From 614822f81f606e0064acdae11d9ec1efd3db4190 Mon Sep 17 00:00:00 2001
From: Luca Miccio <lucmiccio@gmail.com>
Date: Mon, 13 Nov 2017 07:34:08 +0100
Subject: [PATCH] block, bfq: add missing invocations of
 bfqg_stats_update_io_add/remove
Git-commit: 614822f81f606e0064acdae11d9ec1efd3db4190
Patch-mainline: v4.15-rc1
References: bsc#1099918

bfqg_stats_update_io_add and bfqg_stats_update_io_remove are to be
invoked, respectively, when an I/O request enters and when an I/O
request exits the scheduler. Unfortunately, bfq does not fully comply
with this scheme, because it does not invoke these functions for
requests that are inserted into or extracted from its priority
dispatch list. This commit fixes this mistake.

Tested-by: Lee Tibbert <lee.tibbert@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>
---
 block/bfq-iosched.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 889a8549d97f..91703eba63f0 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -1359,7 +1359,6 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
 			bfqq->ttime.last_end_request +
 			bfqd->bfq_slice_idle * 3;
 
-	bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags);
 
 	/*
 	 * bfqq deserves to be weight-raised if:
@@ -1633,7 +1632,6 @@ static void bfq_remove_request(struct request_queue *q,
 	if (rq->cmd_flags & REQ_META)
 		bfqq->meta_pending--;
 
-	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
 }
 
 static bool bfq_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
@@ -1746,6 +1744,7 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
 		bfqq->next_rq = rq;
 
 	bfq_remove_request(q, next);
+	bfqg_stats_update_io_remove(bfqq_group(bfqq), next->cmd_flags);
 
 	spin_unlock_irq(&bfqq->bfqd->lock);
 end:
@@ -3700,6 +3699,9 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
 	spin_lock_irq(&bfqd->lock);
 
 	rq = __bfq_dispatch_request(hctx);
+	if (rq && RQ_BFQQ(rq))
+		bfqg_stats_update_io_remove(bfqq_group(RQ_BFQQ(rq)),
+					    rq->cmd_flags);
 	spin_unlock_irq(&bfqd->lock);
 
 	return rq;
@@ -4224,6 +4226,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 {
 	struct request_queue *q = hctx->queue;
 	struct bfq_data *bfqd = q->elevator->elevator_data;
+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
 
 	spin_lock_irq(&bfqd->lock);
 	if (blk_mq_sched_try_insert_merge(q, rq)) {
@@ -4243,6 +4246,12 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 			list_add_tail(&rq->queuelist, &bfqd->dispatch);
 	} else {
 		__bfq_insert_request(bfqd, rq);
+		/*
+		 * Update bfqq, because, if a queue merge has occurred
+		 * in __bfq_insert_request, then rq has been
+		 * redirected into a new queue.
+		 */
+		bfqq = RQ_BFQQ(rq);
 
 		if (rq_mergeable(rq)) {
 			elv_rqhash_add(q, rq);
@@ -4251,6 +4260,9 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 		}
 	}
 
+	if (bfqq)
+		bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, rq->cmd_flags);
+
 	spin_unlock_irq(&bfqd->lock);
 }
 
@@ -4428,8 +4440,11 @@ static void bfq_finish_request(struct request *rq)
 		 * lock is held.
 		 */
 
-		if (!RB_EMPTY_NODE(&rq->rb_node))
+		if (!RB_EMPTY_NODE(&rq->rb_node)) {
 			bfq_remove_request(rq->q, rq);
+			bfqg_stats_update_io_remove(bfqq_group(bfqq),
+						    rq->cmd_flags);
+		}
 		bfq_put_rq_priv_body(bfqq);
 	}
 
-- 
2.17.1