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/smp_lock.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/quotaops.h>
18 #include <linux/acct.h>
19 #include <linux/capability.h>
20 #include <linux/module.h>
21 #include <linux/sysfs.h>
22 #include <linux/seq_file.h>
23 #include <linux/namespace.h>
24 #include <linux/namei.h>
25 #include <linux/security.h>
26 #include <linux/mount.h>
27 #include <linux/ramfs.h>
28 #include <asm/uaccess.h>
29 #include <asm/unistd.h>
32 /* spinlock for vfsmount related operations, inplace of dcache_lock */
33 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(vfsmount_lock
);
37 static struct list_head
*mount_hashtable __read_mostly
;
38 static int hash_mask __read_mostly
, hash_bits __read_mostly
;
39 static kmem_cache_t
*mnt_cache __read_mostly
;
40 static struct rw_semaphore namespace_sem
;
43 decl_subsys(fs
, NULL
, NULL
);
44 EXPORT_SYMBOL_GPL(fs_subsys
);
46 static inline unsigned long hash(struct vfsmount
*mnt
, struct dentry
*dentry
)
48 unsigned long tmp
= ((unsigned long)mnt
/ L1_CACHE_BYTES
);
49 tmp
+= ((unsigned long)dentry
/ L1_CACHE_BYTES
);
50 tmp
= tmp
+ (tmp
>> hash_bits
);
51 return tmp
& hash_mask
;
54 struct vfsmount
*alloc_vfsmnt(const char *name
)
56 struct vfsmount
*mnt
= kmem_cache_alloc(mnt_cache
, GFP_KERNEL
);
58 memset(mnt
, 0, sizeof(struct vfsmount
));
59 atomic_set(&mnt
->mnt_count
, 1);
60 INIT_LIST_HEAD(&mnt
->mnt_hash
);
61 INIT_LIST_HEAD(&mnt
->mnt_child
);
62 INIT_LIST_HEAD(&mnt
->mnt_mounts
);
63 INIT_LIST_HEAD(&mnt
->mnt_list
);
64 INIT_LIST_HEAD(&mnt
->mnt_expire
);
65 INIT_LIST_HEAD(&mnt
->mnt_share
);
66 INIT_LIST_HEAD(&mnt
->mnt_slave_list
);
67 INIT_LIST_HEAD(&mnt
->mnt_slave
);
69 int size
= strlen(name
) + 1;
70 char *newname
= kmalloc(size
, GFP_KERNEL
);
72 memcpy(newname
, name
, size
);
73 mnt
->mnt_devname
= newname
;
80 int simple_set_mnt(struct vfsmount
*mnt
, struct super_block
*sb
)
83 mnt
->mnt_root
= dget(sb
->s_root
);
87 EXPORT_SYMBOL(simple_set_mnt
);
89 void free_vfsmnt(struct vfsmount
*mnt
)
91 kfree(mnt
->mnt_devname
);
92 kmem_cache_free(mnt_cache
, mnt
);
96 * find the first or last mount at @dentry on vfsmount @mnt depending on
97 * @dir. If @dir is set return the first mount else return the last mount.
99 struct vfsmount
*__lookup_mnt(struct vfsmount
*mnt
, struct dentry
*dentry
,
102 struct list_head
*head
= mount_hashtable
+ hash(mnt
, dentry
);
103 struct list_head
*tmp
= head
;
104 struct vfsmount
*p
, *found
= NULL
;
107 tmp
= dir
? tmp
->next
: tmp
->prev
;
111 p
= list_entry(tmp
, struct vfsmount
, mnt_hash
);
112 if (p
->mnt_parent
== mnt
&& p
->mnt_mountpoint
== dentry
) {
121 * lookup_mnt increments the ref count before returning
122 * the vfsmount struct.
124 struct vfsmount
*lookup_mnt(struct vfsmount
*mnt
, struct dentry
*dentry
)
126 struct vfsmount
*child_mnt
;
127 spin_lock(&vfsmount_lock
);
128 if ((child_mnt
= __lookup_mnt(mnt
, dentry
, 1)))
130 spin_unlock(&vfsmount_lock
);
134 static inline int check_mnt(struct vfsmount
*mnt
)
136 return mnt
->mnt_namespace
== current
->nsproxy
->namespace;
139 static void touch_namespace(struct namespace *ns
)
143 wake_up_interruptible(&ns
->poll
);
147 static void __touch_namespace(struct namespace *ns
)
149 if (ns
&& ns
->event
!= event
) {
151 wake_up_interruptible(&ns
->poll
);
155 static void detach_mnt(struct vfsmount
*mnt
, struct nameidata
*old_nd
)
157 old_nd
->dentry
= mnt
->mnt_mountpoint
;
158 old_nd
->mnt
= mnt
->mnt_parent
;
159 mnt
->mnt_parent
= mnt
;
160 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
161 list_del_init(&mnt
->mnt_child
);
162 list_del_init(&mnt
->mnt_hash
);
163 old_nd
->dentry
->d_mounted
--;
166 void mnt_set_mountpoint(struct vfsmount
*mnt
, struct dentry
*dentry
,
167 struct vfsmount
*child_mnt
)
169 child_mnt
->mnt_parent
= mntget(mnt
);
170 child_mnt
->mnt_mountpoint
= dget(dentry
);
174 static void attach_mnt(struct vfsmount
*mnt
, struct nameidata
*nd
)
176 mnt_set_mountpoint(nd
->mnt
, nd
->dentry
, mnt
);
177 list_add_tail(&mnt
->mnt_hash
, mount_hashtable
+
178 hash(nd
->mnt
, nd
->dentry
));
179 list_add_tail(&mnt
->mnt_child
, &nd
->mnt
->mnt_mounts
);
183 * the caller must hold vfsmount_lock
185 static void commit_tree(struct vfsmount
*mnt
)
187 struct vfsmount
*parent
= mnt
->mnt_parent
;
190 struct namespace *n
= parent
->mnt_namespace
;
192 BUG_ON(parent
== mnt
);
194 list_add_tail(&head
, &mnt
->mnt_list
);
195 list_for_each_entry(m
, &head
, mnt_list
)
196 m
->mnt_namespace
= n
;
197 list_splice(&head
, n
->list
.prev
);
199 list_add_tail(&mnt
->mnt_hash
, mount_hashtable
+
200 hash(parent
, mnt
->mnt_mountpoint
));
201 list_add_tail(&mnt
->mnt_child
, &parent
->mnt_mounts
);
205 static struct vfsmount
*next_mnt(struct vfsmount
*p
, struct vfsmount
*root
)
207 struct list_head
*next
= p
->mnt_mounts
.next
;
208 if (next
== &p
->mnt_mounts
) {
212 next
= p
->mnt_child
.next
;
213 if (next
!= &p
->mnt_parent
->mnt_mounts
)
218 return list_entry(next
, struct vfsmount
, mnt_child
);
221 static struct vfsmount
*skip_mnt_tree(struct vfsmount
*p
)
223 struct list_head
*prev
= p
->mnt_mounts
.prev
;
224 while (prev
!= &p
->mnt_mounts
) {
225 p
= list_entry(prev
, struct vfsmount
, mnt_child
);
226 prev
= p
->mnt_mounts
.prev
;
231 static struct vfsmount
*clone_mnt(struct vfsmount
*old
, struct dentry
*root
,
234 struct super_block
*sb
= old
->mnt_sb
;
235 struct vfsmount
*mnt
= alloc_vfsmnt(old
->mnt_devname
);
238 mnt
->mnt_flags
= old
->mnt_flags
;
239 atomic_inc(&sb
->s_active
);
241 mnt
->mnt_root
= dget(root
);
242 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
243 mnt
->mnt_parent
= mnt
;
245 if (flag
& CL_SLAVE
) {
246 list_add(&mnt
->mnt_slave
, &old
->mnt_slave_list
);
247 mnt
->mnt_master
= old
;
248 CLEAR_MNT_SHARED(mnt
);
250 if ((flag
& CL_PROPAGATION
) || IS_MNT_SHARED(old
))
251 list_add(&mnt
->mnt_share
, &old
->mnt_share
);
252 if (IS_MNT_SLAVE(old
))
253 list_add(&mnt
->mnt_slave
, &old
->mnt_slave
);
254 mnt
->mnt_master
= old
->mnt_master
;
256 if (flag
& CL_MAKE_SHARED
)
259 /* stick the duplicate mount on the same expiry list
260 * as the original if that was on one */
261 if (flag
& CL_EXPIRE
) {
262 spin_lock(&vfsmount_lock
);
263 if (!list_empty(&old
->mnt_expire
))
264 list_add(&mnt
->mnt_expire
, &old
->mnt_expire
);
265 spin_unlock(&vfsmount_lock
);
271 static inline void __mntput(struct vfsmount
*mnt
)
273 struct super_block
*sb
= mnt
->mnt_sb
;
276 deactivate_super(sb
);
279 void mntput_no_expire(struct vfsmount
*mnt
)
282 if (atomic_dec_and_lock(&mnt
->mnt_count
, &vfsmount_lock
)) {
283 if (likely(!mnt
->mnt_pinned
)) {
284 spin_unlock(&vfsmount_lock
);
288 atomic_add(mnt
->mnt_pinned
+ 1, &mnt
->mnt_count
);
290 spin_unlock(&vfsmount_lock
);
291 acct_auto_close_mnt(mnt
);
292 security_sb_umount_close(mnt
);
297 EXPORT_SYMBOL(mntput_no_expire
);
299 void mnt_pin(struct vfsmount
*mnt
)
301 spin_lock(&vfsmount_lock
);
303 spin_unlock(&vfsmount_lock
);
306 EXPORT_SYMBOL(mnt_pin
);
308 void mnt_unpin(struct vfsmount
*mnt
)
310 spin_lock(&vfsmount_lock
);
311 if (mnt
->mnt_pinned
) {
312 atomic_inc(&mnt
->mnt_count
);
315 spin_unlock(&vfsmount_lock
);
318 EXPORT_SYMBOL(mnt_unpin
);
321 static void *m_start(struct seq_file
*m
, loff_t
*pos
)
323 struct namespace *n
= m
->private;
327 down_read(&namespace_sem
);
328 list_for_each(p
, &n
->list
)
330 return list_entry(p
, struct vfsmount
, mnt_list
);
334 static void *m_next(struct seq_file
*m
, void *v
, loff_t
*pos
)
336 struct namespace *n
= m
->private;
337 struct list_head
*p
= ((struct vfsmount
*)v
)->mnt_list
.next
;
339 return p
== &n
->list
? NULL
: list_entry(p
, struct vfsmount
, mnt_list
);
342 static void m_stop(struct seq_file
*m
, void *v
)
344 up_read(&namespace_sem
);
347 static inline void mangle(struct seq_file
*m
, const char *s
)
349 seq_escape(m
, s
, " \t\n\\");
352 static int show_vfsmnt(struct seq_file
*m
, void *v
)
354 struct vfsmount
*mnt
= v
;
356 static struct proc_fs_info
{
360 { MS_SYNCHRONOUS
, ",sync" },
361 { MS_DIRSYNC
, ",dirsync" },
362 { MS_MANDLOCK
, ",mand" },
365 static struct proc_fs_info mnt_info
[] = {
366 { MNT_NOSUID
, ",nosuid" },
367 { MNT_NODEV
, ",nodev" },
368 { MNT_NOEXEC
, ",noexec" },
369 { MNT_NOATIME
, ",noatime" },
370 { MNT_NODIRATIME
, ",nodiratime" },
373 struct proc_fs_info
*fs_infop
;
375 mangle(m
, mnt
->mnt_devname
? mnt
->mnt_devname
: "none");
377 seq_path(m
, mnt
, mnt
->mnt_root
, " \t\n\\");
379 mangle(m
, mnt
->mnt_sb
->s_type
->name
);
380 seq_puts(m
, mnt
->mnt_sb
->s_flags
& MS_RDONLY
? " ro" : " rw");
381 for (fs_infop
= fs_info
; fs_infop
->flag
; fs_infop
++) {
382 if (mnt
->mnt_sb
->s_flags
& fs_infop
->flag
)
383 seq_puts(m
, fs_infop
->str
);
385 for (fs_infop
= mnt_info
; fs_infop
->flag
; fs_infop
++) {
386 if (mnt
->mnt_flags
& fs_infop
->flag
)
387 seq_puts(m
, fs_infop
->str
);
389 if (mnt
->mnt_sb
->s_op
->show_options
)
390 err
= mnt
->mnt_sb
->s_op
->show_options(m
, mnt
);
391 seq_puts(m
, " 0 0\n");
395 struct seq_operations mounts_op
= {
402 static int show_vfsstat(struct seq_file
*m
, void *v
)
404 struct vfsmount
*mnt
= v
;
408 if (mnt
->mnt_devname
) {
409 seq_puts(m
, "device ");
410 mangle(m
, mnt
->mnt_devname
);
412 seq_puts(m
, "no device");
415 seq_puts(m
, " mounted on ");
416 seq_path(m
, mnt
, mnt
->mnt_root
, " \t\n\\");
419 /* file system type */
420 seq_puts(m
, "with fstype ");
421 mangle(m
, mnt
->mnt_sb
->s_type
->name
);
423 /* optional statistics */
424 if (mnt
->mnt_sb
->s_op
->show_stats
) {
426 err
= mnt
->mnt_sb
->s_op
->show_stats(m
, mnt
);
433 struct seq_operations mountstats_op
= {
437 .show
= show_vfsstat
,
441 * may_umount_tree - check if a mount tree is busy
442 * @mnt: root of mount tree
444 * This is called to check if a tree of mounts has any
445 * open files, pwds, chroots or sub mounts that are
448 int may_umount_tree(struct vfsmount
*mnt
)
451 int minimum_refs
= 0;
454 spin_lock(&vfsmount_lock
);
455 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
456 actual_refs
+= atomic_read(&p
->mnt_count
);
459 spin_unlock(&vfsmount_lock
);
461 if (actual_refs
> minimum_refs
)
467 EXPORT_SYMBOL(may_umount_tree
);
470 * may_umount - check if a mount point is busy
471 * @mnt: root of mount
473 * This is called to check if a mount point has any
474 * open files, pwds, chroots or sub mounts. If the
475 * mount has sub mounts this will return busy
476 * regardless of whether the sub mounts are busy.
478 * Doesn't take quota and stuff into account. IOW, in some cases it will
479 * give false negatives. The main reason why it's here is that we need
480 * a non-destructive way to look for easily umountable filesystems.
482 int may_umount(struct vfsmount
*mnt
)
485 spin_lock(&vfsmount_lock
);
486 if (propagate_mount_busy(mnt
, 2))
488 spin_unlock(&vfsmount_lock
);
492 EXPORT_SYMBOL(may_umount
);
494 void release_mounts(struct list_head
*head
)
496 struct vfsmount
*mnt
;
497 while (!list_empty(head
)) {
498 mnt
= list_entry(head
->next
, struct vfsmount
, mnt_hash
);
499 list_del_init(&mnt
->mnt_hash
);
500 if (mnt
->mnt_parent
!= mnt
) {
501 struct dentry
*dentry
;
503 spin_lock(&vfsmount_lock
);
504 dentry
= mnt
->mnt_mountpoint
;
506 mnt
->mnt_mountpoint
= mnt
->mnt_root
;
507 mnt
->mnt_parent
= mnt
;
508 spin_unlock(&vfsmount_lock
);
516 void umount_tree(struct vfsmount
*mnt
, int propagate
, struct list_head
*kill
)
520 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
))
521 list_move(&p
->mnt_hash
, kill
);
524 propagate_umount(kill
);
526 list_for_each_entry(p
, kill
, mnt_hash
) {
527 list_del_init(&p
->mnt_expire
);
528 list_del_init(&p
->mnt_list
);
529 __touch_namespace(p
->mnt_namespace
);
530 p
->mnt_namespace
= NULL
;
531 list_del_init(&p
->mnt_child
);
532 if (p
->mnt_parent
!= p
)
533 p
->mnt_mountpoint
->d_mounted
--;
534 change_mnt_propagation(p
, MS_PRIVATE
);
538 static int do_umount(struct vfsmount
*mnt
, int flags
)
540 struct super_block
*sb
= mnt
->mnt_sb
;
542 LIST_HEAD(umount_list
);
544 retval
= security_sb_umount(mnt
, flags
);
549 * Allow userspace to request a mountpoint be expired rather than
550 * unmounting unconditionally. Unmount only happens if:
551 * (1) the mark is already set (the mark is cleared by mntput())
552 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
554 if (flags
& MNT_EXPIRE
) {
555 if (mnt
== current
->fs
->rootmnt
||
556 flags
& (MNT_FORCE
| MNT_DETACH
))
559 if (atomic_read(&mnt
->mnt_count
) != 2)
562 if (!xchg(&mnt
->mnt_expiry_mark
, 1))
567 * If we may have to abort operations to get out of this
568 * mount, and they will themselves hold resources we must
569 * allow the fs to do things. In the Unix tradition of
570 * 'Gee thats tricky lets do it in userspace' the umount_begin
571 * might fail to complete on the first run through as other tasks
572 * must return, and the like. Thats for the mount program to worry
573 * about for the moment.
577 if (sb
->s_op
->umount_begin
)
578 sb
->s_op
->umount_begin(mnt
, flags
);
582 * No sense to grab the lock for this test, but test itself looks
583 * somewhat bogus. Suggestions for better replacement?
584 * Ho-hum... In principle, we might treat that as umount + switch
585 * to rootfs. GC would eventually take care of the old vfsmount.
586 * Actually it makes sense, especially if rootfs would contain a
587 * /reboot - static binary that would close all descriptors and
588 * call reboot(9). Then init(8) could umount root and exec /reboot.
590 if (mnt
== current
->fs
->rootmnt
&& !(flags
& MNT_DETACH
)) {
592 * Special case for "unmounting" root ...
593 * we just try to remount it readonly.
595 down_write(&sb
->s_umount
);
596 if (!(sb
->s_flags
& MS_RDONLY
)) {
599 retval
= do_remount_sb(sb
, MS_RDONLY
, NULL
, 0);
602 up_write(&sb
->s_umount
);
606 down_write(&namespace_sem
);
607 spin_lock(&vfsmount_lock
);
611 if (flags
& MNT_DETACH
|| !propagate_mount_busy(mnt
, 2)) {
612 if (!list_empty(&mnt
->mnt_list
))
613 umount_tree(mnt
, 1, &umount_list
);
616 spin_unlock(&vfsmount_lock
);
618 security_sb_umount_busy(mnt
);
619 up_write(&namespace_sem
);
620 release_mounts(&umount_list
);
625 * Now umount can handle mount points as well as block devices.
626 * This is important for filesystems which use unnamed block devices.
628 * We now support a flag for forced unmount like the other 'big iron'
629 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
632 asmlinkage
long sys_umount(char __user
* name
, int flags
)
637 retval
= __user_walk(name
, LOOKUP_FOLLOW
, &nd
);
641 if (nd
.dentry
!= nd
.mnt
->mnt_root
)
643 if (!check_mnt(nd
.mnt
))
647 if (!capable(CAP_SYS_ADMIN
))
650 retval
= do_umount(nd
.mnt
, flags
);
652 path_release_on_umount(&nd
);
657 #ifdef __ARCH_WANT_SYS_OLDUMOUNT
660 * The 2.0 compatible umount. No flags.
662 asmlinkage
long sys_oldumount(char __user
* name
)
664 return sys_umount(name
, 0);
669 static int mount_is_safe(struct nameidata
*nd
)
671 if (capable(CAP_SYS_ADMIN
))
675 if (S_ISLNK(nd
->dentry
->d_inode
->i_mode
))
677 if (nd
->dentry
->d_inode
->i_mode
& S_ISVTX
) {
678 if (current
->uid
!= nd
->dentry
->d_inode
->i_uid
)
681 if (vfs_permission(nd
, MAY_WRITE
))
687 static int lives_below_in_same_fs(struct dentry
*d
, struct dentry
*dentry
)
692 if (d
== NULL
|| d
== d
->d_parent
)
698 struct vfsmount
*copy_tree(struct vfsmount
*mnt
, struct dentry
*dentry
,
701 struct vfsmount
*res
, *p
, *q
, *r
, *s
;
704 if (!(flag
& CL_COPY_ALL
) && IS_MNT_UNBINDABLE(mnt
))
707 res
= q
= clone_mnt(mnt
, dentry
, flag
);
710 q
->mnt_mountpoint
= mnt
->mnt_mountpoint
;
713 list_for_each_entry(r
, &mnt
->mnt_mounts
, mnt_child
) {
714 if (!lives_below_in_same_fs(r
->mnt_mountpoint
, dentry
))
717 for (s
= r
; s
; s
= next_mnt(s
, r
)) {
718 if (!(flag
& CL_COPY_ALL
) && IS_MNT_UNBINDABLE(s
)) {
719 s
= skip_mnt_tree(s
);
722 while (p
!= s
->mnt_parent
) {
728 nd
.dentry
= p
->mnt_mountpoint
;
729 q
= clone_mnt(p
, p
->mnt_root
, flag
);
732 spin_lock(&vfsmount_lock
);
733 list_add_tail(&q
->mnt_list
, &res
->mnt_list
);
735 spin_unlock(&vfsmount_lock
);
741 LIST_HEAD(umount_list
);
742 spin_lock(&vfsmount_lock
);
743 umount_tree(res
, 0, &umount_list
);
744 spin_unlock(&vfsmount_lock
);
745 release_mounts(&umount_list
);
751 * @source_mnt : mount tree to be attached
752 * @nd : place the mount tree @source_mnt is attached
753 * @parent_nd : if non-null, detach the source_mnt from its parent and
754 * store the parent mount and mountpoint dentry.
755 * (done when source_mnt is moved)
757 * NOTE: in the table below explains the semantics when a source mount
758 * of a given type is attached to a destination mount of a given type.
759 * ---------------------------------------------------------------------------
760 * | BIND MOUNT OPERATION |
761 * |**************************************************************************
762 * | source-->| shared | private | slave | unbindable |
766 * |**************************************************************************
767 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
769 * |non-shared| shared (+) | private | slave (*) | invalid |
770 * ***************************************************************************
771 * A bind operation clones the source mount and mounts the clone on the
774 * (++) the cloned mount is propagated to all the mounts in the propagation
775 * tree of the destination mount and the cloned mount is added to
776 * the peer group of the source mount.
777 * (+) the cloned mount is created under the destination mount and is marked
778 * as shared. The cloned mount is added to the peer group of the source
780 * (+++) the mount is propagated to all the mounts in the propagation tree
781 * of the destination mount and the cloned mount is made slave
782 * of the same master as that of the source mount. The cloned mount
783 * is marked as 'shared and slave'.
784 * (*) the cloned mount is made a slave of the same master as that of the
787 * ---------------------------------------------------------------------------
788 * | MOVE MOUNT OPERATION |
789 * |**************************************************************************
790 * | source-->| shared | private | slave | unbindable |
794 * |**************************************************************************
795 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
797 * |non-shared| shared (+*) | private | slave (*) | unbindable |
798 * ***************************************************************************
800 * (+) the mount is moved to the destination. And is then propagated to
801 * all the mounts in the propagation tree of the destination mount.
802 * (+*) the mount is moved to the destination.
803 * (+++) the mount is moved to the destination and is then propagated to
804 * all the mounts belonging to the destination mount's propagation tree.
805 * the mount is marked as 'shared and slave'.
806 * (*) the mount continues to be a slave at the new location.
808 * if the source mount is a tree, the operations explained above is
809 * applied to each mount in the tree.
810 * Must be called without spinlocks held, since this function can sleep
813 static int attach_recursive_mnt(struct vfsmount
*source_mnt
,
814 struct nameidata
*nd
, struct nameidata
*parent_nd
)
816 LIST_HEAD(tree_list
);
817 struct vfsmount
*dest_mnt
= nd
->mnt
;
818 struct dentry
*dest_dentry
= nd
->dentry
;
819 struct vfsmount
*child
, *p
;
821 if (propagate_mnt(dest_mnt
, dest_dentry
, source_mnt
, &tree_list
))
824 if (IS_MNT_SHARED(dest_mnt
)) {
825 for (p
= source_mnt
; p
; p
= next_mnt(p
, source_mnt
))
829 spin_lock(&vfsmount_lock
);
831 detach_mnt(source_mnt
, parent_nd
);
832 attach_mnt(source_mnt
, nd
);
833 touch_namespace(current
->nsproxy
->namespace);
835 mnt_set_mountpoint(dest_mnt
, dest_dentry
, source_mnt
);
836 commit_tree(source_mnt
);
839 list_for_each_entry_safe(child
, p
, &tree_list
, mnt_hash
) {
840 list_del_init(&child
->mnt_hash
);
843 spin_unlock(&vfsmount_lock
);
847 static int graft_tree(struct vfsmount
*mnt
, struct nameidata
*nd
)
850 if (mnt
->mnt_sb
->s_flags
& MS_NOUSER
)
853 if (S_ISDIR(nd
->dentry
->d_inode
->i_mode
) !=
854 S_ISDIR(mnt
->mnt_root
->d_inode
->i_mode
))
858 mutex_lock(&nd
->dentry
->d_inode
->i_mutex
);
859 if (IS_DEADDIR(nd
->dentry
->d_inode
))
862 err
= security_sb_check_sb(mnt
, nd
);
867 if (IS_ROOT(nd
->dentry
) || !d_unhashed(nd
->dentry
))
868 err
= attach_recursive_mnt(mnt
, nd
, NULL
);
870 mutex_unlock(&nd
->dentry
->d_inode
->i_mutex
);
872 security_sb_post_addmount(mnt
, nd
);
877 * recursively change the type of the mountpoint.
879 static int do_change_type(struct nameidata
*nd
, int flag
)
881 struct vfsmount
*m
, *mnt
= nd
->mnt
;
882 int recurse
= flag
& MS_REC
;
883 int type
= flag
& ~MS_REC
;
885 if (nd
->dentry
!= nd
->mnt
->mnt_root
)
888 down_write(&namespace_sem
);
889 spin_lock(&vfsmount_lock
);
890 for (m
= mnt
; m
; m
= (recurse
? next_mnt(m
, mnt
) : NULL
))
891 change_mnt_propagation(m
, type
);
892 spin_unlock(&vfsmount_lock
);
893 up_write(&namespace_sem
);
900 static int do_loopback(struct nameidata
*nd
, char *old_name
, int recurse
)
902 struct nameidata old_nd
;
903 struct vfsmount
*mnt
= NULL
;
904 int err
= mount_is_safe(nd
);
907 if (!old_name
|| !*old_name
)
909 err
= path_lookup(old_name
, LOOKUP_FOLLOW
, &old_nd
);
913 down_write(&namespace_sem
);
915 if (IS_MNT_UNBINDABLE(old_nd
.mnt
))
918 if (!check_mnt(nd
->mnt
) || !check_mnt(old_nd
.mnt
))
923 mnt
= copy_tree(old_nd
.mnt
, old_nd
.dentry
, 0);
925 mnt
= clone_mnt(old_nd
.mnt
, old_nd
.dentry
, 0);
930 err
= graft_tree(mnt
, nd
);
932 LIST_HEAD(umount_list
);
933 spin_lock(&vfsmount_lock
);
934 umount_tree(mnt
, 0, &umount_list
);
935 spin_unlock(&vfsmount_lock
);
936 release_mounts(&umount_list
);
940 up_write(&namespace_sem
);
941 path_release(&old_nd
);
946 * change filesystem flags. dir should be a physical root of filesystem.
947 * If you've mounted a non-root directory somewhere and want to do remount
948 * on it - tough luck.
950 static int do_remount(struct nameidata
*nd
, int flags
, int mnt_flags
,
954 struct super_block
*sb
= nd
->mnt
->mnt_sb
;
956 if (!capable(CAP_SYS_ADMIN
))
959 if (!check_mnt(nd
->mnt
))
962 if (nd
->dentry
!= nd
->mnt
->mnt_root
)
965 down_write(&sb
->s_umount
);
966 err
= do_remount_sb(sb
, flags
, data
, 0);
968 nd
->mnt
->mnt_flags
= mnt_flags
;
969 up_write(&sb
->s_umount
);
971 security_sb_post_remount(nd
->mnt
, flags
, data
);
975 static inline int tree_contains_unbindable(struct vfsmount
*mnt
)
978 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
979 if (IS_MNT_UNBINDABLE(p
))
985 static int do_move_mount(struct nameidata
*nd
, char *old_name
)
987 struct nameidata old_nd
, parent_nd
;
990 if (!capable(CAP_SYS_ADMIN
))
992 if (!old_name
|| !*old_name
)
994 err
= path_lookup(old_name
, LOOKUP_FOLLOW
, &old_nd
);
998 down_write(&namespace_sem
);
999 while (d_mountpoint(nd
->dentry
) && follow_down(&nd
->mnt
, &nd
->dentry
))
1002 if (!check_mnt(nd
->mnt
) || !check_mnt(old_nd
.mnt
))
1006 mutex_lock(&nd
->dentry
->d_inode
->i_mutex
);
1007 if (IS_DEADDIR(nd
->dentry
->d_inode
))
1010 if (!IS_ROOT(nd
->dentry
) && d_unhashed(nd
->dentry
))
1014 if (old_nd
.dentry
!= old_nd
.mnt
->mnt_root
)
1017 if (old_nd
.mnt
== old_nd
.mnt
->mnt_parent
)
1020 if (S_ISDIR(nd
->dentry
->d_inode
->i_mode
) !=
1021 S_ISDIR(old_nd
.dentry
->d_inode
->i_mode
))
1024 * Don't move a mount residing in a shared parent.
1026 if (old_nd
.mnt
->mnt_parent
&& IS_MNT_SHARED(old_nd
.mnt
->mnt_parent
))
1029 * Don't move a mount tree containing unbindable mounts to a destination
1030 * mount which is shared.
1032 if (IS_MNT_SHARED(nd
->mnt
) && tree_contains_unbindable(old_nd
.mnt
))
1035 for (p
= nd
->mnt
; p
->mnt_parent
!= p
; p
= p
->mnt_parent
)
1036 if (p
== old_nd
.mnt
)
1039 if ((err
= attach_recursive_mnt(old_nd
.mnt
, nd
, &parent_nd
)))
1042 spin_lock(&vfsmount_lock
);
1043 /* if the mount is moved, it should no longer be expire
1045 list_del_init(&old_nd
.mnt
->mnt_expire
);
1046 spin_unlock(&vfsmount_lock
);
1048 mutex_unlock(&nd
->dentry
->d_inode
->i_mutex
);
1050 up_write(&namespace_sem
);
1052 path_release(&parent_nd
);
1053 path_release(&old_nd
);
1058 * create a new mount for userspace and request it to be added into the
1061 static int do_new_mount(struct nameidata
*nd
, char *type
, int flags
,
1062 int mnt_flags
, char *name
, void *data
)
1064 struct vfsmount
*mnt
;
1066 if (!type
|| !memchr(type
, 0, PAGE_SIZE
))
1069 /* we need capabilities... */
1070 if (!capable(CAP_SYS_ADMIN
))
1073 mnt
= do_kern_mount(type
, flags
, name
, data
);
1075 return PTR_ERR(mnt
);
1077 return do_add_mount(mnt
, nd
, mnt_flags
, NULL
);
1081 * add a mount into a namespace's mount tree
1082 * - provide the option of adding the new mount to an expiration list
1084 int do_add_mount(struct vfsmount
*newmnt
, struct nameidata
*nd
,
1085 int mnt_flags
, struct list_head
*fslist
)
1089 down_write(&namespace_sem
);
1090 /* Something was mounted here while we slept */
1091 while (d_mountpoint(nd
->dentry
) && follow_down(&nd
->mnt
, &nd
->dentry
))
1094 if (!check_mnt(nd
->mnt
))
1097 /* Refuse the same filesystem on the same mount point */
1099 if (nd
->mnt
->mnt_sb
== newmnt
->mnt_sb
&&
1100 nd
->mnt
->mnt_root
== nd
->dentry
)
1104 if (S_ISLNK(newmnt
->mnt_root
->d_inode
->i_mode
))
1107 newmnt
->mnt_flags
= mnt_flags
;
1108 if ((err
= graft_tree(newmnt
, nd
)))
1112 /* add to the specified expiration list */
1113 spin_lock(&vfsmount_lock
);
1114 list_add_tail(&newmnt
->mnt_expire
, fslist
);
1115 spin_unlock(&vfsmount_lock
);
1117 up_write(&namespace_sem
);
1121 up_write(&namespace_sem
);
1126 EXPORT_SYMBOL_GPL(do_add_mount
);
1128 static void expire_mount(struct vfsmount
*mnt
, struct list_head
*mounts
,
1129 struct list_head
*umounts
)
1131 spin_lock(&vfsmount_lock
);
1134 * Check if mount is still attached, if not, let whoever holds it deal
1137 if (mnt
->mnt_parent
== mnt
) {
1138 spin_unlock(&vfsmount_lock
);
1143 * Check that it is still dead: the count should now be 2 - as
1144 * contributed by the vfsmount parent and the mntget above
1146 if (!propagate_mount_busy(mnt
, 2)) {
1147 /* delete from the namespace */
1148 touch_namespace(mnt
->mnt_namespace
);
1149 list_del_init(&mnt
->mnt_list
);
1150 mnt
->mnt_namespace
= NULL
;
1151 umount_tree(mnt
, 1, umounts
);
1152 spin_unlock(&vfsmount_lock
);
1155 * Someone brought it back to life whilst we didn't have any
1156 * locks held so return it to the expiration list
1158 list_add_tail(&mnt
->mnt_expire
, mounts
);
1159 spin_unlock(&vfsmount_lock
);
1164 * go through the vfsmounts we've just consigned to the graveyard to
1165 * - check that they're still dead
1166 * - delete the vfsmount from the appropriate namespace under lock
1167 * - dispose of the corpse
1169 static void expire_mount_list(struct list_head
*graveyard
, struct list_head
*mounts
)
1171 struct namespace *namespace;
1172 struct vfsmount
*mnt
;
1174 while (!list_empty(graveyard
)) {
1176 mnt
= list_entry(graveyard
->next
, struct vfsmount
, mnt_expire
);
1177 list_del_init(&mnt
->mnt_expire
);
1179 /* don't do anything if the namespace is dead - all the
1180 * vfsmounts from it are going away anyway */
1181 namespace = mnt
->mnt_namespace
;
1182 if (!namespace || !namespace->root
)
1184 get_namespace(namespace);
1186 spin_unlock(&vfsmount_lock
);
1187 down_write(&namespace_sem
);
1188 expire_mount(mnt
, mounts
, &umounts
);
1189 up_write(&namespace_sem
);
1190 release_mounts(&umounts
);
1192 put_namespace(namespace);
1193 spin_lock(&vfsmount_lock
);
1198 * process a list of expirable mountpoints with the intent of discarding any
1199 * mountpoints that aren't in use and haven't been touched since last we came
1202 void mark_mounts_for_expiry(struct list_head
*mounts
)
1204 struct vfsmount
*mnt
, *next
;
1205 LIST_HEAD(graveyard
);
1207 if (list_empty(mounts
))
1210 spin_lock(&vfsmount_lock
);
1212 /* extract from the expiration list every vfsmount that matches the
1213 * following criteria:
1214 * - only referenced by its parent vfsmount
1215 * - still marked for expiry (marked on the last call here; marks are
1216 * cleared by mntput())
1218 list_for_each_entry_safe(mnt
, next
, mounts
, mnt_expire
) {
1219 if (!xchg(&mnt
->mnt_expiry_mark
, 1) ||
1220 atomic_read(&mnt
->mnt_count
) != 1)
1224 list_move(&mnt
->mnt_expire
, &graveyard
);
1227 expire_mount_list(&graveyard
, mounts
);
1229 spin_unlock(&vfsmount_lock
);
1232 EXPORT_SYMBOL_GPL(mark_mounts_for_expiry
);
1235 * Ripoff of 'select_parent()'
1237 * search the list of submounts for a given mountpoint, and move any
1238 * shrinkable submounts to the 'graveyard' list.
1240 static int select_submounts(struct vfsmount
*parent
, struct list_head
*graveyard
)
1242 struct vfsmount
*this_parent
= parent
;
1243 struct list_head
*next
;
1247 next
= this_parent
->mnt_mounts
.next
;
1249 while (next
!= &this_parent
->mnt_mounts
) {
1250 struct list_head
*tmp
= next
;
1251 struct vfsmount
*mnt
= list_entry(tmp
, struct vfsmount
, mnt_child
);
1254 if (!(mnt
->mnt_flags
& MNT_SHRINKABLE
))
1257 * Descend a level if the d_mounts list is non-empty.
1259 if (!list_empty(&mnt
->mnt_mounts
)) {
1264 if (!propagate_mount_busy(mnt
, 1)) {
1266 list_move_tail(&mnt
->mnt_expire
, graveyard
);
1271 * All done at this level ... ascend and resume the search
1273 if (this_parent
!= parent
) {
1274 next
= this_parent
->mnt_child
.next
;
1275 this_parent
= this_parent
->mnt_parent
;
1282 * process a list of expirable mountpoints with the intent of discarding any
1283 * submounts of a specific parent mountpoint
1285 void shrink_submounts(struct vfsmount
*mountpoint
, struct list_head
*mounts
)
1287 LIST_HEAD(graveyard
);
1290 spin_lock(&vfsmount_lock
);
1292 /* extract submounts of 'mountpoint' from the expiration list */
1293 while ((found
= select_submounts(mountpoint
, &graveyard
)) != 0)
1294 expire_mount_list(&graveyard
, mounts
);
1296 spin_unlock(&vfsmount_lock
);
1299 EXPORT_SYMBOL_GPL(shrink_submounts
);
1302 * Some copy_from_user() implementations do not return the exact number of
1303 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
1304 * Note that this function differs from copy_from_user() in that it will oops
1305 * on bad values of `to', rather than returning a short copy.
1307 static long exact_copy_from_user(void *to
, const void __user
* from
,
1311 const char __user
*f
= from
;
1314 if (!access_ok(VERIFY_READ
, from
, n
))
1318 if (__get_user(c
, f
)) {
1329 int copy_mount_options(const void __user
* data
, unsigned long *where
)
1339 if (!(page
= __get_free_page(GFP_KERNEL
)))
1342 /* We only care that *some* data at the address the user
1343 * gave us is valid. Just in case, we'll zero
1344 * the remainder of the page.
1346 /* copy_from_user cannot cross TASK_SIZE ! */
1347 size
= TASK_SIZE
- (unsigned long)data
;
1348 if (size
> PAGE_SIZE
)
1351 i
= size
- exact_copy_from_user((void *)page
, data
, size
);
1357 memset((char *)page
+ i
, 0, PAGE_SIZE
- i
);
1363 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
1364 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
1366 * data is a (void *) that can point to any structure up to
1367 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
1368 * information (or be NULL).
1370 * Pre-0.97 versions of mount() didn't have a flags word.
1371 * When the flags word was introduced its top half was required
1372 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
1373 * Therefore, if this magic number is present, it carries no information
1374 * and must be discarded.
1376 long do_mount(char *dev_name
, char *dir_name
, char *type_page
,
1377 unsigned long flags
, void *data_page
)
1379 struct nameidata nd
;
1384 if ((flags
& MS_MGC_MSK
) == MS_MGC_VAL
)
1385 flags
&= ~MS_MGC_MSK
;
1387 /* Basic sanity checks */
1389 if (!dir_name
|| !*dir_name
|| !memchr(dir_name
, 0, PAGE_SIZE
))
1391 if (dev_name
&& !memchr(dev_name
, 0, PAGE_SIZE
))
1395 ((char *)data_page
)[PAGE_SIZE
- 1] = 0;
1397 /* Separate the per-mountpoint flags */
1398 if (flags
& MS_NOSUID
)
1399 mnt_flags
|= MNT_NOSUID
;
1400 if (flags
& MS_NODEV
)
1401 mnt_flags
|= MNT_NODEV
;
1402 if (flags
& MS_NOEXEC
)
1403 mnt_flags
|= MNT_NOEXEC
;
1404 if (flags
& MS_NOATIME
)
1405 mnt_flags
|= MNT_NOATIME
;
1406 if (flags
& MS_NODIRATIME
)
1407 mnt_flags
|= MNT_NODIRATIME
;
1409 flags
&= ~(MS_NOSUID
| MS_NOEXEC
| MS_NODEV
| MS_ACTIVE
|
1410 MS_NOATIME
| MS_NODIRATIME
);
1412 /* ... and get the mountpoint */
1413 retval
= path_lookup(dir_name
, LOOKUP_FOLLOW
, &nd
);
1417 retval
= security_sb_mount(dev_name
, &nd
, type_page
, flags
, data_page
);
1421 if (flags
& MS_REMOUNT
)
1422 retval
= do_remount(&nd
, flags
& ~MS_REMOUNT
, mnt_flags
,
1424 else if (flags
& MS_BIND
)
1425 retval
= do_loopback(&nd
, dev_name
, flags
& MS_REC
);
1426 else if (flags
& (MS_SHARED
| MS_PRIVATE
| MS_SLAVE
| MS_UNBINDABLE
))
1427 retval
= do_change_type(&nd
, flags
);
1428 else if (flags
& MS_MOVE
)
1429 retval
= do_move_mount(&nd
, dev_name
);
1431 retval
= do_new_mount(&nd
, type_page
, flags
, mnt_flags
,
1432 dev_name
, data_page
);
1439 * Allocate a new namespace structure and populate it with contents
1440 * copied from the namespace of the passed in task structure.
1442 struct namespace *dup_namespace(struct task_struct
*tsk
, struct fs_struct
*fs
)
1444 struct namespace *namespace = tsk
->nsproxy
->namespace;
1445 struct namespace *new_ns
;
1446 struct vfsmount
*rootmnt
= NULL
, *pwdmnt
= NULL
, *altrootmnt
= NULL
;
1447 struct vfsmount
*p
, *q
;
1449 new_ns
= kmalloc(sizeof(struct namespace), GFP_KERNEL
);
1453 atomic_set(&new_ns
->count
, 1);
1454 INIT_LIST_HEAD(&new_ns
->list
);
1455 init_waitqueue_head(&new_ns
->poll
);
1458 down_write(&namespace_sem
);
1459 /* First pass: copy the tree topology */
1460 new_ns
->root
= copy_tree(namespace->root
, namespace->root
->mnt_root
,
1461 CL_COPY_ALL
| CL_EXPIRE
);
1462 if (!new_ns
->root
) {
1463 up_write(&namespace_sem
);
1467 spin_lock(&vfsmount_lock
);
1468 list_add_tail(&new_ns
->list
, &new_ns
->root
->mnt_list
);
1469 spin_unlock(&vfsmount_lock
);
1472 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
1473 * as belonging to new namespace. We have already acquired a private
1474 * fs_struct, so tsk->fs->lock is not needed.
1476 p
= namespace->root
;
1479 q
->mnt_namespace
= new_ns
;
1481 if (p
== fs
->rootmnt
) {
1483 fs
->rootmnt
= mntget(q
);
1485 if (p
== fs
->pwdmnt
) {
1487 fs
->pwdmnt
= mntget(q
);
1489 if (p
== fs
->altrootmnt
) {
1491 fs
->altrootmnt
= mntget(q
);
1494 p
= next_mnt(p
, namespace->root
);
1495 q
= next_mnt(q
, new_ns
->root
);
1497 up_write(&namespace_sem
);
1509 int copy_namespace(int flags
, struct task_struct
*tsk
)
1511 struct namespace *namespace = tsk
->nsproxy
->namespace;
1512 struct namespace *new_ns
;
1518 get_namespace(namespace);
1520 if (!(flags
& CLONE_NEWNS
))
1523 if (!capable(CAP_SYS_ADMIN
)) {
1528 new_ns
= dup_namespace(tsk
, tsk
->fs
);
1534 tsk
->nsproxy
->namespace = new_ns
;
1537 put_namespace(namespace);
1541 asmlinkage
long sys_mount(char __user
* dev_name
, char __user
* dir_name
,
1542 char __user
* type
, unsigned long flags
,
1546 unsigned long data_page
;
1547 unsigned long type_page
;
1548 unsigned long dev_page
;
1551 retval
= copy_mount_options(type
, &type_page
);
1555 dir_page
= getname(dir_name
);
1556 retval
= PTR_ERR(dir_page
);
1557 if (IS_ERR(dir_page
))
1560 retval
= copy_mount_options(dev_name
, &dev_page
);
1564 retval
= copy_mount_options(data
, &data_page
);
1569 retval
= do_mount((char *)dev_page
, dir_page
, (char *)type_page
,
1570 flags
, (void *)data_page
);
1572 free_page(data_page
);
1575 free_page(dev_page
);
1579 free_page(type_page
);
1584 * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
1585 * It can block. Requires the big lock held.
1587 void set_fs_root(struct fs_struct
*fs
, struct vfsmount
*mnt
,
1588 struct dentry
*dentry
)
1590 struct dentry
*old_root
;
1591 struct vfsmount
*old_rootmnt
;
1592 write_lock(&fs
->lock
);
1593 old_root
= fs
->root
;
1594 old_rootmnt
= fs
->rootmnt
;
1595 fs
->rootmnt
= mntget(mnt
);
1596 fs
->root
= dget(dentry
);
1597 write_unlock(&fs
->lock
);
1600 mntput(old_rootmnt
);
1605 * Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
1606 * It can block. Requires the big lock held.
1608 void set_fs_pwd(struct fs_struct
*fs
, struct vfsmount
*mnt
,
1609 struct dentry
*dentry
)
1611 struct dentry
*old_pwd
;
1612 struct vfsmount
*old_pwdmnt
;
1614 write_lock(&fs
->lock
);
1616 old_pwdmnt
= fs
->pwdmnt
;
1617 fs
->pwdmnt
= mntget(mnt
);
1618 fs
->pwd
= dget(dentry
);
1619 write_unlock(&fs
->lock
);
1627 static void chroot_fs_refs(struct nameidata
*old_nd
, struct nameidata
*new_nd
)
1629 struct task_struct
*g
, *p
;
1630 struct fs_struct
*fs
;
1632 read_lock(&tasklist_lock
);
1633 do_each_thread(g
, p
) {
1637 atomic_inc(&fs
->count
);
1639 if (fs
->root
== old_nd
->dentry
1640 && fs
->rootmnt
== old_nd
->mnt
)
1641 set_fs_root(fs
, new_nd
->mnt
, new_nd
->dentry
);
1642 if (fs
->pwd
== old_nd
->dentry
1643 && fs
->pwdmnt
== old_nd
->mnt
)
1644 set_fs_pwd(fs
, new_nd
->mnt
, new_nd
->dentry
);
1648 } while_each_thread(g
, p
);
1649 read_unlock(&tasklist_lock
);
1653 * pivot_root Semantics:
1654 * Moves the root file system of the current process to the directory put_old,
1655 * makes new_root as the new root file system of the current process, and sets
1656 * root/cwd of all processes which had them on the current root to new_root.
1659 * The new_root and put_old must be directories, and must not be on the
1660 * same file system as the current process root. The put_old must be
1661 * underneath new_root, i.e. adding a non-zero number of /.. to the string
1662 * pointed to by put_old must yield the same directory as new_root. No other
1663 * file system may be mounted on put_old. After all, new_root is a mountpoint.
1665 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
1666 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
1667 * in this situation.
1670 * - we don't move root/cwd if they are not at the root (reason: if something
1671 * cared enough to change them, it's probably wrong to force them elsewhere)
1672 * - it's okay to pick a root that isn't the root of a file system, e.g.
1673 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
1674 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
1677 asmlinkage
long sys_pivot_root(const char __user
* new_root
,
1678 const char __user
* put_old
)
1680 struct vfsmount
*tmp
;
1681 struct nameidata new_nd
, old_nd
, parent_nd
, root_parent
, user_nd
;
1684 if (!capable(CAP_SYS_ADMIN
))
1689 error
= __user_walk(new_root
, LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
,
1694 if (!check_mnt(new_nd
.mnt
))
1697 error
= __user_walk(put_old
, LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
, &old_nd
);
1701 error
= security_sb_pivotroot(&old_nd
, &new_nd
);
1703 path_release(&old_nd
);
1707 read_lock(¤t
->fs
->lock
);
1708 user_nd
.mnt
= mntget(current
->fs
->rootmnt
);
1709 user_nd
.dentry
= dget(current
->fs
->root
);
1710 read_unlock(¤t
->fs
->lock
);
1711 down_write(&namespace_sem
);
1712 mutex_lock(&old_nd
.dentry
->d_inode
->i_mutex
);
1714 if (IS_MNT_SHARED(old_nd
.mnt
) ||
1715 IS_MNT_SHARED(new_nd
.mnt
->mnt_parent
) ||
1716 IS_MNT_SHARED(user_nd
.mnt
->mnt_parent
))
1718 if (!check_mnt(user_nd
.mnt
))
1721 if (IS_DEADDIR(new_nd
.dentry
->d_inode
))
1723 if (d_unhashed(new_nd
.dentry
) && !IS_ROOT(new_nd
.dentry
))
1725 if (d_unhashed(old_nd
.dentry
) && !IS_ROOT(old_nd
.dentry
))
1728 if (new_nd
.mnt
== user_nd
.mnt
|| old_nd
.mnt
== user_nd
.mnt
)
1729 goto out2
; /* loop, on the same file system */
1731 if (user_nd
.mnt
->mnt_root
!= user_nd
.dentry
)
1732 goto out2
; /* not a mountpoint */
1733 if (user_nd
.mnt
->mnt_parent
== user_nd
.mnt
)
1734 goto out2
; /* not attached */
1735 if (new_nd
.mnt
->mnt_root
!= new_nd
.dentry
)
1736 goto out2
; /* not a mountpoint */
1737 if (new_nd
.mnt
->mnt_parent
== new_nd
.mnt
)
1738 goto out2
; /* not attached */
1739 tmp
= old_nd
.mnt
; /* make sure we can reach put_old from new_root */
1740 spin_lock(&vfsmount_lock
);
1741 if (tmp
!= new_nd
.mnt
) {
1743 if (tmp
->mnt_parent
== tmp
)
1744 goto out3
; /* already mounted on put_old */
1745 if (tmp
->mnt_parent
== new_nd
.mnt
)
1747 tmp
= tmp
->mnt_parent
;
1749 if (!is_subdir(tmp
->mnt_mountpoint
, new_nd
.dentry
))
1751 } else if (!is_subdir(old_nd
.dentry
, new_nd
.dentry
))
1753 detach_mnt(new_nd
.mnt
, &parent_nd
);
1754 detach_mnt(user_nd
.mnt
, &root_parent
);
1755 attach_mnt(user_nd
.mnt
, &old_nd
); /* mount old root on put_old */
1756 attach_mnt(new_nd
.mnt
, &root_parent
); /* mount new_root on / */
1757 touch_namespace(current
->nsproxy
->namespace);
1758 spin_unlock(&vfsmount_lock
);
1759 chroot_fs_refs(&user_nd
, &new_nd
);
1760 security_sb_post_pivotroot(&user_nd
, &new_nd
);
1762 path_release(&root_parent
);
1763 path_release(&parent_nd
);
1765 mutex_unlock(&old_nd
.dentry
->d_inode
->i_mutex
);
1766 up_write(&namespace_sem
);
1767 path_release(&user_nd
);
1768 path_release(&old_nd
);
1770 path_release(&new_nd
);
1775 spin_unlock(&vfsmount_lock
);
1779 static void __init
init_mount_tree(void)
1781 struct vfsmount
*mnt
;
1782 struct namespace *namespace;
1784 mnt
= do_kern_mount("rootfs", 0, "rootfs", NULL
);
1786 panic("Can't create rootfs");
1787 namespace = kmalloc(sizeof(*namespace), GFP_KERNEL
);
1789 panic("Can't allocate initial namespace");
1790 atomic_set(&namespace->count
, 1);
1791 INIT_LIST_HEAD(&namespace->list
);
1792 init_waitqueue_head(&namespace->poll
);
1793 namespace->event
= 0;
1794 list_add(&mnt
->mnt_list
, &namespace->list
);
1795 namespace->root
= mnt
;
1796 mnt
->mnt_namespace
= namespace;
1798 init_task
.nsproxy
->namespace = namespace;
1799 get_namespace(namespace);
1801 set_fs_pwd(current
->fs
, namespace->root
, namespace->root
->mnt_root
);
1802 set_fs_root(current
->fs
, namespace->root
, namespace->root
->mnt_root
);
1805 void __init
mnt_init(unsigned long mempages
)
1807 struct list_head
*d
;
1808 unsigned int nr_hash
;
1812 init_rwsem(&namespace_sem
);
1814 mnt_cache
= kmem_cache_create("mnt_cache", sizeof(struct vfsmount
),
1815 0, SLAB_HWCACHE_ALIGN
| SLAB_PANIC
, NULL
, NULL
);
1817 mount_hashtable
= (struct list_head
*)__get_free_page(GFP_ATOMIC
);
1819 if (!mount_hashtable
)
1820 panic("Failed to allocate mount hash table\n");
1823 * Find the power-of-two list-heads that can fit into the allocation..
1824 * We don't guarantee that "sizeof(struct list_head)" is necessarily
1827 nr_hash
= PAGE_SIZE
/ sizeof(struct list_head
);
1831 } while ((nr_hash
>> hash_bits
) != 0);
1835 * Re-calculate the actual number of entries and the mask
1836 * from the number of bits we can fit.
1838 nr_hash
= 1UL << hash_bits
;
1839 hash_mask
= nr_hash
- 1;
1841 printk("Mount-cache hash table entries: %d\n", nr_hash
);
1843 /* And initialize the newly allocated array */
1844 d
= mount_hashtable
;
1853 printk(KERN_WARNING
"%s: sysfs_init error: %d\n",
1855 err
= subsystem_register(&fs_subsys
);
1857 printk(KERN_WARNING
"%s: subsystem_register error: %d\n",
1863 void __put_namespace(struct namespace *namespace)
1865 struct vfsmount
*root
= namespace->root
;
1866 LIST_HEAD(umount_list
);
1867 namespace->root
= NULL
;
1868 spin_unlock(&vfsmount_lock
);
1869 down_write(&namespace_sem
);
1870 spin_lock(&vfsmount_lock
);
1871 umount_tree(root
, 0, &umount_list
);
1872 spin_unlock(&vfsmount_lock
);
1873 up_write(&namespace_sem
);
1874 release_mounts(&umount_list
);