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 C20ACC3A5A1 for ; Thu, 22 Aug 2019 00:09:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9E03C22CE3 for ; Thu, 22 Aug 2019 00:09:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728412AbfHVAJa (ORCPT ); Wed, 21 Aug 2019 20:09:30 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:39564 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726828AbfHVAJa (ORCPT ); Wed, 21 Aug 2019 20:09:30 -0400 Received: by mail-wm1-f65.google.com with SMTP id i63so3872834wmg.4; Wed, 21 Aug 2019 17:09:28 -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=32/0yIVdzlJ2KJ3NplTUO5+v34KMaLLDclpZ7tzJ9aE=; b=XFklBSV1ROpQHezo5lCXW6jYtyDmA7+IaKiARuK6gJadBKQ6t9IsUF+lJHd3ctp6DR EG9mWqQgn35EdGLTGl2lsrVOh/JLzYrLDLZD4GH2jgI6l4slYeDi9js90BlNdDOxLX4l 2l1zjaGglt+QzvERRNqy+Ftw9z7BmxC7p2/Dfm/wUzLn0bWSB+Y/9/Ja2IPFzH5b+JZL sn3ZbwzZLEe8ErXiSEgU4cUm5iY7/RoMaTHp3f2OOVoRr15iiHpHjqlqHSApm5jWi9dC j7OWRhx7f2Om+zpynK3XovyzQYaU48ZlwKJuAHQtJIqQxgyAkpKFOtxN9HOiwFkHCroJ 0s6A== X-Gm-Message-State: APjAAAVANRDHLtpelZYVXCO4luEWska1FhKRGHLuri9D6M30WGm+UEBu NWZSF7ZrUKT4zRpV3yUyrbY= X-Google-Smtp-Source: APXvYqwuT0kmih8HKsX3ht5823hsz+gh7dNnKBV5RVKrdbL46NznsoXAK7FHnNlGyRd4vEhe81JUTw== X-Received: by 2002:a1c:2314:: with SMTP id j20mr2598763wmj.152.1566432568173; Wed, 21 Aug 2019 17:09:28 -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 r16sm50444348wrc.81.2019.08.21.17.09.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 21 Aug 2019 17:09:27 -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: Date: Wed, 21 Aug 2019 17:09:23 -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: <5717f515-e051-c420-07b7-299bcfcd1f32@mellanox.com> 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)