scsi: add support for multiple hardware queues in scsi_(host_)find_tag

Modify scsi_find_tag() and scsi_host_find_tag() such that these
functions can translate a tag generated by blk_mq_unique_tag().
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

include/scsi/scsi_tcq.h

@@ -111,18 +111,21 @@ static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
 }
 
 static inline struct scsi_cmnd *scsi_mq_find_tag(struct Scsi_Host *shost,
-		unsigned int hw_ctx, int tag)
+						 int unique_tag)
 {
-	struct request *req;
+	u16 hwq = blk_mq_unique_tag_to_hwq(unique_tag);
+	struct request *req = NULL;
 
-	req = blk_mq_tag_to_rq(shost->tag_set.tags[hw_ctx], tag);
+	if (hwq < shost->tag_set.nr_hw_queues)
+		req = blk_mq_tag_to_rq(shost->tag_set.tags[hwq],
+				       blk_mq_unique_tag_to_tag(unique_tag));
 	return req ? (struct scsi_cmnd *)req->special : NULL;
 }
 
 /**
  * scsi_find_tag - find a tagged command by device
  * @SDpnt:	pointer to the ScSI device
- * @tag:	the tag number
+ * @tag:	tag generated by blk_mq_unique_tag()
  *
  * Notes:
  *	Only works with tags allocated by the generic blk layer.
@@ -133,9 +136,9 @@ static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
 
         if (tag != SCSI_NO_TAG) {
 		if (shost_use_blk_mq(sdev->host))
-			return scsi_mq_find_tag(sdev->host, 0, tag);
+			return scsi_mq_find_tag(sdev->host, tag);
 
-        	req = blk_queue_find_tag(sdev->request_queue, tag);
+		req = blk_queue_find_tag(sdev->request_queue, tag);
 	        return req ? (struct scsi_cmnd *)req->special : NULL;
 	}
 
@@ -174,7 +177,7 @@ static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
 /**
  * scsi_host_find_tag - find the tagged command by host
  * @shost:	pointer to scsi_host
- * @tag:	tag of the scsi_cmnd
+ * @tag:	tag generated by blk_mq_unique_tag()
  *
  * Notes:
  *	Only works with tags allocated by the generic blk layer.
@@ -186,7 +189,7 @@ static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost,
 
 	if (tag != SCSI_NO_TAG) {
 		if (shost_use_blk_mq(shost))
-			return scsi_mq_find_tag(shost, 0, tag);
+			return scsi_mq_find_tag(shost, tag);
 		req = blk_map_queue_find_tag(shost->bqt, tag);
 		return req ? (struct scsi_cmnd *)req->special : NULL;
 	}