From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754366Ab2G3Nv0 (ORCPT ); Mon, 30 Jul 2012 09:51:26 -0400 Received: from verein.lst.de ([213.95.11.211]:49789 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754319Ab2G3NvQ (ORCPT ); Mon, 30 Jul 2012 09:51:16 -0400 Date: Mon, 30 Jul 2012 15:44:24 +0200 From: Christoph Hellwig To: Paolo Bonzini Cc: Asias He , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, "Michael S. Tsirkin" , Christoph Hellwig , Minchan Kim , Rusty Russell Subject: Re: [PATCH V3 3/3] virtio-blk: Add bio-based IO path for virtio-blk Message-ID: <20120730134424.GC6041@lst.de> References: <971756309.4742543.1343457753475.JavaMail.root@redhat.com> <501610E0.8000504@redhat.com> <5016383A.5090008@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5016383A.5090008@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 30, 2012 at 09:31:06AM +0200, Paolo Bonzini wrote: > You only need to add REQ_FLUSH support. The virtio-blk protocol does > not support REQ_FUA, because there's no easy way to do it in userspace. A bio-based driver needs to handle both REQ_FLUSH and REQ_FUA as it does not get the sequencing of REQ_FUA into REQ_FLUSH that request based drivers can request. To what the REQ_FUA request gets translated is a different story.