mnt: In umount_tree reuse mnt_list instead of mnt_hash
umount_tree builds a list of mounts that need to be unmounted.
Utilize mnt_list for this purpose instead of mnt_hash. This begins to
allow keeping a mount on the mnt_hash after it is unmounted, which is
necessary for a properly functioning MNT_LOCKED implementation.
The fact that mnt_list is an ordinary list makding available list_move
is nice bonus.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/namespace.c b/fs/namespace.c
index c68d9fc..54cbef1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1327,23 +1327,25 @@
*/
static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
{
- HLIST_HEAD(tmp_list);
+ LIST_HEAD(tmp_list);
struct mount *p;
- for (p = mnt; p; p = next_mnt(p, mnt)) {
+ /* Gather the mounts to umount */
+ for (p = mnt; p; p = next_mnt(p, mnt))
+ list_move(&p->mnt_list, &tmp_list);
+
+ /* Hide the mounts from lookup_mnt and mnt_mounts */
+ list_for_each_entry(p, &tmp_list, mnt_list) {
hlist_del_init_rcu(&p->mnt_hash);
- hlist_add_head(&p->mnt_hash, &tmp_list);
+ list_del_init(&p->mnt_child);
}
- hlist_for_each_entry(p, &tmp_list, mnt_hash)
- list_del_init(&p->mnt_child);
-
+ /* Add propogated mounts to the tmp_list */
if (how & UMOUNT_PROPAGATE)
propagate_umount(&tmp_list);
- while (!hlist_empty(&tmp_list)) {
- p = hlist_entry(tmp_list.first, struct mount, mnt_hash);
- hlist_del_init_rcu(&p->mnt_hash);
+ while (!list_empty(&tmp_list)) {
+ p = list_first_entry(&tmp_list, struct mount, mnt_list);
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns);
