docs: def volume_list(self, search_opts=None):
          '''
          List all block volumes
          '''
          if self.volume_conn is None:
              raise SaltCloudSystemExit('No cinder endpoint available')
          nt_ks = self.volume_conn
          volumes = nt_ks.volumes.list(search_opts=search_opts)
          response = {}
          for volume in volumes:
              response[volume.display_name] = {
                  'name': volume.display_name,
                  'size': volume.size,
                  'id': volume.id,
                  'description': volume.display_description,
                  'attachments': volume.attachments,
                  'status': volume.status
              }
          return response