commit e85f82ff upstream.

Nothing prevents mischief on upper layer while we are busy copying up the
data.

Move the lookup right before the looked up dentry is actually used.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 01ad3eb8 ("ovl: concurrent copy up of regular files")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>