Re: [PATCH V2 3/6] blk-mq: reconfigure poll after queue map is changed

[John Garry <john.garry@xxxxxxxxxx>]

On 02/03/2022 12:14, Ming Lei wrote:
> queue map can be changed when updating nr_hw_queues, so we need to
> reconfigure queue's poll capability. Add one helper for doing this job.

nvme_mpath_alloc_disk() seems to have similar code to this helper, so 
maybe we can reuse this helper function there (obviously it would need 
to made public)

> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>

Regardless of comment:

Reviewed-by: John Garry <john.garry@xxxxxxxxxx>

> ---
>   block/blk-mq.c | 16 +++++++++++++---
>   1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 64fddb36c93c..57ae9df0f4dc 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -4010,6 +4010,17 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
>   	mutex_unlock(&q->sysfs_lock);
>   }
>   
> +static void blk_mq_update_poll_flag(struct request_queue *q)
> +{
> +	struct blk_mq_tag_set *set = q->tag_set;
> +
> +	if (set->nr_maps > HCTX_TYPE_POLL &&
> +	    set->map[HCTX_TYPE_POLL].nr_queues)
> +		blk_queue_flag_set(QUEUE_FLAG_POLL, q);
> +	else
> +		blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
> +}
> +
>   int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
>   		struct request_queue *q)
>   {
> @@ -4044,9 +4055,7 @@ int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
>   	q->tag_set = set;
>   
>   	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
> -	if (set->nr_maps > HCTX_TYPE_POLL &&
> -	    set->map[HCTX_TYPE_POLL].nr_queues)
> -		blk_queue_flag_set(QUEUE_FLAG_POLL, q);
> +	blk_mq_update_poll_flag(q);
>   
>   	INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
>   	INIT_LIST_HEAD(&q->requeue_list);
> @@ -4512,6 +4521,7 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
>   	blk_mq_update_queue_map(set);
>   	list_for_each_entry(q, &set->tag_list, tag_set_list) {
>   		blk_mq_realloc_hw_ctxs(set, q);
> +		blk_mq_update_poll_flag(q);
>   		if (q->nr_hw_queues != set->nr_hw_queues) {
>   			int i = prev_nr_hw_queues;
>