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=-2.3 required=3.0 tests=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 6D2CAC3A5A1 for ; Thu, 22 Aug 2019 19:17:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45F1923402 for ; Thu, 22 Aug 2019 19:17:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389265AbfHVTRn (ORCPT ); Thu, 22 Aug 2019 15:17:43 -0400 Received: from mail-ot1-f65.google.com ([209.85.210.65]:46571 "EHLO mail-ot1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391860AbfHVTRn (ORCPT ); Thu, 22 Aug 2019 15:17:43 -0400 Received: by mail-ot1-f65.google.com with SMTP id z17so6471255otk.13; Thu, 22 Aug 2019 12:17:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=24eP7T52+CYL2dNJV8R097RDf634lSS5yuSIePFHGwk=; b=eAbrKm5FJNzAHkCS/Z5RTD47hOZKeWADSxBDfsmBNfsJa31aNePzf2DAaBqnqn+TcN cE6/kDiRsa4mthXJs42kKSP5E3jo1dtIjG1EoYi8ecz9tgmWp3xWrNniJhAxNcU5cT6B 5N57E849AJefGrd7xA4mMC5jrWcWLH/P0B1gaPs+wEwfvKVe3gEw5/eBrVebsO0CrZPI 5ifJJOXkzLBJMYgJr0qz+HSfHrRieVvlty7C3ioBSzq5L+GbxOW5RWJo2esyu3cQuIqh pB38rZMsIIQ6K5avEvVQzxHRuU2q/uGX1GyIjlAADceGGKw5vMCY/+Y+VOIgkQXyOpc0 XcQA== X-Gm-Message-State: APjAAAUbqws7Ok41kGbUAZJeq/ROhgLjIO9Jcz0rWCtbhYtQusVcm/mR EPc19iKyO2mt6bZtfTqBiPI= X-Google-Smtp-Source: APXvYqxop+1c9JiQDuqjxLlVpuweprhgD1ihezKlsMDwXHi6Dx3GUbjgB7f6MqabctH5Zf2GXdALrg== X-Received: by 2002:a05:6830:1db2:: with SMTP id z18mr1087490oti.110.1566501462198; Thu, 22 Aug 2019 12:17:42 -0700 (PDT) Received: from ?IPv6:2600:1700:65a0:78e0:514:7862:1503:8e4d? ([2600:1700:65a0:78e0:514:7862:1503:8e4d]) by smtp.gmail.com with ESMTPSA id j6sm157680otq.16.2019.08.22.12.17.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 22 Aug 2019 12:17:41 -0700 (PDT) Subject: Re: [PATCH v7 08/14] nvmet-core: allow one host per passthru-ctrl From: Sagi Grimberg To: Max Gurtovoy , Logan Gunthorpe , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: Chaitanya Kulkarni , Stephen Bates , Jens Axboe , Keith Busch , Christoph Hellwig References: <20190801234514.7941-1-logang@deltatee.com> <20190801234514.7941-9-logang@deltatee.com> <05a74e81-1dbd-725f-1369-5ca5c5918db1@mellanox.com> <5717f515-e051-c420-07b7-299bcfcd1f32@mellanox.com> <24e2ddd0-4b2a-8092-cf91-df8c0fb482e5@grimberg.me> Message-ID: Date: Thu, 22 Aug 2019 12:17:39 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <24e2ddd0-4b2a-8092-cf91-df8c0fb482e5@grimberg.me> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org >>>> I don't understand why we don't limit a regular ctrl to single >>>> access and we do it for the PT ctrl. >>>> >>>> I guess the block layer helps to sync between multiple access in >>>> parallel but we can do it as well. >>>> >>>> Also, let's say you limit the access to this subsystem to 1 user, >>>> the bdev is still accessibly for local user and also you can create >>>> a different subsystem that will use this device (PT and non-PT ctrl). >>>> >>>> Sagi, >>>> >>>> can you explain the trouble you meant and how this limitation solve >>>> it ? >>> >>> Its different to emulate the controller with all its admin >>> commands vs. passing it through to the nvme device.. (think of format >>> nvm) >>> >>> >>> >> we don't need to support format command for PT ctrl as we don't >> support other commands such create_sq/cq. > > That is just an example, basically every command that we are not aware > of we simply passthru to the drive without knowing the implications > on a multi-host environment.. If we were to change the logic of nvmet_parse_passthru_admin_cmd to have the default case do nvmet_parse_admin_cmd, and only have the vendor-specific space opcodes do nvmet_passthru_execute_cmd then I could not see at the moment how we can break a multi-host export...