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 6EF47C83016 for ; Tue, 1 Dec 2020 19:39:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35DAF206E3 for ; Tue, 1 Dec 2020 19:39:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392441AbgLATjH (ORCPT ); Tue, 1 Dec 2020 14:39:07 -0500 Received: from verein.lst.de ([213.95.11.211]:51136 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727534AbgLATjF (ORCPT ); Tue, 1 Dec 2020 14:39:05 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 7A23967373; Tue, 1 Dec 2020 20:38:23 +0100 (CET) Date: Tue, 1 Dec 2020 20:38:23 +0100 From: Christoph Hellwig To: Keith Busch Cc: Javier =?iso-8859-1?Q?Gonz=E1lez?= , Minwoo Im , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, hch@lst.de, sagi@grimberg.me Subject: Re: [PATCH 4/4] nvme: enable char device per namespace Message-ID: <20201201193823.GA3522@lst.de> References: <20201201125610.17138-1-javier.gonz@samsung.com> <20201201125610.17138-5-javier.gonz@samsung.com> <20201201140348.GA5138@localhost.localdomain> <20201201185732.unlurqed2kaqwjsb@MacBook-Pro.localdomain> <20201201193002.GB27728@redsun51.ssa.fujisawa.hgst.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201201193002.GB27728@redsun51.ssa.fujisawa.hgst.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Dec 02, 2020 at 04:30:02AM +0900, Keith Busch wrote: > > > In multi-path, private namespaces for a head are not in /dev, so I don't > > > think this will hurt private namespaces (e.g., nvme0c0n1), But it looks > > > like it will make a little bit confusions between chardev and hidden blkdev. > > > > > > I don't against to update nvme-cli things also even naming conventions are > > > going to become different than nvmeXcYnZ. > > > > Agree. But as I understand it, Keith had a good argument to keep names > > aligned with the hidden bdev. > > My suggested naming makes it as obvious as possible that the character > device in /dev/ and the hidden block device in /sys/ are referring to > the same thing. What is confusing about that? > > > It is also true that in that comment he suggested nesting the char > > device in /dev/nvme > > Yeah, I'm okay with sub-directories for these special handles, but there > are arguments against it too. I don't feel that strongly about it either > way. I'd prefer different naming for the char vs the block devices. Yes, this will require a little work in the userspace tools to support the character device, but I think it is much cleaner. Devices in subdirectories of /dev/ are very rare and keep causing problem with userspace tooling for the few drivers that use them, so I don't think they are a good idea.