diff options
author | Ram Pai <linuxram@us.ibm.com> | 2005-11-07 17:20:17 -0500 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-11-07 21:18:11 -0500 |
commit | a05964f3917c7c55368c229d7985f8e7c9977e97 (patch) | |
tree | 7ec25550267ef050572c00ba2f37d6a4ff9c469e | |
parent | 2144440327fa01b2f3f65e355120a78211685702 (diff) |
[PATCH] shared mounts handling: umount
An unmount of a mount creates a umount event on the parent. If the
parent is a shared mount, it gets propagated to all mounts in the peer
group.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r-- | fs/namespace.c | 56 | ||||
-rw-r--r-- | fs/pnode.c | 87 | ||||
-rw-r--r-- | fs/pnode.h | 2 | ||||
-rw-r--r-- | include/linux/dcache.h | 1 | ||||
-rw-r--r-- | include/linux/fs.h | 2 |
5 files changed, 128 insertions, 20 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 1487982dbc24..4b1af01c2fb4 100644 --- a/fs/namespace.c +++ b/fs/namespace.c | |||
@@ -86,31 +86,44 @@ void free_vfsmnt(struct vfsmount *mnt) | |||
86 | } | 86 | } |
87 | 87 | ||
88 | /* | 88 | /* |
89 | * Now, lookup_mnt increments the ref count before returning | 89 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
90 | * the vfsmount struct. | 90 | * @dir. If @dir is set return the first mount else return the last mount. |
91 | */ | 91 | */ |
92 | struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) | 92 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
93 | int dir) | ||
93 | { | 94 | { |
94 | struct list_head *head = mount_hashtable + hash(mnt, dentry); | 95 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
95 | struct list_head *tmp = head; | 96 | struct list_head *tmp = head; |
96 | struct vfsmount *p, *found = NULL; | 97 | struct vfsmount *p, *found = NULL; |
97 | 98 | ||
98 | spin_lock(&vfsmount_lock); | ||
99 | for (;;) { | 99 | for (;;) { |
100 | tmp = tmp->next; | 100 | tmp = dir ? tmp->next : tmp->prev; |
101 | p = NULL; | 101 | p = NULL; |
102 | if (tmp == head) | 102 | if (tmp == head) |
103 | break; | 103 | break; |
104 | p = list_entry(tmp, struct vfsmount, mnt_hash); | 104 | p = list_entry(tmp, struct vfsmount, mnt_hash); |
105 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { | 105 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { |
106 | found = mntget(p); | 106 | found = p; |
107 | break; | 107 | break; |
108 | } | 108 | } |
109 | } | 109 | } |
110 | spin_unlock(&vfsmount_lock); | ||
111 | return found; | 110 | return found; |
112 | } | 111 | } |
113 | 112 | ||
113 | /* | ||
114 | * lookup_mnt increments the ref count before returning | ||
115 | * the vfsmount struct. | ||
116 | */ | ||
117 | struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) | ||
118 | { | ||
119 | struct vfsmount *child_mnt; | ||
120 | spin_lock(&vfsmount_lock); | ||
121 | if ((child_mnt = __lookup_mnt(mnt, dentry, 1))) | ||
122 | mntget(child_mnt); | ||
123 | spin_unlock(&vfsmount_lock); | ||
124 | return child_mnt; | ||
125 | } | ||
126 | |||
114 | static inline int check_mnt(struct vfsmount *mnt) | 127 | static inline int check_mnt(struct vfsmount *mnt) |
115 | { | 128 | { |
116 | return mnt->mnt_namespace == current->namespace; | 129 | return mnt->mnt_namespace == current->namespace; |
@@ -404,9 +417,12 @@ EXPORT_SYMBOL(may_umount_tree); | |||
404 | */ | 417 | */ |
405 | int may_umount(struct vfsmount *mnt) | 418 | int may_umount(struct vfsmount *mnt) |
406 | { | 419 | { |
407 | if (atomic_read(&mnt->mnt_count) > 2) | 420 | int ret = 0; |
408 | return -EBUSY; | 421 | spin_lock(&vfsmount_lock); |
409 | return 0; | 422 | if (propagate_mount_busy(mnt, 2)) |
423 | ret = -EBUSY; | ||
424 | spin_unlock(&vfsmount_lock); | ||
425 | return ret; | ||
410 | } | 426 | } |
411 | 427 | ||
412 | EXPORT_SYMBOL(may_umount); | 428 | EXPORT_SYMBOL(may_umount); |
@@ -433,7 +449,7 @@ void release_mounts(struct list_head *head) | |||
433 | } | 449 | } |
434 | } | 450 | } |
435 | 451 | ||
436 | void umount_tree(struct vfsmount *mnt, struct list_head *kill) | 452 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
437 | { | 453 | { |
438 | struct vfsmount *p; | 454 | struct vfsmount *p; |
439 | 455 | ||
@@ -442,6 +458,9 @@ void umount_tree(struct vfsmount *mnt, struct list_head *kill) | |||
442 | list_add(&p->mnt_hash, kill); | 458 | list_add(&p->mnt_hash, kill); |
443 | } | 459 | } |
444 | 460 | ||
461 | if (propagate) | ||
462 | propagate_umount(kill); | ||
463 | |||
445 | list_for_each_entry(p, kill, mnt_hash) { | 464 | list_for_each_entry(p, kill, mnt_hash) { |
446 | list_del_init(&p->mnt_expire); | 465 | list_del_init(&p->mnt_expire); |
447 | list_del_init(&p->mnt_list); | 466 | list_del_init(&p->mnt_list); |
@@ -450,6 +469,7 @@ void umount_tree(struct vfsmount *mnt, struct list_head *kill) | |||
450 | list_del_init(&p->mnt_child); | 469 | list_del_init(&p->mnt_child); |
451 | if (p->mnt_parent != p) | 470 | if (p->mnt_parent != p) |
452 | mnt->mnt_mountpoint->d_mounted--; | 471 | mnt->mnt_mountpoint->d_mounted--; |
472 | change_mnt_propagation(p, MS_PRIVATE); | ||
453 | } | 473 | } |
454 | } | 474 | } |
455 | 475 | ||
@@ -526,9 +546,9 @@ static int do_umount(struct vfsmount *mnt, int flags) | |||
526 | event++; | 546 | event++; |
527 | 547 | ||
528 | retval = -EBUSY; | 548 | retval = -EBUSY; |
529 | if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) { | 549 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
530 | if (!list_empty(&mnt->mnt_list)) | 550 | if (!list_empty(&mnt->mnt_list)) |
531 | umount_tree(mnt, &umount_list); | 551 | umount_tree(mnt, 1, &umount_list); |
532 | retval = 0; | 552 | retval = 0; |
533 | } | 553 | } |
534 | spin_unlock(&vfsmount_lock); | 554 | spin_unlock(&vfsmount_lock); |
@@ -651,7 +671,7 @@ Enomem: | |||
651 | if (res) { | 671 | if (res) { |
652 | LIST_HEAD(umount_list); | 672 | LIST_HEAD(umount_list); |
653 | spin_lock(&vfsmount_lock); | 673 | spin_lock(&vfsmount_lock); |
654 | umount_tree(res, &umount_list); | 674 | umount_tree(res, 0, &umount_list); |
655 | spin_unlock(&vfsmount_lock); | 675 | spin_unlock(&vfsmount_lock); |
656 | release_mounts(&umount_list); | 676 | release_mounts(&umount_list); |
657 | } | 677 | } |
@@ -827,7 +847,7 @@ static int do_loopback(struct nameidata *nd, char *old_name, int recurse) | |||
827 | if (err) { | 847 | if (err) { |
828 | LIST_HEAD(umount_list); | 848 | LIST_HEAD(umount_list); |
829 | spin_lock(&vfsmount_lock); | 849 | spin_lock(&vfsmount_lock); |
830 | umount_tree(mnt, &umount_list); | 850 | umount_tree(mnt, 0, &umount_list); |
831 | spin_unlock(&vfsmount_lock); | 851 | spin_unlock(&vfsmount_lock); |
832 | release_mounts(&umount_list); | 852 | release_mounts(&umount_list); |
833 | } | 853 | } |
@@ -1023,12 +1043,12 @@ static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, | |||
1023 | * Check that it is still dead: the count should now be 2 - as | 1043 | * Check that it is still dead: the count should now be 2 - as |
1024 | * contributed by the vfsmount parent and the mntget above | 1044 | * contributed by the vfsmount parent and the mntget above |
1025 | */ | 1045 | */ |
1026 | if (atomic_read(&mnt->mnt_count) == 2) { | 1046 | if (!propagate_mount_busy(mnt, 2)) { |
1027 | /* delete from the namespace */ | 1047 | /* delete from the namespace */ |
1028 | touch_namespace(mnt->mnt_namespace); | 1048 | touch_namespace(mnt->mnt_namespace); |
1029 | list_del_init(&mnt->mnt_list); | 1049 | list_del_init(&mnt->mnt_list); |
1030 | mnt->mnt_namespace = NULL; | 1050 | mnt->mnt_namespace = NULL; |
1031 | umount_tree(mnt, umounts); | 1051 | umount_tree(mnt, 1, umounts); |
1032 | spin_unlock(&vfsmount_lock); | 1052 | spin_unlock(&vfsmount_lock); |
1033 | } else { | 1053 | } else { |
1034 | /* | 1054 | /* |
@@ -1647,7 +1667,7 @@ void __put_namespace(struct namespace *namespace) | |||
1647 | spin_unlock(&vfsmount_lock); | 1667 | spin_unlock(&vfsmount_lock); |
1648 | down_write(&namespace_sem); | 1668 | down_write(&namespace_sem); |
1649 | spin_lock(&vfsmount_lock); | 1669 | spin_lock(&vfsmount_lock); |
1650 | umount_tree(root, &umount_list); | 1670 | umount_tree(root, 0, &umount_list); |
1651 | spin_unlock(&vfsmount_lock); | 1671 | spin_unlock(&vfsmount_lock); |
1652 | up_write(&namespace_sem); | 1672 | up_write(&namespace_sem); |
1653 | release_mounts(&umount_list); | 1673 | release_mounts(&umount_list); |
diff --git a/fs/pnode.c b/fs/pnode.c index 2d572b88e6f6..7bc942d047cd 100644 --- a/fs/pnode.c +++ b/fs/pnode.c | |||
@@ -99,9 +99,94 @@ out: | |||
99 | while (!list_empty(&tmp_list)) { | 99 | while (!list_empty(&tmp_list)) { |
100 | child = list_entry(tmp_list.next, struct vfsmount, mnt_hash); | 100 | child = list_entry(tmp_list.next, struct vfsmount, mnt_hash); |
101 | list_del_init(&child->mnt_hash); | 101 | list_del_init(&child->mnt_hash); |
102 | umount_tree(child, &umount_list); | 102 | umount_tree(child, 0, &umount_list); |
103 | } | 103 | } |
104 | spin_unlock(&vfsmount_lock); | 104 | spin_unlock(&vfsmount_lock); |
105 | release_mounts(&umount_list); | 105 | release_mounts(&umount_list); |
106 | return ret; | 106 | return ret; |
107 | } | 107 | } |
108 | |||
109 | /* | ||
110 | * return true if the refcount is greater than count | ||
111 | */ | ||
112 | static inline int do_refcount_check(struct vfsmount *mnt, int count) | ||
113 | { | ||
114 | int mycount = atomic_read(&mnt->mnt_count); | ||
115 | return (mycount > count); | ||
116 | } | ||
117 | |||
118 | /* | ||
119 | * check if the mount 'mnt' can be unmounted successfully. | ||
120 | * @mnt: the mount to be checked for unmount | ||
121 | * NOTE: unmounting 'mnt' would naturally propagate to all | ||
122 | * other mounts its parent propagates to. | ||
123 | * Check if any of these mounts that **do not have submounts** | ||
124 | * have more references than 'refcnt'. If so return busy. | ||
125 | */ | ||
126 | int propagate_mount_busy(struct vfsmount *mnt, int refcnt) | ||
127 | { | ||
128 | struct vfsmount *m, *child; | ||
129 | struct vfsmount *parent = mnt->mnt_parent; | ||
130 | int ret = 0; | ||
131 | |||
132 | if (mnt == parent) | ||
133 | return do_refcount_check(mnt, refcnt); | ||
134 | |||
135 | /* | ||
136 | * quickly check if the current mount can be unmounted. | ||
137 | * If not, we don't have to go checking for all other | ||
138 | * mounts | ||
139 | */ | ||
140 | if (!list_empty(&mnt->mnt_mounts) || do_refcount_check(mnt, refcnt)) | ||
141 | return 1; | ||
142 | |||
143 | for (m = propagation_next(parent, parent); m; | ||
144 | m = propagation_next(m, parent)) { | ||
145 | child = __lookup_mnt(m, mnt->mnt_mountpoint, 0); | ||
146 | if (child && list_empty(&child->mnt_mounts) && | ||
147 | (ret = do_refcount_check(child, 1))) | ||
148 | break; | ||
149 | } | ||
150 | return ret; | ||
151 | } | ||
152 | |||
153 | /* | ||
154 | * NOTE: unmounting 'mnt' naturally propagates to all other mounts its | ||
155 | * parent propagates to. | ||
156 | */ | ||
157 | static void __propagate_umount(struct vfsmount *mnt) | ||
158 | { | ||
159 | struct vfsmount *parent = mnt->mnt_parent; | ||
160 | struct vfsmount *m; | ||
161 | |||
162 | BUG_ON(parent == mnt); | ||
163 | |||
164 | for (m = propagation_next(parent, parent); m; | ||
165 | m = propagation_next(m, parent)) { | ||
166 | |||
167 | struct vfsmount *child = __lookup_mnt(m, | ||
168 | mnt->mnt_mountpoint, 0); | ||
169 | /* | ||
170 | * umount the child only if the child has no | ||
171 | * other children | ||
172 | */ | ||
173 | if (child && list_empty(&child->mnt_mounts)) { | ||
174 | list_del(&child->mnt_hash); | ||
175 | list_add_tail(&child->mnt_hash, &mnt->mnt_hash); | ||
176 | } | ||
177 | } | ||
178 | } | ||
179 | |||
180 | /* | ||
181 | * collect all mounts that receive propagation from the mount in @list, | ||
182 | * and return these additional mounts in the same list. | ||
183 | * @list: the list of mounts to be unmounted. | ||
184 | */ | ||
185 | int propagate_umount(struct list_head *list) | ||
186 | { | ||
187 | struct vfsmount *mnt; | ||
188 | |||
189 | list_for_each_entry(mnt, list, mnt_hash) | ||
190 | __propagate_umount(mnt); | ||
191 | return 0; | ||
192 | } | ||
diff --git a/fs/pnode.h b/fs/pnode.h index c62c72fad212..9b88ba06794a 100644 --- a/fs/pnode.h +++ b/fs/pnode.h | |||
@@ -29,4 +29,6 @@ static inline void set_mnt_shared(struct vfsmount *mnt) | |||
29 | void change_mnt_propagation(struct vfsmount *, int); | 29 | void change_mnt_propagation(struct vfsmount *, int); |
30 | int propagate_mnt(struct vfsmount *, struct dentry *, struct vfsmount *, | 30 | int propagate_mnt(struct vfsmount *, struct dentry *, struct vfsmount *, |
31 | struct list_head *); | 31 | struct list_head *); |
32 | int propagate_umount(struct list_head *); | ||
33 | int propagate_mount_busy(struct vfsmount *, int); | ||
32 | #endif /* _LINUX_PNODE_H */ | 34 | #endif /* _LINUX_PNODE_H */ |
diff --git a/include/linux/dcache.h b/include/linux/dcache.h index ab04b4f9b0db..46a2ba617595 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h | |||
@@ -329,6 +329,7 @@ static inline int d_mountpoint(struct dentry *dentry) | |||
329 | } | 329 | } |
330 | 330 | ||
331 | extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *); | 331 | extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *); |
332 | extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int); | ||
332 | extern struct dentry *lookup_create(struct nameidata *nd, int is_dir); | 333 | extern struct dentry *lookup_create(struct nameidata *nd, int is_dir); |
333 | 334 | ||
334 | extern int sysctl_vfs_cache_pressure; | 335 | extern int sysctl_vfs_cache_pressure; |
diff --git a/include/linux/fs.h b/include/linux/fs.h index 5e188b773e9c..8bdb504be73b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h | |||
@@ -1251,7 +1251,7 @@ extern int unregister_filesystem(struct file_system_type *); | |||
1251 | extern struct vfsmount *kern_mount(struct file_system_type *); | 1251 | extern struct vfsmount *kern_mount(struct file_system_type *); |
1252 | extern int may_umount_tree(struct vfsmount *); | 1252 | extern int may_umount_tree(struct vfsmount *); |
1253 | extern int may_umount(struct vfsmount *); | 1253 | extern int may_umount(struct vfsmount *); |
1254 | extern void umount_tree(struct vfsmount *, struct list_head *); | 1254 | extern void umount_tree(struct vfsmount *, int, struct list_head *); |
1255 | extern void release_mounts(struct list_head *); | 1255 | extern void release_mounts(struct list_head *); |
1256 | extern long do_mount(char *, char *, char *, unsigned long, void *); | 1256 | extern long do_mount(char *, char *, char *, unsigned long, void *); |
1257 | extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int); | 1257 | extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int); |