blktrace: port to tracepoints

This was a forward port of work done by Mathieu Desnoyers, I changed it to
encode the 'what' parameter on the tracepoint name, so that one can register
interest in specific events and not on classes of events to then check the
'what' parameter.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

block/Kconfig

@@ -47,6 +47,7 @@ config BLK_DEV_IO_TRACE
 	depends on SYSFS
 	select RELAY
 	select DEBUG_FS
+	select TRACEPOINTS
 	help
 	  Say Y here if you want to be able to trace the block layer actions
 	  on a given queue. Tracing allows you to see any traffic happening

block/blk-core.c

@@ -28,6 +28,7 @@
 #include <linux/task_io_accounting_ops.h>
 #include <linux/blktrace_api.h>
 #include <linux/fault-inject.h>
+#include <trace/block.h>
 
 #include "blk.h"
 
@@ -205,7 +206,7 @@ void blk_plug_device(struct request_queue *q)
 
 	if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) {
 		mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
-		blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
+		trace_block_plug(q);
 	}
 }
 EXPORT_SYMBOL(blk_plug_device);
@@ -292,19 +293,15 @@ void blk_unplug_work(struct work_struct *work)
 	struct request_queue *q =
 		container_of(work, struct request_queue, unplug_work);
 
-	blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
-				q->rq.count[READ] + q->rq.count[WRITE]);
-
+	trace_block_unplug_io(q);
 	q->unplug_fn(q);
 }
 
 void blk_unplug_timeout(unsigned long data)
 {
 	struct request_queue *q = (struct request_queue *)data;
 
-	blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL,
-				q->rq.count[READ] + q->rq.count[WRITE]);
-
+	trace_block_unplug_timer(q);
 	kblockd_schedule_work(q, &q->unplug_work);
 }
 
@@ -314,9 +311,7 @@ void blk_unplug(struct request_queue *q)
 	 * devices don't necessarily have an ->unplug_fn defined
 	 */
 	if (q->unplug_fn) {
-		blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
-					q->rq.count[READ] + q->rq.count[WRITE]);
-
+		trace_block_unplug_io(q);
 		q->unplug_fn(q);
 	}
 }
@@ -822,7 +817,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 	if (ioc_batching(q, ioc))
 		ioc->nr_batch_requests--;
 
-	blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
+	trace_block_getrq(q, bio, rw);
 out:
 	return rq;
 }
@@ -848,7 +843,7 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
 		prepare_to_wait_exclusive(&rl->wait[rw], &wait,
 				TASK_UNINTERRUPTIBLE);
 
-		blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
+		trace_block_sleeprq(q, bio, rw);
 
 		__generic_unplug_device(q);
 		spin_unlock_irq(q->queue_lock);
@@ -928,7 +923,7 @@ void blk_requeue_request(struct request_queue *q, struct request *rq)
 {
 	blk_delete_timer(rq);
 	blk_clear_rq_complete(rq);
-	blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
+	trace_block_rq_requeue(q, rq);
 
 	if (blk_rq_tagged(rq))
 		blk_queue_end_tag(q, rq);
@@ -1167,7 +1162,7 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 		if (!ll_back_merge_fn(q, req, bio))
 			break;
 
-		blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
+		trace_block_bio_backmerge(q, bio);
 
 		req->biotail->bi_next = bio;
 		req->biotail = bio;
@@ -1186,7 +1181,7 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 		if (!ll_front_merge_fn(q, req, bio))
 			break;
 
-		blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
+		trace_block_bio_frontmerge(q, bio);
 
 		bio->bi_next = req->bio;
 		req->bio = bio;
@@ -1269,7 +1264,7 @@ static inline void blk_partition_remap(struct bio *bio)
 		bio->bi_sector += p->start_sect;
 		bio->bi_bdev = bdev->bd_contains;
 
-		blk_add_trace_remap(bdev_get_queue(bio->bi_bdev), bio,
+		trace_block_remap(bdev_get_queue(bio->bi_bdev), bio,
 				    bdev->bd_dev, bio->bi_sector,
 				    bio->bi_sector - p->start_sect);
 	}
@@ -1441,10 +1436,10 @@ static inline void __generic_make_request(struct bio *bio)
 			goto end_io;
 
 		if (old_sector != -1)
-			blk_add_trace_remap(q, bio, old_dev, bio->bi_sector,
+			trace_block_remap(q, bio, old_dev, bio->bi_sector,
 					    old_sector);
 
-		blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
+		trace_block_bio_queue(q, bio);
 
 		old_sector = bio->bi_sector;
 		old_dev = bio->bi_bdev->bd_dev;
@@ -1656,7 +1651,7 @@ static int __end_that_request_first(struct request *req, int error,
 	int total_bytes, bio_nbytes, next_idx = 0;
 	struct bio *bio;
 
-	blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
+	trace_block_rq_complete(req->q, req);
 
 	/*
 	 * for a REQ_TYPE_BLOCK_PC request, we want to carry any eventual