[ 38/82] vfs: umount_tree() might be called on subtree that had never made it

[Greg KH]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 63d37a84ab6004c235314ffd7a76c5eb28c2fae0 upstream.

__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...

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/namespace.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1073,8 +1073,9 @@ void umount_tree(struct mount *mnt, int
 		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++;


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