From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Aneesh Kumar K.V" Subject: Re: The meaning of data=ordered as it relates to delayed allocation Date: Mon, 19 Jan 2009 20:15:54 +0530 Message-ID: <20090119144554.GJ9482@skywalker> References: <20090119044345.GB9482@skywalker> <20090119124513.GC7598@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Theodore Tso Return-path: Received: from e28smtp04.in.ibm.com ([59.145.155.4]:36859 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1749667AbZASOqE (ORCPT ); Mon, 19 Jan 2009 09:46:04 -0500 Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by e28smtp04.in.ibm.com (8.13.1/8.13.1) with ESMTP id n0JEk1vM001089 for ; Mon, 19 Jan 2009 20:16:01 +0530 Received: from d28av02.in.ibm.com (d28av02.in.ibm.com [9.184.220.64]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id n0JEi5U94395080 for ; Mon, 19 Jan 2009 20:14:05 +0530 Received: from d28av02.in.ibm.com (loopback [127.0.0.1]) by d28av02.in.ibm.com (8.13.1/8.13.3) with ESMTP id n0JEk19p028762 for ; Tue, 20 Jan 2009 01:46:01 +1100 Content-Disposition: inline In-Reply-To: <20090119124513.GC7598@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, Jan 19, 2009 at 07:45:13AM -0500, Theodore Tso wrote: > On Mon, Jan 19, 2009 at 10:13:45AM +0530, Aneesh Kumar K.V wrote: > > > So I wonder if we should either: > > > > > > (a) make data=ordered force block allocation and writeback --- which > > > should just be a matter of disabling the > > > redirty_page_for_writepage() code path in ext4_da_writepage() > > > > We can't do that because we cannot do block allocation there. So we need > > to redirty the page that have unmapped buffer_heads. > > What is preventing us from doing block allocation from > ext4_da_writepage()? > The callback is called with page lock held and we can't start a journal with page lock held. -aneesh