[Bug 1037634] The devicemapper volumes are not removed after container is removed

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1037634

--- Comment #4 from Alexander Larsson  ---
Michal: Not sure what you mean, you seem to have some mounts with 3.2 gigs of
data in /var/lib/devicemapper/mnt, which implies that you have either a
container or an image. Plus, the loopback mounts in the devicemapper folder are
not zero size even if there are no containers/images in it.