Re: [PATCH 5/5] kernfs: add exportfs operations

[Tejun Heo]

Hello, Christoph.

On Tue, May 23, 2017 at 12:40:19AM -0700, Christoph Hellwig wrote:
> On Mon, May 22, 2017 at 03:53:09PM -0700, Shaohua Li wrote:
> > Now we have the facilities to implement exportfs operations.
> 
> But do we have a use case?  I'd rather avoid this..

Yeah, this is one of the repeatedly requested features - a cgroup id
which can be looked up in a scalable way.  We probably should have
added this earlier too as we already have places where we're passing
in full cgroup path into the kernel (ipt_cgroup match).

IIUC, Shaohua is adding it so that block tracing can be made aware of
cgroups but something like this is necessary whenever we try to refer
to a cgroup in a race-free / scalable way.

If you have any other ideas, I'm all ears.

Thanks.

-- 
tejun