Re: [PATCH] blk-mq: quiesce queue while reallocating hctxs

[Yu Kuai]

Hi,

friendly ping ...

Thanks,
Kuai

在 2023/02/21 17:24, Yu Kuai 写道:
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> commit 8237c01f1696 ("blk-mq: use quiesced elevator switch when
> reinitializing queues") add quiesce queue while switching elevator,
> however, if old elevator is none, queue is still not quiesced. Hence
> reallocating hctxs can concurrent with run queue. Fix it by also
> quiesce queue in the beginning of __blk_mq_update_nr_hw_queues().
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> ---
>   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 d3494a796ba8..fb44ef0dff8a 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -4691,8 +4691,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
>   	if (set->nr_maps == 1 && nr_hw_queues == set->nr_hw_queues)
>   		return;
>   
> -	list_for_each_entry(q, &set->tag_list, tag_set_list)
> +	list_for_each_entry(q, &set->tag_list, tag_set_list) {
>   		blk_mq_freeze_queue(q);
> +		blk_mq_quiesce_queue(q);
> +	}
>   	/*
>   	 * Switch IO scheduler to 'none', cleaning up the data associated
>   	 * with the previous scheduler. We will switch back once we are done
> @@ -4741,8 +4743,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
>   	list_for_each_entry(q, &set->tag_list, tag_set_list)
>   		blk_mq_elv_switch_back(&head, q);
>   
> -	list_for_each_entry(q, &set->tag_list, tag_set_list)
> +	list_for_each_entry(q, &set->tag_list, tag_set_list) {
> +		blk_mq_unquiesce_queue(q);
>   		blk_mq_unfreeze_queue(q);
> +	}
>   }
>   
>   void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)