From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754699Ab1IKAeF (ORCPT ); Sat, 10 Sep 2011 20:34:05 -0400 Received: from acsinet15.oracle.com ([141.146.126.227]:56209 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753247Ab1IKAeD (ORCPT ); Sat, 10 Sep 2011 20:34:03 -0400 Date: Sat, 10 Sep 2011 20:33:06 -0400 From: Konrad Rzeszutek Wilk To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, JBeulich@novell.com, jeremy.fitzhardinge@citrix.com, axboe@kernel.dk Subject: Re: [PATCH 1/3] xen/blk[front|back]: Use the full FLUSH | FUA instead of just FLUSH. Message-ID: <20110911003306.GB9989@oracle.com> References: <1315593060-20031-1-git-send-email-konrad.wilk@oracle.com> <1315593060-20031-2-git-send-email-konrad.wilk@oracle.com> <20110910180849.GA6621@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110910180849.GA6621@infradead.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet22.oracle.com [141.146.126.238] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090206.4E6C01D1.0072:SCFMA922111,ss=1,re=-4.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 10, 2011 at 02:08:49PM -0400, Christoph Hellwig wrote: > On Fri, Sep 09, 2011 at 02:30:59PM -0400, Konrad Rzeszutek Wilk wrote: > > During a FLUSH we can pass sector number that we want to > > have flushed - which is what FUA requests are. > > No, that is not the case. > > REQ_FLUSH without data -> pure flush > REQ_FLUSH with data -> preflush plus write Excellent. So we have been doing it right all along. > REQ_FUA -> write and ranged postflush Ah, somehow I was thinking that you can't write data with a REQ_FLUSH, but that is nonsense as the block/blk-flush.c explains in great details. Will drop this patch - and thanks for clarifying it!