From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754110Ab0E2COK (ORCPT ); Fri, 28 May 2010 22:14:10 -0400 Received: from bosmailout08.eigbox.net ([66.96.189.8]:51472 "EHLO bosmailout08.eigbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752244Ab0E2COI (ORCPT ); Fri, 28 May 2010 22:14:08 -0400 X-Greylist: delayed 1925 seconds by postgrey-1.27 at vger.kernel.org; Fri, 28 May 2010 22:14:08 EDT X-EN-OrigOutIP: 10.20.18.3 X-EN-IMPSID: PDhx1e00503yW7601DhxDn Message-ID: <4C0070D8.8060500@jaysonking.com> Date: Fri, 28 May 2010 20:41:44 -0500 From: "Jayson R. King" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.8) Gecko/20100301 Fedora/3.0.3-1.fc11 Thunderbird/3.0.3 MIME-Version: 1.0 To: tytso@mit.edu CC: "Jayson R. King" , Stable team , LKML , Greg Kroah-Hartman , "Aneesh Kumar K.V" , Dave Chinner , Ext4 Developers List , Kay Diederichs Subject: Re: [PATCH 2.6.27.y 1/3] ext4: Use our own write_cache_pages() References: <4C001888.8020006@jaysonking.com> <4C0018E1.5060007@jaysonking.com> <20100529004913.GL26177@thunk.org> In-Reply-To: <20100529004913.GL26177@thunk.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-EN-UserInfo: 06af1bc540adb20c3d2d7097199478a6:08dd1976e651f6e3791fbe97eaa5f898 X-EN-AuthUser: jaysonking@jaysonking.com X-EN-OrigIP: 68.93.139.172 X-EN-OrigHost: unknown Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/28/2010 07:49 PM, tytso@mit.edu wrote: > This doesn't fix a bug; it's to make it easy for Dave Chinner to make > some changes to fix XFS's performance and to undo some ext4-specific > changes to write_cache_pages(). I'm not sure there's a good reason to > backport this to 2.6.27.y.... The difference is that, 2.6.27's write_cache_pages() in page-writeback.c still updates wbc->nr_to_write, since the patch which changed that behavior was dropped from .27-rc2 due to the XFS regression it causes on mainline. ext4 appears to want the behavior of write_cache_pages which does not update wbc->nr_to_write. This write_cache_pages_da() does what ext4 wants, without introducing the XFS regression. So I believe it is needed. Did I mis-judge? Rgds, Jayson