock(&sb_lock);
293 if (test) list_for_each(p, &type->fs_supers) {
294 struct super_block *old;
295 old = list_entry(p, struct super_block, s_instances);
296 if (!test(old, data))
297 continue;
298 if (!grab_super(old))
299 goto retry;
300 if (s)
301 destroy_super(s);
302 return old;
303 }
304 if (!s) {
305 spin_unlock(&sb_lock);
306 s = alloc_super(type);
307 if (!s)
308 return ERR_PTR(-ENOMEM);
309 goto retry;
310 }
312 err = set(s, data);
313 if (err) {
314 spin_unlock(&sb_lock);
315 destroy_super(s);
316 return ERR_PTR(err);
317 }
318 s->s_type = type;
319 strlcpy(s->s_id, type->name, sizeof(s->s_id));
320 list_add_tail(&s->s_list, &super_blocks);
321 list_add(&s->s_instances, &type->fs_supers);
322 spin_unlock(&sb_lock);
323 get_filesystem(type);
324 return s;
325 }
327 EXPORT_SYMBOL(sget);
329 void drop_super(struct super_block *sb)
330 {
331 up_read(&sb->s_umount);
332 put_super(sb);
333 }
335 EXPORT_SYMBOL(drop_super);
337 static inline void write_super(struct super_block *sb)
338 {
339 lock_super(sb);
340 if (sb->s_root && sb->s_dirt)
341 if (sb->s_op->write_super)
342 sb->s_op->write_super(sb);
343 unlock_super(sb);
344 }
346 /*
347 * Note: check the dirty flag before waiting, so we don't
348 * hold up the sync while mounting a device. (The newly
349 * mounted device won't need syncing.)
350 */
351 void sync_supers(void)
352 {
353 struct super_block *sb;
355 spin_lock(&sb_lock);
356 restart:
357 list_for_each_entry(sb, &super_blocks, s_list) {
358 if (sb->s_dirt) {
359 sb->s_count++;
360 spin_unlock(&sb_lock);
361 down_read(&sb->s_umount);
362 write_super(sb);
363 up_read(&sb->s_umount);
364 spin_lock(&sb_lock);
365 if (__put_super_and_need_restart(sb))
366 goto restart;
367 }
368 }
369 spin_unlock(&sb_lock);
370 }
372 /*
373 * Call the ->sync_fs super_op against all filesytems which are r/w and
374 * which implement it.
375 *
376 * This operation is careful to avoid the livelock which could easily happen
377 * if two or more filesystems are being continuously dirtied. s_need_sync_fs
378 * is used only here. We set it against all filesystems and then clear it as
379 * we sync them. So redirtied filesystems are skipped.
380 *
381 * But if process A is currently running sync_filesytems and then process B
382 * calls sync_filesystems as well, process B will set all the s_need_sync_fs
383 * flags again, which will cause process A to resync everything. Fix that with
384 * a local mutex.
385 *
386 * (Fabian) Avoid sync_fs with clean fs & wait mode 0
387 */
388 void sync_filesystems(int wait)
389 {
390 struct super_block *sb;
391 static DEFINE_MUTEX(mutex);
393 mutex_lock(&mutex); /* Could be down_interruptible */
394 spin_lock(&sb_lock);
395 list_for_each_entry(sb, &super_blocks, s_list) {
396 if (!sb->s_op->sync_fs)
397 continue;
398 if (sb->s_flags & MS_RDONLY)
399 continue;
400 sb->s_need_sync_fs = 1;
401 }
403 restart:
404 list_for_each_entry(sb, &super_blocks, s_list) {
405 if (!sb->s_need_sync_fs)
406 continue;
407 sb->s_need_sync_fs = 0;
408 if (sb->s_flags & MS_RDONLY)
409 continue; /* hm. Was remounted r/o meanwhile */
410 sb->s_count++;
411 spin_unlock(&sb_lock);
412 down_read(&sb->s_umount);
413 if (sb->s_root && (wait || sb->s_dirt))
414 sb->s_op->sync_fs(sb, wait);
415 up_read(&sb->s_umount);
416 /* restart only when sb is no longer on the list */
417 spin_lock(&sb_lock);
418 if (__put_super_and_need_restart(sb))
419 goto restart;
420 }
421 spin_unlock(&sb_lock);
422 mutex_unlock(&mutex);
423 }
425 /**
426 * get_super - get the superblock of a device
427 * @bdev: device to get the superblock for
428 *
429 * Scans the superblock list and finds the superblock of the file system
430 * mounted on the device given. %NULL is returned if no match is found.
431 */
433 struct super_block * get_super(struct block_device *bdev)
434 {
435 struct super_block *sb;
437 if (!bdev)
438 return NULL;
440 spin_lock(&sb_lock);
441 rescan:
442 list_for_each_entry(sb, &super_blocks, s_list) {
443 if (sb->s_bdev == bdev) {
444 sb->s_count++;
445 spin_unlock(&sb_lock);
446 down_read(&sb->s_umount);
447 if (sb->s_root)
448 return sb;
449 up_read(&sb->s_umount);
450 /* restart only when sb is no longer on the list */
451 spin_lock(&sb_lock);
452 if (__put_super_and_need_restart(sb))
453 goto rescan;
454 }
455 }
456 spin_unlock(&sb_lock);
457 return NULL;
458 }
460 EXPORT_SYMBOL(get_super);
462 struct super_block * user_get_super(dev_t dev)
463 {
464 struct super_block *sb;
466 spin_lock(&sb_lock);
467 rescan:
468 list_for_each_entry(sb, &super_blocks, s_list) {
469 if (sb->s_dev == dev) {
470 sb->s_count++;
471 spin_unlock(&sb_lock);
472 down_read(&sb->s_umount);
473 if (sb->s_root)
474 return sb;
475 up_read(&sb->s_umount);
476 /* restart only when sb is no longer on the list */
477 spin_lock(&sb_lock);
478 if (__put_super_and_need_restart(sb))
479 goto rescan;
480 }
481 }
482 spin_unlock(&sb_lock);
483 return NULL;
484 }
486 asmlinkage long sys_ustat(unsigned dev, struct ustat __user * ubuf)
487 {
488 struct super_block *s;
489 struct ustat tmp;
490 struct kstatfs sbuf;
491 int err = -EINVAL;
493 s = user_get_super(new_decode_dev(dev));
494 if (s == NULL)
495 goto out;
496 err = vfs_statfs(s->s_root, &sbuf);
497 drop_super(s);
498 if (err)
499 goto out;
501 memset(&tmp,0,sizeof(struct ustat));
502 tmp.f_tfree = sbuf.f_bfree;
503 tmp.f_tinode = sbuf.f_ffree;
505 err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
506 out:
507 return err;
508 }
510 /**
511 * mark_files_ro
512 * @sb: superblock in question
513 *
514 * All files are marked read/only. We don't care about pending
515 * delete files so this should be used in 'force' mode only
516 */
518 static void mark_files_ro(struct super_block *sb)
519 {
520 struct file *f;
522 file_list_lock();
523 list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
524 if (S_ISREG(f->f_dentry->d_inode->i_mode) && file_count(f))
525 f->f_mode &= ~FMODE_WRITE;
526 }
527 file_list_unlock();
528 }
530 /**
531 * do_remount_sb - asks filesystem to change mount options.
532 * @sb: superblock in question
533 * @flags: numeric part of options
534 * @data: the rest of options
535 * @force: whether or not to force the change
536 *
537 * Alters the mount options of a mounted file system.
538 */
539 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
540 {
541 int retval;
543 if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
544 return -EACCES;
545 if (flags & MS_RDONLY)
546 acct_auto_close(sb);
547 shrink_dcache_sb(sb);
548 fsync_super(sb);
550 /* If we are remounting RDONLY and current sb is read/write,
551 make sure there are no rw files opened */
552 if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
553 if (force)
554 mark_files_ro(sb);
555 else if (!fs_may_remount_ro(sb))
556 return -EBUSY;
557 }
559 if (sb->s_op->remount_fs) {
560 lock_super(sb);
561 retval = sb->s_op->remount_fs(sb, &flags, data);
562 unlock_super(sb);
563 if (retval)
564 return retval;
565 }
566 sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
567 return 0;
568 }
570 static void do_emergency_remount(unsigned long foo)
571 {
572 struct super_block *sb;
574 spin_lock(&sb_lock);
575 list_for_each_entry(sb, &super_blocks, s_list) {
576 sb->s_count++;
577 spin_unlock(&sb_lock);
578 down_read(&sb->s_umount);
579 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
580 /*
581 * ->remount_fs needs lock_kernel().
582 *
583 * What lock protects sb->s_flags??
584 */
585 lock_kernel();
586 do_remount_sb(sb, MS_RDONLY, NULL, 1);
587 unlock_kernel();
588 }
589 drop_super(sb);
590 spin_lock(&sb_lock);
591 }
592 spin_unlock(&sb_lock);
593 printk("Emergency Remount complete\n");
594 }
596 void emergency_remount(void)
597 {
598 pdflush_operation(do_emergency_remount, 0);
599 }
601 /*
602 * Unnamed block devices are dummy devices used by virtual
603 * filesystems which don't use real block-devices. -- jrs
604 */
606 static struct idr unnamed_dev_idr;
607 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
609 int set_anon_super(struct super_block *s, void *data)
610 {
611 int dev;
612 int error;
614 retry:
615 if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
616 return -ENOMEM;
617 spin_lock(&unnamed_dev_lock);
618 error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
619 spin_unlock(&unnamed_dev_lock);
620 if (error == -EAGAIN)
621 /* We raced and lost with another CPU. */
622 goto retry;
623 else if (error)
624 return -EAGAIN;
626 if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
627 spin_lock(&unnamed_dev_lock);
628 idr_remove(&unnamed_dev_idr, dev);
629 spin_unlock(&unnamed_dev_lock);
630 return -EMFILE;
631 }
632 s->s_dev = MKDEV(0, dev & MINORMASK);
633 return 0;
634 }
636 EXPORT_SYMBOL(set_anon_super);
638 void kill_anon_super(struct super_block *sb)
639 {
640 int slot = MINOR(sb->s_dev);
642 generic_shutdown_super(sb);
643 spin_lock(&unnamed_dev_lock);
644 idr_remove(&unnamed_dev_idr, slot);
645 spin_unlock(&unnamed_dev_lock);
646 }
648 EXPORT_SYMBOL(kill_anon_super);
650 void __init unnamed_dev_init(void)
651 {
652 idr_init(&unnamed_dev_idr);
653 }
655 void kill_litter_super(struct super_block *sb)
656 {
657 if (sb->s_root)
658 d_genocide(sb->s_root);
659 kill_anon_super(sb);
660 }
662 EXPORT_SYMBOL(kill_litter_super);
664 static int set_bdev_super(struct super_block *s, void *data)
665 {
666 s->s_bdev = data;
667 s->s_dev = s->s_bdev->bd_dev;
668 return 0;
669 }
671 static int test_bdev_super(struct super_block *s, void *data)
672 {
673 return (void *)s->s_bdev == data;
674 }
676 static void bdev_uevent(struct block_device *bdev, enum kobject_action action)
677 {
678 if (bdev->bd_disk) {
679 if (bdev->bd_part)
680 kobject_uevent(&bdev->bd_part->kobj, action);
681 else
682 kobject_uevent(&bdev->bd_disk->kobj, action);
683 }
684 }
686 int get_sb_bdev(struct file_system_type *fs_type,
687 int flags, const char *dev_name, void *data,
688 int (*fill_super)(struct super_block *, void *, int),
689 struct vfsmount *mnt)
690 {
691 struct block_device *bdev;
692 struct super_block *s;
693 int error = 0;
695 bdev = open_bdev_excl(dev_name, flags, fs_type);
696 if (IS_ERR(bdev))
697 return PTR_ERR(bdev);
699 /*
700 * once the super is inserted into the list by sget, s_umount
701 * will protect the lockfs code from trying to start a snapshot
702 * while we are mounting
703 */
704 mutex_lock(&bdev->bd_mount_mutex);
705 s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
706 mutex_unlock(&bdev->bd_mount_mutex);
707 if (IS_ERR(s))
708 goto error_s;
710 if (s->s_root) {
711 if ((flags ^ s->s_flags) & MS_RDONLY) {
712 up_write(&s->s_umount);
713 deactivate_super(s);
714 error = -EBUSY;
715 goto error_bdev;
716 }
718 close_bdev_excl(bdev);
719 } else {
720 char b[BDEVNAME_SIZE];
722 s->s_flags = flags;
723 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
724 sb_set_blocksize(s, block_size(bdev));
725 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
726 if (error) {
727 up_write(&s->s_umount);
728 deactivate_super(s);
729 goto error;
730 }
732 s->s_flags |= MS_ACTIVE;
733 bdev_uevent(bdev, KOBJ_MOUNT);
734 }
736 return simple_set_mnt(mnt, s);
738 error_s:
739 error = PTR_ERR(s);
740 error_bdev:
741 close_bdev_excl(bdev);
742 error:
743 return error;
744 }
746 EXPORT_SYMBOL(get_sb_bdev);
748 void kill_block_super(struct super_block *sb)
749 {
750 struct block_device *bdev = sb->s_bdev;
752 bdev_uevent(bdev, KOBJ_UMOUNT);
753 generic_shutdown_super(sb);
754 sync_blockdev(bdev);
755 close_bdev_excl(bdev);
756 }
758 EXPORT_SYMBOL(kill_block_super);
760 int get_sb_nodev(struct file_system_type *fs_type,
761 int flags, void *data,
762 int (*fill_super)(struct super_block *, void *, int),
763 struct vfsmount *mnt)
764 {
765 int error;
766 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
768 if (IS_ERR(s))
769 return PTR_ERR(s);
771 s->s_flags = flags;
773 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
774 if (error) {
775 up_write(&s->s_umount);
776 deactivate_super(s);
777 return error;
778 }
779 s->s_flags |= MS_ACTIVE;
780 return simple_set_mnt(mnt, s);
781 }
783 EXPORT_SYMBOL(get_sb_nodev);
785 static int compare_single(struct super_block *s, void *p)
786 {
787 return 1;
788 }
790 int get_sb_single(struct file_system_type *fs_type,
791 int flags, void *data,
792 int (*fill_super)(struct super_block *, void *, int),
793 struct vfsmount *mnt)
794 {
795 struct super_block *s;
796 int error;
798 s = sget(fs_type, compare_single, set_anon_super, NULL);
799 if (IS_ERR(s))
800 return PTR_ERR(s);
801 if (!s->s_root) {
802 s->s_flags = flags;
803 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
804 if (error) {
805 up_write(&s->s_umount);
806 deactivate_super(s);
807 return error;
808 }
809 s->s_flags |= MS_ACTIVE;
810 }
811 do_remount_sb(s, flags, data, 0);
812 return simple_set_mnt(mnt, s);
813 }
815 EXPORT_SYMBOL(get_sb_single);
817 struct vfsmount *
818 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
819 {
820 struct vfsmount *mnt;
821 char *secdata = NULL;
822 int error;
824 if (!type)
825 return ERR_PTR(-ENODEV);
827 error = -ENOMEM;
828 mnt = alloc_vfsmnt(name);
829 if (!mnt)
830 goto out;
832 if (data) {
833 secdata = alloc_secdata();
834 if (!secdata)
835 goto out_mnt;
837 error = security_sb_copy_data(type, data, secdata);
838 if (error)
839 goto out_free_secdata;
840 }
842 error = type->get_sb(type, flags, name, data, mnt);
843 if (error < 0)
844 goto out_free_secdata;
846 error = security_sb_kern_mount(mnt->mnt_sb, secdata);
847 if (error)
848 goto out_sb;
850 mnt->mnt_mountpoint = mnt->mnt_root;
851 mnt->mnt_parent = mnt;
852 up_write(&mnt->mnt_sb->s_umount);
853 free_secdata(secdata);
854 return mnt;
855 out_sb:
856 dput(mnt->mnt_root);
857 up_write(&mnt->mnt_sb->s_umount);
858 deactivate_super(mnt->mnt_sb);
859 out_free_secdata:
860 free_secdata(secdata);
861 out_mnt:
862 free_vfsmnt(mnt);
863 out:
864 return ERR_PTR(error);
865 }
867 EXPORT_SYMBOL_GPL(vfs_kern_mount);
869 struct vfsmount *
870 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
871 {
872 struct file_system_type *type = get_fs_type(fstype);
873 struct vfsmount *mnt;
874 if (!type)
875 return ERR_PTR(-ENODEV);
876 mnt = vfs_kern_mount(type, flags, name, data);
877 put_filesystem(type);
878 return mnt;
879 }
881 struct vfsmount *kern_mount(struct file_system_type *type)
882 {
883 return vfs_kern_mount(type, 0, type->name, NULL);
884 }
886 EXPORT_SYMBOL(kern_mount);