block: remove legacy rq tagging

It's now unused, kill it.

Reviewed-by: Hannes Reinecke <[email protected]>
Tested-by: Ming Lei <[email protected]>
Reviewed-by: Omar Sandoval <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Documentation/block/biodoc.txt

@@ -65,7 +65,6 @@ Description of Contents:
     3.2.3 I/O completion
     3.2.4 Implications for drivers that do not interpret bios (don't handle
  	  multiple segments)
-    3.2.5 Request command tagging
   3.3 I/O submission
 4. The I/O scheduler
 5. Scalability related changes
@@ -708,93 +707,6 @@ is crossed on completion of a transfer. (The end*request* functions should
 be used if only if the request has come down from block/bio path, not for
 direct access requests which only specify rq->buffer without a valid rq->bio)
 
-3.2.5 Generic request command tagging
-
-3.2.5.1 Tag helpers
-
-Block now offers some simple generic functionality to help support command
-queueing (typically known as tagged command queueing), ie manage more than
-one outstanding command on a queue at any given time.
-
-	blk_queue_init_tags(struct request_queue *q, int depth)
-
-	Initialize internal command tagging structures for a maximum
-	depth of 'depth'.
-
-	blk_queue_free_tags((struct request_queue *q)
-
-	Teardown tag info associated with the queue. This will be done
-	automatically by block if blk_queue_cleanup() is called on a queue
-	that is using tagging.
-
-The above are initialization and exit management, the main helpers during
-normal operations are:
-
-	blk_queue_start_tag(struct request_queue *q, struct request *rq)
-
-	Start tagged operation for this request. A free tag number between
-	0 and 'depth' is assigned to the request (rq->tag holds this number),
-	and 'rq' is added to the internal tag management. If the maximum depth
-	for this queue is already achieved (or if the tag wasn't started for
-	some other reason), 1 is returned. Otherwise 0 is returned.
-
-	blk_queue_end_tag(struct request_queue *q, struct request *rq)
-
-	End tagged operation on this request. 'rq' is removed from the internal
-	book keeping structures.
-
-To minimize struct request and queue overhead, the tag helpers utilize some
-of the same request members that are used for normal request queue management.
-This means that a request cannot both be an active tag and be on the queue
-list at the same time. blk_queue_start_tag() will remove the request, but
-the driver must remember to call blk_queue_end_tag() before signalling
-completion of the request to the block layer. This means ending tag
-operations before calling end_that_request_last()! For an example of a user
-of these helpers, see the IDE tagged command queueing support.
-
-3.2.5.2 Tag info
-
-Some block functions exist to query current tag status or to go from a
-tag number to the associated request. These are, in no particular order:
-
-	blk_queue_tagged(q)
-
-	Returns 1 if the queue 'q' is using tagging, 0 if not.
-
-	blk_queue_tag_request(q, tag)
-
-	Returns a pointer to the request associated with tag 'tag'.
-
-	blk_queue_tag_depth(q)
-
-	Return current queue depth.
-
-	blk_queue_tag_queue(q)
-
-	Returns 1 if the queue can accept a new queued command, 0 if we are
-	at the maximum depth already.
-
-	blk_queue_rq_tagged(rq)
-
-	Returns 1 if the request 'rq' is tagged.
-
-3.2.5.2 Internal structure
-
-Internally, block manages tags in the blk_queue_tag structure:
-
-	struct blk_queue_tag {
-		struct request **tag_index;	/* array or pointers to rq */
-		unsigned long *tag_map;		/* bitmap of free tags */
-		struct list_head busy_list;	/* fifo list of busy tags */
-		int busy;			/* queue depth */
-		int max_depth;			/* max queue depth */
-	};
-
-Most of the above is simple and straight forward, however busy_list may need
-a bit of explaining. Normally we don't care too much about request ordering,
-but in the event of any barrier requests in the tag queue we need to ensure
-that requests are restarted in the order they were queue.
-
 3.3 I/O Submission
 
 The routine submit_bio() is used to submit a single io. Higher level i/o

block/Makefile

@@ -3,7 +3,7 @@
 # Makefile for the kernel block layer
 #
 
-obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-tag.o blk-sysfs.o \
+obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-sysfs.o \
 			blk-flush.o blk-settings.o blk-ioc.o blk-map.o \
 			blk-exec.o blk-merge.o blk-softirq.o blk-timeout.o \
 			blk-lib.o blk-mq.o blk-mq-tag.o blk-stat.o \

block/blk-core.c

@@ -1658,9 +1658,6 @@ void blk_requeue_request(struct request_queue *q, struct request *rq)
 	trace_block_rq_requeue(q, rq);
 	rq_qos_requeue(q, rq);
 
-	if (rq->rq_flags & RQF_QUEUED)
-		blk_queue_end_tag(q, rq);
-
 	BUG_ON(blk_queued_rq(rq));
 
 	elv_requeue_request(q, rq);
@@ -3174,9 +3171,6 @@ void blk_finish_request(struct request *req, blk_status_t error)
 	if (req->rq_flags & RQF_STATS)
 		blk_stat_add(req, now);
 
-	if (req->rq_flags & RQF_QUEUED)
-		blk_queue_end_tag(q, req);
-
 	BUG_ON(blk_queued_rq(req));
 
 	if (unlikely(laptop_mode) && !blk_rq_is_passthrough(req))

block/blk-mq-debugfs.c

@@ -112,7 +112,6 @@ static int queue_pm_only_show(void *data, struct seq_file *m)
 
 #define QUEUE_FLAG_NAME(name) [QUEUE_FLAG_##name] = #name
 static const char *const blk_queue_flag_name[] = {
-	QUEUE_FLAG_NAME(QUEUED),
 	QUEUE_FLAG_NAME(STOPPED),
 	QUEUE_FLAG_NAME(DYING),
 	QUEUE_FLAG_NAME(BYPASS),
@@ -318,7 +317,6 @@ static const char *const cmd_flag_name[] = {
 static const char *const rqf_name[] = {
 	RQF_NAME(SORTED),
 	RQF_NAME(STARTED),
-	RQF_NAME(QUEUED),
 	RQF_NAME(SOFTBARRIER),
 	RQF_NAME(FLUSH_SEQ),
 	RQF_NAME(MIXED_MERGE),

block/blk-mq-tag.c

@@ -530,10 +530,8 @@ u32 blk_mq_unique_tag(struct request *rq)
 	struct blk_mq_hw_ctx *hctx;
 	int hwq = 0;
 
-	if (q->mq_ops) {
-		hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
-		hwq = hctx->queue_num;
-	}
+	hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
+	hwq = hctx->queue_num;
 
 	return (hwq << BLK_MQ_UNIQUE_TAG_BITS) |
 		(rq->tag & BLK_MQ_UNIQUE_TAG_MASK);

block/blk-sysfs.c

@@ -849,9 +849,6 @@ static void __blk_release_queue(struct work_struct *work)
 
 	blk_exit_rl(q, &q->root_rl);
 
-	if (q->queue_tags)
-		__blk_queue_free_tags(q);
-
 	blk_queue_free_zone_bitmaps(q);
 
 	if (!q->mq_ops) {