From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [RFC][PATCH] ns: Syscalls for better namespace sharing control. Date: Fri, 26 Feb 2010 12:35:56 -0800 Message-ID: References: <4B4F24AC.70105@trash.net> <1263481549.23480.24.camel@bigi> <4B4F3A50.1050400@trash.net> <1263490403.23480.109.camel@bigi> <4B50403A.6010507@trash.net> <1263568754.23480.142.camel@bigi> <1266875729.3673.12.camel@bigi> <1266931623.3973.643.camel@bigi> <1266934817.3973.654.camel@bigi> <1266966581.3973.675.camel@bigi> <4B86EC45.3060005@free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: hadi@cyberus.ca, Linux Netdev List , containers@lists.linux-foundation.org, Netfilter Development Mailinglist , Ben Greear , Daniel Lezcano To: Daniel Lezcano Return-path: In-Reply-To: (Eric W. Biederman's message of "Thu\, 25 Feb 2010 13\:49\:48 -0800") Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org > No, the plan is only one namespace at a time. Looking at this a bit more I am frustrated and relieved. I was looking at what it would take to join an arbitrary mount namespace and I realized it is completely non-obvious what fs->root and fs->pwd should be set to. If I leave them untouched the new mount namespace is useless, as all path lookups will give results in a different mount namespace, so not even mount or umount can be used. I can not change fs->root to mnt_ns->root as that is rootfs and there is always something mounted on top so I can not use that. In comparison an unshare of the mount namespace doesn't have to move fs->root or fs->pwd at all and only has to update their mounts to the corresponding mounts in the new mount namespace. I might be able to find the topmost root filesystem and put at least root there, but I'm not particularly fond of that option. Eric