tree d89bbdf299c4cbc37f49a9964b8127f09eedd50b
parent b46413367961c2e8bd827e067a231be982aaeee2
author Al Viro <viro@zeniv.linux.org.uk> 1321983081 -0500
committer Al Viro <viro@zeniv.linux.org.uk> 1321983081 -0500

mount_subtree() pointless use-after-free

d'oh... we'd carefully pinned mnt->mnt_sb down, dropped mnt and attempt
to grab s_umount on mnt->mnt_sb.  The trouble is, *mnt might've been
overwritten by now...

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