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=-2.4 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 F1622C65BAF for ; Wed, 12 Dec 2018 12:39:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D9972084E for ; Wed, 12 Dec 2018 12:39:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D9972084E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=canonical.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727313AbeLLMjP (ORCPT ); Wed, 12 Dec 2018 07:39:15 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:34817 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727308AbeLLMjO (ORCPT ); Wed, 12 Dec 2018 07:39:14 -0500 Received: from [191.13.172.85] (helo=calabresa) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1gX3nD-0005Nt-0H; Wed, 12 Dec 2018 12:39:11 +0000 Date: Wed, 12 Dec 2018 10:39:06 -0200 From: Thadeu Lima de Souza Cascardo To: Christoph Hellwig Cc: linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Jens Axboe Subject: Re: [PATCH 4/4] block: expose devt for GENHD_FL_HIDDEN disks Message-ID: <20181212123906.GI4269@calabresa> References: <20181206164812.30925-1-cascardo@canonical.com> <20181206164812.30925-5-cascardo@canonical.com> <20181206202200.GA32080@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181206202200.GA32080@lst.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Dec 06, 2018 at 09:22:00PM +0100, Christoph Hellwig wrote: > On Thu, Dec 06, 2018 at 02:48:12PM -0200, Thadeu Lima de Souza Cascardo wrote: > > Without this exposure, lsblk will fail as it tries to find out the > > device's dev_t numbers. This causes a real problem for nvme multipath > > devices, as their slaves are hidden. > > > > Exposing them fixes the problem, even though trying to open the devices > > returns an error in the case of nvme multipath. So, right now, it's the > > driver's responsibility to return a failure to open hidden devices. > > So the problem with this is that it will cause udev to actually create > the /dev/nvmeXcYnZ nodes, which due to the previous patch will always > fail to open, which is a bit confusing. I guess we could live with this > if we add udev rules to supress the creation or something, but in general > it is a bit ugly. Well, udev could just look at the hidden attribute. At least to some, the fact that lsblk would fail was reason enough to revert the patches, so I would rather apply the entire set. We could add a message to the log when users try to open them, but given that some programs (udev is one) would open them without any user interaction, maybe we shouldn't. Cascardo.