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Date: Mon, 23 Feb 2015 16:53:58 -0500
From: Max Reitz <mreitz@redhat.com>
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Subject: Re: [Qemu-devel] [RFC PATCH 09/14] block: give backing image its
 own BlockBackend
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To: Wen Congyang <wency@cn.fujitsu.com>, qemu devel <qemu-devel@nongnu.org>, Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>, Jiang Yunhong <yunhong.jiang@intel.com>, Dong Eddie <eddie.dong@intel.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Gonglei <arei.gonglei@huawei.com>, Yang Hongyang <yanghy@cn.fujitsu.com>, zhanghailiang <zhang.zhanghailiang@huawei.com>

On 2015-02-11 at 22:07, Wen Congyang wrote:
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> ---
>   block.c | 11 +++++++----
>   1 file changed, 7 insertions(+), 4 deletions(-)

Our current stance on BlockBackends is (as far as I know, anyway) that a 
BlockBackend always comes with a user. In case you're creating a 
BlockBackend through -drive or blockdev-add, the user is the monitor 
(which can use it to attach it to a device, for instance). In this case, 
there is no user and nobody holds a reference to the BB (other than the 
BDS, but that doesn't count).

Therefore, this patch doesn't look quite right.

Max