Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-ie0-f173.google.com ([209.85.223.173]:60507 "EHLO mail-ie0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752879Ab3LBNo1 convert rfc822-to-8bit (ORCPT ); Mon, 2 Dec 2013 08:44:27 -0500 Received: by mail-ie0-f173.google.com with SMTP id to1so20667828ieb.18 for ; Mon, 02 Dec 2013 05:44:26 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 7.0 \(1812\)) Subject: Re: [PATCH 00/11] [RFC] repair net namespace damage to rpc_pipefs From: Trond Myklebust In-Reply-To: <20131202081233.GA6953@infradead.org> Date: Mon, 2 Dec 2013 08:44:25 -0500 Cc: Viro Alexander , Linux NFS Mailing List , Devel FS Linux , Torvalds Linus , Eric Biederman Message-Id: <3C65EB4C-6592-44F8-B08D-E5A9EFD6C8C6@primarydata.com> References: <20131201131441.790963326@bombadil.infradead.org> <20131201181329.GC10323@ZenIV.linux.org.uk> <20131202081233.GA6953@infradead.org> To: Christoph Hellwig Sender: linux-nfs-owner@vger.kernel.org List-ID: On Dec 2, 2013, at 3:12, Christoph Hellwig wrote: > On Sun, Dec 01, 2013 at 06:13:29PM +0000, Al Viro wrote: >> Making the series no-go in that form, obviously. > > Looking at the mess it made I'd almost be tempted to say a little leak > for a less used features is better than lots of pain for everyone.. > > Looking at the mess it made I'm really upset. > >>> Given that the namespace kraken has infected various internal filesystem >>> and will get more soon I suspect this problem is or will become generic >>> and will need a proper solution anyway. Al, any good ideas how to deal >>> with this? Most straight forward way would be to add a counter of >>> user vfsmount to the superblock and methods when it goes to 1 and 0, >>> but that seems a bit ugly. >> >> Folks, please, _please_, let's formulate the lifecycle rules first; we >> already had way too much trouble from putting mechanism first only to >> run into questions like the above ("what happens if somebody tries to >> allocate a PID in pid_ns that is already scheduled for shutdown?"). >> Remember the (recurring) fun with kobject-related lifetime issues? >> Or rpc_pipefs notifier ugliness, for that matter... > > I'll have to let the net namespace folks chime in for that, as far as > I'm concerned it's a featured better config'ed off. If they can't come > up with anything better the procfs hack above would be it. The lifetime of the kernel mount only needs to match that of the rpc_client, since each rpc_client is associated to a single net namespace, and each net namespace is in a 1-1 relationship with an rpc_pipefs super block. IOW: move the kernel mount/umount back to the rpc_client create/destroy methods and all should be well. Cheers Trond