From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764221AbdEWS5P (ORCPT ); Tue, 23 May 2017 14:57:15 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:36553 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761795AbdEWS5N (ORCPT ); Tue, 23 May 2017 14:57:13 -0400 Date: Tue, 23 May 2017 14:57:11 -0400 From: Tejun Heo To: Christoph Hellwig Cc: Shaohua Li , linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, Kernel-team@fb.com Subject: Re: [PATCH 5/5] kernfs: add exportfs operations Message-ID: <20170523185711.GB13222@htj.duckdns.org> References: <3d3a0860317afa0fb722c1a6df58e04593fc700a.1495490800.git.shli@fb.com> <20170523074019.GC29525@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170523074019.GC29525@infradead.org> User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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