[PATCH] mount expiry fixes
- clean up the ugliness in may_umount_tree()
- fix a bug in do_loopback(). after cloning a tree, do_loopback()
unlinks only the topmost mount of the cloned tree, leaving behind the
children mounts on their corresponding expiry list.
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>
diff --git a/fs/namespace.c b/fs/namespace.c
index c2ffa0f..65f9c0e 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -27,6 +27,8 @@
extern int __init init_rootfs(void);
+#define CL_EXPIRE 0x01
+
#ifdef CONFIG_SYSFS
extern int __init sysfs_init(void);
#else
@@ -165,7 +167,8 @@
return list_entry(next, struct vfsmount, mnt_child);
}
-static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root)
+static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
+ int flag)
{
struct super_block *sb = old->mnt_sb;
struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
@@ -181,10 +184,12 @@
/* stick the duplicate mount on the same expiry list
* as the original if that was on one */
- spin_lock(&vfsmount_lock);
- if (!list_empty(&old->mnt_expire))
- list_add(&mnt->mnt_expire, &old->mnt_expire);
- spin_unlock(&vfsmount_lock);
+ if (flag & CL_EXPIRE) {
+ spin_lock(&vfsmount_lock);
+ if (!list_empty(&old->mnt_expire))
+ list_add(&mnt->mnt_expire, &old->mnt_expire);
+ spin_unlock(&vfsmount_lock);
+ }
}
return mnt;
}
@@ -331,36 +336,14 @@
*/
int may_umount_tree(struct vfsmount *mnt)
{
- struct list_head *next;
- struct vfsmount *this_parent = mnt;
- int actual_refs;
- int minimum_refs;
+ int actual_refs = 0;
+ int minimum_refs = 0;
+ struct vfsmount *p;
spin_lock(&vfsmount_lock);
- actual_refs = atomic_read(&mnt->mnt_count);
- minimum_refs = 2;
-repeat:
- next = this_parent->mnt_mounts.next;
-resume:
- while (next != &this_parent->mnt_mounts) {
- struct vfsmount *p =
- list_entry(next, struct vfsmount, mnt_child);
-
- next = next->next;
-
+ for (p = mnt; p; p = next_mnt(p, mnt)) {
actual_refs += atomic_read(&p->mnt_count);
minimum_refs += 2;
-
- if (!list_empty(&p->mnt_mounts)) {
- this_parent = p;
- goto repeat;
- }
- }
-
- if (this_parent != mnt) {
- next = this_parent->mnt_child.next;
- this_parent = this_parent->mnt_parent;
- goto resume;
}
spin_unlock(&vfsmount_lock);
@@ -596,12 +579,13 @@
}
}
-static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry)
+static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
+ int flag)
{
struct vfsmount *res, *p, *q, *r, *s;
struct nameidata nd;
- res = q = clone_mnt(mnt, dentry);
+ res = q = clone_mnt(mnt, dentry, flag);
if (!q)
goto Enomem;
q->mnt_mountpoint = mnt->mnt_mountpoint;
@@ -619,7 +603,7 @@
p = s;
nd.mnt = q;
nd.dentry = p->mnt_mountpoint;
- q = clone_mnt(p, p->mnt_root);
+ q = clone_mnt(p, p->mnt_root, flag);
if (!q)
goto Enomem;
spin_lock(&vfsmount_lock);
@@ -701,18 +685,13 @@
err = -ENOMEM;
if (recurse)
- mnt = copy_tree(old_nd.mnt, old_nd.dentry);
+ mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0);
else
- mnt = clone_mnt(old_nd.mnt, old_nd.dentry);
+ mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0);
if (!mnt)
goto out;
- /* stop bind mounts from expiring */
- spin_lock(&vfsmount_lock);
- list_del_init(&mnt->mnt_expire);
- spin_unlock(&vfsmount_lock);
-
err = graft_tree(mnt, nd);
if (err) {
LIST_HEAD(umount_list);
@@ -1155,7 +1134,8 @@
down_write(&tsk->namespace->sem);
/* First pass: copy the tree topology */
- new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root);
+ new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root,
+ CL_EXPIRE);
if (!new_ns->root) {
up_write(&tsk->namespace->sem);
kfree(new_ns);