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[209.132.180.67]) by mx.google.com with ESMTP id 11si29434979pgy.408.2018.11.16.01.41.46; Fri, 16 Nov 2018 01:42:00 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389457AbeKPTwQ (ORCPT + 99 others); Fri, 16 Nov 2018 14:52:16 -0500 Received: from mx2.suse.de ([195.135.220.15]:34652 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727442AbeKPTwQ (ORCPT ); Fri, 16 Nov 2018 14:52:16 -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 626E2AEDB; Fri, 16 Nov 2018 09:40:42 +0000 (UTC) Subject: Re: [PATCH] nvme: allow ANA support to be independent of native multipathing To: Christoph Hellwig , Mike Snitzer Cc: linux-nvme@lists.infradead.org, Keith Busch , Sagi Grimberg , axboe@kernel.dk, Martin Wilck , lijie , xose.vazquez@gmail.com, chengjike.cheng@huawei.com, shenhong09@huawei.com, dm-devel@redhat.com, wangzhoumengjian@huawei.com, christophe.varoqui@opensvc.com, bmarzins@redhat.com, sschremm@netapp.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org 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> <20181114174746.GA18526@redhat.com> <87c931e5-4ac9-1795-8d40-cc5541d3ebcf@suse.de> <20181115174605.GA19782@redhat.com> <20181116091458.GA17267@lst.de> From: Hannes Reinecke Message-ID: <37098edd-4dea-b58f-bca6-3be9af8ec4ee@suse.de> Date: Fri, 16 Nov 2018 10:40:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <20181116091458.GA17267@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/16/18 10:14 AM, Christoph Hellwig wrote: > On Thu, Nov 15, 2018 at 12:46:05PM -0500, Mike Snitzer wrote: >> Whether or not ANA is present is a choice of the target implementation; >> the host (and whether it supports multipathing) has _zero_ influence on >> this. If the target declares a path as 'inaccessible' the path _is_ >> inaccessible to the host. As such, ANA support should be functional >> even if native multipathing is not. >> >> Introduce ability to always re-read ANA log page as required due to ANA >> error and make current ANA state available via sysfs -- even if native >> multipathing is disabled on the host (e.g. nvme_core.multipath=N). > > The first part I could see, but I still want to make it conditional > in some way as nvme is going into deeply embedded setups, and I don't > want to carry the weight of the ANA code around for everyone. > Can you clarify this a bit? We _do_ have the NVME multipath config option to deconfigure the whole thing during compile time; that isn't influenced with this patch. So are you worried about the size of the ANA implementation itself? Or are you worried about the size of the ANA structures? > The second I fundamentally disagree with. And even if you found agreement > it would have to be in a separate patch as it is a separate feature. > Why? Where's the problem with re-reading the ANA log pages if we get an event indicating that we should? Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)