scsi: core: Clear driver private data when retrying request

After commit 1bad6c4a57ef ("scsi: zero per-cmd private driver data for each
MQ I/O"), the xen-scsifront/virtio_scsi/snic drivers all removed code that
explicitly zeroed driver-private command data.

In combination with commit 464a00c9e0ad ("scsi: core: Kill DRIVER_SENSE"),
after virtio_scsi performs a capacity expansion, the first request will
return a unit attention to indicate that the capacity has changed. And then
the original command is retried. As driver-private command data was not
cleared, the request would return UA again and eventually time out and fail.

Zero driver-private command data when a request is retried.

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@huawei.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20250217021628.2929248-1-yebin@huaweicloud.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index be0890e4e7062ebb387d3964b509bc4f3be5cb35..f1cfe0bb89b20c9e3566ca01cbd12ae166137ad6 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1669,13 +1669,6 @@ 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);
-
        cmd->prot_op = SCSI_PROT_NORMAL;
        if (blk_rq_bytes(req))
                cmd->sc_data_direction = rq_dma_dir(req);
@@ -1842,6 +1835,13 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
        if (!scsi_host_queue_ready(q, shost, sdev, cmd))
                goto out_dec_target_busy;
 
+       /*
+        * Only clear the driver-private command data if the LLD does not supply
+        * a function to initialize that data.
+        */
+       if (shost->hostt->cmd_size && !shost->hostt->init_cmd_priv)
+               memset(cmd + 1, 0, shost->hostt->cmd_size);
+
        if (!(req->rq_flags & RQF_DONTPREP)) {
                ret = scsi_prepare_cmd(req);
                if (ret != BLK_STS_OK)