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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 22B86C04AAC for ; Mon, 20 May 2019 13:06:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E759120856 for ; Mon, 20 May 2019 13:06:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=web.de header.i=@web.de header.b="EZXkc4bY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730381AbfETNGC (ORCPT ); Mon, 20 May 2019 09:06:02 -0400 Received: from mout.web.de ([217.72.192.78]:44645 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730323AbfETNGC (ORCPT ); Mon, 20 May 2019 09:06:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=web.de; s=dbaedf251592; t=1558357557; bh=rknzXpVaKA2Z+lrTZafpzIVeQ28bvD9kBYiBb6H96ic=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=EZXkc4bYTZ/TbhmvGirI8SLZSQ9hzqHeEOfxJNMFOxfUz1pvfz1lL9nyDdj7so25P sWFoygbBHBzNQ+dTSzhKbHvRbtoJ/QLw6PmD82qWWniaLuCmYiYz9OwEoXxa4wRghI j5OArNRwxE+TAs3iniryKArXAhWL2fi5PbDOLaxE= X-UI-Sender-Class: c548c8c5-30a9-4db5-a2e7-cb6cb037b8f9 Received: from [10.1.1.111] ([109.192.195.184]) by smtp.web.de (mrweb102 [213.165.67.124]) with ESMTPSA (Nemesis) id 0LfzxX-1gqtBe3CZf-00padR; Mon, 20 May 2019 15:05:57 +0200 Subject: Re: Adding QCOW2 reading/writing support To: Roman Penyaev Cc: Hannes Reinecke , linux-block@vger.kernel.org, linux-block-owner@vger.kernel.org References: <60bbe5e0-317d-8ead-0eb8-d1dc79927bc8@web.de> <762bceb9-c66c-0a45-7d6b-e5ed0df56cbf@web.de> <7a74dd35a390df25f2874aa7b4f8547e@suse.de> From: Manuel Bentele Message-ID: Date: Mon, 20 May 2019 15:05:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <7a74dd35a390df25f2874aa7b4f8547e@suse.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US X-Provags-ID: V03:K1:yyv654e6Wyg+/XSTC+Ql5KDcGLh6R14Mki7g1cv9ANZZEzzNLRx YyuVRTxRdOR4JFPPF5/rcfhIYdbX+pBMM/qbKUskht1jDHw5M5EPYclFnz902oEBN9qqmAc h65ij1f3WscPZKDU9b/bnXs0+4Zyw9UPs8aIhB2jW7zHT6hKP6I2KznRkYOkfiu1Asr+wbb UqK6BV1V4FLQzTGxDoFTQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:KoXLAHIM9CI=:b8tiTQ5yipXNdQl2Vc6u8d OOilbudedLA3A4h+MxuJhxWRvF3YqrD4jAPIuqywXZ01WQI98GzRCFaMCF2z/xb/Gw46UDcVO 6INBpM8K0Oe0Q//5nNal6iLzuInI91ERWHo1rx0aAiYY5orWhKsHICm8wH4Mg2gCiMJ7u326k 8wo9sJY1phPN1/ysQT3XrwtA0RhK0WJzdJJ1k89UB9esBj5R0uSMfzfPdj67SWiMNrVtxwpD2 Qt/pRJK4CDfYHa/cc9CijZ9L0auPlkjapdQsNfL+PG5yE5EDMbjet0oFqAB7pcxt25KJHJapG X7EDesa5Euk509ikLWOEjlmQmFLQ0i5yqPk6nqllZR78v8E18LZ8PnuueJcqbC4WkKPs0lRpi DDRpSw4CFRjRyh5gvaMAg8uRdtVLvcg6r3yrz01pjE/+VbzJfzVomiw74lGQP4T/v47Thro5P HM9ToV45OOxppxmFkaxoEo+yTLimXJn98bKFvPFTFyY67Wl81RYkJ459IMygn7zrHo41hWrSa n3RnRxYQF8D0WY0CmHCAZ2umOhxxqnBJa1Y78i4guyC2n2IvwOUflmcYbVHFMwALMCqJfsU4C YmaplNJYu8CVz51j+xSBajFwmsMwEebtb619Vp+UWESQAqSELQTSLwxmEAn/LV78xsIJnLwaw y661rVosCJ5gze4Qy0TvjdWkKKS2e8uzRnwwZxuMsf5isyqZDOBlokrgBpLb/y5M0vzUayy79 QbMesXzhD2zMQ/tncFwYfdZaUzQB08VPu5iDwxX8djGtvYYST+cAvhpIFeuLMBokWcUBknM9E VkJ29URlCYhBUeMjJp7Q/mdRiZzHW0LFb99anCXWcIKHcTfGjoyvjUWzsb0YE20eXsNF2bwOo sE7UHIjokLh/NyvFkUYP4ZHXmfUOZ0Yr9zhblSP7iBw3U/NHYnd1nIkIdbgcC0dkKjx6yzi9e 0QRnjUdMErt6KNRTX15ElTLmNi19lJ7+d4RsrNex2XEZSgO7PyWF4 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi, On 5/14/19 4:28 PM, Roman Penyaev wrote: > On 2019-04-17 23:53, Manuel Bentele wrote: > > [cut] > >> If you have an idea to solve the opposition for file formats that are >> acting as a container or virtual disk node for various data, please let >> me know. > > If you need a raw block device you can export qcow2 image as a network > block > device, something as the following: > > # modprobe nbd > # qemu-nbd --connect=3D/dev/nbd0 image.qcow2 > # fdisk -l /dev/nbd0 > > I suppose simplest variant. > > -- > Roman Thanks for your suggestion. We already discussed this during a project meeting. Some time ago, I have summarized that already (sorry for the diverging conversation of this topic on the mailinglist). All in all, the crucial point is the performance: > [...] > > A workaround for that problem could be the local usage of nbd to include > the QCOW2 disk image as block device, but it involves a lot of > interaction between user and kernel space and thus an decreasing > performance. That leads to the motivation to implement the reading of > QCOW2 disk images directly in the kernel and aim for an merge into the > mainline kernel source to avoid out-of-kernel-tree maintenance. > > [...] =2D- Manuel