[PATCH 04/16] md: add queue limit helpers

[Yu Kuai]

  Hi,

在 2024/02/26 18:29, Christoph Hellwig 写道:
> Add a few helpers that wrap the block queue limits API for use in MD.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>   drivers/md/md.c | 37 +++++++++++++++++++++++++++++++++++++
>   drivers/md/md.h |  3 +++
>   2 files changed, 40 insertions(+)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 75266c34b1f99b..23823823f80c6b 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -5699,6 +5699,43 @@ static const struct kobj_type md_ktype = {
>   
>   int mdp_major = 0;
>   
> +/* stack the limit for all rdevs into lim */
> +void mddev_stack_rdev_limits(struct mddev *mddev, struct queue_limits *lim)
> +{
> +	struct md_rdev *rdev;
> +
> +	rdev_for_each(rdev, mddev) {
> +		queue_limits_stack_bdev(lim, rdev->bdev, rdev->data_offset,
> +					mddev->gendisk->disk_name);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(mddev_stack_rdev_limits);
> +
> +/* apply the extra stacking limits from a new rdev into mddev */
> +int mddev_stack_new_rdev(struct mddev *mddev, struct md_rdev *rdev)
> +{
> +	struct queue_limits lim = queue_limits_start_update(mddev->queue);
> +
> +	queue_limits_stack_bdev(&lim, rdev->bdev, rdev->data_offset,
> +				mddev->gendisk->disk_name);
> +	return queue_limits_commit_update(mddev->queue, &lim);
> +}
> +EXPORT_SYMBOL_GPL(mddev_stack_new_rdev);
> +
> +/* update the optimal I/O size after a reshape */
> +void mddev_update_io_opt(struct mddev *mddev, unsigned int nr_stripes)
> +{
> +	struct queue_limits lim;
> +	int ret;
> +
> +	blk_mq_freeze_queue(mddev->queue);
> +	lim = queue_limits_start_update(mddev->queue);
> +	lim.io_opt = lim.io_min * nr_stripes;
> +	ret = queue_limits_commit_update(mddev->queue, &lim);
> +	blk_mq_unfreeze_queue(mddev->queue);

Any reason to use blk_mq_freeze/unfreeze_queue ? I don't think this is
meaningful for raid, this only wait for IO submission, not IO done.

raid should already handle concurrent IO with reshape, so I think this
can just be removed.

Thanks,
Kuai

> +}
> +EXPORT_SYMBOL_GPL(mddev_update_io_opt);
> +
>   static void mddev_delayed_delete(struct work_struct *ws)
>   {
>   	struct mddev *mddev = container_of(ws, struct mddev, del_work);
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 8d881cc597992f..25b19614aa3239 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -860,6 +860,9 @@ void md_autostart_arrays(int part);
>   int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info);
>   int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info);
>   int do_md_run(struct mddev *mddev);
> +void mddev_stack_rdev_limits(struct mddev *mddev, struct queue_limits *lim);
> +int mddev_stack_new_rdev(struct mddev *mddev, struct md_rdev *rdev);
> +void mddev_update_io_opt(struct mddev *mddev, unsigned int nr_stripes);
>   
>   extern const struct block_device_operations md_fops;
>   
>