ublk_io_release
ret = io_buffer_register_bvec(cmd, req, ublk_io_release,
ret = io_buffer_register_bvec(cmd, req, ublk_io_release, index,
ret = io_buffer_register_bvec(cmd, req, ublk_io_release, index,
static void ublk_io_release(void *priv);