Check for the rootDir first because the mergeDir may not exist if root
is present.
Also fix unmounting in the defer to make sure it does not have a
refcount.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Upstream-commit: 36a82c20321936a71b30fcfde8bc6c76d6cc8d1f
Component: engine