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/export.h>
13 #include <linux/capability.h>
14 #include <linux/mnt_namespace.h>
15 #include <linux/user_namespace.h>
16 #include <linux/namei.h>
17 #include <linux/security.h>
18 #include <linux/idr.h>
19 #include <linux/acct.h> /* acct_auto_close_mnt */
20 #include <linux/ramfs.h> /* init_rootfs */
21 #include <linux/fs_struct.h> /* get_fs_root et.al. */
22 #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */
23 #include <linux/uaccess.h>
24 //#define UMOUNT_LOG //enable kernel layer unmount log when unmount fail
26 #include <linux/types.h>
28 #include <linux/proc_ns.h>
29 #include <linux/magic.h>
33 #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head))
34 #define HASH_SIZE (1UL << HASH_SHIFT)
37 static DEFINE_IDA(mnt_id_ida
);
38 static DEFINE_IDA(mnt_group_ida
);
39 static DEFINE_SPINLOCK(mnt_id_lock
);
40 static int mnt_id_start
= 0;
41 static int mnt_group_start
= 1;
43 static struct list_head
*mount_hashtable __read_mostly
;
44 static struct list_head
*mountpoint_hashtable __read_mostly
;
45 static struct kmem_cache
*mnt_cache __read_mostly
;
46 static struct rw_semaphore namespace_sem
;
49 struct kobject
*fs_kobj
;
50 EXPORT_SYMBOL_GPL(fs_kobj
);
53 * vfsmount lock may be taken for read to prevent changes to the
54 * vfsmount hash, ie. during mountpoint lookups or walking back
57 * It should be taken for write in all cases where the vfsmount
58 * tree or hash is modified or when a vfsmount structure is modified.
60 DEFINE_BRLOCK(vfsmount_lock
);
62 static inline unsigned long hash(struct vfsmount
*mnt
, struct dentry
*dentry
)
64 unsigned long tmp
= ((unsigned long)mnt
/ L1_CACHE_BYTES
);
65 tmp
+= ((unsigned long)dentry
/ L1_CACHE_BYTES
);
66 tmp
= tmp
+ (tmp
>> HASH_SHIFT
);
67 return tmp
& (HASH_SIZE
- 1);
70 #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16)
73 * allocation is serialized by namespace_sem, but we need the spinlock to
74 * serialize with freeing.
76 static int mnt_alloc_id(struct mount
*mnt
)
81 ida_pre_get(&mnt_id_ida
, GFP_KERNEL
);
82 spin_lock(&mnt_id_lock
);
83 res
= ida_get_new_above(&mnt_id_ida
, mnt_id_start
, &mnt
->mnt_id
);
85 mnt_id_start
= mnt
->mnt_id
+ 1;
86 spin_unlock(&mnt_id_lock
);
93 static void mnt_free_id(struct mount
*mnt
)
96 spin_lock(&mnt_id_lock
);
97 ida_remove(&mnt_id_ida
, id
);
98 if (mnt_id_start
> id
)
100 spin_unlock(&mnt_id_lock
);
104 * Allocate a new peer group ID
106 * mnt_group_ida is protected by namespace_sem
108 static int mnt_alloc_group_id(struct mount
*mnt
)
112 if (!ida_pre_get(&mnt_group_ida
, GFP_KERNEL
))
115 res
= ida_get_new_above(&mnt_group_ida
,
119 mnt_group_start
= mnt
->mnt_group_id
+ 1;
125 * Release a peer group ID
127 void mnt_release_group_id(struct mount
*mnt
)
129 int id
= mnt
->mnt_group_id
;
130 ida_remove(&mnt_group_ida
, id
);
131 if (mnt_group_start
> id
)
132 mnt_group_start
= id
;
133 mnt
->mnt_group_id
= 0;
137 * vfsmount lock must be held for read
140 #define UMOUNT_Partition "/emmc@usrdata"
141 struct record_ref_count
{
143 char name
[TASK_COMM_LEN
];
145 struct record_ref_count
*next
;
148 struct record_ref_count
*ref_head
= NULL
;
149 struct record_ref_count
*ref_current
= NULL
;
150 struct record_ref_count
*ref_prev
= NULL
;
151 int s_total_count
= 0;
153 static inline void mnt_add_count(struct mount
*mnt
, int n
)
156 int print_link_list
=0;
161 if (strcmp(UMOUNT_Partition
,mnt
->mnt_devname
)==0)
163 //if (strcmp("mobile_log_d",current->comm)!=0)
165 //if (current->pid < 100) //((current->pid < 70) && (current->pid > 60))
167 //printk("Ahsin n=%d current->pid=%d name=%s \n",n,current->pid,current->comm);
168 spin_lock(&mnt_id_lock
);
169 if (ref_head
== NULL
) //linked list head (start)
171 printk("Ahsin link list init mnt_get_count=%d \n",mnt_get_count(mnt
));
173 ref_current
= kmalloc(sizeof(struct record_ref_count
), GFP_KERNEL
);
174 if (ref_current
== NULL
)
175 printk("Ahsin can't allocate memory for ref_current /n");
177 ref_current
->next
= NULL
;
178 ref_current
->pid
= current
->pid
;
179 strncpy(ref_current
->name
, current
->comm
, TASK_COMM_LEN
-1);
180 ref_current
->name
[TASK_COMM_LEN
-1] = '\0';
181 ref_current
->count
= n
;
182 s_total_count
= s_total_count
+ n
;
183 ref_head
= ref_current
;
185 printk("Ahsin ref_head == NULL pid=%d name=%s counter=%d n=%d \n",ref_current
->pid
,ref_current
->name
,ref_current
->count
,n
);
187 else //check exist first and then add linked list or modify counter
190 while(ref_prev
!= NULL
)
192 //printk("Ahsin PID= %d, Name= %s, Count= %d n=%d current->pid=%d \n", ref_prev->pid, ref_prev->name, ref_prev->count,n,current->pid);
193 if (strcmp(ref_prev
->name
,current
->comm
)==0) //(ref_prev->pid==current->pid)//exist and find, modify counter
195 ref_prev
->count
= ref_prev
->count
+ n
;
196 s_total_count
= s_total_count
+ n
;
197 //printk("Ahsin (ref_prev->name,current->comm) pid=%d name=%s counter=%d n=%d \n",ref_prev->pid,ref_prev->name,ref_prev->count,n);
202 if (ref_prev
->next
!= NULL
)
203 ref_prev
= ref_prev
->next
;
205 { // end of link list
206 ref_current
= kmalloc(sizeof(struct record_ref_count
), GFP_KERNEL
);
207 if (ref_current
== NULL
)
208 printk("Ahsin can't allocate memory for ref_prev /n");
210 ref_current
->next
= NULL
;
211 ref_current
->pid
= current
->pid
;
212 strncpy(ref_current
->name
, current
->comm
, TASK_COMM_LEN
-1);
213 ref_current
->name
[TASK_COMM_LEN
-1] = '\0';
214 ref_current
->count
= n
;
215 s_total_count
= s_total_count
+ n
;
216 ref_prev
->next
= ref_current
;
217 //printk("Ahsin new node(end of link list) pid=%d name=%s counter=%d n=%d \n",ref_current->pid,ref_current->name,ref_current->count,n);
224 spin_unlock(&mnt_id_lock
);
234 this_cpu_add(mnt
->mnt_pcp
->mnt_count
, n
);
237 if (strcmp(UMOUNT_Partition
,mnt
->mnt_devname
)==0)
239 if (strcmp("mobile_log_d",current
->comm
)!=0)
241 printk("Ahsin s_total_count=%d mnt_get_count=%d n=%d current->pid=%d \n",s_total_count
,mnt_get_count(mnt
),n
,current
->pid
);
242 //if (current->pid < 100)
245 spin_lock(&mnt_id_lock
);
246 ref_current
= ref_head
;
247 while(ref_current
!= NULL
)
249 if (ref_current
->count
)
251 print_link_list
= print_link_list
+ ref_current
->count
;
252 //printk("Ahsin PID= %d, Name = %s, Count= %d \n", ref_current->pid, ref_current->name, ref_current->count);
254 ref_current
= ref_current
->next
;
256 spin_unlock(&mnt_id_lock
);
257 printk("Ahsin print_link_list=%d \n",print_link_list
);
271 * vfsmount lock must be held for write
273 unsigned int mnt_get_count(struct mount
*mnt
)
276 unsigned int count
= 0;
279 for_each_possible_cpu(cpu
) {
280 count
+= per_cpu_ptr(mnt
->mnt_pcp
, cpu
)->mnt_count
;
285 return mnt
->mnt_count
;
289 static struct mount
*alloc_vfsmnt(const char *name
)
291 struct mount
*mnt
= kmem_cache_zalloc(mnt_cache
, GFP_KERNEL
);
295 err
= mnt_alloc_id(mnt
);
300 mnt
->mnt_devname
= kstrdup(name
, GFP_KERNEL
);
301 if (!mnt
->mnt_devname
)
306 mnt
->mnt_pcp
= alloc_percpu(struct mnt_pcp
);
308 goto out_free_devname
;
311 if (strcmp(UMOUNT_Partition
,mnt
->mnt_devname
)==0)
313 printk("Ahsin alloc_vfsmnt current->pid=%d name=%s \n",current
->pid
,current
->comm
);
316 this_cpu_add(mnt
->mnt_pcp
->mnt_count
, 1);
319 mnt
->mnt_writers
= 0;
322 INIT_LIST_HEAD(&mnt
->mnt_hash
);
323 INIT_LIST_HEAD(&mnt
->mnt_child
);
324 INIT_LIST_HEAD(&mnt
->mnt_mounts
);
325 INIT_LIST_HEAD(&mnt
->mnt_list
);
326 INIT_LIST_HEAD(&mnt
->mnt_expire
);
327 INIT_LIST_HEAD(&mnt
->mnt_share
);
328 INIT_LIST_HEAD(&mnt
->mnt_slave_list
);
329 INIT_LIST_HEAD(&mnt
->mnt_slave
);
330 #ifdef CONFIG_FSNOTIFY
331 INIT_HLIST_HEAD(&mnt
->mnt_fsnotify_marks
);
338 kfree(mnt
->mnt_devname
);
343 kmem_cache_free(mnt_cache
, mnt
);
348 * Most r/o checks on a fs are for operations that take
349 * discrete amounts of time, like a write() or unlink().
350 * We must keep track of when those operations start
351 * (for permission checks) and when they end, so that
352 * we can determine when writes are able to occur to
356 * __mnt_is_readonly: check whether a mount is read-only
357 * @mnt: the mount to check for its write status
359 * This shouldn't be used directly ouside of the VFS.
360 * It does not guarantee that the filesystem will stay
361 * r/w, just that it is right *now*. This can not and
362 * should not be used in place of IS_RDONLY(inode).
363 * mnt_want/drop_write() will _keep_ the filesystem
366 int __mnt_is_readonly(struct vfsmount
*mnt
)
368 if (mnt
->mnt_flags
& MNT_READONLY
)
370 if (mnt
->mnt_sb
->s_flags
& MS_RDONLY
)
374 EXPORT_SYMBOL_GPL(__mnt_is_readonly
);
376 static inline void mnt_inc_writers(struct mount
*mnt
)
379 this_cpu_inc(mnt
->mnt_pcp
->mnt_writers
);
385 static inline void mnt_dec_writers(struct mount
*mnt
)
388 this_cpu_dec(mnt
->mnt_pcp
->mnt_writers
);
394 static unsigned int mnt_get_writers(struct mount
*mnt
)
397 unsigned int count
= 0;
400 for_each_possible_cpu(cpu
) {
401 count
+= per_cpu_ptr(mnt
->mnt_pcp
, cpu
)->mnt_writers
;
406 return mnt
->mnt_writers
;
410 static int mnt_is_readonly(struct vfsmount
*mnt
)
412 if (mnt
->mnt_sb
->s_readonly_remount
)
414 /* Order wrt setting s_flags/s_readonly_remount in do_remount() */
416 return __mnt_is_readonly(mnt
);
420 * Most r/o & frozen checks on a fs are for operations that take discrete
421 * amounts of time, like a write() or unlink(). We must keep track of when
422 * those operations start (for permission checks) and when they end, so that we
423 * can determine when writes are able to occur to a filesystem.
426 * __mnt_want_write - get write access to a mount without freeze protection
427 * @m: the mount on which to take a write
429 * This tells the low-level filesystem that a write is about to be performed to
430 * it, and makes sure that writes are allowed (mnt it read-write) before
431 * returning success. This operation does not protect against filesystem being
432 * frozen. When the write operation is finished, __mnt_drop_write() must be
433 * called. This is effectively a refcount.
435 int __mnt_want_write(struct vfsmount
*m
)
437 struct mount
*mnt
= real_mount(m
);
441 mnt_inc_writers(mnt
);
443 * The store to mnt_inc_writers must be visible before we pass
444 * MNT_WRITE_HOLD loop below, so that the slowpath can see our
445 * incremented count after it has set MNT_WRITE_HOLD.
448 while (ACCESS_ONCE(mnt
->mnt
.mnt_flags
) & MNT_WRITE_HOLD
)
451 * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
452 * be set to match its requirements. So we must not load that until
453 * MNT_WRITE_HOLD is cleared.
456 if (mnt_is_readonly(m
)) {
457 mnt_dec_writers(mnt
);
466 * mnt_want_write - get write access to a mount
467 * @m: the mount on which to take a write
469 * This tells the low-level filesystem that a write is about to be performed to
470 * it, and makes sure that writes are allowed (mount is read-write, filesystem
471 * is not frozen) before returning success. When the write operation is
472 * finished, mnt_drop_write() must be called. This is effectively a refcount.
474 int mnt_want_write(struct vfsmount
*m
)
478 sb_start_write(m
->mnt_sb
);
479 ret
= __mnt_want_write(m
);
481 sb_end_write(m
->mnt_sb
);
484 EXPORT_SYMBOL_GPL(mnt_want_write
);
487 * mnt_clone_write - get write access to a mount
488 * @mnt: the mount on which to take a write
490 * This is effectively like mnt_want_write, except
491 * it must only be used to take an extra write reference
492 * on a mountpoint that we already know has a write reference
493 * on it. This allows some optimisation.
495 * After finished, mnt_drop_write must be called as usual to
496 * drop the reference.
498 int mnt_clone_write(struct vfsmount
*mnt
)
500 /* superblock may be r/o */
501 if (__mnt_is_readonly(mnt
))
504 mnt_inc_writers(real_mount(mnt
));
508 EXPORT_SYMBOL_GPL(mnt_clone_write
);
511 * __mnt_want_write_file - get write access to a file's mount
512 * @file: the file who's mount on which to take a write
514 * This is like __mnt_want_write, but it takes a file and can
515 * do some optimisations if the file is open for write already
517 int __mnt_want_write_file(struct file
*file
)
519 struct inode
*inode
= file_inode(file
);
521 if (!(file
->f_mode
& FMODE_WRITE
) || special_file(inode
->i_mode
))
522 return __mnt_want_write(file
->f_path
.mnt
);
524 return mnt_clone_write(file
->f_path
.mnt
);
528 * mnt_want_write_file - get write access to a file's mount
529 * @file: the file who's mount on which to take a write
531 * This is like mnt_want_write, but it takes a file and can
532 * do some optimisations if the file is open for write already
534 int mnt_want_write_file(struct file
*file
)
538 sb_start_write(file
->f_path
.mnt
->mnt_sb
);
539 ret
= __mnt_want_write_file(file
);
541 sb_end_write(file
->f_path
.mnt
->mnt_sb
);
544 EXPORT_SYMBOL_GPL(mnt_want_write_file
);
547 * __mnt_drop_write - give up write access to a mount
548 * @mnt: the mount on which to give up write access
550 * Tells the low-level filesystem that we are done
551 * performing writes to it. Must be matched with
552 * __mnt_want_write() call above.
554 void __mnt_drop_write(struct vfsmount
*mnt
)
557 mnt_dec_writers(real_mount(mnt
));
562 * mnt_drop_write - give up write access to a mount
563 * @mnt: the mount on which to give up write access
565 * Tells the low-level filesystem that we are done performing writes to it and
566 * also allows filesystem to be frozen again. Must be matched with
567 * mnt_want_write() call above.
569 void mnt_drop_write(struct vfsmount
*mnt
)
571 __mnt_drop_write(mnt
);
572 sb_end_write(mnt
->mnt_sb
);
574 EXPORT_SYMBOL_GPL(mnt_drop_write
);
576 void __mnt_drop_write_file(struct file
*file
)
578 __mnt_drop_write(file
->f_path
.mnt
);
581 void mnt_drop_write_file(struct file
*file
)
583 mnt_drop_write(file
->f_path
.mnt
);
585 EXPORT_SYMBOL(mnt_drop_write_file
);
587 static int mnt_make_readonly(struct mount
*mnt
)
591 br_write_lock(&vfsmount_lock
);
592 mnt
->mnt
.mnt_flags
|= MNT_WRITE_HOLD
;
594 * After storing MNT_WRITE_HOLD, we'll read the counters. This store
595 * should be visible before we do.
600 * With writers on hold, if this value is zero, then there are
601 * definitely no active writers (although held writers may subsequently
602 * increment the count, they'll have to wait, and decrement it after
603 * seeing MNT_READONLY).
605 * It is OK to have counter incremented on one CPU and decremented on
606 * another: the sum will add up correctly. The danger would be when we
607 * sum up each counter, if we read a counter before it is incremented,
608 * but then read another CPU's count which it has been subsequently
609 * decremented from -- we would see more decrements than we should.
610 * MNT_WRITE_HOLD protects against this scenario, because
611 * mnt_want_write first increments count, then smp_mb, then spins on
612 * MNT_WRITE_HOLD, so it can't be decremented by another CPU while
613 * we're counting up here.
615 if (mnt_get_writers(mnt
) > 0)
618 mnt
->mnt
.mnt_flags
|= MNT_READONLY
;
620 * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers
621 * that become unheld will see MNT_READONLY.
624 mnt
->mnt
.mnt_flags
&= ~MNT_WRITE_HOLD
;
625 br_write_unlock(&vfsmount_lock
);
629 static void __mnt_unmake_readonly(struct mount
*mnt
)
631 br_write_lock(&vfsmount_lock
);
632 mnt
->mnt
.mnt_flags
&= ~MNT_READONLY
;
633 br_write_unlock(&vfsmount_lock
);
636 int sb_prepare_remount_readonly(struct super_block
*sb
)
641 /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */
642 if (atomic_long_read(&sb
->s_remove_count
))
645 br_write_lock(&vfsmount_lock
);
646 list_for_each_entry(mnt
, &sb
->s_mounts
, mnt_instance
) {
647 if (!(mnt
->mnt
.mnt_flags
& MNT_READONLY
)) {
648 mnt
->mnt
.mnt_flags
|= MNT_WRITE_HOLD
;
650 if (mnt_get_writers(mnt
) > 0) {
656 if (!err
&& atomic_long_read(&sb
->s_remove_count
))
660 sb
->s_readonly_remount
= 1;
663 list_for_each_entry(mnt
, &sb
->s_mounts
, mnt_instance
) {
664 if (mnt
->mnt
.mnt_flags
& MNT_WRITE_HOLD
)
665 mnt
->mnt
.mnt_flags
&= ~MNT_WRITE_HOLD
;
667 br_write_unlock(&vfsmount_lock
);
672 static void free_vfsmnt(struct mount
*mnt
)
674 kfree(mnt
->mnt_devname
);
677 free_percpu(mnt
->mnt_pcp
);
679 kmem_cache_free(mnt_cache
, mnt
);
683 * find the first or last mount at @dentry on vfsmount @mnt depending on
684 * @dir. If @dir is set return the first mount else return the last mount.
685 * vfsmount_lock must be held for read or write.
687 struct mount
*__lookup_mnt(struct vfsmount
*mnt
, struct dentry
*dentry
,
690 struct list_head
*head
= mount_hashtable
+ hash(mnt
, dentry
);
691 struct list_head
*tmp
= head
;
692 struct mount
*p
, *found
= NULL
;
695 tmp
= dir
? tmp
->next
: tmp
->prev
;
699 p
= list_entry(tmp
, struct mount
, mnt_hash
);
700 if (&p
->mnt_parent
->mnt
== mnt
&& p
->mnt_mountpoint
== dentry
) {
709 * lookup_mnt - Return the first child mount mounted at path
711 * "First" means first mounted chronologically. If you create the
714 * mount /dev/sda1 /mnt
715 * mount /dev/sda2 /mnt
716 * mount /dev/sda3 /mnt
718 * Then lookup_mnt() on the base /mnt dentry in the root mount will
719 * return successively the root dentry and vfsmount of /dev/sda1, then
720 * /dev/sda2, then /dev/sda3, then NULL.
722 * lookup_mnt takes a reference to the found vfsmount.
724 struct vfsmount
*lookup_mnt(struct path
*path
)
726 struct mount
*child_mnt
;
728 br_read_lock(&vfsmount_lock
);
729 child_mnt
= __lookup_mnt(path
->mnt
, path
->dentry
, 1);
731 mnt_add_count(child_mnt
, 1);
732 br_read_unlock(&vfsmount_lock
);
733 return &child_mnt
->mnt
;
735 br_read_unlock(&vfsmount_lock
);
740 static struct mountpoint
*new_mountpoint(struct dentry
*dentry
)
742 struct list_head
*chain
= mountpoint_hashtable
+ hash(NULL
, dentry
);
743 struct mountpoint
*mp
;
745 list_for_each_entry(mp
, chain
, m_hash
) {
746 if (mp
->m_dentry
== dentry
) {
747 /* might be worth a WARN_ON() */
748 if (d_unlinked(dentry
))
749 return ERR_PTR(-ENOENT
);
755 mp
= kmalloc(sizeof(struct mountpoint
), GFP_KERNEL
);
757 return ERR_PTR(-ENOMEM
);
759 spin_lock(&dentry
->d_lock
);
760 if (d_unlinked(dentry
)) {
761 spin_unlock(&dentry
->d_lock
);
763 return ERR_PTR(-ENOENT
);
765 dentry
->d_flags
|= DCACHE_MOUNTED
;
766 spin_unlock(&dentry
->d_lock
);
767 mp
->m_dentry
= dentry
;
769 list_add(&mp
->m_hash
, chain
);
773 static void put_mountpoint(struct mountpoint
*mp
)
775 if (!--mp
->m_count
) {
776 struct dentry
*dentry
= mp
->m_dentry
;
777 spin_lock(&dentry
->d_lock
);
778 dentry
->d_flags
&= ~DCACHE_MOUNTED
;
779 spin_unlock(&dentry
->d_lock
);
780 list_del(&mp
->m_hash
);
785 static inline int check_mnt(struct mount
*mnt
)
787 return mnt
->mnt_ns
== current
->nsproxy
->mnt_ns
;
791 * vfsmount lock must be held for write
793 static void touch_mnt_namespace(struct mnt_namespace
*ns
)
797 wake_up_interruptible(&ns
->poll
);
802 * vfsmount lock must be held for write
804 static void __touch_mnt_namespace(struct mnt_namespace
*ns
)
806 if (ns
&& ns
->event
!= event
) {
808 wake_up_interruptible(&ns
->poll
);
813 * vfsmount lock must be held for write
815 static void detach_mnt(struct mount
*mnt
, struct path
*old_path
)
817 old_path
->dentry
= mnt
->mnt_mountpoint
;
818 old_path
->mnt
= &mnt
->mnt_parent
->mnt
;
819 mnt
->mnt_parent
= mnt
;
820 mnt
->mnt_mountpoint
= mnt
->mnt
.mnt_root
;
821 list_del_init(&mnt
->mnt_child
);
822 list_del_init(&mnt
->mnt_hash
);
823 put_mountpoint(mnt
->mnt_mp
);
828 * vfsmount lock must be held for write
830 void mnt_set_mountpoint(struct mount
*mnt
,
831 struct mountpoint
*mp
,
832 struct mount
*child_mnt
)
835 mnt_add_count(mnt
, 1); /* essentially, that's mntget */
836 child_mnt
->mnt_mountpoint
= dget(mp
->m_dentry
);
837 child_mnt
->mnt_parent
= mnt
;
838 child_mnt
->mnt_mp
= mp
;
842 * vfsmount lock must be held for write
844 static void attach_mnt(struct mount
*mnt
,
845 struct mount
*parent
,
846 struct mountpoint
*mp
)
848 mnt_set_mountpoint(parent
, mp
, mnt
);
849 list_add_tail(&mnt
->mnt_hash
, mount_hashtable
+
850 hash(&parent
->mnt
, mp
->m_dentry
));
851 list_add_tail(&mnt
->mnt_child
, &parent
->mnt_mounts
);
855 * vfsmount lock must be held for write
857 static void commit_tree(struct mount
*mnt
)
859 struct mount
*parent
= mnt
->mnt_parent
;
862 struct mnt_namespace
*n
= parent
->mnt_ns
;
864 BUG_ON(parent
== mnt
);
866 list_add_tail(&head
, &mnt
->mnt_list
);
867 list_for_each_entry(m
, &head
, mnt_list
)
870 list_splice(&head
, n
->list
.prev
);
872 list_add_tail(&mnt
->mnt_hash
, mount_hashtable
+
873 hash(&parent
->mnt
, mnt
->mnt_mountpoint
));
874 list_add_tail(&mnt
->mnt_child
, &parent
->mnt_mounts
);
875 touch_mnt_namespace(n
);
878 static struct mount
*next_mnt(struct mount
*p
, struct mount
*root
)
880 struct list_head
*next
= p
->mnt_mounts
.next
;
881 if (next
== &p
->mnt_mounts
) {
885 next
= p
->mnt_child
.next
;
886 if (next
!= &p
->mnt_parent
->mnt_mounts
)
891 return list_entry(next
, struct mount
, mnt_child
);
894 static struct mount
*skip_mnt_tree(struct mount
*p
)
896 struct list_head
*prev
= p
->mnt_mounts
.prev
;
897 while (prev
!= &p
->mnt_mounts
) {
898 p
= list_entry(prev
, struct mount
, mnt_child
);
899 prev
= p
->mnt_mounts
.prev
;
905 vfs_kern_mount(struct file_system_type
*type
, int flags
, const char *name
, void *data
)
911 return ERR_PTR(-ENODEV
);
913 mnt
= alloc_vfsmnt(name
);
915 return ERR_PTR(-ENOMEM
);
917 if (flags
& MS_KERNMOUNT
)
918 mnt
->mnt
.mnt_flags
= MNT_INTERNAL
;
920 root
= mount_fs(type
, flags
, name
, data
);
923 return ERR_CAST(root
);
926 mnt
->mnt
.mnt_root
= root
;
927 mnt
->mnt
.mnt_sb
= root
->d_sb
;
928 mnt
->mnt_mountpoint
= mnt
->mnt
.mnt_root
;
929 mnt
->mnt_parent
= mnt
;
930 br_write_lock(&vfsmount_lock
);
931 list_add_tail(&mnt
->mnt_instance
, &root
->d_sb
->s_mounts
);
932 br_write_unlock(&vfsmount_lock
);
935 EXPORT_SYMBOL_GPL(vfs_kern_mount
);
937 static struct mount
*clone_mnt(struct mount
*old
, struct dentry
*root
,
940 struct super_block
*sb
= old
->mnt
.mnt_sb
;
944 mnt
= alloc_vfsmnt(old
->mnt_devname
);
946 return ERR_PTR(-ENOMEM
);
948 if (flag
& (CL_SLAVE
| CL_PRIVATE
| CL_SHARED_TO_SLAVE
))
949 mnt
->mnt_group_id
= 0; /* not a peer of original */
951 mnt
->mnt_group_id
= old
->mnt_group_id
;
953 if ((flag
& CL_MAKE_SHARED
) && !mnt
->mnt_group_id
) {
954 err
= mnt_alloc_group_id(mnt
);
959 mnt
->mnt
.mnt_flags
= old
->mnt
.mnt_flags
& ~MNT_WRITE_HOLD
;
960 /* Don't allow unprivileged users to change mount flags */
961 if (flag
& CL_UNPRIVILEGED
) {
962 mnt
->mnt
.mnt_flags
|= MNT_LOCK_ATIME
;
964 if (mnt
->mnt
.mnt_flags
& MNT_READONLY
)
965 mnt
->mnt
.mnt_flags
|= MNT_LOCK_READONLY
;
967 if (mnt
->mnt
.mnt_flags
& MNT_NODEV
)
968 mnt
->mnt
.mnt_flags
|= MNT_LOCK_NODEV
;
970 if (mnt
->mnt
.mnt_flags
& MNT_NOSUID
)
971 mnt
->mnt
.mnt_flags
|= MNT_LOCK_NOSUID
;
973 if (mnt
->mnt
.mnt_flags
& MNT_NOEXEC
)
974 mnt
->mnt
.mnt_flags
|= MNT_LOCK_NOEXEC
;
977 atomic_inc(&sb
->s_active
);
978 mnt
->mnt
.mnt_sb
= sb
;
979 mnt
->mnt
.mnt_root
= dget(root
);
980 mnt
->mnt_mountpoint
= mnt
->mnt
.mnt_root
;
981 mnt
->mnt_parent
= mnt
;
982 br_write_lock(&vfsmount_lock
);
983 list_add_tail(&mnt
->mnt_instance
, &sb
->s_mounts
);
984 br_write_unlock(&vfsmount_lock
);
986 if ((flag
& CL_SLAVE
) ||
987 ((flag
& CL_SHARED_TO_SLAVE
) && IS_MNT_SHARED(old
))) {
988 list_add(&mnt
->mnt_slave
, &old
->mnt_slave_list
);
989 mnt
->mnt_master
= old
;
990 CLEAR_MNT_SHARED(mnt
);
991 } else if (!(flag
& CL_PRIVATE
)) {
992 if ((flag
& CL_MAKE_SHARED
) || IS_MNT_SHARED(old
))
993 list_add(&mnt
->mnt_share
, &old
->mnt_share
);
994 if (IS_MNT_SLAVE(old
))
995 list_add(&mnt
->mnt_slave
, &old
->mnt_slave
);
996 mnt
->mnt_master
= old
->mnt_master
;
998 if (flag
& CL_MAKE_SHARED
)
1001 /* stick the duplicate mount on the same expiry list
1002 * as the original if that was on one */
1003 if (flag
& CL_EXPIRE
) {
1004 if (!list_empty(&old
->mnt_expire
))
1005 list_add(&mnt
->mnt_expire
, &old
->mnt_expire
);
1012 return ERR_PTR(err
);
1015 static inline void mntfree(struct mount
*mnt
)
1017 struct vfsmount
*m
= &mnt
->mnt
;
1018 struct super_block
*sb
= m
->mnt_sb
;
1021 * This probably indicates that somebody messed
1022 * up a mnt_want/drop_write() pair. If this
1023 * happens, the filesystem was probably unable
1024 * to make r/w->r/o transitions.
1027 * The locking used to deal with mnt_count decrement provides barriers,
1028 * so mnt_get_writers() below is safe.
1030 WARN_ON(mnt_get_writers(mnt
));
1031 fsnotify_vfsmount_delete(m
);
1034 deactivate_super(sb
);
1037 static void mntput_no_expire(struct mount
*mnt
)
1041 br_read_lock(&vfsmount_lock
);
1042 if (likely(mnt
->mnt_ns
)) {
1043 /* shouldn't be the last one */
1044 mnt_add_count(mnt
, -1);
1045 br_read_unlock(&vfsmount_lock
);
1048 br_read_unlock(&vfsmount_lock
);
1050 br_write_lock(&vfsmount_lock
);
1051 mnt_add_count(mnt
, -1);
1052 if (mnt_get_count(mnt
)) {
1053 br_write_unlock(&vfsmount_lock
);
1057 mnt_add_count(mnt
, -1);
1058 if (likely(mnt_get_count(mnt
)))
1060 br_write_lock(&vfsmount_lock
);
1062 if (unlikely(mnt
->mnt_pinned
)) {
1063 mnt_add_count(mnt
, mnt
->mnt_pinned
+ 1);
1064 mnt
->mnt_pinned
= 0;
1065 br_write_unlock(&vfsmount_lock
);
1066 acct_auto_close_mnt(&mnt
->mnt
);
1070 list_del(&mnt
->mnt_instance
);
1071 br_write_unlock(&vfsmount_lock
);
1075 void mntput(struct vfsmount
*mnt
)
1078 struct mount
*m
= real_mount(mnt
);
1079 /* avoid cacheline pingpong, hope gcc doesn't get "smart" */
1080 if (unlikely(m
->mnt_expiry_mark
))
1081 m
->mnt_expiry_mark
= 0;
1082 mntput_no_expire(m
);
1085 EXPORT_SYMBOL(mntput
);
1087 struct vfsmount
*mntget(struct vfsmount
*mnt
)
1090 mnt_add_count(real_mount(mnt
), 1);
1093 EXPORT_SYMBOL(mntget
);
1095 void mnt_pin(struct vfsmount
*mnt
)
1097 br_write_lock(&vfsmount_lock
);
1098 real_mount(mnt
)->mnt_pinned
++;
1099 br_write_unlock(&vfsmount_lock
);
1101 EXPORT_SYMBOL(mnt_pin
);
1103 void mnt_unpin(struct vfsmount
*m
)
1105 struct mount
*mnt
= real_mount(m
);
1106 br_write_lock(&vfsmount_lock
);
1107 if (mnt
->mnt_pinned
) {
1108 mnt_add_count(mnt
, 1);
1111 br_write_unlock(&vfsmount_lock
);
1113 EXPORT_SYMBOL(mnt_unpin
);
1115 static inline void mangle(struct seq_file
*m
, const char *s
)
1117 seq_escape(m
, s
, " \t\n\\");
1121 * Simple .show_options callback for filesystems which don't want to
1122 * implement more complex mount option showing.
1124 * See also save_mount_options().
1126 int generic_show_options(struct seq_file
*m
, struct dentry
*root
)
1128 const char *options
;
1131 options
= rcu_dereference(root
->d_sb
->s_options
);
1133 if (options
!= NULL
&& options
[0]) {
1141 EXPORT_SYMBOL(generic_show_options
);
1144 * If filesystem uses generic_show_options(), this function should be
1145 * called from the fill_super() callback.
1147 * The .remount_fs callback usually needs to be handled in a special
1148 * way, to make sure, that previous options are not overwritten if the
1151 * Also note, that if the filesystem's .remount_fs function doesn't
1152 * reset all options to their default value, but changes only newly
1153 * given options, then the displayed options will not reflect reality
1156 void save_mount_options(struct super_block
*sb
, char *options
)
1158 BUG_ON(sb
->s_options
);
1159 rcu_assign_pointer(sb
->s_options
, kstrdup(options
, GFP_KERNEL
));
1161 EXPORT_SYMBOL(save_mount_options
);
1163 void replace_mount_options(struct super_block
*sb
, char *options
)
1165 char *old
= sb
->s_options
;
1166 rcu_assign_pointer(sb
->s_options
, options
);
1172 EXPORT_SYMBOL(replace_mount_options
);
1174 #ifdef CONFIG_PROC_FS
1175 /* iterator; we want it to have access to namespace_sem, thus here... */
1176 static void *m_start(struct seq_file
*m
, loff_t
*pos
)
1178 struct proc_mounts
*p
= proc_mounts(m
);
1180 down_read(&namespace_sem
);
1181 return seq_list_start(&p
->ns
->list
, *pos
);
1184 static void *m_next(struct seq_file
*m
, void *v
, loff_t
*pos
)
1186 struct proc_mounts
*p
= proc_mounts(m
);
1188 return seq_list_next(v
, &p
->ns
->list
, pos
);
1191 static void m_stop(struct seq_file
*m
, void *v
)
1193 up_read(&namespace_sem
);
1196 static int m_show(struct seq_file
*m
, void *v
)
1198 struct proc_mounts
*p
= proc_mounts(m
);
1199 struct mount
*r
= list_entry(v
, struct mount
, mnt_list
);
1200 return p
->show(m
, &r
->mnt
);
1203 const struct seq_operations mounts_op
= {
1209 #endif /* CONFIG_PROC_FS */
1212 * may_umount_tree - check if a mount tree is busy
1213 * @mnt: root of mount tree
1215 * This is called to check if a tree of mounts has any
1216 * open files, pwds, chroots or sub mounts that are
1219 int may_umount_tree(struct vfsmount
*m
)
1221 struct mount
*mnt
= real_mount(m
);
1222 int actual_refs
= 0;
1223 int minimum_refs
= 0;
1227 /* write lock needed for mnt_get_count */
1228 br_write_lock(&vfsmount_lock
);
1229 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
1230 actual_refs
+= mnt_get_count(p
);
1233 br_write_unlock(&vfsmount_lock
);
1235 if (actual_refs
> minimum_refs
)
1241 EXPORT_SYMBOL(may_umount_tree
);
1244 * may_umount - check if a mount point is busy
1245 * @mnt: root of mount
1247 * This is called to check if a mount point has any
1248 * open files, pwds, chroots or sub mounts. If the
1249 * mount has sub mounts this will return busy
1250 * regardless of whether the sub mounts are busy.
1252 * Doesn't take quota and stuff into account. IOW, in some cases it will
1253 * give false negatives. The main reason why it's here is that we need
1254 * a non-destructive way to look for easily umountable filesystems.
1256 int may_umount(struct vfsmount
*mnt
)
1259 down_read(&namespace_sem
);
1260 br_write_lock(&vfsmount_lock
);
1261 if (propagate_mount_busy(real_mount(mnt
), 2))
1263 br_write_unlock(&vfsmount_lock
);
1264 up_read(&namespace_sem
);
1268 EXPORT_SYMBOL(may_umount
);
1270 static LIST_HEAD(unmounted
); /* protected by namespace_sem */
1272 static void namespace_unlock(void)
1277 if (likely(list_empty(&unmounted
))) {
1278 up_write(&namespace_sem
);
1282 list_splice_init(&unmounted
, &head
);
1283 up_write(&namespace_sem
);
1285 while (!list_empty(&head
)) {
1286 mnt
= list_first_entry(&head
, struct mount
, mnt_hash
);
1287 list_del_init(&mnt
->mnt_hash
);
1288 if (mnt_has_parent(mnt
)) {
1289 struct dentry
*dentry
;
1292 br_write_lock(&vfsmount_lock
);
1293 dentry
= mnt
->mnt_mountpoint
;
1294 m
= mnt
->mnt_parent
;
1295 mnt
->mnt_mountpoint
= mnt
->mnt
.mnt_root
;
1296 mnt
->mnt_parent
= mnt
;
1298 br_write_unlock(&vfsmount_lock
);
1306 static inline void namespace_lock(void)
1308 down_write(&namespace_sem
);
1312 * vfsmount lock must be held for write
1313 * namespace_sem must be held for write
1315 void umount_tree(struct mount
*mnt
, int propagate
)
1317 LIST_HEAD(tmp_list
);
1320 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
))
1321 list_move(&p
->mnt_hash
, &tmp_list
);
1324 propagate_umount(&tmp_list
);
1326 list_for_each_entry(p
, &tmp_list
, mnt_hash
) {
1327 list_del_init(&p
->mnt_expire
);
1328 list_del_init(&p
->mnt_list
);
1329 __touch_mnt_namespace(p
->mnt_ns
);
1331 list_del_init(&p
->mnt_child
);
1332 if (mnt_has_parent(p
)) {
1333 p
->mnt_parent
->mnt_ghosts
++;
1334 put_mountpoint(p
->mnt_mp
);
1337 change_mnt_propagation(p
, MS_PRIVATE
);
1339 list_splice(&tmp_list
, &unmounted
);
1342 static void shrink_submounts(struct mount
*mnt
);
1344 static int do_umount(struct mount
*mnt
, int flags
)
1346 struct super_block
*sb
= mnt
->mnt
.mnt_sb
;
1349 retval
= security_sb_umount(&mnt
->mnt
, flags
);
1354 * Allow userspace to request a mountpoint be expired rather than
1355 * unmounting unconditionally. Unmount only happens if:
1356 * (1) the mark is already set (the mark is cleared by mntput())
1357 * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
1359 if (flags
& MNT_EXPIRE
) {
1360 if (&mnt
->mnt
== current
->fs
->root
.mnt
||
1361 flags
& (MNT_FORCE
| MNT_DETACH
))
1365 * probably don't strictly need the lock here if we examined
1366 * all race cases, but it's a slowpath.
1368 br_write_lock(&vfsmount_lock
);
1369 if (mnt_get_count(mnt
) != 2) {
1370 br_write_unlock(&vfsmount_lock
);
1373 br_write_unlock(&vfsmount_lock
);
1375 if (!xchg(&mnt
->mnt_expiry_mark
, 1))
1380 * If we may have to abort operations to get out of this
1381 * mount, and they will themselves hold resources we must
1382 * allow the fs to do things. In the Unix tradition of
1383 * 'Gee thats tricky lets do it in userspace' the umount_begin
1384 * might fail to complete on the first run through as other tasks
1385 * must return, and the like. Thats for the mount program to worry
1386 * about for the moment.
1389 if (flags
& MNT_FORCE
&& sb
->s_op
->umount_begin
) {
1390 sb
->s_op
->umount_begin(sb
);
1394 * No sense to grab the lock for this test, but test itself looks
1395 * somewhat bogus. Suggestions for better replacement?
1396 * Ho-hum... In principle, we might treat that as umount + switch
1397 * to rootfs. GC would eventually take care of the old vfsmount.
1398 * Actually it makes sense, especially if rootfs would contain a
1399 * /reboot - static binary that would close all descriptors and
1400 * call reboot(9). Then init(8) could umount root and exec /reboot.
1402 if (&mnt
->mnt
== current
->fs
->root
.mnt
&& !(flags
& MNT_DETACH
)) {
1404 * Special case for "unmounting" root ...
1405 * we just try to remount it readonly.
1407 if (!capable(CAP_SYS_ADMIN
))
1409 down_write(&sb
->s_umount
);
1410 if (!(sb
->s_flags
& MS_RDONLY
))
1411 retval
= do_remount_sb(sb
, MS_RDONLY
, NULL
, 0);
1412 up_write(&sb
->s_umount
);
1417 br_write_lock(&vfsmount_lock
);
1420 if (!(flags
& MNT_DETACH
))
1421 shrink_submounts(mnt
);
1424 if (flags
& MNT_DETACH
|| !propagate_mount_busy(mnt
, 2)) {
1425 if (!list_empty(&mnt
->mnt_list
))
1426 umount_tree(mnt
, 1);
1429 br_write_unlock(&vfsmount_lock
);
1435 * Is the caller allowed to modify his namespace?
1437 static inline bool may_mount(void)
1439 return ns_capable(current
->nsproxy
->mnt_ns
->user_ns
, CAP_SYS_ADMIN
);
1443 * Now umount can handle mount points as well as block devices.
1444 * This is important for filesystems which use unnamed block devices.
1446 * We now support a flag for forced unmount like the other 'big iron'
1447 * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD
1450 SYSCALL_DEFINE2(umount
, char __user
*, name
, int, flags
)
1455 int lookup_flags
= 0;
1459 if (flags
& ~(MNT_FORCE
| MNT_DETACH
| MNT_EXPIRE
| UMOUNT_NOFOLLOW
))
1465 if (!(flags
& UMOUNT_NOFOLLOW
))
1466 lookup_flags
|= LOOKUP_FOLLOW
;
1468 retval
= user_path_at(AT_FDCWD
, name
, lookup_flags
, &path
);
1471 mnt
= real_mount(path
.mnt
);
1473 if (path
.dentry
!= path
.mnt
->mnt_root
)
1475 if (!check_mnt(mnt
))
1478 if (flags
& MNT_FORCE
&& !capable(CAP_SYS_ADMIN
))
1481 retval
= do_umount(mnt
, flags
);
1484 printk("Ahsin do_umount retval=%d \n",retval
);
1485 //do_umount success: 0, do_umount busy: -16
1486 //if do_umount fail, need to dump the link list here
1489 printk("Ahsin do_umount fail; mnt_get_count=%d mnt->mnt_devname=%s\n",mnt_get_count(mnt
),mnt
->mnt_devname
);
1491 printk("Ahsin do_umount success; mnt_get_count=%d mnt->mnt_devname=%s\n",mnt_get_count(mnt
),mnt
->mnt_devname
);
1493 // print linked list
1494 spin_lock(&mnt_id_lock
);
1495 ref_current
= ref_head
;
1496 while(ref_current
!= NULL
)
1498 total_value
= total_value
+ ref_current
->count
;
1500 if (ref_current
->count
)
1501 printk("Ahsin PID= %d, Name = %s, Count= %d \n", ref_current
->pid
, ref_current
->name
, ref_current
->count
);
1502 ref_current
= ref_current
->next
;
1504 spin_unlock(&mnt_id_lock
);
1505 printk("Ahsin total_value=%d \n",total_value
);
1509 /* we mustn't call path_put() as that would clear mnt_expiry_mark */
1511 mntput_no_expire(mnt
);
1516 #ifdef __ARCH_WANT_SYS_OLDUMOUNT
1519 * The 2.0 compatible umount. No flags.
1521 SYSCALL_DEFINE1(oldumount
, char __user
*, name
)
1523 return sys_umount(name
, 0);
1528 static bool mnt_ns_loop(struct path
*path
)
1530 /* Could bind mounting the mount namespace inode cause a
1531 * mount namespace loop?
1533 struct inode
*inode
= path
->dentry
->d_inode
;
1535 struct mnt_namespace
*mnt_ns
;
1537 if (!proc_ns_inode(inode
))
1540 ei
= get_proc_ns(inode
);
1541 if (ei
->ns_ops
!= &mntns_operations
)
1545 return current
->nsproxy
->mnt_ns
->seq
>= mnt_ns
->seq
;
1548 struct mount
*copy_tree(struct mount
*mnt
, struct dentry
*dentry
,
1551 struct mount
*res
, *p
, *q
, *r
, *parent
;
1553 if (!(flag
& CL_COPY_ALL
) && IS_MNT_UNBINDABLE(mnt
))
1554 return ERR_PTR(-EINVAL
);
1556 res
= q
= clone_mnt(mnt
, dentry
, flag
);
1560 q
->mnt_mountpoint
= mnt
->mnt_mountpoint
;
1563 list_for_each_entry(r
, &mnt
->mnt_mounts
, mnt_child
) {
1565 if (!is_subdir(r
->mnt_mountpoint
, dentry
))
1568 for (s
= r
; s
; s
= next_mnt(s
, r
)) {
1569 if (!(flag
& CL_COPY_ALL
) && IS_MNT_UNBINDABLE(s
)) {
1570 s
= skip_mnt_tree(s
);
1573 while (p
!= s
->mnt_parent
) {
1579 q
= clone_mnt(p
, p
->mnt
.mnt_root
, flag
);
1582 br_write_lock(&vfsmount_lock
);
1583 list_add_tail(&q
->mnt_list
, &res
->mnt_list
);
1584 attach_mnt(q
, parent
, p
->mnt_mp
);
1585 br_write_unlock(&vfsmount_lock
);
1591 br_write_lock(&vfsmount_lock
);
1592 umount_tree(res
, 0);
1593 br_write_unlock(&vfsmount_lock
);
1598 /* Caller should check returned pointer for errors */
1600 struct vfsmount
*collect_mounts(struct path
*path
)
1604 tree
= copy_tree(real_mount(path
->mnt
), path
->dentry
,
1605 CL_COPY_ALL
| CL_PRIVATE
);
1608 return ERR_CAST(tree
);
1612 void drop_collected_mounts(struct vfsmount
*mnt
)
1615 br_write_lock(&vfsmount_lock
);
1616 umount_tree(real_mount(mnt
), 0);
1617 br_write_unlock(&vfsmount_lock
);
1621 int iterate_mounts(int (*f
)(struct vfsmount
*, void *), void *arg
,
1622 struct vfsmount
*root
)
1625 int res
= f(root
, arg
);
1628 list_for_each_entry(mnt
, &real_mount(root
)->mnt_list
, mnt_list
) {
1629 res
= f(&mnt
->mnt
, arg
);
1636 static void cleanup_group_ids(struct mount
*mnt
, struct mount
*end
)
1640 for (p
= mnt
; p
!= end
; p
= next_mnt(p
, mnt
)) {
1641 if (p
->mnt_group_id
&& !IS_MNT_SHARED(p
))
1642 mnt_release_group_id(p
);
1646 static int invent_group_ids(struct mount
*mnt
, bool recurse
)
1650 for (p
= mnt
; p
; p
= recurse
? next_mnt(p
, mnt
) : NULL
) {
1651 if (!p
->mnt_group_id
&& !IS_MNT_SHARED(p
)) {
1652 int err
= mnt_alloc_group_id(p
);
1654 cleanup_group_ids(mnt
, p
);
1664 * @source_mnt : mount tree to be attached
1665 * @nd : place the mount tree @source_mnt is attached
1666 * @parent_nd : if non-null, detach the source_mnt from its parent and
1667 * store the parent mount and mountpoint dentry.
1668 * (done when source_mnt is moved)
1670 * NOTE: in the table below explains the semantics when a source mount
1671 * of a given type is attached to a destination mount of a given type.
1672 * ---------------------------------------------------------------------------
1673 * | BIND MOUNT OPERATION |
1674 * |**************************************************************************
1675 * | source-->| shared | private | slave | unbindable |
1679 * |**************************************************************************
1680 * | shared | shared (++) | shared (+) | shared(+++)| invalid |
1682 * |non-shared| shared (+) | private | slave (*) | invalid |
1683 * ***************************************************************************
1684 * A bind operation clones the source mount and mounts the clone on the
1685 * destination mount.
1687 * (++) the cloned mount is propagated to all the mounts in the propagation
1688 * tree of the destination mount and the cloned mount is added to
1689 * the peer group of the source mount.
1690 * (+) the cloned mount is created under the destination mount and is marked
1691 * as shared. The cloned mount is added to the peer group of the source
1693 * (+++) the mount is propagated to all the mounts in the propagation tree
1694 * of the destination mount and the cloned mount is made slave
1695 * of the same master as that of the source mount. The cloned mount
1696 * is marked as 'shared and slave'.
1697 * (*) the cloned mount is made a slave of the same master as that of the
1700 * ---------------------------------------------------------------------------
1701 * | MOVE MOUNT OPERATION |
1702 * |**************************************************************************
1703 * | source-->| shared | private | slave | unbindable |
1707 * |**************************************************************************
1708 * | shared | shared (+) | shared (+) | shared(+++) | invalid |
1710 * |non-shared| shared (+*) | private | slave (*) | unbindable |
1711 * ***************************************************************************
1713 * (+) the mount is moved to the destination. And is then propagated to
1714 * all the mounts in the propagation tree of the destination mount.
1715 * (+*) the mount is moved to the destination.
1716 * (+++) the mount is moved to the destination and is then propagated to
1717 * all the mounts belonging to the destination mount's propagation tree.
1718 * the mount is marked as 'shared and slave'.
1719 * (*) the mount continues to be a slave at the new location.
1721 * if the source mount is a tree, the operations explained above is
1722 * applied to each mount in the tree.
1723 * Must be called without spinlocks held, since this function can sleep
1726 static int attach_recursive_mnt(struct mount
*source_mnt
,
1727 struct mount
*dest_mnt
,
1728 struct mountpoint
*dest_mp
,
1729 struct path
*parent_path
)
1731 LIST_HEAD(tree_list
);
1732 struct mount
*child
, *p
;
1735 if (IS_MNT_SHARED(dest_mnt
)) {
1736 err
= invent_group_ids(source_mnt
, true);
1740 err
= propagate_mnt(dest_mnt
, dest_mp
, source_mnt
, &tree_list
);
1742 goto out_cleanup_ids
;
1744 br_write_lock(&vfsmount_lock
);
1746 if (IS_MNT_SHARED(dest_mnt
)) {
1747 for (p
= source_mnt
; p
; p
= next_mnt(p
, source_mnt
))
1751 detach_mnt(source_mnt
, parent_path
);
1752 attach_mnt(source_mnt
, dest_mnt
, dest_mp
);
1753 touch_mnt_namespace(source_mnt
->mnt_ns
);
1755 mnt_set_mountpoint(dest_mnt
, dest_mp
, source_mnt
);
1756 commit_tree(source_mnt
);
1759 list_for_each_entry_safe(child
, p
, &tree_list
, mnt_hash
) {
1760 list_del_init(&child
->mnt_hash
);
1763 br_write_unlock(&vfsmount_lock
);
1768 if (IS_MNT_SHARED(dest_mnt
))
1769 cleanup_group_ids(source_mnt
, NULL
);
1774 static struct mountpoint
*lock_mount(struct path
*path
)
1776 struct vfsmount
*mnt
;
1777 struct dentry
*dentry
= path
->dentry
;
1779 mutex_lock(&dentry
->d_inode
->i_mutex
);
1780 if (unlikely(cant_mount(dentry
))) {
1781 mutex_unlock(&dentry
->d_inode
->i_mutex
);
1782 return ERR_PTR(-ENOENT
);
1785 mnt
= lookup_mnt(path
);
1787 struct mountpoint
*mp
= new_mountpoint(dentry
);
1790 mutex_unlock(&dentry
->d_inode
->i_mutex
);
1796 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
1799 dentry
= path
->dentry
= dget(mnt
->mnt_root
);
1803 static void unlock_mount(struct mountpoint
*where
)
1805 struct dentry
*dentry
= where
->m_dentry
;
1806 put_mountpoint(where
);
1808 mutex_unlock(&dentry
->d_inode
->i_mutex
);
1811 static int graft_tree(struct mount
*mnt
, struct mount
*p
, struct mountpoint
*mp
)
1813 if (mnt
->mnt
.mnt_sb
->s_flags
& MS_NOUSER
)
1816 if (S_ISDIR(mp
->m_dentry
->d_inode
->i_mode
) !=
1817 S_ISDIR(mnt
->mnt
.mnt_root
->d_inode
->i_mode
))
1820 return attach_recursive_mnt(mnt
, p
, mp
, NULL
);
1824 * Sanity check the flags to change_mnt_propagation.
1827 static int flags_to_propagation_type(int flags
)
1829 int type
= flags
& ~(MS_REC
| MS_SILENT
);
1831 /* Fail if any non-propagation flags are set */
1832 if (type
& ~(MS_SHARED
| MS_PRIVATE
| MS_SLAVE
| MS_UNBINDABLE
))
1834 /* Only one propagation flag should be set */
1835 if (!is_power_of_2(type
))
1841 * recursively change the type of the mountpoint.
1843 static int do_change_type(struct path
*path
, int flag
)
1846 struct mount
*mnt
= real_mount(path
->mnt
);
1847 int recurse
= flag
& MS_REC
;
1851 if (path
->dentry
!= path
->mnt
->mnt_root
)
1854 type
= flags_to_propagation_type(flag
);
1859 if (type
== MS_SHARED
) {
1860 err
= invent_group_ids(mnt
, recurse
);
1865 br_write_lock(&vfsmount_lock
);
1866 for (m
= mnt
; m
; m
= (recurse
? next_mnt(m
, mnt
) : NULL
))
1867 change_mnt_propagation(m
, type
);
1868 br_write_unlock(&vfsmount_lock
);
1876 * do loopback mount.
1878 static int do_loopback(struct path
*path
, const char *old_name
,
1881 struct path old_path
;
1882 struct mount
*mnt
= NULL
, *old
, *parent
;
1883 struct mountpoint
*mp
;
1885 if (!old_name
|| !*old_name
)
1887 err
= kern_path(old_name
, LOOKUP_FOLLOW
|LOOKUP_AUTOMOUNT
, &old_path
);
1892 if (mnt_ns_loop(&old_path
))
1895 mp
= lock_mount(path
);
1900 old
= real_mount(old_path
.mnt
);
1901 parent
= real_mount(path
->mnt
);
1904 if (IS_MNT_UNBINDABLE(old
))
1907 if (!check_mnt(parent
) || !check_mnt(old
))
1911 mnt
= copy_tree(old
, old_path
.dentry
, 0);
1913 mnt
= clone_mnt(old
, old_path
.dentry
, 0);
1920 err
= graft_tree(mnt
, parent
, mp
);
1922 br_write_lock(&vfsmount_lock
);
1923 umount_tree(mnt
, 0);
1924 br_write_unlock(&vfsmount_lock
);
1929 path_put(&old_path
);
1933 static int change_mount_flags(struct vfsmount
*mnt
, int ms_flags
)
1936 int readonly_request
= 0;
1938 if (ms_flags
& MS_RDONLY
)
1939 readonly_request
= 1;
1940 if (readonly_request
== __mnt_is_readonly(mnt
))
1943 if (readonly_request
)
1944 error
= mnt_make_readonly(real_mount(mnt
));
1946 __mnt_unmake_readonly(real_mount(mnt
));
1951 * change filesystem flags. dir should be a physical root of filesystem.
1952 * If you've mounted a non-root directory somewhere and want to do remount
1953 * on it - tough luck.
1955 static int do_remount(struct path
*path
, int flags
, int mnt_flags
,
1959 struct super_block
*sb
= path
->mnt
->mnt_sb
;
1960 struct mount
*mnt
= real_mount(path
->mnt
);
1962 if (!check_mnt(mnt
))
1965 if (path
->dentry
!= path
->mnt
->mnt_root
)
1968 /* Don't allow changing of locked mnt flags.
1970 * No locks need to be held here while testing the various
1971 * MNT_LOCK flags because those flags can never be cleared
1972 * once they are set.
1974 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_READONLY
) &&
1975 !(mnt_flags
& MNT_READONLY
)) {
1978 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_NODEV
) &&
1979 !(mnt_flags
& MNT_NODEV
)) {
1980 /* Was the nodev implicitly added in mount? */
1981 if ((mnt
->mnt_ns
->user_ns
!= &init_user_ns
) &&
1982 !(sb
->s_type
->fs_flags
& FS_USERNS_DEV_MOUNT
)) {
1983 mnt_flags
|= MNT_NODEV
;
1988 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_NOSUID
) &&
1989 !(mnt_flags
& MNT_NOSUID
)) {
1992 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_NOEXEC
) &&
1993 !(mnt_flags
& MNT_NOEXEC
)) {
1996 if ((mnt
->mnt
.mnt_flags
& MNT_LOCK_ATIME
) &&
1997 ((mnt
->mnt
.mnt_flags
& MNT_ATIME_MASK
) != (mnt_flags
& MNT_ATIME_MASK
))) {
2001 err
= security_sb_remount(sb
, data
);
2005 down_write(&sb
->s_umount
);
2006 if (flags
& MS_BIND
)
2007 err
= change_mount_flags(path
->mnt
, flags
);
2008 else if (!capable(CAP_SYS_ADMIN
))
2011 err
= do_remount_sb(sb
, flags
, data
, 0);
2013 br_write_lock(&vfsmount_lock
);
2014 mnt_flags
|= mnt
->mnt
.mnt_flags
& ~MNT_USER_SETTABLE_MASK
;
2015 mnt
->mnt
.mnt_flags
= mnt_flags
;
2016 br_write_unlock(&vfsmount_lock
);
2018 up_write(&sb
->s_umount
);
2020 br_write_lock(&vfsmount_lock
);
2021 touch_mnt_namespace(mnt
->mnt_ns
);
2022 br_write_unlock(&vfsmount_lock
);
2027 static inline int tree_contains_unbindable(struct mount
*mnt
)
2030 for (p
= mnt
; p
; p
= next_mnt(p
, mnt
)) {
2031 if (IS_MNT_UNBINDABLE(p
))
2037 static int do_move_mount(struct path
*path
, const char *old_name
)
2039 struct path old_path
, parent_path
;
2042 struct mountpoint
*mp
;
2044 if (!old_name
|| !*old_name
)
2046 err
= kern_path(old_name
, LOOKUP_FOLLOW
, &old_path
);
2050 mp
= lock_mount(path
);
2055 old
= real_mount(old_path
.mnt
);
2056 p
= real_mount(path
->mnt
);
2059 if (!check_mnt(p
) || !check_mnt(old
))
2063 if (old_path
.dentry
!= old_path
.mnt
->mnt_root
)
2066 if (!mnt_has_parent(old
))
2069 if (S_ISDIR(path
->dentry
->d_inode
->i_mode
) !=
2070 S_ISDIR(old_path
.dentry
->d_inode
->i_mode
))
2073 * Don't move a mount residing in a shared parent.
2075 if (IS_MNT_SHARED(old
->mnt_parent
))
2078 * Don't move a mount tree containing unbindable mounts to a destination
2079 * mount which is shared.
2081 if (IS_MNT_SHARED(p
) && tree_contains_unbindable(old
))
2084 for (; mnt_has_parent(p
); p
= p
->mnt_parent
)
2088 err
= attach_recursive_mnt(old
, real_mount(path
->mnt
), mp
, &parent_path
);
2092 /* if the mount is moved, it should no longer be expire
2094 list_del_init(&old
->mnt_expire
);
2099 path_put(&parent_path
);
2100 path_put(&old_path
);
2104 static struct vfsmount
*fs_set_subtype(struct vfsmount
*mnt
, const char *fstype
)
2107 const char *subtype
= strchr(fstype
, '.');
2116 mnt
->mnt_sb
->s_subtype
= kstrdup(subtype
, GFP_KERNEL
);
2118 if (!mnt
->mnt_sb
->s_subtype
)
2124 return ERR_PTR(err
);
2128 * add a mount into a namespace's mount tree
2130 static int do_add_mount(struct mount
*newmnt
, struct path
*path
, int mnt_flags
)
2132 struct mountpoint
*mp
;
2133 struct mount
*parent
;
2136 mnt_flags
&= ~(MNT_SHARED
| MNT_WRITE_HOLD
| MNT_INTERNAL
);
2138 mp
= lock_mount(path
);
2142 parent
= real_mount(path
->mnt
);
2144 if (unlikely(!check_mnt(parent
))) {
2145 /* that's acceptable only for automounts done in private ns */
2146 if (!(mnt_flags
& MNT_SHRINKABLE
))
2148 /* ... and for those we'd better have mountpoint still alive */
2149 if (!parent
->mnt_ns
)
2153 /* Refuse the same filesystem on the same mount point */
2155 if (path
->mnt
->mnt_sb
== newmnt
->mnt
.mnt_sb
&&
2156 path
->mnt
->mnt_root
== path
->dentry
)
2160 if (S_ISLNK(newmnt
->mnt
.mnt_root
->d_inode
->i_mode
))
2163 newmnt
->mnt
.mnt_flags
= mnt_flags
;
2164 err
= graft_tree(newmnt
, parent
, mp
);
2172 * create a new mount for userspace and request it to be added into the
2175 static int do_new_mount(struct path
*path
, const char *fstype
, int flags
,
2176 int mnt_flags
, const char *name
, void *data
)
2178 struct file_system_type
*type
;
2179 struct user_namespace
*user_ns
= current
->nsproxy
->mnt_ns
->user_ns
;
2180 struct vfsmount
*mnt
;
2186 type
= get_fs_type(fstype
);
2190 if (user_ns
!= &init_user_ns
) {
2191 if (!(type
->fs_flags
& FS_USERNS_MOUNT
)) {
2192 put_filesystem(type
);
2195 /* Only in special cases allow devices from mounts
2196 * created outside the initial user namespace.
2198 if (!(type
->fs_flags
& FS_USERNS_DEV_MOUNT
)) {
2200 mnt_flags
|= MNT_NODEV
| MNT_LOCK_NODEV
;
2204 mnt
= vfs_kern_mount(type
, flags
, name
, data
);
2205 if (!IS_ERR(mnt
) && (type
->fs_flags
& FS_HAS_SUBTYPE
) &&
2206 !mnt
->mnt_sb
->s_subtype
)
2207 mnt
= fs_set_subtype(mnt
, fstype
);
2209 put_filesystem(type
);
2211 return PTR_ERR(mnt
);
2213 err
= do_add_mount(real_mount(mnt
), path
, mnt_flags
);
2219 int finish_automount(struct vfsmount
*m
, struct path
*path
)
2221 struct mount
*mnt
= real_mount(m
);
2223 /* The new mount record should have at least 2 refs to prevent it being
2224 * expired before we get a chance to add it
2226 BUG_ON(mnt_get_count(mnt
) < 2);
2228 if (m
->mnt_sb
== path
->mnt
->mnt_sb
&&
2229 m
->mnt_root
== path
->dentry
) {
2234 err
= do_add_mount(mnt
, path
, path
->mnt
->mnt_flags
| MNT_SHRINKABLE
);
2238 /* remove m from any expiration list it may be on */
2239 if (!list_empty(&mnt
->mnt_expire
)) {
2241 br_write_lock(&vfsmount_lock
);
2242 list_del_init(&mnt
->mnt_expire
);
2243 br_write_unlock(&vfsmount_lock
);
2252 * mnt_set_expiry - Put a mount on an expiration list
2253 * @mnt: The mount to list.
2254 * @expiry_list: The list to add the mount to.
2256 void mnt_set_expiry(struct vfsmount
*mnt
, struct list_head
*expiry_list
)
2259 br_write_lock(&vfsmount_lock
);
2261 list_add_tail(&real_mount(mnt
)->mnt_expire
, expiry_list
);
2263 br_write_unlock(&vfsmount_lock
);
2266 EXPORT_SYMBOL(mnt_set_expiry
);
2269 * process a list of expirable mountpoints with the intent of discarding any
2270 * mountpoints that aren't in use and haven't been touched since last we came
2273 void mark_mounts_for_expiry(struct list_head
*mounts
)
2275 struct mount
*mnt
, *next
;
2276 LIST_HEAD(graveyard
);
2278 if (list_empty(mounts
))
2282 br_write_lock(&vfsmount_lock
);
2284 /* extract from the expiration list every vfsmount that matches the
2285 * following criteria:
2286 * - only referenced by its parent vfsmount
2287 * - still marked for expiry (marked on the last call here; marks are
2288 * cleared by mntput())
2290 list_for_each_entry_safe(mnt
, next
, mounts
, mnt_expire
) {
2291 if (!xchg(&mnt
->mnt_expiry_mark
, 1) ||
2292 propagate_mount_busy(mnt
, 1))
2294 list_move(&mnt
->mnt_expire
, &graveyard
);
2296 while (!list_empty(&graveyard
)) {
2297 mnt
= list_first_entry(&graveyard
, struct mount
, mnt_expire
);
2298 touch_mnt_namespace(mnt
->mnt_ns
);
2299 umount_tree(mnt
, 1);
2301 br_write_unlock(&vfsmount_lock
);
2305 EXPORT_SYMBOL_GPL(mark_mounts_for_expiry
);
2308 * Ripoff of 'select_parent()'
2310 * search the list of submounts for a given mountpoint, and move any
2311 * shrinkable submounts to the 'graveyard' list.
2313 static int select_submounts(struct mount
*parent
, struct list_head
*graveyard
)
2315 struct mount
*this_parent
= parent
;
2316 struct list_head
*next
;
2320 next
= this_parent
->mnt_mounts
.next
;
2322 while (next
!= &this_parent
->mnt_mounts
) {
2323 struct list_head
*tmp
= next
;
2324 struct mount
*mnt
= list_entry(tmp
, struct mount
, mnt_child
);
2327 if (!(mnt
->mnt
.mnt_flags
& MNT_SHRINKABLE
))
2330 * Descend a level if the d_mounts list is non-empty.
2332 if (!list_empty(&mnt
->mnt_mounts
)) {
2337 if (!propagate_mount_busy(mnt
, 1)) {
2338 list_move_tail(&mnt
->mnt_expire
, graveyard
);
2343 * All done at this level ... ascend and resume the search
2345 if (this_parent
!= parent
) {
2346 next
= this_parent
->mnt_child
.next
;
2347 this_parent
= this_parent
->mnt_parent
;
2354 * process a list of expirable mountpoints with the intent of discarding any
2355 * submounts of a specific parent mountpoint
2357 * vfsmount_lock must be held for write
2359 static void shrink_submounts(struct mount
*mnt
)
2361 LIST_HEAD(graveyard
);
2364 /* extract submounts of 'mountpoint' from the expiration list */
2365 while (select_submounts(mnt
, &graveyard
)) {
2366 while (!list_empty(&graveyard
)) {
2367 m
= list_first_entry(&graveyard
, struct mount
,
2369 touch_mnt_namespace(m
->mnt_ns
);
2376 * Some copy_from_user() implementations do not return the exact number of
2377 * bytes remaining to copy on a fault. But copy_mount_options() requires that.
2378 * Note that this function differs from copy_from_user() in that it will oops
2379 * on bad values of `to', rather than returning a short copy.
2381 static long exact_copy_from_user(void *to
, const void __user
* from
,
2385 const char __user
*f
= from
;
2388 if (!access_ok(VERIFY_READ
, from
, n
))
2392 if (__get_user(c
, f
)) {
2403 int copy_mount_options(const void __user
* data
, unsigned long *where
)
2413 if (!(page
= __get_free_page(GFP_KERNEL
)))
2416 /* We only care that *some* data at the address the user
2417 * gave us is valid. Just in case, we'll zero
2418 * the remainder of the page.
2420 /* copy_from_user cannot cross TASK_SIZE ! */
2421 size
= TASK_SIZE
- (unsigned long)data
;
2422 if (size
> PAGE_SIZE
)
2425 i
= size
- exact_copy_from_user((void *)page
, data
, size
);
2431 memset((char *)page
+ i
, 0, PAGE_SIZE
- i
);
2436 int copy_mount_string(const void __user
*data
, char **where
)
2445 tmp
= strndup_user(data
, PAGE_SIZE
);
2447 return PTR_ERR(tmp
);
2454 * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to
2455 * be given to the mount() call (ie: read-only, no-dev, no-suid etc).
2457 * data is a (void *) that can point to any structure up to
2458 * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent
2459 * information (or be NULL).
2461 * Pre-0.97 versions of mount() didn't have a flags word.
2462 * When the flags word was introduced its top half was required
2463 * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9.
2464 * Therefore, if this magic number is present, it carries no information
2465 * and must be discarded.
2467 long do_mount(const char *dev_name
, const char *dir_name
,
2468 const char *type_page
, unsigned long flags
, void *data_page
)
2475 if ((flags
& MS_MGC_MSK
) == MS_MGC_VAL
)
2476 flags
&= ~MS_MGC_MSK
;
2478 /* Basic sanity checks */
2480 if (!dir_name
|| !*dir_name
|| !memchr(dir_name
, 0, PAGE_SIZE
))
2484 ((char *)data_page
)[PAGE_SIZE
- 1] = 0;
2486 /* ... and get the mountpoint */
2487 retval
= kern_path(dir_name
, LOOKUP_FOLLOW
, &path
);
2491 retval
= security_sb_mount(dev_name
, &path
,
2492 type_page
, flags
, data_page
);
2493 if (!retval
&& !may_mount())
2498 /* Default to relatime unless overriden */
2499 if (!(flags
& MS_NOATIME
))
2500 mnt_flags
|= MNT_RELATIME
;
2502 /* Separate the per-mountpoint flags */
2503 if (flags
& MS_NOSUID
)
2504 mnt_flags
|= MNT_NOSUID
;
2505 if (flags
& MS_NODEV
)
2506 mnt_flags
|= MNT_NODEV
;
2507 if (flags
& MS_NOEXEC
)
2508 mnt_flags
|= MNT_NOEXEC
;
2509 if (flags
& MS_NOATIME
)
2510 mnt_flags
|= MNT_NOATIME
;
2511 if (flags
& MS_NODIRATIME
)
2512 mnt_flags
|= MNT_NODIRATIME
;
2513 if (flags
& MS_STRICTATIME
)
2514 mnt_flags
&= ~(MNT_RELATIME
| MNT_NOATIME
);
2515 if (flags
& MS_RDONLY
)
2516 mnt_flags
|= MNT_READONLY
;
2518 /* The default atime for remount is preservation */
2519 if ((flags
& MS_REMOUNT
) &&
2520 ((flags
& (MS_NOATIME
| MS_NODIRATIME
| MS_RELATIME
|
2521 MS_STRICTATIME
)) == 0)) {
2522 mnt_flags
&= ~MNT_ATIME_MASK
;
2523 mnt_flags
|= path
.mnt
->mnt_flags
& MNT_ATIME_MASK
;
2526 flags
&= ~(MS_NOSUID
| MS_NOEXEC
| MS_NODEV
| MS_ACTIVE
| MS_BORN
|
2527 MS_NOATIME
| MS_NODIRATIME
| MS_RELATIME
| MS_KERNMOUNT
|
2530 if (flags
& MS_REMOUNT
)
2531 retval
= do_remount(&path
, flags
& ~MS_REMOUNT
, mnt_flags
,
2533 else if (flags
& MS_BIND
)
2534 retval
= do_loopback(&path
, dev_name
, flags
& MS_REC
);
2535 else if (flags
& (MS_SHARED
| MS_PRIVATE
| MS_SLAVE
| MS_UNBINDABLE
))
2536 retval
= do_change_type(&path
, flags
);
2537 else if (flags
& MS_MOVE
)
2538 retval
= do_move_mount(&path
, dev_name
);
2540 retval
= do_new_mount(&path
, type_page
, flags
, mnt_flags
,
2541 dev_name
, data_page
);
2547 static void free_mnt_ns(struct mnt_namespace
*ns
)
2549 proc_free_inum(ns
->proc_inum
);
2550 put_user_ns(ns
->user_ns
);
2555 * Assign a sequence number so we can detect when we attempt to bind
2556 * mount a reference to an older mount namespace into the current
2557 * mount namespace, preventing reference counting loops. A 64bit
2558 * number incrementing at 10Ghz will take 12,427 years to wrap which
2559 * is effectively never, so we can ignore the possibility.
2561 static atomic64_t mnt_ns_seq
= ATOMIC64_INIT(1);
2563 static struct mnt_namespace
*alloc_mnt_ns(struct user_namespace
*user_ns
)
2565 struct mnt_namespace
*new_ns
;
2568 new_ns
= kmalloc(sizeof(struct mnt_namespace
), GFP_KERNEL
);
2570 return ERR_PTR(-ENOMEM
);
2571 ret
= proc_alloc_inum(&new_ns
->proc_inum
);
2574 return ERR_PTR(ret
);
2576 new_ns
->seq
= atomic64_add_return(1, &mnt_ns_seq
);
2577 atomic_set(&new_ns
->count
, 1);
2578 new_ns
->root
= NULL
;
2579 INIT_LIST_HEAD(&new_ns
->list
);
2580 init_waitqueue_head(&new_ns
->poll
);
2582 new_ns
->user_ns
= get_user_ns(user_ns
);
2587 * Allocate a new namespace structure and populate it with contents
2588 * copied from the namespace of the passed in task structure.
2590 static struct mnt_namespace
*dup_mnt_ns(struct mnt_namespace
*mnt_ns
,
2591 struct user_namespace
*user_ns
, struct fs_struct
*fs
)
2593 struct mnt_namespace
*new_ns
;
2594 struct vfsmount
*rootmnt
= NULL
, *pwdmnt
= NULL
;
2595 struct mount
*p
, *q
;
2596 struct mount
*old
= mnt_ns
->root
;
2600 new_ns
= alloc_mnt_ns(user_ns
);
2605 /* First pass: copy the tree topology */
2606 copy_flags
= CL_COPY_ALL
| CL_EXPIRE
;
2607 if (user_ns
!= mnt_ns
->user_ns
)
2608 copy_flags
|= CL_SHARED_TO_SLAVE
| CL_UNPRIVILEGED
;
2609 new = copy_tree(old
, old
->mnt
.mnt_root
, copy_flags
);
2612 free_mnt_ns(new_ns
);
2613 return ERR_CAST(new);
2616 br_write_lock(&vfsmount_lock
);
2617 list_add_tail(&new_ns
->list
, &new->mnt_list
);
2618 br_write_unlock(&vfsmount_lock
);
2621 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
2622 * as belonging to new namespace. We have already acquired a private
2623 * fs_struct, so tsk->fs->lock is not needed.
2630 if (&p
->mnt
== fs
->root
.mnt
) {
2631 fs
->root
.mnt
= mntget(&q
->mnt
);
2634 if (&p
->mnt
== fs
->pwd
.mnt
) {
2635 fs
->pwd
.mnt
= mntget(&q
->mnt
);
2639 p
= next_mnt(p
, old
);
2640 q
= next_mnt(q
, new);
2652 struct mnt_namespace
*copy_mnt_ns(unsigned long flags
, struct mnt_namespace
*ns
,
2653 struct user_namespace
*user_ns
, struct fs_struct
*new_fs
)
2655 struct mnt_namespace
*new_ns
;
2660 if (!(flags
& CLONE_NEWNS
))
2663 new_ns
= dup_mnt_ns(ns
, user_ns
, new_fs
);
2670 * create_mnt_ns - creates a private namespace and adds a root filesystem
2671 * @mnt: pointer to the new root filesystem mountpoint
2673 static struct mnt_namespace
*create_mnt_ns(struct vfsmount
*m
)
2675 struct mnt_namespace
*new_ns
= alloc_mnt_ns(&init_user_ns
);
2676 if (!IS_ERR(new_ns
)) {
2677 struct mount
*mnt
= real_mount(m
);
2678 mnt
->mnt_ns
= new_ns
;
2680 list_add(&mnt
->mnt_list
, &new_ns
->list
);
2687 struct dentry
*mount_subtree(struct vfsmount
*mnt
, const char *name
)
2689 struct mnt_namespace
*ns
;
2690 struct super_block
*s
;
2694 ns
= create_mnt_ns(mnt
);
2696 return ERR_CAST(ns
);
2698 err
= vfs_path_lookup(mnt
->mnt_root
, mnt
,
2699 name
, LOOKUP_FOLLOW
|LOOKUP_AUTOMOUNT
, &path
);
2704 return ERR_PTR(err
);
2706 /* trade a vfsmount reference for active sb one */
2707 s
= path
.mnt
->mnt_sb
;
2708 atomic_inc(&s
->s_active
);
2710 /* lock the sucker */
2711 down_write(&s
->s_umount
);
2712 /* ... and return the root of (sub)tree on it */
2715 EXPORT_SYMBOL(mount_subtree
);
2717 SYSCALL_DEFINE5(mount
, char __user
*, dev_name
, char __user
*, dir_name
,
2718 char __user
*, type
, unsigned long, flags
, void __user
*, data
)
2722 struct filename
*kernel_dir
;
2724 unsigned long data_page
;
2726 ret
= copy_mount_string(type
, &kernel_type
);
2730 kernel_dir
= getname(dir_name
);
2731 if (IS_ERR(kernel_dir
)) {
2732 ret
= PTR_ERR(kernel_dir
);
2736 ret
= copy_mount_string(dev_name
, &kernel_dev
);
2740 ret
= copy_mount_options(data
, &data_page
);
2744 ret
= do_mount(kernel_dev
, kernel_dir
->name
, kernel_type
, flags
,
2745 (void *) data_page
);
2747 free_page(data_page
);
2751 putname(kernel_dir
);
2759 * Return true if path is reachable from root
2761 * namespace_sem or vfsmount_lock is held
2763 bool is_path_reachable(struct mount
*mnt
, struct dentry
*dentry
,
2764 const struct path
*root
)
2766 while (&mnt
->mnt
!= root
->mnt
&& mnt_has_parent(mnt
)) {
2767 dentry
= mnt
->mnt_mountpoint
;
2768 mnt
= mnt
->mnt_parent
;
2770 return &mnt
->mnt
== root
->mnt
&& is_subdir(dentry
, root
->dentry
);
2773 int path_is_under(struct path
*path1
, struct path
*path2
)
2776 br_read_lock(&vfsmount_lock
);
2777 res
= is_path_reachable(real_mount(path1
->mnt
), path1
->dentry
, path2
);
2778 br_read_unlock(&vfsmount_lock
);
2781 EXPORT_SYMBOL(path_is_under
);
2784 * pivot_root Semantics:
2785 * Moves the root file system of the current process to the directory put_old,
2786 * makes new_root as the new root file system of the current process, and sets
2787 * root/cwd of all processes which had them on the current root to new_root.
2790 * The new_root and put_old must be directories, and must not be on the
2791 * same file system as the current process root. The put_old must be
2792 * underneath new_root, i.e. adding a non-zero number of /.. to the string
2793 * pointed to by put_old must yield the same directory as new_root. No other
2794 * file system may be mounted on put_old. After all, new_root is a mountpoint.
2796 * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem.
2797 * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives
2798 * in this situation.
2801 * - we don't move root/cwd if they are not at the root (reason: if something
2802 * cared enough to change them, it's probably wrong to force them elsewhere)
2803 * - it's okay to pick a root that isn't the root of a file system, e.g.
2804 * /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
2805 * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
2808 SYSCALL_DEFINE2(pivot_root
, const char __user
*, new_root
,
2809 const char __user
*, put_old
)
2811 struct path
new, old
, parent_path
, root_parent
, root
;
2812 struct mount
*new_mnt
, *root_mnt
, *old_mnt
;
2813 struct mountpoint
*old_mp
, *root_mp
;
2819 error
= user_path_dir(new_root
, &new);
2823 error
= user_path_dir(put_old
, &old
);
2827 error
= security_sb_pivotroot(&old
, &new);
2831 get_fs_root(current
->fs
, &root
);
2832 old_mp
= lock_mount(&old
);
2833 error
= PTR_ERR(old_mp
);
2838 new_mnt
= real_mount(new.mnt
);
2839 root_mnt
= real_mount(root
.mnt
);
2840 old_mnt
= real_mount(old
.mnt
);
2841 if (IS_MNT_SHARED(old_mnt
) ||
2842 IS_MNT_SHARED(new_mnt
->mnt_parent
) ||
2843 IS_MNT_SHARED(root_mnt
->mnt_parent
))
2845 if (!check_mnt(root_mnt
) || !check_mnt(new_mnt
))
2848 if (d_unlinked(new.dentry
))
2851 if (new_mnt
== root_mnt
|| old_mnt
== root_mnt
)
2852 goto out4
; /* loop, on the same file system */
2854 if (root
.mnt
->mnt_root
!= root
.dentry
)
2855 goto out4
; /* not a mountpoint */
2856 if (!mnt_has_parent(root_mnt
))
2857 goto out4
; /* not attached */
2858 root_mp
= root_mnt
->mnt_mp
;
2859 if (new.mnt
->mnt_root
!= new.dentry
)
2860 goto out4
; /* not a mountpoint */
2861 if (!mnt_has_parent(new_mnt
))
2862 goto out4
; /* not attached */
2863 /* make sure we can reach put_old from new_root */
2864 if (!is_path_reachable(old_mnt
, old
.dentry
, &new))
2866 /* make certain new is below the root */
2867 if (!is_path_reachable(new_mnt
, new.dentry
, &root
))
2869 root_mp
->m_count
++; /* pin it so it won't go away */
2870 br_write_lock(&vfsmount_lock
);
2871 detach_mnt(new_mnt
, &parent_path
);
2872 detach_mnt(root_mnt
, &root_parent
);
2873 /* mount old root on put_old */
2874 attach_mnt(root_mnt
, old_mnt
, old_mp
);
2875 /* mount new_root on / */
2876 attach_mnt(new_mnt
, real_mount(root_parent
.mnt
), root_mp
);
2877 touch_mnt_namespace(current
->nsproxy
->mnt_ns
);
2878 br_write_unlock(&vfsmount_lock
);
2879 chroot_fs_refs(&root
, &new);
2880 put_mountpoint(root_mp
);
2883 unlock_mount(old_mp
);
2885 path_put(&root_parent
);
2886 path_put(&parent_path
);
2898 static void __init
init_mount_tree(void)
2900 struct vfsmount
*mnt
;
2901 struct mnt_namespace
*ns
;
2903 struct file_system_type
*type
;
2905 type
= get_fs_type("rootfs");
2907 panic("Can't find rootfs type");
2908 mnt
= vfs_kern_mount(type
, 0, "rootfs", NULL
);
2909 put_filesystem(type
);
2911 panic("Can't create rootfs");
2913 ns
= create_mnt_ns(mnt
);
2915 panic("Can't allocate initial namespace");
2917 init_task
.nsproxy
->mnt_ns
= ns
;
2921 root
.dentry
= mnt
->mnt_root
;
2923 set_fs_pwd(current
->fs
, &root
);
2924 set_fs_root(current
->fs
, &root
);
2927 void __init
mnt_init(void)
2932 init_rwsem(&namespace_sem
);
2934 mnt_cache
= kmem_cache_create("mnt_cache", sizeof(struct mount
),
2935 0, SLAB_HWCACHE_ALIGN
| SLAB_PANIC
, NULL
);
2937 mount_hashtable
= (struct list_head
*)__get_free_page(GFP_ATOMIC
);
2938 mountpoint_hashtable
= (struct list_head
*)__get_free_page(GFP_ATOMIC
);
2940 if (!mount_hashtable
|| !mountpoint_hashtable
)
2941 panic("Failed to allocate mount hash table\n");
2943 printk(KERN_INFO
"Mount-cache hash table entries: %lu\n", HASH_SIZE
);
2945 for (u
= 0; u
< HASH_SIZE
; u
++)
2946 INIT_LIST_HEAD(&mount_hashtable
[u
]);
2947 for (u
= 0; u
< HASH_SIZE
; u
++)
2948 INIT_LIST_HEAD(&mountpoint_hashtable
[u
]);
2950 br_lock_init(&vfsmount_lock
);
2954 printk(KERN_WARNING
"%s: sysfs_init error: %d\n",
2956 fs_kobj
= kobject_create_and_add("fs", NULL
);
2958 printk(KERN_WARNING
"%s: kobj create error\n", __func__
);
2963 void put_mnt_ns(struct mnt_namespace
*ns
)
2965 if (!atomic_dec_and_test(&ns
->count
))
2968 br_write_lock(&vfsmount_lock
);
2969 umount_tree(ns
->root
, 0);
2970 br_write_unlock(&vfsmount_lock
);
2975 struct vfsmount
*kern_mount_data(struct file_system_type
*type
, void *data
)
2977 struct vfsmount
*mnt
;
2978 mnt
= vfs_kern_mount(type
, MS_KERNMOUNT
, type
->name
, data
);
2981 * it is a longterm mount, don't release mnt until
2982 * we unmount before file sys is unregistered
2984 real_mount(mnt
)->mnt_ns
= MNT_NS_INTERNAL
;
2988 EXPORT_SYMBOL_GPL(kern_mount_data
);
2990 void kern_unmount(struct vfsmount
*mnt
)
2992 /* release long term mount so mount point can be released */
2993 if (!IS_ERR_OR_NULL(mnt
)) {
2994 br_write_lock(&vfsmount_lock
);
2995 real_mount(mnt
)->mnt_ns
= NULL
;
2996 br_write_unlock(&vfsmount_lock
);
3000 EXPORT_SYMBOL(kern_unmount
);
3002 bool our_mnt(struct vfsmount
*mnt
)
3004 return check_mnt(real_mount(mnt
));
3007 bool current_chrooted(void)
3009 /* Does the current process have a non-standard root */
3010 struct path ns_root
;
3011 struct path fs_root
;
3014 /* Find the namespace root */
3015 ns_root
.mnt
= ¤t
->nsproxy
->mnt_ns
->root
->mnt
;
3016 ns_root
.dentry
= ns_root
.mnt
->mnt_root
;
3018 while (d_mountpoint(ns_root
.dentry
) && follow_down_one(&ns_root
))
3021 get_fs_root(current
->fs
, &fs_root
);
3023 chrooted
= !path_equal(&fs_root
, &ns_root
);
3031 void update_mnt_policy(struct user_namespace
*userns
)
3033 struct mnt_namespace
*ns
= current
->nsproxy
->mnt_ns
;
3036 down_read(&namespace_sem
);
3037 list_for_each_entry(mnt
, &ns
->list
, mnt_list
) {
3038 switch (mnt
->mnt
.mnt_sb
->s_magic
) {
3040 userns
->may_mount_sysfs
= true;
3042 case PROC_SUPER_MAGIC
:
3043 userns
->may_mount_proc
= true;
3046 if (userns
->may_mount_sysfs
&& userns
->may_mount_proc
)
3049 up_read(&namespace_sem
);
3052 static void *mntns_get(struct task_struct
*task
)
3054 struct mnt_namespace
*ns
= NULL
;
3055 struct nsproxy
*nsproxy
;
3058 nsproxy
= task_nsproxy(task
);
3060 ns
= nsproxy
->mnt_ns
;
3068 static void mntns_put(void *ns
)
3073 static int mntns_install(struct nsproxy
*nsproxy
, void *ns
)
3075 struct fs_struct
*fs
= current
->fs
;
3076 struct mnt_namespace
*mnt_ns
= ns
;
3079 if (!ns_capable(mnt_ns
->user_ns
, CAP_SYS_ADMIN
) ||
3080 !nsown_capable(CAP_SYS_CHROOT
) ||
3081 !nsown_capable(CAP_SYS_ADMIN
))
3088 put_mnt_ns(nsproxy
->mnt_ns
);
3089 nsproxy
->mnt_ns
= mnt_ns
;
3092 root
.mnt
= &mnt_ns
->root
->mnt
;
3093 root
.dentry
= mnt_ns
->root
->mnt
.mnt_root
;
3095 while(d_mountpoint(root
.dentry
) && follow_down_one(&root
))
3098 /* Update the pwd and root */
3099 set_fs_pwd(fs
, &root
);
3100 set_fs_root(fs
, &root
);
3106 static unsigned int mntns_inum(void *ns
)
3108 struct mnt_namespace
*mnt_ns
= ns
;
3109 return mnt_ns
->proc_inum
;
3112 const struct proc_ns_operations mntns_operations
= {
3114 .type
= CLONE_NEWNS
,
3117 .install
= mntns_install
,