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 99C03C00A89 for ; Mon, 2 Nov 2020 18:08:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F30922245 for ; Mon, 2 Nov 2020 18:08:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725791AbgKBSIl (ORCPT ); Mon, 2 Nov 2020 13:08:41 -0500 Received: from verein.lst.de ([213.95.11.211]:34229 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725789AbgKBSIk (ORCPT ); Mon, 2 Nov 2020 13:08:40 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 7881868B05; Mon, 2 Nov 2020 19:08:37 +0100 (CET) Date: Mon, 2 Nov 2020 19:08:37 +0100 From: "hch@lst.de" To: Javier Gonzalez Cc: "kbusch@kernel.org" , "javier@javigon.com" , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" , "hch@lst.de" , "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: <20201102180836.GC20182@lst.de> References: <0916865d50c640e3aa95dc542f3986b9@CAMSVWEXC01.scsc.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0916865d50c640e3aa95dc542f3986b9@CAMSVWEXC01.scsc.local> 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 04:15:01PM +0000, Javier Gonzalez wrote: > That said, I don't mind the concept, though I recall Christoph had > concerns about the existing 0-capacity namespace used for invalid > formats, so I'd like to hear more on that if he has some spare time to > comment. Yes, I really don't think 0 sized block devices are the right interface for namespaces we can't access. I think the proper fix is to ensure that we have a character device that allows submitting I/O commands for each namespaces including those where we don't understand the I/O command set or parts of it. That should also really help to have a proper access model for the KV command set. Initially we only need NVME_IOCTL_IO64_CMD, but eventually we'll need some support for async submissions, be that through io_uring or other ways.