Re: [PATCH v3 3/7] blk-mq: add a new queue sysfs attribute async_depth

[Nilay Shroff]

On 10/10/25 7:58 AM, Yu Kuai wrote:
> +static ssize_t
> +queue_async_depth_store(struct gendisk *disk, const char *page, size_t count)
> +{
> +	struct request_queue *q = disk->queue;
> +	unsigned int memflags;
> +	unsigned long nr;
> +	int ret;
> +
> +	if (!queue_is_mq(q))
> +		return -EINVAL;
> +
> +	ret = queue_var_store(&nr, page, count);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (nr == 0)
> +		return -EINVAL;
> +
> +	memflags = blk_mq_freeze_queue(q);
> +	scoped_guard(mutex, &q->elevator_lock) {
> +		if (q->elevator) {
> +			q->async_depth = min(q->nr_requests, nr);
> +			if (q->elevator->type->ops.depth_updated)
> +				q->elevator->type->ops.depth_updated(q);
> +		} else {
> +			ret = -EINVAL;
> +		}
> +	}
> +	blk_mq_unfreeze_queue(q, memflags);
> +
> +	return ret;
> +}
> +
With this change, we've got the first user of scoped_guard() in the 
block subsystem!

Looks good to me:
Reviewed-by: Nilay Shroff <nilay@xxxxxxxxxxxxx>