On 29.05.19 17:46, Vladimir Sementsov-Ogievskiy wrote:
> Teach bdrv_debug_breakpoint and bdrv_debug_remove_breakpoint skip
> filters with backing. This is needed to implement and use in backup job
> it's own backup_top filter driver (like mirror already has one), and
> without this improvement, breakpoint removal will fail at least in 55
> iotest.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block.c | 34 ++++++++++++++++++++++++++--------
>  1 file changed, 26 insertions(+), 8 deletions(-)

Well, it would work in the meantime, but the real fix of course is to
use bdrv_primary_bs().

Max