mnt: Delay removal from the mount hash.

- Modify __lookup_mnt_hash_last to ignore mounts that have MNT_UMOUNTED set.
- Don't remove mounts from the mount hash table in propogate_umount
- Don't remove mounts from the mount hash table in umount_tree before
  the entire list of mounts to be umounted is selected.
- Remove mounts from the mount hash table as the last thing that
  happens in the case where a mount has a parent in umount_tree.
  Mounts without parents are not hashed (by definition).

This paves the way for delaying removal from the mount hash table even
farther and fixing the MNT_LOCKED vs MNT_DETACH issue.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/fs/pnode.c b/fs/pnode.c
index ac3aa0d43b90..c27ae38ee250 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -383,7 +383,6 @@ static void __propagate_umount(struct mount *mnt)
 		 */
 		if (child && list_empty(&child->mnt_mounts)) {
 			list_del_init(&child->mnt_child);
-			hlist_del_init_rcu(&child->mnt_hash);
 			child->mnt.mnt_flags |= MNT_UMOUNT;
 			list_move_tail(&child->mnt_list, &mnt->mnt_list);
 		}