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

[Stefan Hajnoczi]

On Mon, Jul 13, 2015 at 10:41:53AM +0800, Wen Congyang wrote:
> 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 <address@hidden>
> >>>> ---
> >>>>  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 for explaining.  That makes sense.

Please resend with a commit description.

Stefan

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