Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752724AbWLTATN (ORCPT ); Tue, 19 Dec 2006 19:19:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752903AbWLTATN (ORCPT ); Tue, 19 Dec 2006 19:19:13 -0500 Received: from smtp.osdl.org ([65.172.181.25]:48308 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752420AbWLTATM (ORCPT ); Tue, 19 Dec 2006 19:19:12 -0500 Date: Tue, 19 Dec 2006 16:18:34 -0800 From: Andrew Morton To: Linus Torvalds Cc: Peter Zijlstra , Nick Piggin , 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 Message-Id: <20061219161834.5466ecf6.akpm@osdl.org> In-Reply-To: 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> <45878BE8.8010700@yahoo.com.au> <4587B762.2030603@yahoo.com.au> <1166563828.10372.162.camel@twins> <20061219145818.5b36381c.akpm@osdl.org> <1166569582.10372.165.camel@twins> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-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: 1663 Lines: 46 On Tue, 19 Dec 2006 16:03:49 -0800 (PST) Linus Torvalds wrote: > > > On Wed, 20 Dec 2006, Peter Zijlstra wrote: > > > On Tue, 2006-12-19 at 14:58 -0800, Andrew Morton wrote: > > > > > Well... we'd need to see (corruption && this-not-triggering) to be sure. > > > > > > Peter, have you been able to trigger the corruption? > > > > Yes; however the mail I send describing that seems to be lost in space. > > Btw, can somebody actually explain the mess that is ext3 "dirtying". > > Ext3 does NOT use __set_page_dirty_buffers. It does > > static int ext3_journalled_set_page_dirty(struct page *page) > { > SetPageChecked(page); > return __set_page_dirty_nobuffers(page); > } > > and uses that "Checked" bit as a "whole page is dirty" bit (which it tests > in "writepage()". This is purely for data=journal, which is rarely used. In journalled-data mode, write(), write-fault, etc are not allowed to dirty the pages and buffers, because the data has to be written to the journal first. After the data has been written to the journal we only then mark buffers (and hence pages) dirty as far as the VFS is concerned. For checkpointing the data back to its real place on the disk. For MAP_SHARED pages ext3 cheats madly and doesn't journal the data at all. In all journalling modes, MAP_SHARED data follows the regular ext2-style handling. Which is a bit of a wart. - 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/