scsi: always assign block layer tags if enabled

Allow a driver to ask for block layer tags by setting .use_blk_tags in the
host template, in which case it will always see a valid value in
request->tag, similar to the behavior when using blk-mq.  This means even
SCSI "untagged" commands will now have a tag, which is especially useful
when using a host-wide tag map.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
diff --git a/drivers/scsi/pmcraid.c b/drivers/scsi/pmcraid.c
index d5fb31fa..71f9f59 100644
--- a/drivers/scsi/pmcraid.c
+++ b/drivers/scsi/pmcraid.c
@@ -251,7 +251,6 @@
 
 	if (scsi_dev->tagged_supported &&
 	    (RES_IS_GSCSI(res->cfg_entry) || RES_IS_VSET(res->cfg_entry))) {
-		scsi_activate_tcq(scsi_dev, scsi_dev->queue_depth);
 		scsi_adjust_queue_depth(scsi_dev, MSG_SIMPLE_TAG,
 					scsi_dev->host->cmd_per_lun);
 	} else {
@@ -4295,7 +4294,8 @@
 	.cmd_per_lun = PMCRAID_MAX_CMD_PER_LUN,
 	.use_clustering = ENABLE_CLUSTERING,
 	.shost_attrs = pmcraid_host_attrs,
-	.proc_name = PMCRAID_DRIVER_NAME
+	.proc_name = PMCRAID_DRIVER_NAME,
+	.use_blk_tags = 1,
 };
 
 /*