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 87FD6C3A5A3 for ; Thu, 22 Aug 2019 17:41:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B39220870 for ; Thu, 22 Aug 2019 17:41:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404260AbfHVRlS (ORCPT ); Thu, 22 Aug 2019 13:41:18 -0400 Received: from mail-oi1-f196.google.com ([209.85.167.196]:33561 "EHLO mail-oi1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404269AbfHVRlN (ORCPT ); Thu, 22 Aug 2019 13:41:13 -0400 Received: by mail-oi1-f196.google.com with SMTP id l2so5014692oil.0; Thu, 22 Aug 2019 10:41:12 -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:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=S3Wtmx63qYO2RYwlc+u7gYjYEryNsm6UT+kYuRsp+wI=; b=sslPEcfdgZ9KQvOL+TIkZ3p39+WJ/J1pxAnS69kBC5lwFuS1liEHgWhwPwHsB4YgnZ 1a2a38KNO3cCxO93DUcaUQEqA+czK18SqAATh2ZaVt5hFmRVr55jKzLdyn2bLoHlVNUG 72WePR9MVNTtEbEYjiF8IbClzrD0EpwSiO8A1ALSvjSgfskZewtIpBr6CX7D76EiKG5E Ui6JWU1bpQHU+TRnFq0Buki8SxfL1IlSXx107CeGu8ImQpd6GbU9+/Fdo+NR6n4E2olf tO/JYLdOJ2+/MdobZKxY82rtEZ0F9enWAySyYVOdMe4WKXSsJ+PxOwH+/H5HY6oHEapQ dygQ== X-Gm-Message-State: APjAAAWB4coirRjoeXyl9gDo33VOcK6VtRUwkcKYe0n6dzuJWcTIHekX J07Rv+RKxaDi7YFF1WT37Bg= X-Google-Smtp-Source: APXvYqxXzyiGzvP9QOEziqdHlRZkxskbjNq0zGJS3yjldmavVtqqk7S7wFueDS6GCxtSQweXW/XKyg== X-Received: by 2002:aca:3887:: with SMTP id f129mr224476oia.108.1566495671970; Thu, 22 Aug 2019 10:41:11 -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 o26sm71264otl.34.2019.08.22.10.41.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 22 Aug 2019 10:41:11 -0700 (PDT) Subject: Re: [PATCH v7 08/14] nvmet-core: allow one host per passthru-ctrl 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> From: Sagi Grimberg Message-ID: <24e2ddd0-4b2a-8092-cf91-df8c0fb482e5@grimberg.me> Date: Thu, 22 Aug 2019 10:41:09 -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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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..