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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 1C45BC2D0D2 for ; Fri, 20 Dec 2019 21:16:43 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DCA222146E for ; Fri, 20 Dec 2019 21:16:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Pb+IY75J" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DCA222146E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:33584 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iiPdZ-0005A5-Ut for qemu-devel@archiver.kernel.org; Fri, 20 Dec 2019 16:16:41 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:42905) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iiPcl-0004Qf-Po for qemu-devel@nongnu.org; Fri, 20 Dec 2019 16:15:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iiPcj-0005wv-Ll for qemu-devel@nongnu.org; Fri, 20 Dec 2019 16:15:50 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:28918 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iiPcj-0005pt-7i for qemu-devel@nongnu.org; Fri, 20 Dec 2019 16:15:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576876548; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6YwlPvLKkmwsaDFGVvhzaX7ZeqjWU7mJPAhls62iI8A=; b=Pb+IY75JlH2VBgAhPu87BhbkgJinKLSOeczFIsz3xO9vzR4SmvqqXjTxCbLFcIUpFUlNyk unR/vRkIj7LXnwsV7VQwe7n2R9T0hJ055YgTIaaU3C/DK+Jako2kFGzjiU1jv27dB/lsMZ xtOV8xfcsDT4JUvSPJiWHqHrFzfq4Z8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-324-ro9RlhEkN9SciKb1cJsw3A-1; Fri, 20 Dec 2019 16:15:44 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BD3561883520; Fri, 20 Dec 2019 21:15:43 +0000 (UTC) Received: from [10.3.116.246] (ovpn-116-246.phx2.redhat.com [10.3.116.246]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3B3301CB; Fri, 20 Dec 2019 21:15:43 +0000 (UTC) Subject: Re: [PATCH 02/18] fuse: Allow exporting BDSs via FUSE To: Max Reitz , qemu-block@nongnu.org References: <20191219143818.1646168-1-mreitz@redhat.com> <20191219143818.1646168-3-mreitz@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Fri, 20 Dec 2019 15:15:42 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191219143818.1646168-3-mreitz@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: ro9RlhEkN9SciKb1cJsw3A-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-devel@nongnu.org, "Richard W.M. Jones" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 12/19/19 8:38 AM, Max Reitz wrote: > fuse-export-add allows mounting block graph nodes via FUSE on some > existing regular file. That file should then appears like a raw disk > image, and accesses to it result in accesses to the exported BDS. > > Right now, we only set up the mount point and tear all mount points down > in bdrv_close_all(). We do not implement any access functions, so > accessing the mount point only results in errors. This will be > addressed by a followup patch. > > The set of exported nodes is kept in a hash table so we can later add a > fuse-export-remove that allows unmounting. Before I review this, a quick question: How does this compare to the recently added nbdfuse? https://www.redhat.com/archives/libguestfs/2019-October/msg00080.html Or put another way, maybe we get the same effect by combining qemu-nbd with nbdfuse, but this new utility would cut out a middleman for more efficiency, right? > +++ b/block/fuse.c > @@ -0,0 +1,260 @@ > +/* > + * Present a block device as a raw image through FUSE > + * > + * Copyright (c) 2019 Max Reitz -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org