From: Kemeng Shi Date: Mon, 16 Jan 2023 09:51:46 +0000 (+0800) Subject: block, bfq: correctly raise inject limit in bfq_choose_bfqq_for_injection X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0c3e09e8854bcd3f7c45de85007ed283342b3464;p=linux.git block, bfq: correctly raise inject limit in bfq_choose_bfqq_for_injection Function bfq_choose_bfqq_for_injection may temporarily raise inject limit to one request if current inject_limit is 0 before search of the source queue for injection. However the search below will reset inject limit to bfqd->in_service_queue which is zero for raised inject limit. Then the temporarily raised inject limit never works as expected. Assigment limit to bfqd->in_service_queue in search is needed as limit maybe overwriten to min_t(unsigned int, 1, limit) for condition that a large in-flight request is on non-rotational devices in found queue. So we need to reset limit to bfqd->in_service_queue for normal case. Actually, we have already make sure bfqd->rq_in_driver is < limit before search, then -Limit is >= 1 as bfqd->rq_in_driver is >= 0. Then min_t(unsigned int, 1, limit) is always 1. So we can simply check bfqd->rq_in_driver with 1 instead of result of min_t(unsigned int, 1, limit) for larget request in non-rotational device case to avoid overwritting limit and the bug is gone. -For normal case, we have already check bfqd->rq_in_driver is < limit, so we can return found bfqq unconditionally to remove unncessary check. Signed-off-by: Kemeng Shi Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230116095153.3810101-2-shikemeng@huaweicloud.com Signed-off-by: Jens Axboe --- diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 815b884d6c5ac..8836221a26732 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -4730,12 +4730,10 @@ bfq_choose_bfqq_for_injection(struct bfq_data *bfqd) */ if (blk_queue_nonrot(bfqd->queue) && blk_rq_sectors(bfqq->next_rq) >= - BFQQ_SECT_THR_NONROT) - limit = min_t(unsigned int, 1, limit); - else - limit = in_serv_bfqq->inject_limit; - - if (bfqd->tot_rq_in_driver < limit) { + BFQQ_SECT_THR_NONROT && + bfqd->tot_rq_in_driver >= 1) + continue; + else { bfqd->rqs_injected = true; return bfqq; }