On Sat, Jun 02, 2018 at 12:59:21PM +0800, Ming Lei wrote:
> If the current io scheduler is 'none', the max allowed 'nr_requests'
> should be from set->queue_depth, instead of the tags's depth, which
> can be adjusted before.
>
> This patch fixes this issue by using set->queue_depth as the max
> allowed 'nr_requests', meantime updating q->nr_requests when switching
> to 'none' scheduler.
>
> Cc: Marco Patalano <mpatalan@xxxxxxxxxx>
> Cc: "Ewan D. Milne" <emilne@xxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
>
> This issue can be reproduced by the blktests block/021, which will
> be posted soon.
>
>
> block/blk-mq-sched.c | 1 +
> block/blk-mq-tag.c | 6 ++++--
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index b0f2c2a40a0c..b087d8884a08 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -585,6 +585,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
>
> if (!e) {
> q->elevator = NULL;
> + q->nr_requests = q->tag_set->queue_depth;
> return 0;
> }
>
> diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
> index a4e58fc28a06..a178d862a29a 100644
> --- a/block/blk-mq-tag.c
> +++ b/block/blk-mq-tag.c
> @@ -423,7 +423,9 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
> struct blk_mq_tags **tagsptr, unsigned int tdepth,
> bool can_grow)
> {
> + struct blk_mq_tag_set *set = hctx->queue->tag_set;
> struct blk_mq_tags *tags = *tagsptr;
> + unsigned int max_depth;
>
> if (tdepth <= tags->nr_reserved_tags)
> return -EINVAL;
> @@ -434,8 +436,8 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
> * If we are allowed to grow beyond the original size, allocate
> * a new set of tags before freeing the old one.
> */
> - if (tdepth > tags->nr_tags) {
> - struct blk_mq_tag_set *set = hctx->queue->tag_set;
> + max_depth = can_grow ? tags->nr_tags: set->queue_depth;
> + if (tdepth > max_depth) {
> struct blk_mq_tags *new;
> bool ret;
Turns out the change on blk_mq_tag_update_depth() isn't necessary,
will post a new one.
Thanks,
Ming
