From: Luo Jiaxing <luojiaxing@huawei.com>
Date: Wed, 26 Aug 2020 15:24:26 +0800
Subject: scsi: libsas: Set data_dir as DMA_NONE if libata marks qc as NODATA
Git-commit: 53de092f47ff40e8d4d78d590d95819d391bf2e0
Patch-mainline: v5.9-rc5
References: bsc#1186534

It was discovered that sdparm will fail when attempting to disable write
cache on a SATA disk connected via libsas.

In the ATA command set the write cache state is controlled through the SET
FEATURES operation. This is roughly corresponds to MODE SELECT in SCSI and
the latter command is what is used in the SCSI-ATA translation layer. A
subtle difference is that a MODE SELECT carries data whereas SET FEATURES
is defined as a non-data command in ATA.

Set the DMA data direction to DMA_NONE if the requested ATA command is
identified as non-data.

[mkp: commit desc]

Fixes: fa1c1e8f1ece ("[SCSI] Add SATA support to libsas")
Link: https://lore.kernel.org/r/1598426666-54544-1-git-send-email-luojiaxing@huawei.com
Reviewed-by: John Garry <john.garry@huawei.com>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Luo Jiaxing <luojiaxing@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/scsi/libsas/sas_ata.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 1b93332daa6b..8b424c8ab834 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -209,7 +209,10 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
 		task->num_scatter = si;
 	}
 
-	task->data_dir = qc->dma_dir;
+	if (qc->tf.protocol == ATA_PROT_NODATA)
+		task->data_dir = DMA_NONE;
+	else
+		task->data_dir = qc->dma_dir;
 	task->scatter = qc->sg;
 	task->ata_task.retry_count = 1;
 	task->task_state_flags = SAS_TASK_STATE_PENDING;