On 09/21/2017 09:17 AM, weiping zhang wrote: > 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 <[email protected]> > --- > block/blk-mq.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 98a1860..479c35a 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -2642,8 +2642,12 @@ 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) { > + ret = -EINVAL; > + break; > + } > + > + ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr, > false);
What am I missing here? blk_mq_tag_update_depth() should already return -EINVAL for the case where we can't grow the tags. Looks like this patch should simply remove the min(nr, set->queue_depth) and just pass in 'nr'. Should not need the duplicated check for depth. -- Jens Axboe
