Re: [Qemu-devel] [PATCH] more check for replaced node

[Wen Congyang <wency@cn.fujitsu.com>]

On 07/02/2015 10:48 PM, Stefan Hajnoczi wrote:
> On Wed, Jul 01, 2015 at 04:49:40PM +0800, Wen Congyang wrote:
>> On 07/01/2015 04:39 PM, Stefan Hajnoczi wrote:
>>> On Thu, Jun 25, 2015 at 02:55:10PM +0800, Wen Congyang wrote:
>>>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>>>> ---
>>>>  block.c               | 5 +++--
>>>>  block/mirror.c        | 3 ++-
>>>>  blockdev.c            | 2 +-
>>>>  include/block/block.h | 3 ++-
>>>>  4 files changed, 8 insertions(+), 5 deletions(-)
>>>
>>> This patch is missing a commit description.  What is the justification
>>> for this change?
>>
>> Sorry, I forgot to add commit messages..
>>
>> Without this patch, the replace node can be any node, and it can be
>> top BDS with BB, or another quorum's child. With this patch, the replace node
>> must be this quorum's child.
> 
> I think the point of the replace operation was to swap a quorum child
> with a new drive.  It sounds like this patch will break that use case?
> 
> The idea was that a failed child needs to be replaced.  The user adds a
> new -drive and then uses the mirror+replace to include it into the
> quorum.  I think the new child is not be part of the quorum BDS graph
> until replacement occurs.

bs/s->common.bs is quorum, and to_replace is the broken child.
The new child is target_bs. With this patch, we just check if
the broken child is part of the quorum BDS.

Do I misunderstand something?

Thanks
Wen Congyang

> 
> Stefan
>