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 <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-core.c b/block/blk-core.c
index 93a18d1..91037f7 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1549,11 +1549,9 @@
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) {