From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753242AbZINNmJ (ORCPT ); Mon, 14 Sep 2009 09:42:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751665AbZINNmI (ORCPT ); Mon, 14 Sep 2009 09:42:08 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:32970 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751233AbZINNmG (ORCPT ); Mon, 14 Sep 2009 09:42:06 -0400 Date: Mon, 14 Sep 2009 09:42:07 -0400 From: Christoph Hellwig To: Jan Kara Cc: Jens Axboe , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, chris.mason@oracle.com, hch@infradead.org, tytso@mit.edu, akpm@linux-foundation.org, trond.myklebust@fys.uio.no Subject: Re: [PATCH 6/7] writeback: separate starting of sync vs opportunistic writeback Message-ID: <20090914134207.GA14830@infradead.org> References: <1252920994-11141-1-git-send-email-jens.axboe@oracle.com> <1252920994-11141-7-git-send-email-jens.axboe@oracle.com> <20090914133307.GJ24075@duck.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090914133307.GJ24075@duck.suse.cz> User-Agent: Mutt/1.5.19 (2009-01-05) 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 14, 2009 at 03:33:07PM +0200, Jan Kara wrote: > On Mon 14-09-09 11:36:33, Jens Axboe wrote: > > bdi_start_writeback() is currently split into two paths, one for > > WB_SYNC_NONE and one for WB_SYNC_ALL. Add bdi_sync_writeback() > > for WB_SYNC_ALL writeback and let bdi_start_writeback() handle > > only WB_SYNC_NONE. > What I don't like about this patch is that if somebody sets up > writeback_control with WB_SYNC_ALL mode set and then submits it to disk via > bdi_start_writeback() it will just silently convert his writeback to an > asynchronous one. > So I'd maybe leave setting of sync_mode to the caller and just WARN_ON if > it does not match the purpose of the function... Or initialize the wb entirely inside these functions. For the sync case we really only need a superblock as argument, and for writeback it's bdi + nr_pages. And also make sure they consistenly return void as no one cares about the return value.