vfs: umount_tree() might be called on subtree that had never made it

__mnt_make_shortterm() in there undoes the effect of __mnt_make_longterm()
we'd done back when we set ->mnt_ns non-NULL; it should not be done to
vfsmounts that had never gone through commit_tree() and friends.  Kudos to
lczerner for catching that one...

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namespace.c b/fs/namespace.c
index 224aff1c0dfda0d964e8d5248b658c8c8c334af1..1e4a5fe3d7b7f789d66839f37b1f917c1fa3e2ba 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1074,8 +1074,9 @@ void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
                list_del_init(&p->mnt_expire);
                list_del_init(&p->mnt_list);
                __touch_mnt_namespace(p->mnt_ns);
+               if (p->mnt_ns)
+                       __mnt_make_shortterm(p);
                p->mnt_ns = NULL;
-               __mnt_make_shortterm(p);
                list_del_init(&p->mnt_child);
                if (mnt_has_parent(p)) {
                        p->mnt_parent->mnt_ghosts++;