With volume layout the volume we use to back a share can
be pre-created (part of the volume pool provided for Manila),
or can be created by Manila (that happens if share is created
from snapshot, in which case the volume is obtained by performing
a 'snapshot clone' gluster operation).
In terms of resource management, pre-created volumes are owned
by the pool, and Manila cloned ones are owned by Manila. So
far we kept all the volumes upon giving up its use (ie. deleting
the share it belonged to) -- we only ran a cleanup routine on them.
However, that's appropriate action only for the pool owned ones.
However, the ones we own should rather be extinguished to avoid
a resource leak. This patch implements this practice by marking
Manila owned volumes with a gluster user option.
Closes-Bug: #1506298
Change-Id: I165cc225cb7aca44785ed9ef60f459b8d46af564
52bfb25a51