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 5DA41C3A5A1 for ; Thu, 22 Aug 2019 19:41:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3ACCB233FC for ; Thu, 22 Aug 2019 19:41:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391999AbfHVTlr (ORCPT ); Thu, 22 Aug 2019 15:41:47 -0400 Received: from ale.deltatee.com ([207.54.116.67]:50158 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731942AbfHVTlr (ORCPT ); Thu, 22 Aug 2019 15:41:47 -0400 Received: from s0106ac1f6bb1ecac.cg.shawcable.net ([70.73.163.230] helo=[192.168.11.155]) by ale.deltatee.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1i0sxm-0002GA-Tu; Thu, 22 Aug 2019 13:41:39 -0600 To: Sagi Grimberg , Max Gurtovoy , 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> From: Logan Gunthorpe Message-ID: <5e53b732-5c33-c331-0c77-d52d5075306a@deltatee.com> Date: Thu, 22 Aug 2019 13:41:32 -0600 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 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 70.73.163.230 X-SA-Exim-Rcpt-To: hch@lst.de, kbusch@kernel.org, axboe@fb.com, sbates@raithlin.com, Chaitanya.Kulkarni@wdc.com, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, maxg@mellanox.com, sagi@grimberg.me X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v7 08/14] nvmet-core: allow one host per passthru-ctrl X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2019-08-22 1:17 p.m., Sagi Grimberg wrote: > >>>>> 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... That makes sense. I'll make that change and resend a v8 next week. Logan