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 <zhangweiping@xxxxxxxxxxxxxxx>
> ---
> 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
