From: Joel Becker Subject: Re: [PATCH 4/4] jbd2: don't dirty original metadata buffer on abort Date: Mon, 13 Oct 2008 13:36:42 -0700 Message-ID: <20081013203641.GA6469@mail.oracle.com> References: <48EF168A.4000705@hitachi.com> <48EF1A11.9090303@hitachi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: tytso@mit.edu, adilger@sun.com, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, jack@suse.cz To: Hidehiro Kawai Return-path: Received: from agminet01.oracle.com ([141.146.126.228]:60130 "EHLO agminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754746AbYJMUiA (ORCPT ); Mon, 13 Oct 2008 16:38:00 -0400 Content-Disposition: inline In-Reply-To: <48EF1A11.9090303@hitachi.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Oct 10, 2008 at 06:02:09PM +0900, Hidehiro Kawai wrote: > Currently, original metadata buffers are dirtied when they are > unfiled whether the journal has aborted or not. Eventually these > buffers will be written-back to the filesystem by pdflush. This > means some metadata buffers are written to the filesystem without > journaling if the journal aborts. So if both journal abort and > system crash happen at the same time, the filesystem would become > inconsistent state. Additionally, replaying journaled metadata > can overwrite the latest metadata on the filesystem partly. > Because, if the journal gets aborted, journaled metadata are > preserved and replayed during the next mount not to lose > uncheckpointed metadata. This would also break the consistency > of the filesystem. > > This patch prevents original metadata buffers from being dirtied > on abort by clearing BH_JBDDirty flag from those buffers. Thus, > no metadata buffers are written to the filesystem without journaling. It's not my place to Ack such patches, but I noticed this bug during Plumbers, and Eric and Andreas pointed me to this patch, which fixes it quite nicely. Just $0.02 :-) Joel -- Life's Little Instruction Book #94 "Make it a habit to do nice things for people who will never find out." Joel Becker Principal Software Developer Oracle E-mail: joel.becker@oracle.com Phone: (650) 506-8127