block: open code __blk_account_io_start()

There is only one caller for __blk_account_io_start(), the function
is small enough to fit in its caller blk_account_io_start().

Remove the function and opencode in the its caller
blk_account_io_start().

Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20230327073427.4403-2-kch@nvidia.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -976,28 +976,24 @@ static inline void blk_account_io_done(struct request *req, u64 now)
 		__blk_account_io_done(req, now);
 }
 
-static void __blk_account_io_start(struct request *rq)
-{
-	/*
-	 * 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 (rq->bio)
-		rq->part = rq->bio->bi_bdev;
-	else
-		rq->part = rq->q->disk->part0;
-
-	part_stat_lock();
-	update_io_ticks(rq->part, jiffies, false);
-	part_stat_unlock();
-}
-
 static inline void blk_account_io_start(struct request *req)
 {
-	if (blk_do_io_stat(req))
-		__blk_account_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;
+
+		part_stat_lock();
+		update_io_ticks(req->part, jiffies, false);
+		part_stat_unlock();
+	}
 }
 
 static inline void __blk_mq_end_request_acct(struct request *rq, u64 now)