def METHOD_NAME(self, image_spec):
    """Perform cache flush on the image
    Args:
        image_spec: <pool>/<image> where cache flush needs to be performed.
    """
    log.info(f"Perform cache flush on image {image_spec}....")
    cmd = f"rbd persistent-cache flush {image_spec}"
    return self.client.exec_command(cmd=cmd, sudo=True)