From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932416AbYBHCsV (ORCPT ); Thu, 7 Feb 2008 21:48:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757097AbYBHCsH (ORCPT ); Thu, 7 Feb 2008 21:48:07 -0500 Received: from smtp2.linux-foundation.org ([207.189.120.14]:43437 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756154AbYBHCsF (ORCPT ); Thu, 7 Feb 2008 21:48:05 -0500 Date: Thu, 7 Feb 2008 18:48:18 -0800 From: Andrew Morton To: Trond Myklebust Cc: Linus Torvalds , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, nfsv4@linux-nfs.org Subject: Re: [GIT] Please pull 2 NFS client fixes Message-Id: <20080207184818.e40d5277.akpm@linux-foundation.org> In-Reply-To: <1202432841.18376.50.camel@heimdal.trondhjem.org> References: <1202432841.18376.50.camel@heimdal.trondhjem.org> X-Mailer: Sylpheed 2.4.1 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 07 Feb 2008 20:07:21 -0500 Trond Myklebust wrote: > commit 5d47a35600270e7115061cb1320ee60ae9bcb6b8 > Author: Trond Myklebust > Date: Thu Feb 7 17:24:07 2008 -0500 > > NFS: Fix a potential file corruption issue when writing > > If the inode is flagged as having an invalid mapping, then we can't rely on > the PageUptodate() flag. Ensure that we don't use the "anti-fragmentation" > write optimisation in nfs_updatepage(), since that will cause NFS to write > out areas of the page that are no longer guaranteed to be up to date. > > A potential corruption could occur in the following scenario: > > client 1 client 2 > =============== =============== > fd=open("f",O_CREAT|O_WRONLY,0644); > write(fd,"fubar\n",6); // cache last page > close(fd); > fd=open("f",O_WRONLY|O_APPEND); > write(fd,"foo\n",4); > close(fd); > > fd=open("f",O_WRONLY|O_APPEND); > write(fd,"bar\n",4); > close(fd); > ----- > The bug may lead to the file "f" reading 'fubar\n\0\0\0\nbar\n' because > client 2 does not update the cached page after re-opening the file for > write. Instead it keeps it marked as PageUptodate() until someone calls > invaldate_inode_pages2() (typically by calling read()). Is this one worth feeding back into 2.6.24.x? (for various values of "4"?)