[PATCH] scsi: core: clear driver private data when retry request

[Ye Bin <yebin@xxxxxxxxxxxxxxx>]

From: Ye Bin <yebin10@xxxxxxxxxx>

After commit 1bad6c4a57ef
("scsi: zero per-cmd private driver data for each MQ I/O"),
xen-scsifront/virtio_scsi/snic driver remove code that zeroes
driver-private command data. If request do retry will lead to
driver-private command data remains. Before commit 464a00c9e0ad
("scsi: core: Kill DRIVER_SENSE") if virtio_scsi do capacity
expansion, first request may return UA then request will do retry,
as driver-private command data remains, request will return UA
again. As a result, the request keeps retrying, and the request
times out and fails.
So zeroes driver-private command data when request do retry.

Fixes: f7de50da1479 ("scsi: xen-scsifront: Remove code that zeroes driver-private command data")
Fixes: c2bb87318baa ("scsi: virtio_scsi: Remove code that zeroes driver-private command data")
Fixes: c3006a926468 ("scsi: snic: Remove code that zeroes driver-private command data")
Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
---
 drivers/scsi/scsi_lib.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index be0890e4e706..5b0c109c89bb 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1645,6 +1645,17 @@ static unsigned int scsi_mq_inline_sgl_size(struct Scsi_Host *shost)
 		sizeof(struct scatterlist);
 }
 
+static inline void scsi_clear_lld_private_data(struct scsi_cmnd *cmd,
+					       struct Scsi_Host *shost)
+{
+	/*
+	 * Only clear the driver-private command data if the LLD does not supply
+	 * a function to initialize that data.
+	 */
+	if (!shost->hostt->init_cmd_priv && shost->hostt->cmd_size)
+		memset(cmd + 1, 0, shost->hostt->cmd_size);
+}
+
 static blk_status_t scsi_prepare_cmd(struct request *req)
 {
 	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
@@ -1669,12 +1680,7 @@ static blk_status_t scsi_prepare_cmd(struct request *req)
 	if (in_flight)
 		__set_bit(SCMD_STATE_INFLIGHT, &cmd->state);
 
-	/*
-	 * Only clear the driver-private command data if the LLD does not supply
-	 * a function to initialize that data.
-	 */
-	if (!shost->hostt->init_cmd_priv)
-		memset(cmd + 1, 0, shost->hostt->cmd_size);
+	scsi_clear_lld_private_data(cmd, shost);
 
 	cmd->prot_op = SCSI_PROT_NORMAL;
 	if (blk_rq_bytes(req))
@@ -1848,6 +1854,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
 			goto out_dec_host_busy;
 		req->rq_flags |= RQF_DONTPREP;
 	} else {
+		scsi_clear_lld_private_data(cmd, shost);
 		clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
 	}
 
-- 
2.34.1