On 12.08.19 14:14, Vladimir Sementsov-Ogievskiy wrote:
> 09.08.2019 19:13, Max Reitz wrote:
>> This changes iotest 204's output, because blkdebug on top of a COW node
>> used to make qemu-img map disregard the rest of the backing chain (the
>> backing chain was broken by the filter).  With this patch, the
>> allocation in the base image is reported correctly.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   qemu-img.c                 | 33 ++++++++++++++++++++-------------
>>   tests/qemu-iotests/204.out |  1 +
>>   2 files changed, 21 insertions(+), 13 deletions(-)
>>
>> diff --git a/qemu-img.c b/qemu-img.c
>> index 79983772de..3b30c5ae70 100644
>> --- a/qemu-img.c
>> +++ b/qemu-img.c

[...]

>> @@ -2490,7 +2492,8 @@ static int img_convert(int argc, char **argv)
>>            * s.target_backing_sectors has to be negative, which it will
>>            * be automatically).  The backing file length is used only
>>            * for optimizations, so such a case is not fatal. */
>> -        s.target_backing_sectors = bdrv_nb_sectors(out_bs->backing->bs);
>> +        s.target_backing_sectors =
>> +            bdrv_nb_sectors(bdrv_filtered_cow_bs(out_bs));
> 
> why not skip_rw_filters? It will fail if out_bs is filter..

Because I forgot this place. :-)  Although backing_chain_next() would be
simpler here and do the same, effectively.

Max