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Mon, 18 Nov 2019 17:03:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574096592; 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=tS4/JJfUyOIkfOccEZ4Dz+J3zLgGC6/2fKmToSRnGug=; b=SwNDtL/n38iaTM4t5UXAYhCqm/NbHHLTPimcBdZxyF8XZ+IvggT/02ocPgcNIVa996sIdX +D8voQQBF3v7RkisIpX2c9yhk9Rkz1jTGCtBEuf1HSoT8XpdNwAxVF9pS6JLSM+FuKoV+Q 6hIEHzE4lkjZsTZGENmrzSP8UFy9Hhc= From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PULL 3/4] block: Remove 'backing': null from bs->{explicit_, }options Date: Mon, 18 Nov 2019 18:02:55 +0100 Message-Id: <20191118170256.31477-4-kwolf@redhat.com> In-Reply-To: <20191118170256.31477-1-kwolf@redhat.com> References: <20191118170256.31477-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: XXNuw2SpMo2TvD8LITrsKQ-1 X-Mimecast-Spam-Score: 0 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 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: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" bs->options and bs->explicit_options shouldn't contain any options for child nodes. bdrv_open_inherited() takes care to remove any options that match a child name after opening the image and the same is done when reopening. However, we miss the case of 'backing': null, which is a child option, but results in no child being created. This means that a 'backing': null remains in bs->options and bs->explicit_options. A typical use for 'backing': null is in live snapshots: blockdev-add for the qcow2 overlay makes sure not to open the backing file (because it is already opened and blockdev-snapshot will attach it). After doing a blockdev-snapshot, bs->options and bs->explicit_options become inconsistent with the actual state (bs has a backing file now, but the options still say null). On the next occasion that the image is reopened, e.g. switching it from read-write to read-only when another snapshot is taken, the option will take effect again and the node incorrectly loses its backing file. Fix bdrv_open_inherited() to remove the 'backing' option from bs->options and bs->explicit_options even for the case where it specifies that no backing file is wanted. Reported-by: Peter Krempa Signed-off-by: Kevin Wolf Reviewed-by: Alberto Garcia Tested-by: Peter Krempa --- block.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/block.c b/block.c index 4cffc2bc35..473eb6eeaa 100644 --- a/block.c +++ b/block.c @@ -3019,6 +3019,8 @@ static BlockDriverState *bdrv_open_inherit(const char= *filename, "use \"backing\": null instead"); } flags |=3D BDRV_O_NO_BACKING; + qdict_del(bs->explicit_options, "backing"); + qdict_del(bs->options, "backing"); qdict_del(options, "backing"); } =20 --=20 2.20.1