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=-2.2 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 CE81AC7618B for ; Fri, 26 Jul 2019 06:23:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A431F217D4 for ; Fri, 26 Jul 2019 06:23:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726107AbfGZGXs (ORCPT ); Fri, 26 Jul 2019 02:23:48 -0400 Received: from mx2.suse.de ([195.135.220.15]:34110 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725864AbfGZGXs (ORCPT ); Fri, 26 Jul 2019 02:23:48 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 32631AFCF; Fri, 26 Jul 2019 06:23:46 +0000 (UTC) Subject: Re: [PATCH v6 00/16] nvmet: add target passthru commands support To: Logan Gunthorpe , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig , Sagi Grimberg , Keith Busch , Jens Axboe , Chaitanya Kulkarni , Max Gurtovoy , Stephen Bates References: <20190725172335.6825-1-logang@deltatee.com> From: Hannes Reinecke Openpgp: preference=signencrypt Autocrypt: addr=hare@suse.de; prefer-encrypt=mutual; keydata= mQINBE6KyREBEACwRN6XKClPtxPiABx5GW+Yr1snfhjzExxkTYaINHsWHlsLg13kiemsS6o7 qrc+XP8FmhcnCOts9e2jxZxtmpB652lxRB9jZE40mcSLvYLM7S6aH0WXKn8bOqpqOGJiY2bc 6qz6rJuqkOx3YNuUgiAxjuoYauEl8dg4bzex3KGkGRuxzRlC8APjHlwmsr+ETxOLBfUoRNuE b4nUtaseMPkNDwM4L9+n9cxpGbdwX0XwKFhlQMbG3rWA3YqQYWj1erKIPpgpfM64hwsdk9zZ QO1krgfULH4poPQFpl2+yVeEMXtsSou915jn/51rBelXeLq+cjuK5+B/JZUXPnNDoxOG3j3V VSZxkxLJ8RO1YamqZZbVP6jhDQ/bLcAI3EfjVbxhw9KWrh8MxTcmyJPn3QMMEp3wpVX9nSOQ tzG72Up/Py67VQe0x8fqmu7R4MmddSbyqgHrab/Nu+ak6g2RRn3QHXAQ7PQUq55BDtj85hd9 W2iBiROhkZ/R+Q14cJkWhzaThN1sZ1zsfBNW0Im8OVn/J8bQUaS0a/NhpXJWv6J1ttkX3S0c QUratRfX4D1viAwNgoS0Joq7xIQD+CfJTax7pPn9rT////hSqJYUoMXkEz5IcO+hptCH1HF3 qz77aA5njEBQrDRlslUBkCZ5P+QvZgJDy0C3xRGdg6ZVXEXJOQARAQABtCpIYW5uZXMgUmVp bmVja2UgKFN1U0UgTGFicykgPGhhcmVAc3VzZS5kZT6JAkEEEwECACsCGwMFCRLMAwAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheABQJOisquAhkBAAoJEGz4yi9OyKjPOHoQAJLeLvr6JNHx GPcHXaJLHQiinz2QP0/wtsT8+hE26dLzxb7hgxLafj9XlAXOG3FhGd+ySlQ5wSbbjdxNjgsq FIjqQ88/Lk1NfnqG5aUTPmhEF+PzkPogEV7Pm5Q17ap22VK623MPaltEba+ly6/pGOODbKBH ak3gqa7Gro5YCQzNU0QVtMpWyeGF7xQK76DY/atvAtuVPBJHER+RPIF7iv5J3/GFIfdrM+wS BubFVDOibgM7UBnpa7aohZ9RgPkzJpzECsbmbttxYaiv8+EOwark4VjvOne8dRaj50qeyJH6 HLpBXZDJH5ZcYJPMgunghSqghgfuUsd5fHmjFr3hDb5EoqAfgiRMSDom7wLZ9TGtT6viDldv hfWaIOD5UhpNYxfNgH6Y102gtMmN4o2P6g3UbZK1diH13s9DA5vI2mO2krGz2c5BOBmcctE5 iS+JWiCizOqia5Op+B/tUNye/YIXSC4oMR++Fgt30OEafB8twxydMAE3HmY+foawCpGq06yM vAguLzvm7f6wAPesDAO9vxRNC5y7JeN4Kytl561ciTICmBR80Pdgs/Obj2DwM6dvHquQbQrU Op4XtD3eGUW4qgD99DrMXqCcSXX/uay9kOG+fQBfK39jkPKZEuEV2QdpE4Pry36SUGfohSNq xXW+bMc6P+irTT39VWFUJMcSuQINBE6KyREBEACvEJggkGC42huFAqJcOcLqnjK83t4TVwEn JRisbY/VdeZIHTGtcGLqsALDzk+bEAcZapguzfp7cySzvuR6Hyq7hKEjEHAZmI/3IDc9nbdh EgdCiFatah0XZ/p4vp7KAelYqbv8YF/ORLylAdLh9rzLR6yHFqVaR4WL4pl4kEWwFhNSHLxe 55G56/dxBuoj4RrFoX3ynerXfbp4dH2KArPc0NfoamqebuGNfEQmDbtnCGE5zKcR0zvmXsRp qU7+caufueZyLwjTU+y5p34U4PlOO2Q7/bdaPEdXfpgvSpWk1o3H36LvkPV/PGGDCLzaNn04 BdiiiPEHwoIjCXOAcR+4+eqM4TSwVpTn6SNgbHLjAhCwCDyggK+3qEGJph+WNtNU7uFfscSP k4jqlxc8P+hn9IqaMWaeX9nBEaiKffR7OKjMdtFFnBRSXiW/kOKuuRdeDjL5gWJjY+IpdafP KhjvUFtfSwGdrDUh3SvB5knSixE3qbxbhbNxmqDVzyzMwunFANujyyVizS31DnWC6tKzANkC k15CyeFC6sFFu+WpRxvC6fzQTLI5CRGAB6FAxz8Hu5rpNNZHsbYs9Vfr/BJuSUfRI/12eOCL IvxRPpmMOlcI4WDW3EDkzqNAXn5Onx/b0rFGFpM4GmSPriEJdBb4M4pSD6fN6Y/Jrng/Bdwk SQARAQABiQIlBBgBAgAPBQJOiskRAhsMBQkSzAMAAAoJEGz4yi9OyKjPgEwQAIP/gy/Xqc1q OpzfFScswk3CEoZWSqHxn/fZasa4IzkwhTUmukuIvRew+BzwvrTxhHcz9qQ8hX7iDPTZBcUt ovWPxz+3XfbGqE+q0JunlIsP4N+K/I10nyoGdoFpMFMfDnAiMUiUatHRf9Wsif/nT6oRiPNJ T0EbbeSyIYe+ZOMFfZBVGPqBCbe8YMI+JiZeez8L9JtegxQ6O3EMQ//1eoPJ5mv5lWXLFQfx f4rAcKseM8DE6xs1+1AIsSIG6H+EE3tVm+GdCkBaVAZo2VMVapx9k8RMSlW7vlGEQsHtI0FT c1XNOCGjaP4ITYUiOpfkh+N0nUZVRTxWnJqVPGZ2Nt7xCk7eoJWTSMWmodFlsKSgfblXVfdM 9qoNScM3u0b9iYYuw/ijZ7VtYXFuQdh0XMM/V6zFrLnnhNmg0pnK6hO1LUgZlrxHwLZk5X8F uD/0MCbPmsYUMHPuJd5dSLUFTlejVXIbKTSAMd0tDSP5Ms8Ds84z5eHreiy1ijatqRFWFJRp ZtWlhGRERnDH17PUXDglsOA08HCls0PHx8itYsjYCAyETlxlLApXWdVl9YVwbQpQ+i693t/Y PGu8jotn0++P19d3JwXW8t6TVvBIQ1dRZHx1IxGLMn+CkDJMOmHAUMWTAXX2rf5tUjas8/v2 azzYF4VRJsdl+d0MCaSy8mUh Message-ID: <1f202de3-1122-f4a3-debd-0d169f545047@suse.de> Date: Fri, 26 Jul 2019 08:23:45 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190725172335.6825-1-logang@deltatee.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi Logan, On 7/25/19 7:23 PM, Logan Gunthorpe wrote: > Hi, > > Chaitainya has asked us to take on these patches as we have an > interest in getting them into upstream. To that end, we've done > a large amount of testing, bug fixes and cleanup. > > Passthru support for nvmet allows users to export an entire > NVMe controller through NVMe-oF. When exported in this way (as opposed > to exporting each namespace as a block device), all the NVMe commands > are passed to the given controller unmodified, including most admin > commands and Vendor Unique Commands (VUCs). A passthru target will > expose all namespaces for a given device to the remote host. > In general I'm very much in favour of this, yet there are some issues which I'm not quite clear about. > There are three major non-bugfix changes that we've done to the series: > > 1) Instead of using a seperate special passthru subsystem in > configfs simply add a passthru directory that's analogous to > the existing namespace directories. The directories have > very similar attributes to namespaces but are mutually exclusive. > If a user enables a namespaces, they can't then enable > passthru controller and vice versa. This simplifies the code > required to implement passthru configfs and IMO creates a much > clearer and uniform interface. > How do you handle subsystem naming? If you enable the 'passthru' device, the (nvmet) subsystem (and its name) is already created. Yet the passthru device will have its own internal subsystem naming, so if you're not extra careful you'll end up with a nvmet subsystem which doesn't have any relationship with the passthru subsystem, making addressing etc ... tricky. Any thoughts about that? Similarly: how do you propose to handle multipath devices? Any NVMe with several paths will be enabling NVMe multipathing automatically, presenting you with a single multipathed namespace. How will these devices be treated? Will the multipathed namespace be used for passthru? Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg)