scsi: add new scsi-command flag for tagged commands

Currently scsi piggy backs on the block layer to define the concept
of a tagged command.  But we want to be able to have block-level host-wide
tags assigned even for untagged commands like the initial INQUIRY, so add
a new SCSI-level flag for commands that are tagged at the scsi level, so
that even commands without that set can have tags assigned to them.  Note
that this alredy is the case for the blk-mq code path, and this just lets
the old path catch up with it.

We also set this flag based upon sdev->simple_tags instead of the block
queue flag, so that it is entirely independent of the block layer tagging,
and thus always correct even if a driver doesn't use block level tagging
yet.

Also remove the old blk_rq_tagged; it was only used by SCSI drivers, and
removing it forces them to look for the proper replacement.

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>

3 files changed, 6 insertions, 5 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index aac0f9e..6d76b8b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1136,7 +1136,6 @@ static inline bool blk_needs_flush_plug(struct task_struct *tsk)
 /*
  * tag stuff
  */
-#define blk_rq_tagged(rq)		((rq)->cmd_flags & REQ_QUEUED)
 extern int blk_queue_start_tag(struct request_queue *, struct request *);
 extern struct request *blk_queue_find_tag(struct request_queue *, int);
 extern void blk_queue_end_tag(struct request_queue *, struct request *);
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 522a5f27..e119142 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -53,6 +53,9 @@ struct scsi_pointer {
 	volatile int phase;
 };
 
+/* for scmd->flags */
+#define SCMD_TAGGED		(1 << 0)
+
 struct scsi_cmnd {
 	struct scsi_device *device;
 	struct list_head list;  /* scsi_cmnd participates in queue lists */
@@ -132,6 +135,7 @@ struct scsi_cmnd {
 					 * to be at an address < 16Mb). */
 
 	int result;		/* Status code from lower level driver */
+	int flags;		/* Command flags */
 
 	unsigned char tag;	/* SCSI-II queued command tag */
 };
diff --git a/include/scsi/scsi_tcq.h b/include/scsi/scsi_tcq.h
index 1712dab..032df74 100644
--- a/include/scsi/scsi_tcq.h
+++ b/include/scsi/scsi_tcq.h
@@ -101,11 +101,9 @@ static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth)
  **/
 static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg)
 {
-        struct request *req = cmd->request;
-
-        if (blk_rq_tagged(req)) {
+        if (cmd->flags & SCMD_TAGGED) {
 		*msg++ = MSG_SIMPLE_TAG;
-        	*msg++ = req->tag;
+        	*msg++ = cmd->request->tag;
         	return 2;
 	}