scsi: sym53c8xx_2: Move the SCSI pointer to private command data

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/20220218195117.25689-45-bvanassche@acm.orgReviewed-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/sym53c8xx_2/sym_glue.c

@@ -118,7 +118,7 @@ struct sym_ucmd {		/* Override the SCSI pointer structure */
 	struct completion *eh_done;		/* SCSI error handling */
 };
 
-#define SYM_UCMD_PTR(cmd)  ((struct sym_ucmd *)(&(cmd)->SCp))
+#define SYM_UCMD_PTR(cmd)  ((struct sym_ucmd *)scsi_cmd_priv(cmd))
 #define SYM_SOFTC_PTR(cmd) sym_get_hcb(cmd->device->host)
 
 /*
@@ -127,7 +127,6 @@ struct sym_ucmd {		/* Override the SCSI pointer structure */
 void sym_xpt_done(struct sym_hcb *np, struct scsi_cmnd *cmd)
 {
 	struct sym_ucmd *ucmd = SYM_UCMD_PTR(cmd);
-	BUILD_BUG_ON(sizeof(struct scsi_pointer) < sizeof(struct sym_ucmd));
 
 	if (ucmd->eh_done)
 		complete(ucmd->eh_done);
@@ -1630,6 +1629,7 @@ static struct scsi_host_template sym2_template = {
 	.module			= THIS_MODULE,
 	.name			= "sym53c8xx",
 	.info			= sym53c8xx_info, 
+	.cmd_size		= sizeof(struct sym_ucmd),
 	.queuecommand		= sym53c8xx_queue_command,
 	.slave_alloc		= sym53c8xx_slave_alloc,
 	.slave_configure	= sym53c8xx_slave_configure,