From 68552709212b9251ba7a3b0f1797f95f7fcf37e0 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 29 May 2012 22:03:48 -0400
Subject: [PATCH] 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>
(cherry picked from commit 63d37a84ab6004c235314ffd7a76c5eb28c2fae0)
---
 fs/namespace.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 224aff1c0dfd..1e4a5fe3d7b7 100644
--- 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++;
-- 
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