From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from out02.mta.xmission.com ([166.70.13.232]:47292 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756246Ab2AJWhW convert rfc822-to-8bit (ORCPT ); Tue, 10 Jan 2012 17:37:22 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Stanislav Kinsbursky Cc: "Trond.Myklebust\@netapp.com" , "linux-nfs\@vger.kernel.org" , Pavel Emelianov , "neilb\@suse.de" , "netdev\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" , James Bottomley , "bfields\@fieldses.org" , "davem\@davemloft.net" , "devel\@openvz.org" Subject: Re: [PATCH 01/11] SYSCTL: export root and set handling routines References: <20111214103602.3991.20990.stgit@localhost6.localdomain6> <20111214104449.3991.61989.stgit@localhost6.localdomain6> <4EEEFC54.10700@parallels.com> <4EEF2C9A.8000403@parallels.com> <4EEF7364.8000407@parallels.com> <4F0C150F.1020007@parallels.com> Date: Tue, 10 Jan 2012 14:39:36 -0800 In-Reply-To: <4F0C150F.1020007@parallels.com> (Stanislav Kinsbursky's message of "Tue, 10 Jan 2012 14:38:07 +0400") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: Stanislav Kinsbursky writes: > 03.01.2012 07:49, Eric W. Biederman пишет: >> Stanislav Kinsbursky writes: >> >>> 19.12.2011 20:37, Eric W. Biederman пишет: >>>> Stanislav Kinsbursky writes: >>>> >>>> Doing that independently of the rest of the sysctls is pretty horrible >>>> and confusing to users. What I am planning might suit your needs and >>>> if not we need to talk some more about how to get the vfs to do >>>> something reasonable. >>>> >>> >>> Ok, Eric. Would be glad to discuss your sysctls plans. >>> But actually you already know my needs: I would like to make sysctls work in the >>> way like sysfs does: i.e. content of files depends on mount maker - >>> not viewer. >> >> What drives the desire to have sysctls depend on the mount maker? > > Because we can (will, actually) have nested fs root's for containers. IOW, > container's root will be accessible from it's creator context. And I want to > tune container's fs from creators context. Tuning the child context from the parent context is an entirely reasonable thing to do. To affect a namespace that is not yours the requirement is simply that we don't use current to lookup the sysctl. So what I am proposing should work for your case. >> Especially what drives that desire not to have it have a /proc//sys >> directory that reflects the sysctls for a given process. >> > > This is not so important for me, where to access sysctl's. But I'm worrying > about backward compatibility. IOW, I'm afraid of changing path > "/proc/sys/sunprc/*" to "/proc//sys/sunrpc". This would break a lot of > user-space programs. The part that keeps it all working is by adding a symlink from /proc/sys to /proc/self/sys. That technique has worked well for /proc/net, and I don't expect there will be any problems with /proc/sys either. It is possible but is very rare for the introduction of a symlink in a path to cause problems. Eric