Re: [PATCH v3 3/3] blk-cgroup: move async bio punt state to blkcg

[Nilay Shroff]

On 9/18/26 9:47 AM, Yu Kuai wrote:
> From: Yu Kuai<yukuai@xxxxxxx>
>
> blkcg_punt_bio_submit() currently queues punted bios on blkg->async_bios,
> so it has to call bio_blkg() to find or create a queue-local blkg.  Bios
> now carry and pin the blkcg css, so punted bio lifetime no longer needs to
> be anchored by a blkg.
>
> Keeping the punt state in blkg can instantiate a blkg even when no blkcg
> policy is enabled, just to bounce submission from a shared kthread.  Move
> async_bio_lock, async_bios and async_bio_work to struct blkcg, and queue
> punted bios on bio_blkcg() for non-root cgroups.  Root or unassociated bios
> are submitted directly.
>
> This preserves the priority-inversion avoidance while preventing
> blkcg_punt_bio_submit() from creating blkgs that are not needed by any
> policy.
>
> Signed-off-by: Yu Kuai<yukuai@xxxxxxx>

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