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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 A903DC00A89 for ; Mon, 2 Nov 2020 18:58:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F29E22275 for ; Mon, 2 Nov 2020 18:58:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725797AbgKBS6y (ORCPT ); Mon, 2 Nov 2020 13:58:54 -0500 Received: from verein.lst.de ([213.95.11.211]:34403 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725817AbgKBS6y (ORCPT ); Mon, 2 Nov 2020 13:58:54 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 6CCF268B05; Mon, 2 Nov 2020 19:58:51 +0100 (CET) Date: Mon, 2 Nov 2020 19:58:51 +0100 From: "hch@lst.de" To: Keith Busch Cc: "hch@lst.de" , Javier Gonzalez , "javier@javigon.com" , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" , "sagi@grimberg.me" , "axboe@kernel.dk" , "joshi.k@samsung.com" , "Klaus B. Jensen" , "Niklas.Cassel@wdc.com" Subject: Re: [PATCH V2] nvme: report capacity 0 for non supported ZNS SSDs Message-ID: <20201102185851.GA21349@lst.de> References: <0916865d50c640e3aa95dc542f3986b9@CAMSVWEXC01.scsc.local> <20201102180836.GC20182@lst.de> <20201102183355.GB1970293@dhcp-10-100-145-180.wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201102183355.GB1970293@dhcp-10-100-145-180.wdc.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, Nov 02, 2020 at 10:33:55AM -0800, Keith Busch wrote: > I can see this going one of two ways: > > a) Set up the existing controller character device with a generic > disk-less request_queue to the IO queues accepting IO commands to > arbitrary NSIDs. > > b) Each namespace that can't be supported gets their own character > device. > > I'm leaning toward option "a". While it doesn't create handles to unique > namespaces, it has more resilience to potentially future changes. And I > recall the target side had a potential use for that, too. The problem with a) is that it can't be used to give users or groups access to just one namespaces, so it causes a real access control nightmare. The problem with b) is that now applications will break when we add support for new command sets or features. I think c) Each namespace gets its own character device, period. is the only sensible option.