block: remove the request_queue argument to the block_split tracepoint

The request_queue can trivially be derived from the bio.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-merge.c

@@ -338,7 +338,7 @@ void __blk_queue_split(struct bio **bio, unsigned int *nr_segs)
 		split->bi_opf |= REQ_NOMERGE;
 
 		bio_chain(split, *bio);
-		trace_block_split(q, split, (*bio)->bi_iter.bi_sector);
+		trace_block_split(split, (*bio)->bi_iter.bi_sector);
 		submit_bio_noacct(*bio);
 		*bio = split;
 	}

drivers/md/dm.c

@@ -1612,7 +1612,7 @@ static blk_qc_t __split_and_process_bio(struct mapped_device *md,
 				part_stat_unlock();
 
 				bio_chain(b, bio);
-				trace_block_split(md->queue, b, bio->bi_iter.bi_sector);
+				trace_block_split(b, bio->bi_iter.bi_sector);
 				ret = submit_bio_noacct(bio);
 				break;
 			}

include/trace/events/block.h

@@ -411,21 +411,19 @@ DEFINE_EVENT(block_unplug, block_unplug,
 
 /**
  * block_split - split a single bio struct into two bio structs
- * @q: queue containing the bio
  * @bio: block operation being split
  * @new_sector: The starting sector for the new bio
  *
- * The bio request @bio in request queue @q needs to be split into two
- * bio requests. The newly created @bio request starts at
- * @new_sector. This split may be required due to hardware limitation
- * such as operation crossing device boundaries in a RAID system.
+ * The bio request @bio needs to be split into two bio requests.  The newly
+ * created @bio request starts at @new_sector. This split may be required due to
+ * hardware limitations such as operation crossing device boundaries in a RAID
+ * system.
  */
 TRACE_EVENT(block_split,
 
-	TP_PROTO(struct request_queue *q, struct bio *bio,
-		 unsigned int new_sector),
+	TP_PROTO(struct bio *bio, unsigned int new_sector),
 
-	TP_ARGS(q, bio, new_sector),
+	TP_ARGS(bio, new_sector),
 
 	TP_STRUCT__entry(
 		__field( dev_t,		dev				)

kernel/trace/blktrace.c

@@ -970,10 +970,9 @@ static void blk_add_trace_unplug(void *ignore, struct request_queue *q,
 	rcu_read_unlock();
 }
 
-static void blk_add_trace_split(void *ignore,
-				struct request_queue *q, struct bio *bio,
-				unsigned int pdu)
+static void blk_add_trace_split(void *ignore, struct bio *bio, unsigned int pdu)
 {
+	struct request_queue *q = bio->bi_disk->queue;
 	struct blk_trace *bt;
 
 	rcu_read_lock();