Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API

[Christoph Hellwig]

> -		task_active_pid_ns(current)->last_pid);
> +		task_active_pid_ns(current)->idr.idr_next-1);

I think we want a well documented helper for this pattern instead
of poking into the internals.

Also is last - 1 always the correct answer?  Even with idr_alloc_cyclic
we could wrap around, couldn't we?