From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756737AbYFVWua (ORCPT ); Sun, 22 Jun 2008 18:50:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754605AbYFVWuU (ORCPT ); Sun, 22 Jun 2008 18:50:20 -0400 Received: from ipmail01.adl6.internode.on.net ([203.16.214.146]:38580 "EHLO ipmail01.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754409AbYFVWuT (ORCPT ); Sun, 22 Jun 2008 18:50:19 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApoEABdyXkh5LG+u/2dsb2JhbACtTA X-IronPort-AV: E=Sophos;i="4.27,686,1204464600"; d="scan'208";a="132509979" Date: Mon, 23 Jun 2008 08:50:14 +1000 From: Dave Chinner To: Jan Kara Cc: Andrew Morton , "Aneesh Kumar K.V" , cmm@us.ibm.com, linux-ext4@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ext2: Use page_mkwrite vma_operations to get mmap write notification. Message-ID: <20080622225014.GC11558@disturbed> Mail-Followup-To: Jan Kara , Andrew Morton , "Aneesh Kumar K.V" , cmm@us.ibm.com, linux-ext4@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1212685513-32237-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20080605123045.445e380a.akpm@linux-foundation.org> <20080611150845.GA21910@skywalker> <20080611120749.d0c5a7de.akpm@linux-foundation.org> <20080612161706.GB12367@duck.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080612161706.GB12367@duck.suse.cz> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 12, 2008 at 06:17:06PM +0200, Jan Kara wrote: > BTW: XFS, OCFS2 or GFS2 define page_mkwrite() in this manner so they do > return SIGBUS when you run out of space when writing to mmapped hole. So > it's not like this change is introducing completely new behavior... I can > understand that we might not want to change the behavior for ext2 or ext3 > but ext4 is IMO definitely free to choose. Yup, and it's the only sane behaviour, IMO. Letting the application continue to oversubscribe filesystem space and then throwing away the data that can't be written well after the fact (potentially after the application has gone away) is a horrendously bad failure mode. This was one of the main publicised features of ->page_mkwrite() - that it would allow up front detection of ENOSPC conditions during mmap writes. I'm extremely surprised to see that this is being considered undesirable after all this time.... Cheers, Dave. -- Dave Chinner david@fromorbit.com