'Update a volume.'

def update(self, req, id, body):

    if ((body is None) or (not body.get('volume')) or (not isinstance(body['volume'], dict))):
        raise exc.HTTPUnprocessableEntity()
    try:
        return _volume_v2_to_v1(super(VolumeController, self).update(req, id, body))
    except exc.HTTPBadRequest:
        raise exc.HTTPUnprocessableEntity()
