[dm-devel] Re: [PATCH 6/7] bio-cgroup: Implement the bio-cgroup

[Takuya Yoshikawa <yoshikawa takuya oss ntt co jp>]

Ryo Tsuruta wrote:
> +static void bio_cgroup_move_task(struct cgroup_subsys *ss,
> +				struct cgroup *cont,
> +				struct cgroup *old_cont,
> +				struct task_struct *p)
> +{
> +	struct mm_struct *mm;
> +	struct bio_cgroup *biog, *old_biog;
> +
> +	if (bio_cgroup_disabled())
> +		return;
> +
> +	mm = get_task_mm(p);
> +	if (mm == NULL)
> +		return;
> +
> +	biog = cgroup_bio(cont);
> +	old_biog = cgroup_bio(old_cont);
> +
> +	mmput(mm);
> +	return;
> +}

Is this function fully implemented?
I tried to put a process into a group by writing to 
"/cgroup/bio/BGROUP/tasks" but failed.

I think this function is not enough to be used as "attach."

> +
> +
> +struct cgroup_subsys bio_cgroup_subsys = {
> +	.name           = "bio",
> +	.subsys_id      = bio_cgroup_subsys_id,
> +	.create         = bio_cgroup_create,
> +	.destroy        = bio_cgroup_destroy,
> +	.pre_destroy	= bio_cgroup_pre_destroy,
> +	.populate       = bio_cgroup_populate,
> +	.attach		= bio_cgroup_move_task,
> +	.early_init	= 0,
> +};

Without "attach" function, it is difficult to check
the effectiveness of block I/O tracking.

Thanks,
- Takuya Yoshikawa