From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5056EC43441 for ; Wed, 14 Nov 2018 10:36:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1DD372087A for ; Wed, 14 Nov 2018 10:36:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1DD372087A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732852AbeKNUjP (ORCPT ); Wed, 14 Nov 2018 15:39:15 -0500 Received: from mx2.suse.de ([195.135.220.15]:46666 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727807AbeKNUjP (ORCPT ); Wed, 14 Nov 2018 15:39:15 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 8DE2AB015; Wed, 14 Nov 2018 10:36:33 +0000 (UTC) Message-ID: <3ade435ef087d61a293863a62c1b794ecf8dba14.camel@suse.de> Subject: Re: [dm-devel] multipath-tools: add ANA support for NVMe device From: Martin Wilck To: Hannes Reinecke , Sagi Grimberg , Keith Busch , axboe@kernel.dk, hch@lst.de, Mike Snitzer Cc: xose.vazquez@gmail.com, chengjike.cheng@huawei.com, lijie , shenhong09@huawei.com, wangzhoumengjian@huawei.com, linux-nvme@lists.infradead.org, sschremm@netapp.com, dm-devel@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 14 Nov 2018 11:36:31 +0100 In-Reply-To: <30cf7af7-8826-55bd-e39a-4f81ed032f6d@suse.de> References: <1541657381-7452-1-git-send-email-lijie34@huawei.com> <2691abf6733f791fb16b86d96446440e4aaff99f.camel@suse.com> <20181112215323.GA7983@redhat.com> <20181113161838.GC9827@localhost.localdomain> <20181113180008.GA12513@redhat.com> <20181114053837.GA15086@redhat.com> <30cf7af7-8826-55bd-e39a-4f81ed032f6d@suse.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2018-11-14 at 08:49 +0100, Hannes Reinecke wrote: > On 11/14/18 6:38 AM, Mike Snitzer wrote: > > > > Not holding my breath BUT: > > if decoupling the reading of ANA state from native NVMe > > multipathing > > specific work during nvme request completion were an acceptable > > advancement I'd gladly do the work. > > > I'd be happy to work on that, given that we'll have to have 'real' > ANA > support for device-mapper anyway for SLE12 SP4 etc. So, what's the way ahead for multipath-tools? Given that, IIUC, at least one official kernel (4.19) has been released with ANA support but without the ANA sysfs attributes exported to user space, multipath-tools can't rely on them being present. I for one have no issue with copying code from nvme-cli and doing NVMe ioctls from multipath-tools, as in Lijie's patch. When those sysfs attributes are added (and work as expected), we will use them, but IMO we'll need to fall back to ioctls until then, and also afterwards, because we can't assume to be always running on the latest kernel. Best, Martin