From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sun, 3 Sep 2017 21:46:39 +0800 From: weiping zhang To: CC: Subject: [PATCH] blk-mq: fix nr_requests wrong value when modify it from sysfs Message-ID: <20170903134634.GA27411@localhost.didichuxing.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-Path: zhangweiping@didichuxing.com List-ID: if blk-mq use "none" io scheduler, nr_request get a wrong value when input a number > tag_set->queue_depth. blk_mq_tag_update_depth will get the smaller one min(nr, set->queue_depth), and then q->nr_request get a wrong value. Reproduce: echo none > /sys/block/nvme0n1/queue/ioscheduler echo 1000000 > /sys/block/nvme0n1/queue/nr_requests cat /sys/block/nvme0n1/queue/nr_requests 1000000 Signed-off-by: weiping zhang --- block/blk-mq.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index f84d145..8303e5e 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2622,8 +2622,11 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) * queue depth. This is similar to what the old code would do. */ if (!hctx->sched_tags) { - ret = blk_mq_tag_update_depth(hctx, &hctx->tags, - min(nr, set->queue_depth), + if (nr > set->queue_depth) { + nr = set->queue_depth; + pr_warn("reduce nr_request to %u\n", nr); + } + ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr, false); } else { ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags, -- 2.9.4