block: add missed trace_block_plug

After flush plug list, the list has no request, so we need to add a
trace_block_plug().

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 3 insertions, 1 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 6403c12f8aa..ea70e6c80cd 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1387,8 +1387,10 @@ get_rq:
                                 if (__rq->q != q)
                                         plug->should_sort = 1;
                         }
-                        if (request_count >= BLK_MAX_REQUEST_COUNT)
+                        if (request_count >= BLK_MAX_REQUEST_COUNT) {
                                 blk_flush_plug_list(plug, false);
+                                trace_block_plug(q);
+                        }
                 }
                 list_add_tail(&req->queuelist, &plug->list);
                 drive_stat_acct(req, 1);