From nobody Mon Feb 9 00:55:25 2026 Delivered-To: importer@patchew.org Received-SPF: temperror (zoho.com: Error in retrieving data from DNS) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=temperror (zoho.com: Error in retrieving data from DNS) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1510352151845870.4068270606787; Fri, 10 Nov 2017 14:15:51 -0800 (PST) Received: from localhost ([::1]:43662 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eDHaG-0005ut-Sh for importer@patchew.org; Fri, 10 Nov 2017 17:15:32 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47506) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eDHYW-0004mq-81 for qemu-devel@nongnu.org; Fri, 10 Nov 2017 17:13:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eDHYV-0005aD-0E for qemu-devel@nongnu.org; Fri, 10 Nov 2017 17:13:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39888) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eDHYS-0005Yv-Nf; Fri, 10 Nov 2017 17:13:40 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D83368765E; Fri, 10 Nov 2017 22:13:39 +0000 (UTC) Received: from localhost (ovpn-204-126.brq.redhat.com [10.40.204.126]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6896F63620; Fri, 10 Nov 2017 22:13:39 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Fri, 10 Nov 2017 23:13:29 +0100 Message-Id: <20171110221329.24176-4-mreitz@redhat.com> In-Reply-To: <20171110221329.24176-1-mreitz@redhat.com> References: <20171110221329.24176-1-mreitz@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 10 Nov 2017 22:13:39 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH for-2.12 3/3] block: Deprecate "backing": "" X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Markus Armbruster , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_6 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" We have a clear replacement, so let's deprecate it. Signed-off-by: Max Reitz Reviewed-by: Markus Armbruster --- qapi/block-core.json | 4 ++-- block.c | 4 ++++ qemu-doc.texi | 7 +++++++ qemu-options.hx | 4 ++-- 4 files changed, 15 insertions(+), 4 deletions(-) diff --git a/qapi/block-core.json b/qapi/block-core.json index 76bf50f813..dfe4d3650c 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -1090,7 +1090,7 @@ # @overlay: reference to the existing block device that will become # the overlay of @node, as part of creating the snapshot. # It must not have a current backing file (this can be -# achieved by passing "backing": "" to blockdev-add). +# achieved by passing "backing": null to blockdev-add). # # Since: 2.5 ## @@ -1238,7 +1238,7 @@ # "node-name": "node1534", # "file": { "driver": "file", # "filename": "hd1.qcow2" }, -# "backing": "" } } +# "backing": null } } # # <- { "return": {} } # diff --git a/block.c b/block.c index bc92ddd5a0..463c4de25b 100644 --- a/block.c +++ b/block.c @@ -2559,6 +2559,10 @@ static BlockDriverState *bdrv_open_inherit(const cha= r *filename, /* See cautionary note on accessing @options above */ backing =3D qdict_get_try_str(options, "backing"); if (qdict_is_qnull(options, "backing") || (backing && *backing =3D=3D = '\0')) { + if (backing) { + warn_report("Use of \"backing\": \"\" is deprecated; " + "use \"backing\": null instead"); + } flags |=3D BDRV_O_NO_BACKING; qdict_del(options, "backing"); } diff --git a/qemu-doc.texi b/qemu-doc.texi index 8c10956a66..8f57d9ad21 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -2537,6 +2537,13 @@ or ``ivshmem-doorbell`` device types. The ``spapr-pci-vfio-host-bridge'' device type is replaced by the ``spapr-pci-host-bridge'' device type. =20 +@section Block device options + +@subsection "backing": "" (since 2.12.0) + +In order to prevent QEMU from automatically opening an image's backing +chain, use ``"backing": null'' instead. + @node License @appendix License =20 diff --git a/qemu-options.hx b/qemu-options.hx index 3728e9b4dd..0ee1a04d00 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -731,8 +731,8 @@ Reference to or definition of the data source block dri= ver node =20 @item backing Reference to or definition of the backing file block device (default is ta= ken -from the image file). It is allowed to pass an empty string here in order = to -disable the default backing file. +from the image file). It is allowed to pass @code{null} here in order to d= isable +the default backing file. =20 @item lazy-refcounts Whether to enable the lazy refcounts feature (on/off; default is taken fro= m the --=20 2.13.6