From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933613AbcIOLqS (ORCPT ); Thu, 15 Sep 2016 07:46:18 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:40077 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756916AbcIOLqO (ORCPT ); Thu, 15 Sep 2016 07:46:14 -0400 Date: Thu, 15 Sep 2016 04:46:10 -0700 From: Christoph Hellwig To: Alex Bligh Cc: Christoph Hellwig , Wouter Verhelst , "nbd-general@lists.sourceforge.net" , Josef Bacik , "linux-kernel@vger.kernel.org" , linux-block@vger.kernel.org, Markus Pargmann , kernel-team@fb.com Subject: Re: [Nbd] [RESEND][PATCH 0/5] nbd improvements Message-ID: <20160915114610.GA6411@infradead.org> References: <1473369130-22986-1-git-send-email-jbacik@fb.com> <20160909200203.phhvodsfs7ymukfp@grep.be> <20160915104935.ohuwgq2chsedz6fl@grep.be> <20160915113807.GA23259@infradead.org> <751994A2-653B-4201-8210-A31495804788@alex.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <751994A2-653B-4201-8210-A31495804788@alex.org.uk> User-Agent: Mutt/1.6.1 (2016-04-27) 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 Thu, Sep 15, 2016 at 12:43:35PM +0100, Alex Bligh wrote: > Sure, it's at: > > https://github.com/yoe/nbd/blob/master/doc/proto.md#ordering-of-messages-and-writes > > and that link takes you to the specific section. > > The treatment of FLUSH and FUA is meant to mirror exactly the > linux block layer (or rather how the linux block layer was a few > years ago). I even asked on LKML to verify a few points. Linux never expected ordering on the wire. Before 2010 we had barriers in the kernel that provided ordering to the caller, but we never required it from the protocol / hardware.