Re: [RFC PATCH] block/io.c: Flush parent for quorum in generic code

[Kevin Wolf <kwolf@redhat.com>]

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Am 18.05.2021 um 08:33 hat Lukas Straub geschrieben:
> On Wed, 12 May 2021 15:49:57 +0800
> Zhang Chen <chen.zhang@intel.com> wrote:
> 
> > Fix the issue from this patch:
> > [PATCH] block: Flush all children in generic code
> > From 883833e29cb800b4d92b5d4736252f4004885191
> > 
> > Quorum driver do not have the primary child.
> > It will caused guest block flush issue when use quorum and NBD.
> > The vm guest flushes failed，and then guest filesystem is shutdown.
> 
> Hi,
> I think the problem is rather that the quorum driver provides
> .bdrv_co_flush_to_disk (which predates .bdrv_co_flush) instead of
> .bdrv_co_flush. Can you try with the following patch instead?
> 
> diff --git a/block/quorum.c b/block/quorum.c
> index cfc1436abb..f2c0805000 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -1279,7 +1279,7 @@ static BlockDriver bdrv_quorum = {
>      .bdrv_dirname                       = quorum_dirname,
>      .bdrv_co_block_status               = quorum_co_block_status,
>  
> -    .bdrv_co_flush_to_disk              = quorum_co_flush,
> +    .bdrv_co_flush                      = quorum_co_flush,
>  
>      .bdrv_getlength                     = quorum_getlength,

Thanks, Lukas. This is exactly what I was going to suggest after having
a look at the code now.

The problem is not related to drivers not having a primary child in
general (though quorum might be the only one in this category at the
moment), but that quorum wants to override the default error handling
semantics with its voting mechanism.

Kevin

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