block: trace all devices plug operation

In func blk_queue_bio, if list of plug is empty,it will call blk_trace_plug. If process deal with a single device,it't ok.But if process deal with multi devices,it only trace the first device. Using request_count to judge, it can soleve this problem. In addition, i modify the comment. Signed-off-by: Jianpeng Ma <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
klaby · Sep 11, 2013 · 7aef2e7 · 7aef2e7
1 parent 6e46645
commit 7aef2e7
Showing 1 changed file with 2 additions and 4 deletions.
diff --git a/block/blk-core.c b/block/blk-core.c
@@ -1549,11 +1549,9 @@ void blk_queue_bio(struct request_queue *q, struct bio *bio)
 	if (plug) {
 		/*
 		 * If this is the first request added after a plug, fire
-		 * of a plug trace. If others have been added before, check
-		 * if we have multiple devices in this plug. If so, make a
-		 * note to sort the list before dispatch.
+		 * of a plug trace.
 		 */
-		if (list_empty(&plug->list))
+		if (!request_count)
 			trace_block_plug(q);
 		else {
 			if (request_count >= BLK_MAX_REQUEST_COUNT) {