[PATCH v10 18/33] scsi: sd: Have scsi-ml retry sd_sync_cache errors

[Mike Christie <michael.christie@oracle.com>]

This has sd_sync_cache have scsi-ml retry errors instead of driving them
itself.

There is one behavior change where we no longer retry when
scsi_execute_cmd returns < 0, but we should be ok. We don't need to retry
for failures like the queue being removed, and for the case where there
are no tags/reqs the block layer waits/retries for us. For possible memory
allocation failures from blk_rq_map_kern we use GFP_NOIO, so retrying
will probably not help.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/sd.c | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 1f110d646896..deac35fb520b 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1605,36 +1605,32 @@ static unsigned int sd_check_events(struct gendisk *disk, unsigned int clearing)
 
 static int sd_sync_cache(struct scsi_disk *sdkp)
 {
-	int retries, res;
+	int res;
 	struct scsi_device *sdp = sdkp->device;
 	const int timeout = sdp->request_queue->rq_timeout
 		* SD_FLUSH_TIMEOUT_MULTIPLIER;
+	/* Leave the rest of the command zero to indicate flush everything. */
+	const unsigned char cmd[16] = { sdp->use_16_for_sync ?
+				SYNCHRONIZE_CACHE_16 : SYNCHRONIZE_CACHE };
 	struct scsi_sense_hdr sshdr;
+	struct scsi_failure failures[] = {
+		{
+			.allowed = 3,
+			.result = SCMD_FAILURE_RESULT_ANY,
+		},
+		{}
+	};
 	const struct scsi_exec_args exec_args = {
 		.req_flags = BLK_MQ_REQ_PM,
 		.sshdr = &sshdr,
+		.failures = failures,
 	};
 
 	if (!scsi_device_online(sdp))
 		return -ENODEV;
 
-	for (retries = 3; retries > 0; --retries) {
-		unsigned char cmd[16] = { 0 };
-
-		if (sdp->use_16_for_sync)
-			cmd[0] = SYNCHRONIZE_CACHE_16;
-		else
-			cmd[0] = SYNCHRONIZE_CACHE;
-		/*
-		 * Leave the rest of the command zero to indicate
-		 * flush everything.
-		 */
-		res = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN, NULL, 0,
-				       timeout, sdkp->max_retries, &exec_args);
-		if (res == 0)
-			break;
-	}
-
+	res = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN, NULL, 0, timeout,
+			       sdkp->max_retries, &exec_args);
 	if (res) {
 		sd_print_result(sdkp, "Synchronize Cache(10) failed", res);
 
-- 
2.34.1