From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 4 Aug 2007 23:00:07 -0700 From: Andrew Morton 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: 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 List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org