Re: [PATCH v2] qcow2: Forbid discard in qcow2 v2 images with backing files

[Alberto Garcia]

On Fri 27 Mar 2020 03:14:42 PM CET, Kevin Wolf wrote:
>> +echo "# Create a backing image and fill it with data"
>> +BACKING_IMG="$TEST_IMG.base"
>> +TEST_IMG="$BACKING_IMG" _make_test_img 128k
>> +$QEMU_IO -c 'write -P 0xff 0 128k' "$BACKING_IMG" | _filter_qemu_io
>> +
>> +for qcow2_compat in 0.10 1.1; do
>> +    echo "# Create an image with compat=$qcow2_compat and a backing file"
>> +    _make_test_img -o "compat=$qcow2_compat" -b "$BACKING_IMG"
>
> I would write some non-zero data to the backing file so that you can
> later distinguish zero clusters from unallocated clusters.

I'm doing that already (immediately before the 'for' loop).

I'll add the output of qemu-img map in v3.

Berto