In order to revert to a snapshot in the LVM driver (and
very likely other drivers) the list of access rules is
needed, so this change modifies the driver interface to
provide this extra information.
This change requires preventing a revert to snapshot
operation while access rules on the affected share are
out of sync.
Closes bug: 1658133
Change-Id: Ia6678bb0e484f9c8f8b05d90e514801ae9baa94b