This makes all users of Put() have a corresponding call to Get() which means we will be able to track whether any particular ID is in use and if not unmount it. Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson) Upstream-commit: bcaf6c2359d83acd5da54f499e21f4a148f491c5 Component: engine