From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754015AbdEXRiZ (ORCPT ); Wed, 24 May 2017 13:38:25 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:45336 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753880AbdEXRiX (ORCPT ); Wed, 24 May 2017 13:38:23 -0400 Date: Wed, 24 May 2017 10:38:22 -0700 From: Christoph Hellwig To: Tejun Heo Cc: Christoph Hellwig , 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: <20170524173822.GB13151@infradead.org> References: <3d3a0860317afa0fb722c1a6df58e04593fc700a.1495490800.git.shli@fb.com> <20170523074019.GC29525@infradead.org> <20170523185711.GB13222@htj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170523185711.GB13222@htj.duckdns.org> User-Agent: Mutt/1.8.0 (2017-02-23) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 23, 2017 at 02:57:11PM -0400, Tejun Heo wrote: > > 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). I still have no idea how this ties into export ops. Currently I don't see any tracing code using export operations, so maybe a big part of the series is missing/ > 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. You can already get i_ino using statx, and i_generation using FS_IOC_GETVERSION, so I'm a little lost on why you need the full exportfs infrastructure.