From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754434Ab1E0U2G (ORCPT ); Fri, 27 May 2011 16:28:06 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:54181 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751277Ab1E0U2D (ORCPT ); Fri, 27 May 2011 16:28:03 -0400 Date: Fri, 27 May 2011 16:27:47 -0400 From: Christoph Hellwig To: Jens Axboe Cc: Namhyung Kim , Mike Snitzer , Christoph Hellwig , "linux-kernel@vger.kernel.org" , Tejun Heo Subject: Re: [PATCH 1/2] blktrace: treat flush as barrier Message-ID: <20110527202747.GA4803@infradead.org> References: <1306501883-23498-1-git-send-email-namhyung@gmail.com> <20110527131237.GA27647@infradead.org> <1306509182.1351.1.camel@leonhard> <4DE006C5.4010906@fusionio.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DE006C5.4010906@fusionio.com> 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 Fri, May 27, 2011 at 10:17:09PM +0200, Jens Axboe wrote: > Agree on Christophs comments, we should not pretend they are the same > (since they are not). Since flush is a request on its own, F works > nicely. For FUA it's associated with a write, so F should work there too > indicating Write Fua (and easily humanly parsed as that, or Write > Flush). WU would look confusing. REQ_FLUSH can also be set on a write bio, it only gets split at the request level. And even there we're at least pondering allowing it to stay as part of the write for some paravirtualized storage protocols.