From: "Jayson R. King" Subject: Re: [PATCH 2.6.27.y 1/3] ext4: Use our own write_cache_pages() Date: Fri, 28 May 2010 21:21:03 -0500 Message-ID: <4C007A0F.6020304@jaysonking.com> References: <4C001888.8020006@jaysonking.com> <4C0018E1.5060007@jaysonking.com> <20100529004913.GL26177@thunk.org> <4C0070D8.8060500@jaysonking.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Jayson R. King" , Stable team , LKML , Greg Kroah-Hartman , "Aneesh Kumar K.V" , Dave Chinner , Ext4 Developers List , Kay Diederichs To: tytso@mit.edu Return-path: Received: from bosmailout19.eigbox.net ([66.96.184.19]:47454 "EHLO bosmailout19.eigbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751264Ab0E2Cwc (ORCPT ); Fri, 28 May 2010 22:52:32 -0400 In-Reply-To: <4C0070D8.8060500@jaysonking.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 05/28/2010 08:41 PM, Jayson R. King wrote: > 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. I meant, it was dropped from .27.47-rc2 stable. Sorry for any confusion. > 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 >