block: remov blk_queue_invalidate_tags

This function is entirely unused, so remove it and the tag_queue_busy
member of struct request_queue.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Documentation/block/biodoc.txt

@@ -752,18 +752,6 @@ 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.
 
-Certain hardware conditions may dictate a need to invalidate the block tag
-queue. For instance, on IDE any tagged request error needs to clear both
-the hardware and software block queue and enable the driver to sanely restart
-all the outstanding requests. There's a third helper to do that:
-
-	blk_queue_invalidate_tags(struct request_queue *q)
-
-	Clear the internal block tag queue and re-add all the pending requests
-	to the request queue. The driver will receive them again on the
-	next request_fn run, just like it did the first time it encountered
-	them.
-
 3.2.5.2 Tag info
 
 Some block functions exist to query current tag status or to go from a
@@ -805,8 +793,7 @@ Internally, block manages tags in the blk_queue_tag structure:
 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. This may happen
-if the driver needs to use blk_queue_invalidate_tags().
+that requests are restarted in the order they were queue.
 
 3.3 I/O Submission
 

block/blk-tag.c

@@ -188,7 +188,6 @@ int blk_queue_init_tags(struct request_queue *q, int depth,
 	 */
 	q->queue_tags = tags;
 	queue_flag_set_unlocked(QUEUE_FLAG_QUEUED, q);
-	INIT_LIST_HEAD(&q->tag_busy_list);
 	return 0;
 }
 EXPORT_SYMBOL(blk_queue_init_tags);
@@ -374,27 +373,6 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq)
 	rq->tag = tag;
 	bqt->tag_index[tag] = rq;
 	blk_start_request(rq);
-	list_add(&rq->queuelist, &q->tag_busy_list);
 	return 0;
 }
 EXPORT_SYMBOL(blk_queue_start_tag);
-
-/**
- * blk_queue_invalidate_tags - invalidate all pending tags
- * @q:  the request queue for the device
- *
- *  Description:
- *   Hardware conditions may dictate a need to stop all pending requests.
- *   In this case, we will safely clear the block side of the tag queue and
- *   readd all requests to the request queue in the right order.
- **/
-void blk_queue_invalidate_tags(struct request_queue *q)
-{
-	struct list_head *tmp, *n;
-
-	lockdep_assert_held(q->queue_lock);
-
-	list_for_each_safe(tmp, n, &q->tag_busy_list)
-		blk_requeue_request(q, list_entry_rq(tmp));
-}
-EXPORT_SYMBOL(blk_queue_invalidate_tags);

include/linux/blkdev.h

@@ -562,7 +562,6 @@ struct request_queue {
 	unsigned int		dma_alignment;
 
 	struct blk_queue_tag	*queue_tags;
-	struct list_head	tag_busy_list;
 
 	unsigned int		nr_sorted;
 	unsigned int		in_flight[2];
@@ -1375,7 +1374,6 @@ extern void blk_queue_end_tag(struct request_queue *, struct request *);
 extern int blk_queue_init_tags(struct request_queue *, int, struct blk_queue_tag *, int);
 extern void blk_queue_free_tags(struct request_queue *);
 extern int blk_queue_resize_tags(struct request_queue *, int);
-extern void blk_queue_invalidate_tags(struct request_queue *);
 extern struct blk_queue_tag *blk_init_tags(int, int);
 extern void blk_free_tags(struct blk_queue_tag *);