[PATCH 5.10 276/593] block: avoid double io accounting for flush request

From: Greg Kroah-Hartman
Date: Mon Jul 12 2021 - 02:54:55 EST


From: Ming Lei <ming.lei@xxxxxxxxxx>

[ Upstream commit 84da7acc3ba53af26f15c4b0ada446127b7a7836 ]

For flush request, rq->end_io() may be called two times, one is from
timeout handling(blk_mq_check_expired()), another is from normal
completion(__blk_mq_end_request()).

Move blk_account_io_flush() after flush_rq->ref drops to zero, so
io accounting can be done just once for flush request.

Fixes: b68663186577 ("block: add iostat counters for flush requests")
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Tested-by: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210511152236.763464-2-ming.lei@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
block/blk-flush.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/block/blk-flush.c b/block/blk-flush.c
index fd5cee9f1a3b..7ee7e5e8905d 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -220,8 +220,6 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
unsigned long flags = 0;
struct blk_flush_queue *fq = blk_get_flush_queue(q, flush_rq->mq_ctx);

- blk_account_io_flush(flush_rq);
-
/* release the tag's ownership to the req cloned from */
spin_lock_irqsave(&fq->mq_flush_lock, flags);

@@ -231,6 +229,7 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
return;
}

+ blk_account_io_flush(flush_rq);
/*
* Flush request has to be marked as IDLE when it is really ended
* because its .end_io() is called from timeout code path too for
--
2.30.2