Re: [PATCH 14/22] quorum: Stop marking it as a filter

[Vladimir Sementsov-Ogievskiy]

20.09.2019 18:27, Max Reitz wrote:
> Quorum is not a filter, for example because it cannot guarantee which of
> its children will serve the next request.  Thus, any of its children may
> differ from the data visible to quorum's parents.
> 
> We have other filters with multiple children, but they differ in this
> aspect:
> 
> - blkverify quits the whole qemu process if its children differ.  As
>    such, we can always skip it when we want to skip it (as a filter node)
>    by going to any of its children.  Both have the same data.
> 
> - replication generally serves requests from bs->file, so this is its
>    only actually filtered child.
> 
> - Block job filters currently only have one child, but they will
>    probably get more children in the future.  Still, they will always
>    have only one actually filtered child.
> 
> Having "filters" as a dedicated node category only makes sense if you
> can skip them by going to a one fixed child that always shows the same
> data as the filter node.  Quorum cannot fulfill this, so it is not a
> filter.
> 
> Signed-off-by: Max Reitz <address@hidden>

Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>

> ---
>   block/quorum.c | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/block/quorum.c b/block/quorum.c
> index 7a8f8b5475..7f56b4df7c 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -1237,7 +1237,6 @@ static BlockDriver bdrv_quorum = {
>   
>       .bdrv_child_perm                    = quorum_child_perm,
>   
> -    .is_filter                          = true,
>       .bdrv_recurse_can_replace           = quorum_recurse_can_replace,
>   
>       .strong_runtime_opts                = quorum_strong_runtime_opts,
> 


-- 
Best regards,
Vladimir