From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161231AbWJRRoc (ORCPT ); Wed, 18 Oct 2006 13:44:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161246AbWJRRoc (ORCPT ); Wed, 18 Oct 2006 13:44:32 -0400 Received: from mx0.karneval.cz ([81.27.192.123]:14658 "EHLO av1.karneval.cz") by vger.kernel.org with ESMTP id S1161231AbWJRRob (ORCPT ); Wed, 18 Oct 2006 13:44:31 -0400 Message-ID: <453667F1.4040504@gmail.com> Date: Wed, 18 Oct 2006 19:44:17 +0200 From: Jiri Slaby User-Agent: Thunderbird 2.0a1 (X11/20060724) MIME-Version: 1.0 To: Trond Myklebust CC: Sven Hoexter , linux-kernel@vger.kernel.org Subject: Re: [REGRESSION] nfs client: Read-only file system (2.6.19-rc1,2) References: <4534F59D.4040505@gmail.com> <1161104051.5559.5.camel@lade.trondhjem.org> <4535EB4F.4070406@gmail.com> <45364C51.2000004@gmail.com> <1161192121.6095.58.camel@lade.trondhjem.org> In-Reply-To: <1161192121.6095.58.camel@lade.trondhjem.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Trond Myklebust wrote: > I'll bet that you have always had a subdirectory of the exact same > filesystem mounted somewhere else ro, right? Yup, exactly: /usr -ro and /home -rw on the same (hda3) partition. > The new NFS mount code will put those in the same superblock, and > whichever directory gets mounted first will determine whether or not the > superblock is marked as read-only. > Basically, NFS is now doing the exact same thing that local filesystems > have been doing all the time: if it is on the same disk, then it is all > represented by the same superblock. OTOH, if your server is exporting > more than one partition, then different partitions will be represented > by different superblocks. > We need to do this for the same reason that local filesystems do it: it > is the only way to ensure cache consistency. Otherwise, if you make > changes to a file that happens to be mounted in more than one place, > then you will see inconsistent results on the other mountpoints. thanks for clarification, -- http://www.fi.muni.cz/~xslaby/ Jiri Slaby faculty of informatics, masaryk university, brno, cz e-mail: jirislaby gmail com, gpg pubkey fingerprint: B674 9967 0407 CE62 ACC8 22A0 32CC 55C3 39D4 7A7E