Re: [PATCH v7 15/47] block: Use CAFs when working with backing chains

[Andrey Shinkevich]

On 25.06.2020 18:21, Max Reitz wrote:
> Use child access functions when iterating through backing chains so
> filters do not break the chain.
>
> In addition, bdrv_find_overlay() will now always return the actual
> overlay; that is, it will never return a filter node but only one with a
> COW backing file (there may be filter nodes between that node and @bs).
>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   block.c | 41 +++++++++++++++++++++++++++++------------
>   1 file changed, 29 insertions(+), 12 deletions(-)
>
> diff --git a/block.c b/block.c
> index a44af9c3c1..712230ef5c 100644
> --- a/block.c
> +++ b/block.c
> @@ -4724,7 +4724,8 @@ int bdrv_change_backing_file(BlockDriverState *bs,
>   }
>   
>   /*
> - * Finds the image layer in the chain that has 'bs' as its backing file.
> + * Finds the image layer in the chain that has 'bs' (or a filter on
> + * top of it) as its backing file.
One can optionally say "Finds the first non-filter parent of bs in the 
chain".
>    

...

Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>