From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:35265)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1Zvovi-0003pV-Fk
	for qemu-devel@nongnu.org; Mon, 09 Nov 2015 11:04:30 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1Zvovh-0006dE-BZ
	for qemu-devel@nongnu.org; Mon, 09 Nov 2015 11:04:26 -0500
Date: Mon, 9 Nov 2015 17:04:17 +0100
From: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20151109160417.GD3621@noname.redhat.com>
References: <1444985866-12969-1-git-send-email-wency@cn.fujitsu.com>
	<1444985866-12969-4-git-send-email-wency@cn.fujitsu.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1444985866-12969-4-git-send-email-wency@cn.fujitsu.com>
Subject: Re: [Qemu-devel] [PATCH v6 3/4] qmp: add monitor command to
	add/remove a child
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Wen Congyang <wency@cn.fujitsu.com>
Cc: Alberto Garcia <berto@igalia.com>, zhanghailiang <zhang.zhanghailiang@huawei.com>, qemu block <qemu-block@nongnu.org>, Markus Armbruster <armbru@redhat.com>, Jiang Yunhong <yunhong.jiang@intel.com>, Dong Eddie <eddie.dong@intel.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, qemu devel <qemu-devel@nongnu.org>, Gonglei <arei.gonglei@huawei.com>, Stefan Hajnoczi <stefanha@redhat.com>, Yang Hongyang <yanghy@cn.fujitsu.com>

Am 16.10.2015 um 10:57 hat Wen Congyang geschrieben:
> +##
> +# @ChangeOperation:
> +#
> +# An enumeration of block device change operation.
> +#
> +# @add: Add a new block driver state to a existed block driver state.
> +#
> +# @delete: Delete a block driver state's child.
> +#
> +# Since: 2.5
> +##
> +{ 'enum': 'ChangeOperation',
> +  'data': [ 'add', 'delete' ] }

What's the advantage of this enum compared to separate QMP commands? The
way it is specified here, ChangeOperation is already implicit by whether
or not child and node are given.

> +##
> +# @x-blockdev-change
> +#
> +# Dynamic reconfigure the block driver state graph. It can be used to
> +# add, remove, insert, replace a block driver state. Currently only
> +# the Quorum driver implements this feature to add and remove its child.
> +# This is useful to fix a broken quorum child.
> +#
> +# @operation: the chanage operation. It can be add, delete.
> +#
> +# @parent: the id or node name of which node will be changed.
> +#
> +# @child: the child node-name which will be deleted.

#optional

Must be present for operation = delete, must not be present otherwise.

> +# @node: the new node-name which will be added.

#optional

Must be present for operation = add, must not be present otherwise.

> +#
> +# Note: this command is experimental, and not a stable API.
> +#
> +# Since: 2.5
> +##
> +{ 'command': 'x-blockdev-change',
> +  'data' : { 'operation': 'ChangeOperation',
> +             'parent': 'str',
> +             '*child': 'str',
> +             '*node': 'str' } }

Let me suggest this alternative:

{ 'command': 'x-blockdev-change',
  'data' : { 'parent': 'str',
             'child': 'str',
             '*node': 'str' } }

child doesn't describe a node name then, but a child name (adds a
dependency on my patches which add a name to BdrvChild, though).
Depending on whether node is given and whether the child already exists,
this may add, remove or replace a child.

Kevin