From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932110AbVHHSdB (ORCPT ); Mon, 8 Aug 2005 14:33:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932183AbVHHSdB (ORCPT ); Mon, 8 Aug 2005 14:33:01 -0400 Received: from tetsuo.zabbo.net ([207.173.201.20]:11959 "EHLO tetsuo.zabbo.net") by vger.kernel.org with ESMTP id S932182AbVHHSdA (ORCPT ); Mon, 8 Aug 2005 14:33:00 -0400 Message-ID: <42F7A557.3000200@zabbo.net> Date: Mon, 08 Aug 2005 11:32:55 -0700 From: Zach Brown User-Agent: Mozilla Thunderbird 1.0.2-1.3.3 (X11/20050513) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Pekka J Enberg Cc: David Teigland , Pekka Enberg , akpm@osdl.org, linux-kernel@vger.kernel.org, linux-cluster@redhat.com, mark.fasheh@oracle.com Subject: Re: GFS References: <20050802071828.GA11217@redhat.com> <84144f0205080203163cab015c@mail.gmail.com> <20050803063644.GD9812@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Pekka J Enberg wrote: > Sorry if this is an obvious question but what prevents another thread > from doing mmap() before we do the second walk and messing up num_gh? Nothing, I suspect. OCFS2 has a problem like this, too. It wants a way for a file system to serialize mmap/munmap/mremap during file IO. Well, more specifically, it wants to make sure that the locks it acquired at the start of the IO really cover the buf regions that might fault during the IO.. mapping activity during the IO can wreck that. - z