4 * (C) Copyright Al Viro 2000, 2001
5 * Released under GPL v2.
7 * Based on code from fs/super.c, copyright Linus Torvalds and others.
11 #include <linux/syscalls.h>
12 #include <linux/slab.h>
13 #include <linux/sched.h>
14 #include <linux/spinlock.h>
15 #include <linux/percpu.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/acct.h>
19 #include <linux/capability.h>
20 #include <linux/cpumask.h>
21 #include <linux/module.h>
22 #include <linux/sysfs.h>
23 #include <linux/seq_file.h>
24 #include <linux/mnt_namespace.h>
25 #include <linux/namei.h>
26 #include <linux/nsproxy.h>
27 #include <linux/security.h>
28 #include <linux/mount.h>
29 #include <linux/ramfs.h>
30 #include <linux/log2.h>
31 #include <linux/idr.h>
32 #include <linux/fs_struct.h>
33 #include <linux/fsnotify.h>
34 #include <asm/uaccess.h>
35 #include <asm/unistd.h>
39 #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head))
40 #define HASH_SIZE (1UL << HASH_SHIFT)
43 static DEFINE_IDA(mnt_id_ida
);
44 static DEFINE_IDA(mnt_group_ida
);
45 static DEFINE_SPINLOCK(mnt_id_lock
);
46 static int mnt_id_start
= 0;
47 static int mnt_group_start
= 1;
49 static struct list_head
*mount_hashtable __read_mostly
;
50 static struct kmem_cache
*mnt_cache __read_mostly
;
51 static struct rw_semaphore namespace_sem
;
54 struct kobject
*fs_kobj
;
55 EXPORT_SYMBOL_GPL(fs_kobj
);
58 * vfsmount lock may be taken for read to prevent changes to the
59 * vfsmount hash, ie. during mountpoint lookups or walking back
62 * It should be taken for write in all cases where the vfsmount
63 * tree or hash is modified or when a vfsmount structure is modified.
65 DEFINE_BRLOCK(vfsmount_lock
);
67 static inline unsigned long hash(struct vfsmount
*mnt
, struct dentry
*dentry
)
69 unsigned long tmp
= ((unsigned long)mnt
/ L1_CACHE_BYTES
);
70 tmp
+= ((unsigned long)dentry
/ L1_CACHE_BYTES
);
71 tmp
= tmp
+ (tmp
>> HASH_SHIFT
);
72 return tmp
& (HASH_SIZE
- 1);
75 #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16)
78 * allocation is serialized by namespace_sem, but we need the spinlock to
79 * serialize with freeing.
81 static int mnt_alloc_id(struct vfsmount
*mnt
)
86 ida_pre_get(&mnt_id_ida
, GFP_KERNEL
);
87 spin_lock(&mnt_id_lock
);
88 res
= ida_get_new_above(&mnt_id_ida
, mnt_id_start
, &mnt
->mnt_id
);
90 mnt_id_start
= mnt
->mnt_id
+ 1;
91 spin_unlock(&mnt_id_lock
);
98 static void mnt_free_id(struct vfsmount
*mnt
)
100 int id
= mnt
->mnt_id
;
101 spin_lock(&mnt_id_lock
);
102 ida_remove(&mnt_id_ida
, id
);
103 if (mnt_id_start
> id
)
105 spin_unlock(&mnt_id_lock
);
109 * Allocate a new peer group ID
111 * mnt_group_ida is protected by namespace_sem
113 static int mnt_alloc_group_id(struct vfsmount
*mnt
)
117 if (!ida_pre_get(&mnt_group_ida
, GFP_KERNEL
))
120 res
= ida_get_new_above(&mnt_group_ida
,
124 mnt_group_start
= mnt
->mnt_group_id
+ 1;
130 * Release a peer group ID
132 void mnt_release_group_id(struct vfsmount
*mnt
)
134 int id
= mnt
->mnt_group_id
;
135 ida_remove(&mnt_group_ida
, id
);
136 if (mnt_group_start
> id
)
137 mnt_group_start
= id
;
138 mnt
->mnt_group_id
= 0;
142 * vfsmount lock must be held for read
144 static inline void mnt_add_count(struct vfsmount
*mnt
, int n
)
147 this_cpu_add(mnt
->mnt_pcp
->mnt_count
, n
);
155 static inline void mnt_set_count(struct vfsmount
*mnt
, int n
)
158 this_cpu_write(mnt
->mnt_pcp
->mnt_count
, n
);
165 * vfsmount lock must be held for read
167 static inline void mnt_inc_count(struct vfsmount
*mnt
)
169 mnt_add_count(mnt
, 1);
173 * vfsmount lock must be held for read
175 static inline void mnt_dec_count(struct vfsmount
*mnt
)
177 mnt_add_count(mnt
, -1);
181 * vfsmount lock must be held for write
183 unsigned int mnt_get_count(struct vfsmount
*mnt
)
186 unsigned int count
= 0;
189 for_each_possible_cpu(cpu
) {
190 count
+= per_cpu_ptr(mnt
->mnt_pcp
, cpu
)->mnt_count
;
195 return mnt
->mnt_count
;
199 struct vfsmount
*alloc_vfsmnt(const char *name
)
201 struct vfsmount
*mnt
= kmem_cache_zalloc(mnt_cache
, GFP_KERNEL
);
205 err
= mnt_alloc_id(mnt
);
210 mnt
->mnt_devname
= kstrdup(name
, GFP_KERNEL
);
211 if (!mnt
->mnt_devname
)
216 mnt
->mnt_pcp
= alloc_percpu(struct mnt_pcp
);
218 goto out_free_devname
;
220 this_cpu_add(mnt
->mnt_pcp
->mnt_count
, 1);
223 mnt
->mnt_writers
= 0;
226 INIT_LIST_HEAD(&mnt
->mnt_hash
);
227 INIT_LIST_HEAD(&mnt
->mnt_child
);
228 INIT_LIST_HEAD(&mnt
->mnt_mounts
);
229 INIT_LIST_HEAD(&mnt
->mnt_list
);
230 INIT_LIST_HEAD(&mnt
->mnt_expire
);
231 INIT_LIST_HEAD(&mnt
->mnt_share
);
232 INIT_LIST_HEAD(&mnt
->mnt_slave_list
);
233 INIT_LIST_HEAD(&mnt
->mnt_slave
);
234 #ifdef CONFIG_FSNOTIFY
235 INIT_HLIST_HEAD(&mnt
->mnt_fsnotify_marks
);
242 kfree(mnt
->mnt_devname
);
247 kmem_cache_free(mnt_cache
, mnt
);
252 * Most r/o checks on a fs are for operations that take
253 * discrete amounts of time, like a write() or unlink().
254 * We must keep track of when those operations start
255 * (for permission checks) and when they end, so that
256 * we can determine when writes are able to occur to
260 * __mnt_is_readonly: check whether a mount is read-only
261 * @mnt: the mount to check for its write status
263 * This shouldn't be used directly ouside of the VFS.
264 * It does not guarantee that the filesystem will stay
265 * r/w, just that it is right *now*. This can not and
266 * should not be used in place of IS_RDONLY(inode).
267 * mnt_want/drop_write() will _keep_ the filesystem
270 int __mnt_is_readonly(struct vfsmount
*mnt
)
272 if (mnt
->mnt_flags
& MNT_READONLY
)
274 if (mnt
->mnt_sb
->s_flags
& MS_RDONLY
)
278 EXPORT_SYMBOL_GPL(__mnt_is_readonly
);
280 static inline void mnt_inc_writers(struct vfsmount
*mnt
)
283 this_cpu_inc(mnt
->mnt_pcp
->mnt_writers
);
289 static inline void mnt_dec_writers(struct vfsmount
*mnt
)
292 this_cpu_dec(mnt
->mnt_pcp
->mnt_writers
);
298 static unsigned int mnt_get_writers(struct vfsmount
*mnt
)
301 unsigned int count
= 0;
304 for_each_possible_cpu(cpu
) {
305 count
+= per_cpu_ptr(mnt
->mnt_pcp
, cpu
)->mnt_writers
;
310 return mnt
->mnt_writers
;
315 * Most r/o checks on a fs are for operations that take
316 * discrete amounts of time, like a write() or unlink().
317 * We must keep track of when those operations start
318 * (for permission checks) and when they end, so that
319 * we can determine when writes are able to occur to
323 * mnt_want_write - get write access to a mount
324 * @mnt: the mount on which to take a write
326 * This tells the low-level filesystem that a write is
327 * about to be performed to it, and makes sure that
328 * writes are allowed before returning success. When
329 * the write operation is finished, mnt_drop_write()
330 * must be called. This is effectively a refcount.
332 int mnt_want_write(struct vfsmount
*mnt
)
337 mnt_inc_writers(mnt
);
339 * The store to mnt_inc_writers must be visible before we pass
340 * MNT_WRITE_HOLD loop below, so that the slowpath can see our
341 * incremented count after it has set MNT_WRITE_HOLD.
344 while (mnt
->mnt_flags
& MNT_WRITE_HOLD
)
347 * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
348 * be set to match its requirements. So we must not load that until
349 * MNT_WRITE_HOLD is cleared.
352 if (__mnt_is_readonly(mnt
)) {
353 mnt_dec_writers(mnt
);
361 EXPORT_SYMBOL_GPL(mnt_want_write
);
364 * mnt_clone_write - get write access to a mount
365 * @mnt: the mount on which to take a write
367 * This is effectively like mnt_want_write, except
368 * it must only be used to take an extra write reference
369 * on a mountpoint that we already know has a write reference
370 * on it. This allows some optimisation.
372 * After finished, mnt_drop_write must be called as usual to
373 * drop the reference.
375 int mnt_clone_write(struct vfsmount
*mnt
)
377 /* superblock may be r/o */
378 if (__mnt_is_readonly(mnt
))
381 mnt_inc_writers(mnt
);
385 EXPORT_SYMBOL_GPL(mnt_clone_write
);
388 * mnt_want_write_file - get write access to a file's mount
389 * @file: the file who's mount on which to take a write
391 * This is like mnt_want_write, but it takes a file and can
392 * do some optimisations if the file is open for write already
394 int mnt_want_write_file(struct file
*file
)
396 struct inode
*inode
= file
->f_dentry
->d_inode
;
397 if (!(file
->f_mode
& FMODE_WRITE
) || special_file(inode
->i_mode
))
398 return mnt_want_write(file
->f_path
.mnt
);
400 return mnt_clone_write(file
->f_path
.mnt
);
402 EXPORT_SYMBOL_GPL(mnt_want_write_file
);
405 * mnt_drop_write - give up write access to a mount
406 * @mnt: the mount on which to give up write access
408 * Tells the low-level filesystem that we are done
409 * performing writes to it. Must be matched with
410 * mnt_want_write() call above.
412 void mnt_drop_write(struct vfsmount
*mnt
)
415 mnt_dec_writers(mnt
);
418 EXPORT_SYMBOL_GPL(mnt_drop_write
);
420 static int mnt_make_readonly(struct vfsmount
*mnt
)
424 br_write_lock(vfsmount_lock
);
425 mnt
->mnt_flags
|= MNT_WRITE_HOLD
;
427 * After storing MNT_WRITE_HOLD, we'll read the counters. This store
428 * should be visible before we do.
433 * With writers on hold, if this value is zero, then there are
434 * definitely no active writers (although held writers may subsequently
435 * increment the count, they'll have to wait, and decrement it after
436 * seeing MNT_READONLY).
438 * It is OK to have counter incremented on one CPU and decremented on
439 * another: the sum will add up correctly. The danger would be when we
440 * sum up each counter, if we read a counter before it is incremented,
441 * but then read another CPU's count which it has been subsequently
442 * decremented from -- we would see more decrements than we should.
443 * MNT_WRITE_HOLD protects against this scenario, because
444 * mnt_want_write first increments count, then smp_mb, then spins on
445 * MNT_WRITE_HOLD, so it can't be decremented by another CPU while
446 * we're counting up here.
448 if (mnt_get_writers(mnt
) > 0)
451 mnt
->mnt_flags
|= MNT_READONLY
;
453 * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers
454 * that become unheld will see MNT_READONLY.
457 mnt
->mnt_flags
&= ~MNT_WRITE_HOLD
;
458 br_write_unlock(vfsmount_lock
);
462 static void __mnt_unmake_readonly(struct vfsmount
*mnt
)
464 br_write_lock(vfsmount_lock
);
465 mnt
->mnt_flags
&= ~MNT_READONLY
;
466 br_write_unlock(vfsmount_lock
);
469 void simple_set_mnt(struct vfsmount
*mnt
, struct super_block
*sb
)
472 mnt
->mnt_root
= dget(sb
->s_root
);
475 EXPORT_SYMBOL(simple_set_mnt
);
477 void free_vfsmnt(struct vfsmount
*mnt
)
479 kfree(mnt
->mnt_devname
);
482 free_percpu(mnt
->mnt_pcp
);
484 kmem_cache_free(mnt_cache
, mnt
);
488 * find the first or last mount at @dentry on vfsmount @mnt depending on
489 * @dir. If @dir is set return the first mount else return the last mount.
490 * vfsmount_lock must be held for read or write.
492 struct vfsmount
*__lookup_mnt(struct vfsmount
*mnt
, struct dentry
*dentry
,
495 struct list_head
*head
= mount_hashtable
+ hash(mnt
, dentry
);
496 struct list_head
*tmp
= head
;
497 struct vfsmount
*p
, *found
= NULL
;
500 tmp
= dir
? tmp
->next
: tmp
->prev
;
504 p
= list_entry(tmp
, struct vfsmount
, mnt_hash
);
505 if (p
->mnt_parent
== mnt
&& p
->mnt_mountpoint
== dentry
) {
514 * lookup_mnt increments the ref count before returning
515 * the vfsmount struct.
517 struct vfsmount
*lookup_mnt(struct path
*path
)
519 struct vfsmount
*child_mnt
;
521 br_read_lock(vfsmount_lock
);
522 if ((child_mnt
= __lookup_mnt(path
->mnt
, path
->dentry
, 1)))
524 br_read_unlock(vfsmount_lock
);
528 static inline int check_mnt(struct vfsmount
*mnt
)
530 return mnt
->mnt_ns
== current
->nsproxy
->mnt_ns
;
534 * vfsmount lock must be held for write
536 static void touch_mnt_namespace(struct mnt_namespace
*ns
)
540 wake_up_interruptible(&ns
->poll
);
545 * vfsmount lock must be held for write
547 static void __touch_mnt_namespace(struct mnt_namespace
*ns
)
549 if (ns
&& ns
->event
!= event
) {
551 wake_up_interruptible(&ns
->poll
);
556 * Clear dentry's mounted state if it has no remaining mounts.
557 * vfsmount_lock must be held for write.
559 static void dentry_reset_mounted(struct vfsmount
*mnt
, struct dentry
*dentry
)
563 for (u
= 0; u
< HASH_SIZE
; u
++) {
566 list_for_each_entry(p
, &mount_hashtable
[u
], mnt_hash
) {
567 if (p
->mnt_mountpoint
== dentry
)
571 spin_lock(&dentry
->d_lock
);
572 dentry
->d_flags
&= ~DCACHE_MOUNTED
;
573 spin_unlock(&dentry
->d_lock
);
577 * vfsmount lock must be held for write
579 static void detach_mnt(struct vfsmount
*mnt
, struct path
*old_path
)
581 old_path
->dentry
= mnt
->mnt_mountpoint
;
582 old_path
->mnt
= mnt
->mnt_parent
;
583 mnt
->mnt_parent
= mnt
;
584 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
585 list_del_init(&mnt
->mnt_child
);
586 list_del_init(&mnt
->mnt_hash
);
587 dentry_reset_mounted(old_path
->mnt
, old_path
->dentry
);
591 * vfsmount lock must be held for write
593 void mnt_set_mountpoint(struct vfsmount
*mnt
, struct dentry
*dentry
,
594 struct vfsmount
*child_mnt
)
596 child_mnt
->mnt_parent
= mntget(mnt
);
597 child_mnt
->mnt_mountpoint
= dget(dentry
);
598 spin_lock(&dentry
->d_lock
);
599 dentry
->d_flags
|= DCACHE_MOUNTED
;
600 spin_unlock(&dentry
->d_lock
);
604 * vfsmount lock must be held for write
606 static void attach_mnt(struct vfsmount
*mnt
, struct path
*path
)
608 mnt_set_mountpoint(path
->mnt
, path
->dentry
, mnt
);
609 list_add_tail(&mnt
->mnt_hash
, mount_hashtable
+
610 hash(path
->mnt
, path
->dentry
));
611 list_add_tail(&mnt
->mnt_child
, &path
->mnt
->mnt_mounts
);
614 static inline void __mnt_make_longterm(struct vfsmount
*mnt
)
617 atomic_inc(&mnt
->mnt_longterm
);
621 /* needs vfsmount lock for write */
622 static inline void __mnt_make_shortterm(struct vfsmount
*mnt
)
625 atomic_dec(&mnt
->mnt_longterm
);
630 * vfsmount lock must be held for write
632 static void commit_tree(struct vfsmount
*mnt
)
634 struct vfsmount
*parent
= mnt
->mnt_parent
;
637 struct mnt_namespace
*n
= parent
->mnt_ns
;
639 BUG_ON(parent
== mnt
);
641 list_add_tail(&head
, &mnt
->mnt_list
);
642 list_for_each_entry(m
, &head
, mnt_list
) {
644 __mnt_make_longterm(m
);
647 list_splice(&head
, n
->list
.prev
);
649 list_add_tail(&mnt
->mnt_hash
, mount_hashtable
+
650 hash(parent
, mnt
->mnt_mountpoint
));
651 list_add_tail(&mnt
->mnt_child
, &parent
->mnt_mounts
);
652 touch_mnt_namespace(n
);
655 static struct vfsmount
*next_mnt(struct vfsmount
*p
, struct vfsmount
*root
)
657 struct list_head
*next
= p
->mnt_mounts
.next
;
658 if (next
== &p
->mnt_mounts
) {
662 next
= p
->mnt_child
.next
;
663 if (next
!= &p
->mnt_parent
->mnt_mounts
)
668 return list_entry(next
, struct vfsmount
, mnt_child
);
671 static struct vfsmount
*skip_mnt_tree(struct vfsmount
*p
)
673 struct list_head
*prev
= p
->mnt_mounts
.prev
;
674 while (prev
!= &p
->mnt_mounts
) {
675 p
= list_entry(prev
, struct vfsmount
, mnt_child
);
676 prev
= p
->mnt_mounts
.prev
;
681 static struct vfsmount
*clone_mnt(struct vfsmount
*old
, struct dentry
*root
,
684 struct super_block
*sb
= old
->mnt_sb
;
685 struct vfsmount
*mnt
= alloc_vfsmnt(old
->mnt_devname
);
688 if (flag
& (CL_SLAVE
| CL_PRIVATE
))
689 mnt
->mnt_group_id
= 0; /* not a peer of original */
691 mnt
->mnt_group_id
= old
->mnt_group_id
;
693 if ((flag
& CL_MAKE_SHARED
) && !mnt
->mnt_group_id
) {
694 int err
= mnt_alloc_group_id(mnt
);
699 mnt
->mnt_flags
= old
->mnt_flags
& ~MNT_WRITE_HOLD
;
700 atomic_inc(&sb
->s_active
);
702 mnt
->mnt_root
= dget(root
);
703 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
704 mnt
->mnt_parent
= mnt
;
706 if (flag
& CL_SLAVE
) {
707 list_add(&mnt
->mnt_slave
, &old
->mnt_slave_list
);
708 mnt
->mnt_master
= old
;
709 CLEAR_MNT_SHARED(mnt
);
710 } else if (!(flag
& CL_PRIVATE
)) {
711 if ((flag
& CL_MAKE_SHARED
) || IS_MNT_SHARED(old
))
712 list_add(&mnt
->mnt_share
, &old
->mnt_share
);
713 if (IS_MNT_SLAVE(old
))
714 list_add(&mnt
->mnt_slave
, &old
->mnt_slave
);
715 mnt
->mnt_master
= old
->mnt_master
;
717 if (flag
& CL_MAKE_SHARED
)
720 /* stick the duplicate mount on the same expiry list
721 * as the original if that was on one */
722 if (flag
& CL_EXPIRE
) {
723 if (!list_empty(&old
->mnt_expire
))
724 list_add(&mnt
->mnt_expire
, &old
->mnt_expire
);
734 static inline void mntfree(struct vfsmount
*mnt
)
736 struct super_block
*sb
= mnt
->mnt_sb
;
739 * This probably indicates that somebody messed
740 * up a mnt_want/drop_write() pair. If this
741 * happens, the filesystem was probably unable
742 * to make r/w->r/o transitions.
745 * The locking used to deal with mnt_count decrement provides barriers,
746 * so mnt_get_writers() below is safe.
748 WARN_ON(mnt_get_writers(mnt
));
749 fsnotify_vfsmount_delete(mnt
);
752 deactivate_super(sb
);
755 static void mntput_no_expire(struct vfsmount
*mnt
)
759 br_read_lock(vfsmount_lock
);
760 if (likely(atomic_read(&mnt
->mnt_longterm
))) {
762 br_read_unlock(vfsmount_lock
);
765 br_read_unlock(vfsmount_lock
);
767 br_write_lock(vfsmount_lock
);
769 if (mnt_get_count(mnt
)) {
770 br_write_unlock(vfsmount_lock
);
775 if (likely(mnt_get_count(mnt
)))
777 br_write_lock(vfsmount_lock
);
779 if (unlikely(mnt
->mnt_pinned
)) {
780 mnt_add_count(mnt
, mnt
->mnt_pinned
+ 1);
782 br_write_unlock(vfsmount_lock
);
783 acct_auto_close_mnt(mnt
);
786 br_write_unlock(vfsmount_lock
);
790 void mntput(struct vfsmount
*mnt
)
793 /* avoid cacheline pingpong, hope gcc doesn't get "smart" */
794 if (unlikely(mnt
->mnt_expiry_mark
))
795 mnt
->mnt_expiry_mark
= 0;
796 mntput_no_expire(mnt
);
799 EXPORT_SYMBOL(mntput
);
801 struct vfsmount
*mntget(struct vfsmount
*mnt
)
807 EXPORT_SYMBOL(mntget
);
809 void mnt_pin(struct vfsmount
*mnt
)
811 br_write_lock(vfsmount_lock
);
813 br_write_unlock(vfsmount_lock
);
815 EXPORT_SYMBOL(mnt_pin
);
817 void mnt_unpin(struct vfsmount
*mnt
)
819 br_write_lock(vfsmount_lock
);
820 if (mnt
->mnt_pinned
) {
824 br_write_unlock(vfsmount_lock
);
826 EXPORT_SYMBOL(mnt_unpin
);
828 static inline void mangle(struct seq_file
*m
, const char *s
)
830 seq_escape(m
, s
, " \t\n\\");
834 * Simple .show_options callback for filesystems which don't want to
835 * implement more complex mount option showing.
837 * See also save_mount_options().
839 int generic_show_options(struct seq_file
*m
, struct vfsmount
*mnt
)
844 options
= rcu_dereference(mnt
->mnt_sb
->s_options
);
846 if (options
!= NULL
&& options
[0]) {
854 EXPORT_SYMBOL(generic_show_options
);
857 * If filesystem uses generic_show_options(), this function should be
858 * called from the fill_super() callback.
860 * The .remount_fs callback usually needs to be handled in a special
861 * way, to make sure, that previous options are not overwritten if the
864 * Also note, that if the filesystem's .remount_fs function doesn't
865 * reset all options to their default value, but changes only newly
866 * given options, then the displayed options will not reflect reality
869 void save_mount_options(struct super_block
*sb
, char *options
)
871 BUG_ON(sb
->s_options
);
872 rcu_assign_pointer(sb
->s_options
, kstrdup(options
, GFP_KERNEL
));
874 EXPORT_SYMBOL(save_mount_options
);
876 void replace_mount_options(struct super_block
*sb
, char *options
)
878 char *old
= sb
->s_options
;
879 rcu_assign_pointer(sb
->s_options
, options
);
885 EXPORT_SYMBOL(replace_mount_options
);
887 #ifdef CONFIG_PROC_FS
889 static void *m_start(struct seq_file
*m
, loff_t
*pos
)
891 struct proc_mounts
*p
= m
->private;
893 down_read(&namespace_sem
);
894 return seq_list_start(&p
->ns
->list
, *pos
);
897 static void *m_next(struct seq_file
*m
, void *v
, loff_t
*pos
)
899 struct proc_mounts
*p
= m
->private;
901 return seq_list_next(v
, &p
->ns
->list
, pos
);
904 static void m_stop(struct seq_file
*m
, void *v
)
906 up_read(&namespace_sem
);
909 int mnt_had_events(struct proc_mounts
*p
)
911 struct mnt_namespace
*ns
= p
->ns
;
914 br_read_lock(vfsmount_lock
);
915 if (p
->event
!= ns
->event
) {
916 p
->event
= ns
->event
;
919 br_read_unlock(vfsmount_lock
);
924 struct proc_fs_info
{
929 static int show_sb_opts(struct seq_file
*m
, struct super_block
*sb
)
931 static const struct proc_fs_info fs_info
[] = {
932 { MS_SYNCHRONOUS
, ",sync" },
933 { MS_DIRSYNC
, ",dirsync" },
934 { MS_MANDLOCK
, ",mand" },
937 const struct proc_fs_info
*fs_infop
;
939 for (fs_infop
= fs_info
; fs_infop
->flag
; fs_infop
++) {
940 if (sb
->s_flags
& fs_infop
->flag
)
941 seq_puts(m
, fs_infop
->str
);
944 return security_sb_show_options(m
, sb
);
947 static void show_mnt_opts(struct seq_file
*m
, struct vfsmount
*mnt
)
949 static const struct proc_fs_info mnt_info
[] = {
950 { MNT_NOSUID
, ",nosuid" },
951 { MNT_NODEV
, ",nodev" },
952 { MNT_NOEXEC
, ",noexec" },
953 { MNT_NOATIME
, ",noatime" },
954 { MNT_NODIRATIME
, ",nodiratime" },
955 { MNT_RELATIME
, ",relatime" },
958 const struct proc_fs_info
*fs_infop
;
960 for (fs_infop
= mnt_info
; fs_infop
->flag
; fs_infop
++) {
961 if (mnt
->mnt_flags
& fs_infop
->flag
)
962 seq_puts(m
, fs_infop
->str
);
966 static void show_type(struct seq_file
*m
, struct super_block
*sb
)
968 mangle(m
, sb
->s_type
->name
);
969 if (sb
->s_subtype
&& sb
->s_subtype
[0]) {
971 mangle(m
, sb
->s_subtype
);
975 static int show_vfsmnt(struct seq_file
*m
, void *v
)
977 struct vfsmount
*mnt
= list_entry(v
, struct vfsmount
, mnt_list
);
979 struct path mnt_path
= { .dentry
= mnt
->mnt_root
, .mnt
= mnt
};
981 mangle(m
, mnt
->mnt_devname
? mnt
->mnt_devname
: "none");
983 seq_path(m
, &mnt_path
, " \t\n\\");
985 show_type(m
, mnt
->mnt_sb
);
986 seq_puts(m
, __mnt_is_readonly(mnt
) ? " ro" : " rw");
987 err
= show_sb_opts(m
, mnt
->mnt_sb
);
990 show_mnt_opts(m
, mnt
);
991 if (mnt
->mnt_sb
->s_op
->show_options
)
992 err
= mnt
->mnt_sb
->s_op
->show_options(m
, mnt
);
993 seq_puts(m
, " 0 0\n");
998 const struct seq_operations mounts_op
= {
1005 static int show_mountinfo(struct seq_file
*m
, void *v
)
1007 struct proc_mounts
*p
= m
->private;
1008 struct vfsmount
*mnt
= list_entry(v
, struct vfsmount
, mnt_list
);
1009 struct super_block
*sb
= mnt
->mnt_sb
;
1010 struct path mnt_path
= { .dentry
= mnt
->mnt_root
, .mnt
= mnt
};
1011 struct path root
= p
->root
;
1014 seq_printf(m
, "%i %i %u:%u ", mnt
->mnt_id
, mnt
->mnt_parent
->mnt_id
,
1015 MAJOR(sb
->s_dev
), MINOR(sb
->s_dev
));
1016 seq_dentry(m
, mnt
->mnt_root
, " \t\n\\");
1018 seq_path_root(m
, &mnt_path
, &root
, " \t\n\\");
1019 if (root
.mnt
!= p
->root
.mnt
|| root
.dentry
!= p
->root
.dentry
) {
1021 * Mountpoint is outside root, discard that one. Ugly,
1022 * but less so than trying to do that in iterator in a
1023 * race-free way (due to renames).
1027 seq_puts(m
, mnt
->mnt_flags
& MNT_READONLY
? " ro" : " rw");
1028 show_mnt_opts(m
, mnt
);
1030 /* Tagged fields ("foo:X" or "bar") */
1031 if (IS_MNT_SHARED(mnt
))
1032 seq_printf(m
, " shared:%i", mnt
->mnt_group_id
);
1033 if (IS_MNT_SLAVE(mnt
)) {
1034 int master
= mnt
->mnt_master
->mnt_group_id
;
1035 int dom
= get_dominating_id(mnt
, &p
->root
);
1036 seq_printf(m
, " master:%i", master
);
1037 if (dom
&& dom
!= master
)
1038 seq_printf(m
, " propagate_from:%i", dom
);
1040 if (IS_MNT_UNBINDABLE(mnt
))
1041 seq_puts(m
, " unbindable");
1043 /* Filesystem specific data */
1047 mangle(m
, mnt
->mnt_devname
? mnt
->mnt_devname
: "none");
1048 seq_puts(m
, sb
->s_flags
& MS_RDONLY
? " ro" : " rw");
1049 err
= show_sb_opts(m
, sb
);
1052 if (sb
->s_op
->show_options
)
1053 err
= sb
->s_op
->show_options(m
, mnt
);
1059 const struct seq_operations mountinfo_op
= {
1063 .show
= show_mountinfo
,
1066 static int show_vfsstat(struct seq_file
*m
, void *v
)
1068 struct vfsmount
*mnt
= list_entry(v
, struct vfsmount
, mnt_list
);
1069 struct path mnt_path
= { .dentry
= mnt
->mnt_root
, .mnt
= mnt
};
1073 if (mnt
->mnt_devname
) {
1074 seq_puts(m
, "device ");
1075 mangle(m
, mnt
->mnt_devname
);
1077 seq_puts(m
, "no device");
1080 seq_puts(m
, " mounted on ");
1081 seq_path(m
, &mnt_path
, " \t\n\\");
1084 /* file system type */
1085 seq_puts(m
, "with fstype ");
1086 show_type(m
, mnt
->mnt_sb
);
1088 /* optional statistics */
1089 if (mnt
->mnt_sb
->s_op
->show_stats
) {
1091 err
= mnt
->mnt_sb
->s_op
->show_stats(m
, mnt
);
1098 const struct seq_operations mountstats_op
= {
1102 .show
= show_vfsstat
,
1104 #endif /* CONFIG_PROC_FS */
1107 * may_umount_tree - check if a mount tree is busy
1108 * @mnt: root of mount tree
1110 * This is called to check if a tree of mounts has any
1111 * open files, pwds, chroots or sub mounts that are
1114 int may_umount_tree(struct vfsmount
*mnt
)
1116 int actual_refs
= 0;
1117 int minimum_refs
= 0;
1120 /* write lock needed for mnt_get_count */
1121 br_write_lock(vfsmount_lock
);
1122 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
1123 actual_refs
+= mnt_get_count(p
);
1126 br_write_unlock(vfsmount_lock
);
1128 if (actual_refs
> minimum_refs
)
1134 EXPORT_SYMBOL(may_umount_tree
);
1137 * may_umount - check if a mount point is busy
1138 * @mnt: root of mount
1140 * This is called to check if a mount point has any
1141 * open files, pwds, chroots or sub mounts. If the
1142 * mount has sub mounts this will return busy
1143 * regardless of whether the sub mounts are busy.
1145 * Doesn't take quota and stuff into account. IOW, in some cases it will
1146 * give false negatives. The main reason why it's here is that we need
1147 * a non-destructive way to look for easily umountable filesystems.
1149 int may_umount(struct vfsmount
*mnt
)
1152 down_read(&namespace_sem
);
1153 br_write_lock(vfsmount_lock
);
1154 if (propagate_mount_busy(mnt
, 2))
1156 br_write_unlock(vfsmount_lock
);
1157 up_read(&namespace_sem
);
1161 EXPORT_SYMBOL(may_umount
);
1163 void release_mounts(struct list_head
*head
)
1165 struct vfsmount
*mnt
;
1166 while (!list_empty(head
)) {
1167 mnt
= list_first_entry(head
, struct vfsmount
, mnt_hash
);
1168 list_del_init(&mnt
->mnt_hash
);
1169 if (mnt
->mnt_parent
!= mnt
) {
1170 struct dentry
*dentry
;
1173 br_write_lock(vfsmount_lock
);
1174 dentry
= mnt
->mnt_mountpoint
;
1175 m
= mnt
->mnt_parent
;
1176 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
1177 mnt
->mnt_parent
= mnt
;
1179 br_write_unlock(vfsmount_lock
);
1188 * vfsmount lock must be held for write
1189 * namespace_sem must be held for write
1191 void umount_tree(struct vfsmount
*mnt
, int propagate
, struct list_head
*kill
)
1193 LIST_HEAD(tmp_list
);
1196 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
))
1197 list_move(&p
->mnt_hash
, &tmp_list
);
1200 propagate_umount(&tmp_list
);
1202 list_for_each_entry(p
, &tmp_list
, mnt_hash
) {
1203 list_del_init(&p
->mnt_expire
);
1204 list_del_init(&p
->mnt_list
);
1205 __touch_mnt_namespace(p
->mnt_ns
);
1207 __mnt_make_shortterm(p
);
1208 list_del_init(&p
->mnt_child
);
1209 if (p
->mnt_parent
!= p
) {
1210 p
->mnt_parent
->mnt_ghosts
++;
1211 dentry_reset_mounted(p
->mnt_parent
, p
->mnt_mountpoint
);
1213 change_mnt_propagation(p
, MS_PRIVATE
);
1215 list_splice(&tmp_list
, kill
);
1218 static void shrink_submounts(struct vfsmount
*mnt
, struct list_head
*umounts
);
1220 static int do_umount(struct vfsmount
*mnt
, int flags
)
1222 struct super_block
*sb
= mnt
->mnt_sb
;
1224 LIST_HEAD(umount_list
);
1226 retval
= security_sb_umount(mnt
, flags
);
1231 * Allow userspace to request a mountpoint be expired rather than
1232 * unmounting unconditionally. Unmount only happens if:
1233 * (1) the mark is already set (the mark is cleared by mntput())
1234 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
1236 if (flags
& MNT_EXPIRE
) {
1237 if (mnt
== current
->fs
->root
.mnt
||
1238 flags
& (MNT_FORCE
| MNT_DETACH
))
1242 * probably don't strictly need the lock here if we examined
1243 * all race cases, but it's a slowpath.
1245 br_write_lock(vfsmount_lock
);
1246 if (mnt_get_count(mnt
) != 2) {
1247 br_write_unlock(vfsmount_lock
);
1250 br_write_unlock(vfsmount_lock
);
1252 if (!xchg(&mnt
->mnt_expiry_mark
, 1))
1257 * If we may have to abort operations to get out of this
1258 * mount, and they will themselves hold resources we must
1259 * allow the fs to do things. In the Unix tradition of
1260 * 'Gee thats tricky lets do it in userspace' the umount_begin
1261 * might fail to complete on the first run through as other tasks
1262 * must return, and the like. Thats for the mount program to worry
1263 * about for the moment.
1266 if (flags
& MNT_FORCE
&& sb
->s_op
->umount_begin
) {
1267 sb
->s_op
->umount_begin(sb
);
1271 * No sense to grab the lock for this test, but test itself looks
1272 * somewhat bogus. Suggestions for better replacement?
1273 * Ho-hum... In principle, we might treat that as umount + switch
1274 * to rootfs. GC would eventually take care of the old vfsmount.
1275 * Actually it makes sense, especially if rootfs would contain a
1276 * /reboot - static binary that would close all descriptors and
1277 * call reboot(9). Then init(8) could umount root and exec /reboot.
1279 if (mnt
== current
->fs
->root
.mnt
&& !(flags
& MNT_DETACH
)) {
1281 * Special case for "unmounting" root ...
1282 * we just try to remount it readonly.
1284 down_write(&sb
->s_umount
);
1285 if (!(sb
->s_flags
& MS_RDONLY
))
1286 retval
= do_remount_sb(sb
, MS_RDONLY
, NULL
, 0);
1287 up_write(&sb
->s_umount
);
1291 down_write(&namespace_sem
);
1292 br_write_lock(vfsmount_lock
);
1295 if (!(flags
& MNT_DETACH
))
1296 shrink_submounts(mnt
, &umount_list
);
1299 if (flags
& MNT_DETACH
|| !propagate_mount_busy(mnt
, 2)) {
1300 if (!list_empty(&mnt
->mnt_list
))
1301 umount_tree(mnt
, 1, &umount_list
);
1304 br_write_unlock(vfsmount_lock
);
1305 up_write(&namespace_sem
);
1306 release_mounts(&umount_list
);
1311 * Now umount can handle mount points as well as block devices.
1312 * This is important for filesystems which use unnamed block devices.
1314 * We now support a flag for forced unmount like the other 'big iron'
1315 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
1318 SYSCALL_DEFINE2(umount
, char __user
*, name
, int, flags
)
1322 int lookup_flags
= 0;
1324 if (flags
& ~(MNT_FORCE
| MNT_DETACH
| MNT_EXPIRE
| UMOUNT_NOFOLLOW
))
1327 if (!(flags
& UMOUNT_NOFOLLOW
))
1328 lookup_flags
|= LOOKUP_FOLLOW
;
1330 retval
= user_path_at(AT_FDCWD
, name
, lookup_flags
, &path
);
1334 if (path
.dentry
!= path
.mnt
->mnt_root
)
1336 if (!check_mnt(path
.mnt
))
1340 if (!capable(CAP_SYS_ADMIN
))
1343 retval
= do_umount(path
.mnt
, flags
);
1345 /* we mustn't call path_put() as that would clear mnt_expiry_mark */
1347 mntput_no_expire(path
.mnt
);
1352 #ifdef __ARCH_WANT_SYS_OLDUMOUNT
1355 * The 2.0 compatible umount. No flags.
1357 SYSCALL_DEFINE1(oldumount
, char __user
*, name
)
1359 return sys_umount(name
, 0);
1364 static int mount_is_safe(struct path
*path
)
1366 if (capable(CAP_SYS_ADMIN
))
1370 if (S_ISLNK(path
->dentry
->d_inode
->i_mode
))
1372 if (path
->dentry
->d_inode
->i_mode
& S_ISVTX
) {
1373 if (current_uid() != path
->dentry
->d_inode
->i_uid
)
1376 if (inode_permission(path
->dentry
->d_inode
, MAY_WRITE
))
1382 struct vfsmount
*copy_tree(struct vfsmount
*mnt
, struct dentry
*dentry
,
1385 struct vfsmount
*res
, *p
, *q
, *r
, *s
;
1388 if (!(flag
& CL_COPY_ALL
) && IS_MNT_UNBINDABLE(mnt
))
1391 res
= q
= clone_mnt(mnt
, dentry
, flag
);
1394 q
->mnt_mountpoint
= mnt
->mnt_mountpoint
;
1397 list_for_each_entry(r
, &mnt
->mnt_mounts
, mnt_child
) {
1398 if (!is_subdir(r
->mnt_mountpoint
, dentry
))
1401 for (s
= r
; s
; s
= next_mnt(s
, r
)) {
1402 if (!(flag
& CL_COPY_ALL
) && IS_MNT_UNBINDABLE(s
)) {
1403 s
= skip_mnt_tree(s
);
1406 while (p
!= s
->mnt_parent
) {
1412 path
.dentry
= p
->mnt_mountpoint
;
1413 q
= clone_mnt(p
, p
->mnt_root
, flag
);
1416 br_write_lock(vfsmount_lock
);
1417 list_add_tail(&q
->mnt_list
, &res
->mnt_list
);
1418 attach_mnt(q
, &path
);
1419 br_write_unlock(vfsmount_lock
);
1425 LIST_HEAD(umount_list
);
1426 br_write_lock(vfsmount_lock
);
1427 umount_tree(res
, 0, &umount_list
);
1428 br_write_unlock(vfsmount_lock
);
1429 release_mounts(&umount_list
);
1434 struct vfsmount
*collect_mounts(struct path
*path
)
1436 struct vfsmount
*tree
;
1437 down_write(&namespace_sem
);
1438 tree
= copy_tree(path
->mnt
, path
->dentry
, CL_COPY_ALL
| CL_PRIVATE
);
1439 up_write(&namespace_sem
);
1443 void drop_collected_mounts(struct vfsmount
*mnt
)
1445 LIST_HEAD(umount_list
);
1446 down_write(&namespace_sem
);
1447 br_write_lock(vfsmount_lock
);
1448 umount_tree(mnt
, 0, &umount_list
);
1449 br_write_unlock(vfsmount_lock
);
1450 up_write(&namespace_sem
);
1451 release_mounts(&umount_list
);
1454 int iterate_mounts(int (*f
)(struct vfsmount
*, void *), void *arg
,
1455 struct vfsmount
*root
)
1457 struct vfsmount
*mnt
;
1458 int res
= f(root
, arg
);
1461 list_for_each_entry(mnt
, &root
->mnt_list
, mnt_list
) {
1469 static void cleanup_group_ids(struct vfsmount
*mnt
, struct vfsmount
*end
)
1473 for (p
= mnt
; p
!= end
; p
= next_mnt(p
, mnt
)) {
1474 if (p
->mnt_group_id
&& !IS_MNT_SHARED(p
))
1475 mnt_release_group_id(p
);
1479 static int invent_group_ids(struct vfsmount
*mnt
, bool recurse
)
1483 for (p
= mnt
; p
; p
= recurse
? next_mnt(p
, mnt
) : NULL
) {
1484 if (!p
->mnt_group_id
&& !IS_MNT_SHARED(p
)) {
1485 int err
= mnt_alloc_group_id(p
);
1487 cleanup_group_ids(mnt
, p
);
1497 * @source_mnt : mount tree to be attached
1498 * @nd : place the mount tree @source_mnt is attached
1499 * @parent_nd : if non-null, detach the source_mnt from its parent and
1500 * store the parent mount and mountpoint dentry.
1501 * (done when source_mnt is moved)
1503 * NOTE: in the table below explains the semantics when a source mount
1504 * of a given type is attached to a destination mount of a given type.
1505 * ---------------------------------------------------------------------------
1506 * | BIND MOUNT OPERATION |
1507 * |**************************************************************************
1508 * | source-->| shared | private | slave | unbindable |
1512 * |**************************************************************************
1513 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
1515 * |non-shared| shared (+) | private | slave (*) | invalid |
1516 * ***************************************************************************
1517 * A bind operation clones the source mount and mounts the clone on the
1518 * destination mount.
1520 * (++) the cloned mount is propagated to all the mounts in the propagation
1521 * tree of the destination mount and the cloned mount is added to
1522 * the peer group of the source mount.
1523 * (+) the cloned mount is created under the destination mount and is marked
1524 * as shared. The cloned mount is added to the peer group of the source
1526 * (+++) the mount is propagated to all the mounts in the propagation tree
1527 * of the destination mount and the cloned mount is made slave
1528 * of the same master as that of the source mount. The cloned mount
1529 * is marked as 'shared and slave'.
1530 * (*) the cloned mount is made a slave of the same master as that of the
1533 * ---------------------------------------------------------------------------
1534 * | MOVE MOUNT OPERATION |
1535 * |**************************************************************************
1536 * | source-->| shared | private | slave | unbindable |
1540 * |**************************************************************************
1541 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
1543 * |non-shared| shared (+*) | private | slave (*) | unbindable |
1544 * ***************************************************************************
1546 * (+) the mount is moved to the destination. And is then propagated to
1547 * all the mounts in the propagation tree of the destination mount.
1548 * (+*) the mount is moved to the destination.
1549 * (+++) the mount is moved to the destination and is then propagated to
1550 * all the mounts belonging to the destination mount's propagation tree.
1551 * the mount is marked as 'shared and slave'.
1552 * (*) the mount continues to be a slave at the new location.
1554 * if the source mount is a tree, the operations explained above is
1555 * applied to each mount in the tree.
1556 * Must be called without spinlocks held, since this function can sleep
1559 static int attach_recursive_mnt(struct vfsmount
*source_mnt
,
1560 struct path
*path
, struct path
*parent_path
)
1562 LIST_HEAD(tree_list
);
1563 struct vfsmount
*dest_mnt
= path
->mnt
;
1564 struct dentry
*dest_dentry
= path
->dentry
;
1565 struct vfsmount
*child
, *p
;
1568 if (IS_MNT_SHARED(dest_mnt
)) {
1569 err
= invent_group_ids(source_mnt
, true);
1573 err
= propagate_mnt(dest_mnt
, dest_dentry
, source_mnt
, &tree_list
);
1575 goto out_cleanup_ids
;
1577 br_write_lock(vfsmount_lock
);
1579 if (IS_MNT_SHARED(dest_mnt
)) {
1580 for (p
= source_mnt
; p
; p
= next_mnt(p
, source_mnt
))
1584 detach_mnt(source_mnt
, parent_path
);
1585 attach_mnt(source_mnt
, path
);
1586 touch_mnt_namespace(parent_path
->mnt
->mnt_ns
);
1588 mnt_set_mountpoint(dest_mnt
, dest_dentry
, source_mnt
);
1589 commit_tree(source_mnt
);
1592 list_for_each_entry_safe(child
, p
, &tree_list
, mnt_hash
) {
1593 list_del_init(&child
->mnt_hash
);
1596 br_write_unlock(vfsmount_lock
);
1601 if (IS_MNT_SHARED(dest_mnt
))
1602 cleanup_group_ids(source_mnt
, NULL
);
1607 static int graft_tree(struct vfsmount
*mnt
, struct path
*path
)
1610 if (mnt
->mnt_sb
->s_flags
& MS_NOUSER
)
1613 if (S_ISDIR(path
->dentry
->d_inode
->i_mode
) !=
1614 S_ISDIR(mnt
->mnt_root
->d_inode
->i_mode
))
1618 mutex_lock(&path
->dentry
->d_inode
->i_mutex
);
1619 if (cant_mount(path
->dentry
))
1622 if (!d_unlinked(path
->dentry
))
1623 err
= attach_recursive_mnt(mnt
, path
, NULL
);
1625 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
1630 * Sanity check the flags to change_mnt_propagation.
1633 static int flags_to_propagation_type(int flags
)
1635 int type
= flags
& ~MS_REC
;
1637 /* Fail if any non-propagation flags are set */
1638 if (type
& ~(MS_SHARED
| MS_PRIVATE
| MS_SLAVE
| MS_UNBINDABLE
))
1640 /* Only one propagation flag should be set */
1641 if (!is_power_of_2(type
))
1647 * recursively change the type of the mountpoint.
1649 static int do_change_type(struct path
*path
, int flag
)
1651 struct vfsmount
*m
, *mnt
= path
->mnt
;
1652 int recurse
= flag
& MS_REC
;
1656 if (!capable(CAP_SYS_ADMIN
))
1659 if (path
->dentry
!= path
->mnt
->mnt_root
)
1662 type
= flags_to_propagation_type(flag
);
1666 down_write(&namespace_sem
);
1667 if (type
== MS_SHARED
) {
1668 err
= invent_group_ids(mnt
, recurse
);
1673 br_write_lock(vfsmount_lock
);
1674 for (m
= mnt
; m
; m
= (recurse
? next_mnt(m
, mnt
) : NULL
))
1675 change_mnt_propagation(m
, type
);
1676 br_write_unlock(vfsmount_lock
);
1679 up_write(&namespace_sem
);
1684 * do loopback mount.
1686 static int do_loopback(struct path
*path
, char *old_name
,
1689 struct path old_path
;
1690 struct vfsmount
*mnt
= NULL
;
1691 int err
= mount_is_safe(path
);
1694 if (!old_name
|| !*old_name
)
1696 err
= kern_path(old_name
, LOOKUP_FOLLOW
, &old_path
);
1700 down_write(&namespace_sem
);
1702 if (IS_MNT_UNBINDABLE(old_path
.mnt
))
1705 if (!check_mnt(path
->mnt
) || !check_mnt(old_path
.mnt
))
1710 mnt
= copy_tree(old_path
.mnt
, old_path
.dentry
, 0);
1712 mnt
= clone_mnt(old_path
.mnt
, old_path
.dentry
, 0);
1717 err
= graft_tree(mnt
, path
);
1719 LIST_HEAD(umount_list
);
1721 br_write_lock(vfsmount_lock
);
1722 umount_tree(mnt
, 0, &umount_list
);
1723 br_write_unlock(vfsmount_lock
);
1724 release_mounts(&umount_list
);
1728 up_write(&namespace_sem
);
1729 path_put(&old_path
);
1733 static int change_mount_flags(struct vfsmount
*mnt
, int ms_flags
)
1736 int readonly_request
= 0;
1738 if (ms_flags
& MS_RDONLY
)
1739 readonly_request
= 1;
1740 if (readonly_request
== __mnt_is_readonly(mnt
))
1743 if (readonly_request
)
1744 error
= mnt_make_readonly(mnt
);
1746 __mnt_unmake_readonly(mnt
);
1751 * change filesystem flags. dir should be a physical root of filesystem.
1752 * If you've mounted a non-root directory somewhere and want to do remount
1753 * on it - tough luck.
1755 static int do_remount(struct path
*path
, int flags
, int mnt_flags
,
1759 struct super_block
*sb
= path
->mnt
->mnt_sb
;
1761 if (!capable(CAP_SYS_ADMIN
))
1764 if (!check_mnt(path
->mnt
))
1767 if (path
->dentry
!= path
->mnt
->mnt_root
)
1770 down_write(&sb
->s_umount
);
1771 if (flags
& MS_BIND
)
1772 err
= change_mount_flags(path
->mnt
, flags
);
1774 err
= do_remount_sb(sb
, flags
, data
, 0);
1776 br_write_lock(vfsmount_lock
);
1777 mnt_flags
|= path
->mnt
->mnt_flags
& MNT_PROPAGATION_MASK
;
1778 path
->mnt
->mnt_flags
= mnt_flags
;
1779 br_write_unlock(vfsmount_lock
);
1781 up_write(&sb
->s_umount
);
1783 br_write_lock(vfsmount_lock
);
1784 touch_mnt_namespace(path
->mnt
->mnt_ns
);
1785 br_write_unlock(vfsmount_lock
);
1790 static inline int tree_contains_unbindable(struct vfsmount
*mnt
)
1793 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
1794 if (IS_MNT_UNBINDABLE(p
))
1800 static int do_move_mount(struct path
*path
, char *old_name
)
1802 struct path old_path
, parent_path
;
1805 if (!capable(CAP_SYS_ADMIN
))
1807 if (!old_name
|| !*old_name
)
1809 err
= kern_path(old_name
, LOOKUP_FOLLOW
, &old_path
);
1813 down_write(&namespace_sem
);
1814 err
= follow_down(path
, true);
1819 if (!check_mnt(path
->mnt
) || !check_mnt(old_path
.mnt
))
1823 mutex_lock(&path
->dentry
->d_inode
->i_mutex
);
1824 if (cant_mount(path
->dentry
))
1827 if (d_unlinked(path
->dentry
))
1831 if (old_path
.dentry
!= old_path
.mnt
->mnt_root
)
1834 if (old_path
.mnt
== old_path
.mnt
->mnt_parent
)
1837 if (S_ISDIR(path
->dentry
->d_inode
->i_mode
) !=
1838 S_ISDIR(old_path
.dentry
->d_inode
->i_mode
))
1841 * Don't move a mount residing in a shared parent.
1843 if (old_path
.mnt
->mnt_parent
&&
1844 IS_MNT_SHARED(old_path
.mnt
->mnt_parent
))
1847 * Don't move a mount tree containing unbindable mounts to a destination
1848 * mount which is shared.
1850 if (IS_MNT_SHARED(path
->mnt
) &&
1851 tree_contains_unbindable(old_path
.mnt
))
1854 for (p
= path
->mnt
; p
->mnt_parent
!= p
; p
= p
->mnt_parent
)
1855 if (p
== old_path
.mnt
)
1858 err
= attach_recursive_mnt(old_path
.mnt
, path
, &parent_path
);
1862 /* if the mount is moved, it should no longer be expire
1864 list_del_init(&old_path
.mnt
->mnt_expire
);
1866 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
1868 up_write(&namespace_sem
);
1870 path_put(&parent_path
);
1871 path_put(&old_path
);
1875 static int do_add_mount(struct vfsmount
*, struct path
*, int);
1878 * create a new mount for userspace and request it to be added into the
1881 static int do_new_mount(struct path
*path
, char *type
, int flags
,
1882 int mnt_flags
, char *name
, void *data
)
1884 struct vfsmount
*mnt
;
1890 /* we need capabilities... */
1891 if (!capable(CAP_SYS_ADMIN
))
1894 mnt
= do_kern_mount(type
, flags
, name
, data
);
1896 return PTR_ERR(mnt
);
1898 err
= do_add_mount(mnt
, path
, mnt_flags
);
1904 int finish_automount(struct vfsmount
*m
, struct path
*path
)
1907 /* The new mount record should have at least 2 refs to prevent it being
1908 * expired before we get a chance to add it
1910 BUG_ON(mnt_get_count(m
) < 2);
1912 if (m
->mnt_sb
== path
->mnt
->mnt_sb
&&
1913 m
->mnt_root
== path
->dentry
) {
1918 err
= do_add_mount(m
, path
, path
->mnt
->mnt_flags
| MNT_SHRINKABLE
);
1922 /* remove m from any expiration list it may be on */
1923 if (!list_empty(&m
->mnt_expire
)) {
1924 down_write(&namespace_sem
);
1925 br_write_lock(vfsmount_lock
);
1926 list_del_init(&m
->mnt_expire
);
1927 br_write_unlock(vfsmount_lock
);
1928 up_write(&namespace_sem
);
1936 * add a mount into a namespace's mount tree
1938 static int do_add_mount(struct vfsmount
*newmnt
, struct path
*path
, int mnt_flags
)
1942 mnt_flags
&= ~(MNT_SHARED
| MNT_WRITE_HOLD
| MNT_INTERNAL
);
1944 down_write(&namespace_sem
);
1945 /* Something was mounted here while we slept */
1946 err
= follow_down(path
, true);
1951 if (!(mnt_flags
& MNT_SHRINKABLE
) && !check_mnt(path
->mnt
))
1954 /* Refuse the same filesystem on the same mount point */
1956 if (path
->mnt
->mnt_sb
== newmnt
->mnt_sb
&&
1957 path
->mnt
->mnt_root
== path
->dentry
)
1961 if (S_ISLNK(newmnt
->mnt_root
->d_inode
->i_mode
))
1964 newmnt
->mnt_flags
= mnt_flags
;
1965 err
= graft_tree(newmnt
, path
);
1968 up_write(&namespace_sem
);
1973 * mnt_set_expiry - Put a mount on an expiration list
1974 * @mnt: The mount to list.
1975 * @expiry_list: The list to add the mount to.
1977 void mnt_set_expiry(struct vfsmount
*mnt
, struct list_head
*expiry_list
)
1979 down_write(&namespace_sem
);
1980 br_write_lock(vfsmount_lock
);
1982 list_add_tail(&mnt
->mnt_expire
, expiry_list
);
1984 br_write_unlock(vfsmount_lock
);
1985 up_write(&namespace_sem
);
1987 EXPORT_SYMBOL(mnt_set_expiry
);
1990 * process a list of expirable mountpoints with the intent of discarding any
1991 * mountpoints that aren't in use and haven't been touched since last we came
1994 void mark_mounts_for_expiry(struct list_head
*mounts
)
1996 struct vfsmount
*mnt
, *next
;
1997 LIST_HEAD(graveyard
);
2000 if (list_empty(mounts
))
2003 down_write(&namespace_sem
);
2004 br_write_lock(vfsmount_lock
);
2006 /* extract from the expiration list every vfsmount that matches the
2007 * following criteria:
2008 * - only referenced by its parent vfsmount
2009 * - still marked for expiry (marked on the last call here; marks are
2010 * cleared by mntput())
2012 list_for_each_entry_safe(mnt
, next
, mounts
, mnt_expire
) {
2013 if (!xchg(&mnt
->mnt_expiry_mark
, 1) ||
2014 propagate_mount_busy(mnt
, 1))
2016 list_move(&mnt
->mnt_expire
, &graveyard
);
2018 while (!list_empty(&graveyard
)) {
2019 mnt
= list_first_entry(&graveyard
, struct vfsmount
, mnt_expire
);
2020 touch_mnt_namespace(mnt
->mnt_ns
);
2021 umount_tree(mnt
, 1, &umounts
);
2023 br_write_unlock(vfsmount_lock
);
2024 up_write(&namespace_sem
);
2026 release_mounts(&umounts
);
2029 EXPORT_SYMBOL_GPL(mark_mounts_for_expiry
);
2032 * Ripoff of 'select_parent()'
2034 * search the list of submounts for a given mountpoint, and move any
2035 * shrinkable submounts to the 'graveyard' list.
2037 static int select_submounts(struct vfsmount
*parent
, struct list_head
*graveyard
)
2039 struct vfsmount
*this_parent
= parent
;
2040 struct list_head
*next
;
2044 next
= this_parent
->mnt_mounts
.next
;
2046 while (next
!= &this_parent
->mnt_mounts
) {
2047 struct list_head
*tmp
= next
;
2048 struct vfsmount
*mnt
= list_entry(tmp
, struct vfsmount
, mnt_child
);
2051 if (!(mnt
->mnt_flags
& MNT_SHRINKABLE
))
2054 * Descend a level if the d_mounts list is non-empty.
2056 if (!list_empty(&mnt
->mnt_mounts
)) {
2061 if (!propagate_mount_busy(mnt
, 1)) {
2062 list_move_tail(&mnt
->mnt_expire
, graveyard
);
2067 * All done at this level ... ascend and resume the search
2069 if (this_parent
!= parent
) {
2070 next
= this_parent
->mnt_child
.next
;
2071 this_parent
= this_parent
->mnt_parent
;
2078 * process a list of expirable mountpoints with the intent of discarding any
2079 * submounts of a specific parent mountpoint
2081 * vfsmount_lock must be held for write
2083 static void shrink_submounts(struct vfsmount
*mnt
, struct list_head
*umounts
)
2085 LIST_HEAD(graveyard
);
2088 /* extract submounts of 'mountpoint' from the expiration list */
2089 while (select_submounts(mnt
, &graveyard
)) {
2090 while (!list_empty(&graveyard
)) {
2091 m
= list_first_entry(&graveyard
, struct vfsmount
,
2093 touch_mnt_namespace(m
->mnt_ns
);
2094 umount_tree(m
, 1, umounts
);
2100 * Some copy_from_user() implementations do not return the exact number of
2101 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
2102 * Note that this function differs from copy_from_user() in that it will oops
2103 * on bad values of `to', rather than returning a short copy.
2105 static long exact_copy_from_user(void *to
, const void __user
* from
,
2109 const char __user
*f
= from
;
2112 if (!access_ok(VERIFY_READ
, from
, n
))
2116 if (__get_user(c
, f
)) {
2127 int copy_mount_options(const void __user
* data
, unsigned long *where
)
2137 if (!(page
= __get_free_page(GFP_KERNEL
)))
2140 /* We only care that *some* data at the address the user
2141 * gave us is valid. Just in case, we'll zero
2142 * the remainder of the page.
2144 /* copy_from_user cannot cross TASK_SIZE ! */
2145 size
= TASK_SIZE
- (unsigned long)data
;
2146 if (size
> PAGE_SIZE
)
2149 i
= size
- exact_copy_from_user((void *)page
, data
, size
);
2155 memset((char *)page
+ i
, 0, PAGE_SIZE
- i
);
2160 int copy_mount_string(const void __user
*data
, char **where
)
2169 tmp
= strndup_user(data
, PAGE_SIZE
);
2171 return PTR_ERR(tmp
);
2178 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
2179 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
2181 * data is a (void *) that can point to any structure up to
2182 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
2183 * information (or be NULL).
2185 * Pre-0.97 versions of mount() didn't have a flags word.
2186 * When the flags word was introduced its top half was required
2187 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
2188 * Therefore, if this magic number is present, it carries no information
2189 * and must be discarded.
2191 long do_mount(char *dev_name
, char *dir_name
, char *type_page
,
2192 unsigned long flags
, void *data_page
)
2199 if ((flags
& MS_MGC_MSK
) == MS_MGC_VAL
)
2200 flags
&= ~MS_MGC_MSK
;
2202 /* Basic sanity checks */
2204 if (!dir_name
|| !*dir_name
|| !memchr(dir_name
, 0, PAGE_SIZE
))
2208 ((char *)data_page
)[PAGE_SIZE
- 1] = 0;
2210 /* ... and get the mountpoint */
2211 retval
= kern_path(dir_name
, LOOKUP_FOLLOW
, &path
);
2215 retval
= security_sb_mount(dev_name
, &path
,
2216 type_page
, flags
, data_page
);
2220 /* Default to relatime unless overriden */
2221 if (!(flags
& MS_NOATIME
))
2222 mnt_flags
|= MNT_RELATIME
;
2224 /* Separate the per-mountpoint flags */
2225 if (flags
& MS_NOSUID
)
2226 mnt_flags
|= MNT_NOSUID
;
2227 if (flags
& MS_NODEV
)
2228 mnt_flags
|= MNT_NODEV
;
2229 if (flags
& MS_NOEXEC
)
2230 mnt_flags
|= MNT_NOEXEC
;
2231 if (flags
& MS_NOATIME
)
2232 mnt_flags
|= MNT_NOATIME
;
2233 if (flags
& MS_NODIRATIME
)
2234 mnt_flags
|= MNT_NODIRATIME
;
2235 if (flags
& MS_STRICTATIME
)
2236 mnt_flags
&= ~(MNT_RELATIME
| MNT_NOATIME
);
2237 if (flags
& MS_RDONLY
)
2238 mnt_flags
|= MNT_READONLY
;
2240 flags
&= ~(MS_NOSUID
| MS_NOEXEC
| MS_NODEV
| MS_ACTIVE
| MS_BORN
|
2241 MS_NOATIME
| MS_NODIRATIME
| MS_RELATIME
| MS_KERNMOUNT
|
2244 if (flags
& MS_REMOUNT
)
2245 retval
= do_remount(&path
, flags
& ~MS_REMOUNT
, mnt_flags
,
2247 else if (flags
& MS_BIND
)
2248 retval
= do_loopback(&path
, dev_name
, flags
& MS_REC
);
2249 else if (flags
& (MS_SHARED
| MS_PRIVATE
| MS_SLAVE
| MS_UNBINDABLE
))
2250 retval
= do_change_type(&path
, flags
);
2251 else if (flags
& MS_MOVE
)
2252 retval
= do_move_mount(&path
, dev_name
);
2254 retval
= do_new_mount(&path
, type_page
, flags
, mnt_flags
,
2255 dev_name
, data_page
);
2261 static struct mnt_namespace
*alloc_mnt_ns(void)
2263 struct mnt_namespace
*new_ns
;
2265 new_ns
= kmalloc(sizeof(struct mnt_namespace
), GFP_KERNEL
);
2267 return ERR_PTR(-ENOMEM
);
2268 atomic_set(&new_ns
->count
, 1);
2269 new_ns
->root
= NULL
;
2270 INIT_LIST_HEAD(&new_ns
->list
);
2271 init_waitqueue_head(&new_ns
->poll
);
2276 void mnt_make_longterm(struct vfsmount
*mnt
)
2278 __mnt_make_longterm(mnt
);
2281 void mnt_make_shortterm(struct vfsmount
*mnt
)
2284 if (atomic_add_unless(&mnt
->mnt_longterm
, -1, 1))
2286 br_write_lock(vfsmount_lock
);
2287 atomic_dec(&mnt
->mnt_longterm
);
2288 br_write_unlock(vfsmount_lock
);
2293 * Allocate a new namespace structure and populate it with contents
2294 * copied from the namespace of the passed in task structure.
2296 static struct mnt_namespace
*dup_mnt_ns(struct mnt_namespace
*mnt_ns
,
2297 struct fs_struct
*fs
)
2299 struct mnt_namespace
*new_ns
;
2300 struct vfsmount
*rootmnt
= NULL
, *pwdmnt
= NULL
;
2301 struct vfsmount
*p
, *q
;
2303 new_ns
= alloc_mnt_ns();
2307 down_write(&namespace_sem
);
2308 /* First pass: copy the tree topology */
2309 new_ns
->root
= copy_tree(mnt_ns
->root
, mnt_ns
->root
->mnt_root
,
2310 CL_COPY_ALL
| CL_EXPIRE
);
2311 if (!new_ns
->root
) {
2312 up_write(&namespace_sem
);
2314 return ERR_PTR(-ENOMEM
);
2316 br_write_lock(vfsmount_lock
);
2317 list_add_tail(&new_ns
->list
, &new_ns
->root
->mnt_list
);
2318 br_write_unlock(vfsmount_lock
);
2321 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
2322 * as belonging to new namespace. We have already acquired a private
2323 * fs_struct, so tsk->fs->lock is not needed.
2329 __mnt_make_longterm(q
);
2331 if (p
== fs
->root
.mnt
) {
2332 fs
->root
.mnt
= mntget(q
);
2333 __mnt_make_longterm(q
);
2334 mnt_make_shortterm(p
);
2337 if (p
== fs
->pwd
.mnt
) {
2338 fs
->pwd
.mnt
= mntget(q
);
2339 __mnt_make_longterm(q
);
2340 mnt_make_shortterm(p
);
2344 p
= next_mnt(p
, mnt_ns
->root
);
2345 q
= next_mnt(q
, new_ns
->root
);
2347 up_write(&namespace_sem
);
2357 struct mnt_namespace
*copy_mnt_ns(unsigned long flags
, struct mnt_namespace
*ns
,
2358 struct fs_struct
*new_fs
)
2360 struct mnt_namespace
*new_ns
;
2365 if (!(flags
& CLONE_NEWNS
))
2368 new_ns
= dup_mnt_ns(ns
, new_fs
);
2375 * create_mnt_ns - creates a private namespace and adds a root filesystem
2376 * @mnt: pointer to the new root filesystem mountpoint
2378 struct mnt_namespace
*create_mnt_ns(struct vfsmount
*mnt
)
2380 struct mnt_namespace
*new_ns
;
2382 new_ns
= alloc_mnt_ns();
2383 if (!IS_ERR(new_ns
)) {
2384 mnt
->mnt_ns
= new_ns
;
2385 __mnt_make_longterm(mnt
);
2387 list_add(&new_ns
->list
, &new_ns
->root
->mnt_list
);
2391 EXPORT_SYMBOL(create_mnt_ns
);
2393 SYSCALL_DEFINE5(mount
, char __user
*, dev_name
, char __user
*, dir_name
,
2394 char __user
*, type
, unsigned long, flags
, void __user
*, data
)
2400 unsigned long data_page
;
2402 ret
= copy_mount_string(type
, &kernel_type
);
2406 kernel_dir
= getname(dir_name
);
2407 if (IS_ERR(kernel_dir
)) {
2408 ret
= PTR_ERR(kernel_dir
);
2412 ret
= copy_mount_string(dev_name
, &kernel_dev
);
2416 ret
= copy_mount_options(data
, &data_page
);
2420 ret
= do_mount(kernel_dev
, kernel_dir
, kernel_type
, flags
,
2421 (void *) data_page
);
2423 free_page(data_page
);
2427 putname(kernel_dir
);
2435 * pivot_root Semantics:
2436 * Moves the root file system of the current process to the directory put_old,
2437 * makes new_root as the new root file system of the current process, and sets
2438 * root/cwd of all processes which had them on the current root to new_root.
2441 * The new_root and put_old must be directories, and must not be on the
2442 * same file system as the current process root. The put_old must be
2443 * underneath new_root, i.e. adding a non-zero number of /.. to the string
2444 * pointed to by put_old must yield the same directory as new_root. No other
2445 * file system may be mounted on put_old. After all, new_root is a mountpoint.
2447 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
2448 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
2449 * in this situation.
2452 * - we don't move root/cwd if they are not at the root (reason: if something
2453 * cared enough to change them, it's probably wrong to force them elsewhere)
2454 * - it's okay to pick a root that isn't the root of a file system, e.g.
2455 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
2456 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
2459 SYSCALL_DEFINE2(pivot_root
, const char __user
*, new_root
,
2460 const char __user
*, put_old
)
2462 struct vfsmount
*tmp
;
2463 struct path
new, old
, parent_path
, root_parent
, root
;
2466 if (!capable(CAP_SYS_ADMIN
))
2469 error
= user_path_dir(new_root
, &new);
2473 error
= user_path_dir(put_old
, &old
);
2477 error
= security_sb_pivotroot(&old
, &new);
2483 get_fs_root(current
->fs
, &root
);
2484 down_write(&namespace_sem
);
2485 mutex_lock(&old
.dentry
->d_inode
->i_mutex
);
2487 if (IS_MNT_SHARED(old
.mnt
) ||
2488 IS_MNT_SHARED(new.mnt
->mnt_parent
) ||
2489 IS_MNT_SHARED(root
.mnt
->mnt_parent
))
2491 if (!check_mnt(root
.mnt
) || !check_mnt(new.mnt
))
2494 if (cant_mount(old
.dentry
))
2496 if (d_unlinked(new.dentry
))
2498 if (d_unlinked(old
.dentry
))
2501 if (new.mnt
== root
.mnt
||
2502 old
.mnt
== root
.mnt
)
2503 goto out2
; /* loop, on the same file system */
2505 if (root
.mnt
->mnt_root
!= root
.dentry
)
2506 goto out2
; /* not a mountpoint */
2507 if (root
.mnt
->mnt_parent
== root
.mnt
)
2508 goto out2
; /* not attached */
2509 if (new.mnt
->mnt_root
!= new.dentry
)
2510 goto out2
; /* not a mountpoint */
2511 if (new.mnt
->mnt_parent
== new.mnt
)
2512 goto out2
; /* not attached */
2513 /* make sure we can reach put_old from new_root */
2515 if (tmp
!= new.mnt
) {
2517 if (tmp
->mnt_parent
== tmp
)
2518 goto out2
; /* already mounted on put_old */
2519 if (tmp
->mnt_parent
== new.mnt
)
2521 tmp
= tmp
->mnt_parent
;
2523 if (!is_subdir(tmp
->mnt_mountpoint
, new.dentry
))
2525 } else if (!is_subdir(old
.dentry
, new.dentry
))
2527 br_write_lock(vfsmount_lock
);
2528 detach_mnt(new.mnt
, &parent_path
);
2529 detach_mnt(root
.mnt
, &root_parent
);
2530 /* mount old root on put_old */
2531 attach_mnt(root
.mnt
, &old
);
2532 /* mount new_root on / */
2533 attach_mnt(new.mnt
, &root_parent
);
2534 touch_mnt_namespace(current
->nsproxy
->mnt_ns
);
2535 br_write_unlock(vfsmount_lock
);
2536 chroot_fs_refs(&root
, &new);
2539 path_put(&root_parent
);
2540 path_put(&parent_path
);
2542 mutex_unlock(&old
.dentry
->d_inode
->i_mutex
);
2543 up_write(&namespace_sem
);
2552 static void __init
init_mount_tree(void)
2554 struct vfsmount
*mnt
;
2555 struct mnt_namespace
*ns
;
2558 mnt
= do_kern_mount("rootfs", 0, "rootfs", NULL
);
2560 panic("Can't create rootfs");
2562 ns
= create_mnt_ns(mnt
);
2564 panic("Can't allocate initial namespace");
2566 init_task
.nsproxy
->mnt_ns
= ns
;
2569 root
.mnt
= ns
->root
;
2570 root
.dentry
= ns
->root
->mnt_root
;
2572 set_fs_pwd(current
->fs
, &root
);
2573 set_fs_root(current
->fs
, &root
);
2576 void __init
mnt_init(void)
2581 init_rwsem(&namespace_sem
);
2583 mnt_cache
= kmem_cache_create("mnt_cache", sizeof(struct vfsmount
),
2584 0, SLAB_HWCACHE_ALIGN
| SLAB_PANIC
, NULL
);
2586 mount_hashtable
= (struct list_head
*)__get_free_page(GFP_ATOMIC
);
2588 if (!mount_hashtable
)
2589 panic("Failed to allocate mount hash table\n");
2591 printk("Mount-cache hash table entries: %lu\n", HASH_SIZE
);
2593 for (u
= 0; u
< HASH_SIZE
; u
++)
2594 INIT_LIST_HEAD(&mount_hashtable
[u
]);
2596 br_lock_init(vfsmount_lock
);
2600 printk(KERN_WARNING
"%s: sysfs_init error: %d\n",
2602 fs_kobj
= kobject_create_and_add("fs", NULL
);
2604 printk(KERN_WARNING
"%s: kobj create error\n", __func__
);
2609 void put_mnt_ns(struct mnt_namespace
*ns
)
2611 LIST_HEAD(umount_list
);
2613 if (!atomic_dec_and_test(&ns
->count
))
2615 down_write(&namespace_sem
);
2616 br_write_lock(vfsmount_lock
);
2617 umount_tree(ns
->root
, 0, &umount_list
);
2618 br_write_unlock(vfsmount_lock
);
2619 up_write(&namespace_sem
);
2620 release_mounts(&umount_list
);
2623 EXPORT_SYMBOL(put_mnt_ns
);