Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754355AbXHEGCb (ORCPT ); Sun, 5 Aug 2007 02:02:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751838AbXHEGCW (ORCPT ); Sun, 5 Aug 2007 02:02:22 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:35909 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752089AbXHEGCP (ORCPT ); Sun, 5 Aug 2007 02:02:15 -0400 Date: Sat, 4 Aug 2007 23:00:07 -0700 From: Andrew Morton To: Florian Weimer Cc: Linus Torvalds , Ingo Molnar , Peter Zijlstra , linux-mm@kvack.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com, nikita@clusterfs.com, trond.myklebust@fys.uio.no, yingchao.zhou@gmail.com, richard@rsk.demon.co.uk Subject: Re: [PATCH 00/23] per device dirty throttling -v8 Message-Id: <20070804230007.30857453.akpm@linux-foundation.org> In-Reply-To: <87wswbjejw.fsf@mid.deneb.enyo.de> References: <20070803123712.987126000@chello.nl> <20070804063217.GA25069@elte.hu> <20070804070737.GA940@elte.hu> <20070804103347.GA1956@elte.hu> <20070804094119.81d8e533.akpm@linux-foundation.org> <87wswbjejw.fsf@mid.deneb.enyo.de> 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 X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1365 Lines: 39 On Sat, 04 Aug 2007 21:16:35 +0200 Florian Weimer wrote: > * Andrew Morton: > > > The easy preventive is to mount with data=writeback. Maybe that should > > have been the default. > > The documentation I could find suggests that this may lead to a > security weakness (old data in blocks of a file that was grown just > before the crash leaks to a different user). yup. This problem also exists in ext2, reiserfs (unless using ordered-mode), JFS, others. > XFS overwrites that data > with zeros upon reboot, which tends to irritate users when it happens. yup. > >From this point of view, data=ordered doesn't seem too bad. If your computer is used by multiple users who don't trust each other, sure. That covers, what? About 2% of machines? I was using data=writeback for a while on my most-thrashed disk. The results were a bit disappointing - not much difference. ext2 is a lot quicker. (I don't use anything which is fsync-happy, btw). (I used to have a patch which sysctl-tunably turned fsync, msync, fdatasync into "return 0" for use on the laptop but I seem to have lost it) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/