How to fix inconcistent Cinder and Nova entries on attached volume after failed instance migration

Issue

Sometimes when an OpenStack instance with the attached Cinder volume fails to be resized or migrated, one may end up in a situation where Cinder and Nova services are in conflict regarding the instance volume state. Cinder marks the volume as "available" while Nova shows it as being attached to the instance For this reason the storage cannot be re-attached to the VM with openstack server add volume command since Nova believes this is already in place. Or, as opposite, Nova may detach the storage from the VM, but Cinder will keep the record that it's still attached. In this state the volume cannot be re-attached as well.