From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: [PATCH] ext4: Add support for data=alloc_on_commit mode Date: Thu, 19 Mar 2009 11:42:03 -0500 Message-ID: <49C275DB.2060906@redhat.com> References: <1237259998-12656-1-git-send-email-tytso@mit.edu> <49C075FC.6070404@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Ext4 Developers List To: "Theodore Ts'o" Return-path: Received: from mx2.redhat.com ([66.187.237.31]:50239 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbZCSQmS (ORCPT ); Thu, 19 Mar 2009 12:42:18 -0400 In-Reply-To: <49C075FC.6070404@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Eric Sandeen wrote: > Theodore Ts'o wrote: >> Add an ext3 bug-for-bug compatible analogue for data=ordered mode. In >> this mode, we force all delayed allocation blocks involved with the >> to-be-commited transaction to be allocated, and then flushed out to >> disk before the transaction is commited. >> >> Signed-off-by: "Theodore Ts'o" > > Haven't really looked into the cause yet but I was playing with this, > and ran: > > # rm -f bigfile smallfile; dd if=/dev/zero of=bigfile bs=1M count=8192; > echo boo > smallfile; time /root/fsync smallfile; time /root/fsync bigfile > > which resulted in: > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000060 > IP: [] alloc_on_commit_callback+0x27/0x7f [ext4] This may have been user error ... ignore for now, I'll follow up if I decide it's real. :) -Eric