Re: [PATCH v7 34/47] backup: Deal with filters

[Andrey Shinkevich]

On 25.06.2020 18:22, Max Reitz wrote:
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   block/backup-top.c |  2 +-
>   block/backup.c     |  9 +++++----
>   blockdev.c         | 19 +++++++++++++++----
>   3 files changed, 21 insertions(+), 9 deletions(-)
>
>
> diff --git a/block/backup.c b/block/backup.c
> index 4f13bb20a5..9afa0bf3b4 100644
> --- a/block/backup.c
> +++ b/block/backup.c
> @@ -297,6 +297,7 @@ static int64_t 
> backup_calculate_cluster_size(BlockDriverState *target,
>   {
>       int ret;
>       BlockDriverInfo bdi;
> +    bool target_does_cow = bdrv_backing_chain_next(target);
>   


Wouldn't it better to make the explicit type conversion or use "!!" 
approach?

Andrey


>       /*
>        * If there is no backing file on the target, we cannot rely on COW if our
> @@ -304,7 +305,7 @@ static int64_t 
> backup_calculate_cluster_size(BlockDriverState *target,
>        * targets with a backing file, try to avoid COW if possible.
>        */
>       ret = bdrv_get_info(target, &bdi);
> -    if (ret == -ENOTSUP && !target->backing) {
> +    if (ret == -ENOTSUP && !target_does_cow) {
>           /* Cluster size is not defined */

...

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