code: def resize_volume(self, size):
          
          curr_size = self.volume.size
          if size <= curr_size:
              raise exc.InvalidVolumeResize("The new volume size must be larger "
                      "than the current volume size of '%s'." % curr_size)
          body = {"volume": {"size": size}}
          self.manager.action(self, "resize", body=body)
docs: Changes the size of the volume for this instance.