[PATCH] block: move iostat check into blk_acount_io_start()

[Jens Axboe <axboe@kernel.dk>]

Rather than have blk_do_io_stat() check for both RQF_IO_STAT and whether
the request is a passthrough requests every time, move both of those
checks into blk_account_io_start(). Then blk_do_io_stat() can be reduced
to just checking for RQF_IO_STAT.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4b2c8e940f59..ee6cde39e52b 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -359,8 +359,6 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
 
 	if (data->flags & BLK_MQ_REQ_PM)
 		data->rq_flags |= RQF_PM;
-	if (blk_queue_io_stat(q))
-		data->rq_flags |= RQF_IO_STAT;
 	rq->rq_flags = data->rq_flags;
 
 	if (data->rq_flags & RQF_SCHED_TAGS) {
@@ -1000,24 +998,28 @@ static inline void blk_account_io_start(struct request *req)
 {
 	trace_block_io_start(req);
 
-	if (blk_do_io_stat(req)) {
-		/*
-		 * All non-passthrough requests are created from a bio with one
-		 * exception: when a flush command that is part of a flush sequence
-		 * generated by the state machine in blk-flush.c is cloned onto the
-		 * lower device by dm-multipath we can get here without a bio.
-		 */
-		if (req->bio)
-			req->part = req->bio->bi_bdev;
-		else
-			req->part = req->q->disk->part0;
+	if (!blk_queue_io_stat(req->q))
+		return;
+	if (blk_rq_is_passthrough(req))
+		return;
 
-		part_stat_lock();
-		update_io_ticks(req->part, jiffies, false);
-		part_stat_local_inc(req->part,
-				    in_flight[op_is_write(req_op(req))]);
-		part_stat_unlock();
-	}
+	req->rq_flags |= RQF_IO_STAT;
+
+	/*
+	 * All non-passthrough requests are created from a bio with one
+	 * exception: when a flush command that is part of a flush sequence
+	 * generated by the state machine in blk-flush.c is cloned onto the
+	 * lower device by dm-multipath we can get here without a bio.
+	 */
+	if (req->bio)
+		req->part = req->bio->bi_bdev;
+	else
+		req->part = req->q->disk->part0;
+
+	part_stat_lock();
+	update_io_ticks(req->part, jiffies, false);
+	part_stat_local_inc(req->part, in_flight[op_is_write(req_op(req))]);
+	part_stat_unlock();
 }
 
 static inline void __blk_mq_end_request_acct(struct request *rq, u64 now)
diff --git a/block/blk.h b/block/blk.h
index c718e4291db0..84178e535533 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -413,7 +413,7 @@ int blk_dev_init(void);
  */
 static inline bool blk_do_io_stat(struct request *rq)
 {
-	return (rq->rq_flags & RQF_IO_STAT) && !blk_rq_is_passthrough(rq);
+	return rq->rq_flags & RQF_IO_STAT;
 }
 
 void update_io_ticks(struct block_device *part, unsigned long now, bool end);

-- 
Jens Axboe