Horrible inefficient, but avoids problems when the root PD size becomes
to big.

v2: remove incr as well.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NChunming Zhou <davdi1.zhou@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>