[PATCH 3/4] block/part_stat: account merge of two requests

[Konstantin Khlebnikov]

Also rename blk_account_io_merge() into blk_account_io_merge_request() to
distinguish it from merging request and bio.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
---
 block/blk-merge.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index a04e991b5ded..37bced39bae8 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -662,20 +662,23 @@ void blk_rq_set_mixed_merge(struct request *rq)
 	rq->rq_flags |= RQF_MIXED_MERGE;
 }
 
-static void blk_account_io_merge(struct request *req)
+static void blk_account_io_merge_request(struct request *req)
 {
 	if (blk_do_io_stat(req)) {
+		const int sgrp = op_stat_group(req_op(req));
 		struct hd_struct *part;
 
 		part_stat_lock();
 		part = req->part;
 
+		part_stat_inc(part, merges[sgrp]);
 		part_dec_in_flight(req->q, part, rq_data_dir(req));
 
 		hd_struct_put(part);
 		part_stat_unlock();
 	}
 }
+
 /*
  * Two cases of handling DISCARD merge:
  * If max_discard_segments > 1, the driver takes every bio
@@ -787,7 +790,7 @@ static struct request *attempt_merge(struct request_queue *q,
 	/*
 	 * 'next' is going away, so update stats accordingly
 	 */
-	blk_account_io_merge(next);
+	blk_account_io_merge_request(next);
 
 	/*
 	 * ownership of bio passed from next to req, return 'next' for