static void scsi_write_data(SCSIRequest *req)
{
    SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);
    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
    SCSIDiskClass *sdc = (SCSIDiskClass *) object_get_class(OBJECT(s));

    /* No data transfer may already be in progress */
    assert(r->req.aiocb == NULL);

    /* The request is used as the AIO opaque value, so add a ref.  */
    scsi_req_ref(&r->req);
    if (r->req.cmd.mode != SCSI_XFER_TO_DEV) {
        trace_scsi_disk_write_data_invalid();
        scsi_write_complete_noio(r, -EINVAL);
        return;
    }

    if (!r->req.sg && !r->qiov.size) {
        /* Called for the first time.  Ask the driver to send us more data.  */
        r->started = true;
        scsi_write_complete_noio(r, 0);
        return;
    }
    if (!blk_is_available(req->dev->conf.blk)) {
        scsi_write_complete_noio(r, -ENOMEDIUM);
        return;
    }

    if (r->req.cmd.buf[0] == VERIFY_10 || r->req.cmd.buf[0] == VERIFY_12 ||
        r->req.cmd.buf[0] == VERIFY_16) {
        if (r->req.sg) {
            scsi_dma_complete_noio(r, 0);
        } else {
            scsi_write_complete_noio(r, 0);
        }
        return;
    }

    if (r->req.sg) {
        dma_acct_start(s->qdev.conf.blk, &r->acct, r->req.sg, BLOCK_ACCT_WRITE);
        r->req.resid -= r->req.sg->size;
        r->req.aiocb = dma_blk_io(blk_get_aio_context(s->qdev.conf.blk),
                                  r->req.sg, r->sector << BDRV_SECTOR_BITS,
                                  BDRV_SECTOR_SIZE,
                                  sdc->dma_writev, r, scsi_dma_complete, r,
                                  DMA_DIRECTION_TO_DEVICE);
    } else {
        block_acct_start(blk_get_stats(s->qdev.conf.blk), &r->acct,
                         r->qiov.size, BLOCK_ACCT_WRITE);
        r->req.aiocb = sdc->dma_writev(r->sector << BDRV_SECTOR_BITS, &r->qiov,
                                       scsi_write_complete, r, r);
    }
}
Unknown