/* Populate back untouched region of new data cluster  */
static void qed_aio_write_postfill(void *opaque, int ret)
/* Populate back untouched region of new data cluster  */
static void qed_aio_write_postfill(void *opaque, int ret)
{
    QEDAIOCB *acb = opaque;
    BDRVQEDState *s = acb_to_s(acb);
    uint64_t start = acb->cur_pos + acb->cur_qiov.size;
    uint64_t len =
        qed_start_of_cluster(s, start + s->header.cluster_size - 1) - start;
    uint64_t offset = acb->cur_cluster +
                      qed_offset_into_cluster(s, acb->cur_pos) +
                      acb->cur_qiov.size;
    if (ret) {
        qed_aio_complete(acb, ret);
        return;
    }
    trace_qed_aio_write_postfill(s, acb, start, len, offset);
    qed_copy_from_backing_file(s, start, len, offset,
                                qed_aio_write_main, acb);
}