From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754509AbZHGBvg (ORCPT ); Thu, 6 Aug 2009 21:51:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752922AbZHGBvf (ORCPT ); Thu, 6 Aug 2009 21:51:35 -0400 Received: from mx1.redhat.com ([66.187.233.31]:42066 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752759AbZHGBvf (ORCPT ); Thu, 6 Aug 2009 21:51:35 -0400 Date: Thu, 6 Aug 2009 21:50:49 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@hs20-bc2-1.build.redhat.com To: Alasdair G Kergon cc: Mark McLoughlin , device-mapper development , Jens Axboe , Rusty Russell , linux-kernel , virtualization Subject: Re: [dm-devel] [PATCH] block: silently error unsupported empty barriers too In-Reply-To: <20090806114550.GL29899@agk-dp.fab.redhat.com> Message-ID: References: <1249557257.3721.55.camel@blaa> <20090806114550.GL29899@agk-dp.fab.redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 6 Aug 2009, Alasdair G Kergon wrote: > On Thu, Aug 06, 2009 at 12:14:17PM +0100, Mark McLoughlin wrote: > > We should error all barriers, even empty barriers, on devices like > > virtio_blk which don't support them. > > Have you considered whether or not virtio_blk actually needs to > support empty barriers? > > Alasdair This is only for request-based drivers, where it is the responsibility of blk-core to translate barriers. I think the empty barrier request anyway in blk_do_ordered, but with an error message. So the patch changes it to discard it early and queitly. It seems ok. Mikulas