scsi: core: Set sc_data_direction to DMA_NONE for no-transfer commands

No having the special DMA_NONE logic makes libata rather unhappy.

Link: https://lore.kernel.org/r/20201008200611.1818099-3-hch@lst.de
Fixes: 40b9383 ("scsi: core: Use rq_dma_dir in scsi_setup_cmnd()")
Reported-by: Qian Cai <cai@redhat.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Christoph Hellwig

drivers/scsi/scsi_lib.c

@@ -1545,7 +1545,10 @@ static blk_status_t scsi_prepare_cmd(struct request *req)
 	cmd->request = req;
 	cmd->tag = req->tag;
 	cmd->prot_op = SCSI_PROT_NORMAL;
-	cmd->sc_data_direction = rq_dma_dir(req);
+	if (blk_rq_bytes(req))
+		cmd->sc_data_direction = rq_dma_dir(req);
+	else
+		cmd->sc_data_direction = DMA_NONE;
 
 	sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
 	cmd->sdb.table.sgl = sg;