From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752917Ab1IZJqA (ORCPT ); Mon, 26 Sep 2011 05:46:00 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:43010 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752677Ab1IZJp7 (ORCPT ); Mon, 26 Sep 2011 05:45:59 -0400 Date: Mon, 26 Sep 2011 05:45:54 -0400 From: Christoph Hellwig To: Shaohua Li Cc: Christoph Hellwig , Jens Axboe , Andrew Morton , lkml Subject: Re: [patch]mm: add more blk plug Message-ID: <20110926094554.GA30827@infradead.org> References: <1317004226.29510.172.camel@sli10-conroe> <20110926073025.GB21079@infradead.org> <1317022727.29510.175.camel@sli10-conroe> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1317022727.29510.175.camel@sli10-conroe> User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 26, 2011 at 03:38:47PM +0800, Shaohua Li wrote: > On Mon, 2011-09-26 at 15:30 +0800, Christoph Hellwig wrote: > > On Mon, Sep 26, 2011 at 10:30:26AM +0800, Shaohua Li wrote: > > > Some filesystems implement .writepages. We don't have blk plug > > > in such filesystems for .writepages. > > > > Please add the plugging in the actual ->writepages instances. > there are several filesystems have ->writepages. Can you share an hint > why we don't add plugging in the do_writepages? Because do_writepages is completely generic code with no knowledge of block I/O. I really don't want to have block plugging be intimately tied into core VM/writeback code all over. We've been there with ->sync_page, and it was a major pain - nevermind the additional (small) overhead for the not block based filesystems.