# \[PATCH AUTOSEL 5.12 061/134\] block, bfq: fix weight-raising resume with !low\_latency - From: Sasha Levin \ - Date: 2021-05-03 16:39:44 - List: linux-block - Page: https://ratatoskr.run/linux-block/2021/05/6356444 - Thread: https://ratatoskr.run/stable/2021/05/6356383/t.md ```text From: Paolo Valente [ Upstream commit 8c544770092a3d7532d01903b75721e537d87001 ] When the io_latency heuristic is off, bfq_queues must not start to be weight-raised. Unfortunately, by mistake, this may happen when the state of a previously weight-raised bfq_queue is resumed after a queue split. This commit fixes this error. Tested-by: Jan Kara Signed-off-by: Paolo Valente Tested-by: Oleksandr Natalenko Link: https://lore.kernel.org/r/20210304174627.161-5-paolo.valente@linaro.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/bfq-iosched.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 95586137194e..20ba5db0f61c 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -1012,7 +1012,7 @@ static void bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd, struct bfq_io_cq *bic, bool bfq_already_existing) { - unsigned int old_wr_coeff = bfqq->wr_coeff; + unsigned int old_wr_coeff = 1; bool busy = bfq_already_existing && bfq_bfqq_busy(bfqq); if (bic->saved_has_short_ttime) @@ -1033,7 +1033,13 @@ bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_data *bfqd, bfqq->ttime = bic->saved_ttime; bfqq->io_start_time = bic->saved_io_start_time; bfqq->tot_idle_time = bic->saved_tot_idle_time; - bfqq->wr_coeff = bic->saved_wr_coeff; + /* + * Restore weight coefficient only if low_latency is on + */ + if (bfqd->low_latency) { + old_wr_coeff = bfqq->wr_coeff; + bfqq->wr_coeff = bic->saved_wr_coeff; + } bfqq->service_from_wr = bic->saved_service_from_wr; bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt; bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish; -- 2.30.2 ```