Archipelago » qemu

            n1 = backing_read1(bs->backing_hd, acb->sector_num,

                               acb->buf, acb->n);

            if (n1 > 0) {

                acb->hd_iov.iov_len = acb->n * 512;

                qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);

                acb->hd_aiocb = bdrv_aio_readv(bs->backing_hd, acb->sector_num,

            goto done;

        }

        acb->hd_iov.iov_len = acb->n * 512;

        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);

        acb->hd_aiocb = bdrv_aio_readv(s->hd,

        acb->buf = acb->orig_buf = qemu_memalign(512, qiov->size);

        if (is_write)

            qemu_iovec_to_buffer(qiov, acb->buf);

    acb->nb_sectors = nb_sectors;

    acb->n = 0;

    acb->cluster_offset = 0;