Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932929AbWLSUDu (ORCPT ); Tue, 19 Dec 2006 15:03:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932927AbWLSUDu (ORCPT ); Tue, 19 Dec 2006 15:03:50 -0500 Received: from twinlark.arctic.org ([207.29.250.54]:55922 "EHLO twinlark.arctic.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932929AbWLSUDt (ORCPT ); Tue, 19 Dec 2006 15:03:49 -0500 Date: Tue, 19 Dec 2006 12:03:48 -0800 (PST) From: dean gaudet To: Linus Torvalds cc: Nick Piggin , Peter Zijlstra , Andrew Morton , andrei.popa@i-neo.ro, Linux Kernel Mailing List , Hugh Dickins , Florian Weimer , Marc Haber , Martin Michlmayr Subject: Re: 2.6.19 file content corruption on ext3 In-Reply-To: Message-ID: References: <1166314399.7018.6.camel@localhost> <20061217040620.91dac272.akpm@osdl.org> <1166362772.8593.2.camel@localhost> <20061217154026.219b294f.akpm@osdl.org> <1166460945.10372.84.camel@twins> <45876C65.7010301@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1528 Lines: 45 On Mon, 18 Dec 2006, Linus Torvalds wrote: > On Tue, 19 Dec 2006, Nick Piggin wrote: > > > > We never want to drop dirty data! (ignoring the truncate case, which is > > handled privately by truncate anyway) > > Bzzt. > > SURE we do. > > We absolutely do want to drop dirty data in the writeout path. > > How do you think dirty data ever _becomes_ clean data? > > In other words, yes, we _do_ want to test-and-clear all the pgtable bits > _and_ the PG_dirty bit. We want to do it for: > - writeout > - truncate > - possibly a "drop" event (which could be a case for a journal entry that > becomes stale due to being replaced or something - kind of "truncate" > on metadata) > > because both of those events _literally_ turn dirty state into clean > state. > > In no other circumstance do we ever want to clear a dirty bit, as far as I > can tell. i admit this may not be entirely relevant, but it seems like a good place to bring up an old problem: when a disk dies with lots of queued writes it can totally bring a system to its knees... even after the disk is removed. i wrote up something about this a while ago: http://lkml.org/lkml/2005/8/18/243 so there's another reason to "clear a dirty bit"... well, in fact -- drop the pages entirely. -dean - 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/