scsi: smartpqi: Stop using the SCSI pointer

Set .cmd_size in the SCSI host template instead of using the SCSI pointer
from struct scsi_cmnd. This patch prepares for removal of the SCSI pointer
from struct scsi_cmnd.

Link: https://lore.kernel.org/r/20220218195117.25689-44-bvanassche@acm.org
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/smartpqi/smartpqi_init.c

@@ -54,6 +54,15 @@ MODULE_DESCRIPTION("Driver for Microchip Smart Family Controller version "
 MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL");
 
+struct pqi_cmd_priv {
+	int this_residual;
+};
+
+static struct pqi_cmd_priv *pqi_cmd_priv(struct scsi_cmnd *cmd)
+{
+	return scsi_cmd_priv(cmd);
+}
+
 static void pqi_verify_structures(void);
 static void pqi_take_ctrl_offline(struct pqi_ctrl_info *ctrl_info,
 	enum pqi_ctrl_shutdown_reason ctrl_shutdown_reason);
@@ -5552,7 +5561,7 @@ static void pqi_aio_io_complete(struct pqi_io_request *io_request,
 	scsi_dma_unmap(scmd);
 	if (io_request->status == -EAGAIN || pqi_raid_bypass_retry_needed(io_request)) {
 		set_host_byte(scmd, DID_IMM_RETRY);
-		scmd->SCp.this_residual++;
+		pqi_cmd_priv(scmd)->this_residual++;
 	}
 
 	pqi_free_io_request(io_request);
@@ -5814,7 +5823,7 @@ static inline bool pqi_is_bypass_eligible_request(struct scsi_cmnd *scmd)
 	if (blk_rq_is_passthrough(scsi_cmd_to_rq(scmd)))
 		return false;
 
-	return scmd->SCp.this_residual == 0;
+	return pqi_cmd_priv(scmd)->this_residual == 0;
 }
 
 /*
@@ -7262,6 +7271,7 @@ static struct scsi_host_template pqi_driver_template = {
 	.map_queues = pqi_map_queues,
 	.sdev_groups = pqi_sdev_groups,
 	.shost_groups = pqi_shost_groups,
+	.cmd_size = sizeof(struct pqi_cmd_priv),
 };
 
 static int pqi_register_scsi(struct pqi_ctrl_info *ctrl_info)