From patchwork Wed Feb 17 11:58:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 12091485 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, 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 01C48C433E6 for ; Wed, 17 Feb 2021 12:00:23 +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 7711B64E42 for ; Wed, 17 Feb 2021 12:00:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7711B64E42 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]:50676 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lCLVF-0003CG-CO for qemu-devel@archiver.kernel.org; Wed, 17 Feb 2021 07:00:21 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:48858) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lCLU0-0002Ll-GL for qemu-devel@nongnu.org; Wed, 17 Feb 2021 06:59:04 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:48011) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lCLTx-0002lk-Mi for qemu-devel@nongnu.org; Wed, 17 Feb 2021 06:59:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613563139; 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; bh=09plxGU+Bsvnk34ZEop/wZlOiub8bmqVmqpQ6t17O4Y=; b=UUwdioV24p3j/J8OIvtsdD6TE4zeCMITcxarSwOjlI3NFDdu1x2euhPWOweQE491aE7RFH dWs1vgRgIOue7v9JwOyjjvhJUsDOqrpbkW6VQDxECqcDcLzy1T3NZ5F42etwhevr7xy8X1 8Ls980FnBYxk9gI60aAxxWygN9SOs6k= 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-415-ruAUQjTRMruOybgliv23kw-1; Wed, 17 Feb 2021 06:58:47 -0500 X-MC-Unique: ruAUQjTRMruOybgliv23kw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C1FC1AFA80; Wed, 17 Feb 2021 11:58:46 +0000 (UTC) Received: from localhost (ovpn-114-112.ams2.redhat.com [10.36.114.112]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3534819D6C; Wed, 17 Feb 2021 11:58:45 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH] qsd: Document FUSE exports Date: Wed, 17 Feb 2021 12:58:44 +0100 Message-Id: <20210217115844.62661-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Implementing FUSE exports required no changes to the storage daemon, so we forgot to document them there. Considering that both NBD and vhost-user-blk exports are documented in its man page (and NBD exports in its --help text), we should probably do the same for FUSE. Signed-off-by: Max Reitz Reviewed-by: Eric Blake --- docs/tools/qemu-storage-daemon.rst | 19 +++++++++++++++++++ storage-daemon/qemu-storage-daemon.c | 4 ++++ 2 files changed, 23 insertions(+) diff --git a/docs/tools/qemu-storage-daemon.rst b/docs/tools/qemu-storage-daemon.rst index f63627eaf6..f5a906f6fc 100644 --- a/docs/tools/qemu-storage-daemon.rst +++ b/docs/tools/qemu-storage-daemon.rst @@ -74,6 +74,7 @@ Standard options: .. option:: --export [type=]nbd,id=,node-name=[,name=][,writable=on|off][,bitmap=] --export [type=]vhost-user-blk,id=,node-name=,addr.type=unix,addr.path=[,writable=on|off][,logical-block-size=][,num-queues=] --export [type=]vhost-user-blk,id=,node-name=,addr.type=fd,addr.str=[,writable=on|off][,logical-block-size=][,num-queues=] + --export [type=]fuse,id=,node-name=,mountpoint=[,growable=on|off][,writable=on|off] is a block export definition. ``node-name`` is the block node that should be exported. ``writable`` determines whether or not the export allows write @@ -91,6 +92,16 @@ Standard options: ``logical-block-size`` sets the logical block size in bytes (the default is 512). ``num-queues`` sets the number of virtqueues (the default is 1). + The ``fuse`` export type takes a mount point, which must be a regular file, + on which to export the given block node. That file will not be changed, it + will just appear to have the block node's content while the export is active + (very much like mounting a filesystem on a directory does not change what the + directory contains, it only shows a different content while the filesystem is + mounted). Consequently, applications that have opened the given file before + the export became active will continue to see its original content. If + ``growable`` is set, writes after the end of the exported file will grow the + block node to fit. + .. option:: --monitor MONITORDEF is a QMP monitor definition. See the :manpage:`qemu(1)` manual page for @@ -142,6 +153,14 @@ domain socket ``vhost-user-blk.sock``:: --blockdev driver=qcow2,node-name=qcow2,file=file \ --export type=vhost-user-blk,id=export,addr.type=unix,addr.path=vhost-user-blk.sock,node-name=qcow2 +Export a qcow2 image file ``disk.qcow2`` via FUSE on itself, so the disk image +file will then appear as a raw image:: + + $ qemu-storage-daemon \ + --blockdev driver=file,node-name=file,filename=disk.qcow2 \ + --blockdev driver=qcow2,node-name=qcow2,file=file \ + --export type=fuse,id=export,node-name=qcow2,mountpoint=disk.qcow2,writable=on + See also -------- diff --git a/storage-daemon/qemu-storage-daemon.c b/storage-daemon/qemu-storage-daemon.c index 9021a46b3a..bdf8877995 100644 --- a/storage-daemon/qemu-storage-daemon.c +++ b/storage-daemon/qemu-storage-daemon.c @@ -97,6 +97,10 @@ static void help(void) " export the specified block node over NBD\n" " (requires --nbd-server)\n" "\n" +" --export [type=]fuse,id=,node-name=,mountpoint=\n" +" [,growable=on|off][,writable=on|off]\n" +" export the specified block node over FUSE\n" +"\n" " --monitor [chardev=]name[,mode=control][,pretty[=on|off]]\n" " configure a QMP monitor\n" "\n"