Re: [PATCH v2 05/21] iotests: Replace IMGOPTS by _unsupported_imgopts

[Max Reitz]

On 06.11.19 16:45, Maxim Levitsky wrote:
> On Tue, 2019-10-15 at 16:27 +0200, Max Reitz wrote:
>> Some tests require compat=1.1 and thus set IMGOPTS='compat=1.1'
>> globally.  That is not how it should be done; instead, they should
>> simply set _unsupported_imgopts to compat=0.10 (compat=1.1 is the
>> default anyway).
>>
>> This makes the tests heed user-specified $IMGOPTS.  Some do not work
>> with all image options, though, so we need to disable them accordingly.
>>
>> Signed-off-by: Max Reitz <address@hidden>
>> ---
>>  tests/qemu-iotests/036 | 3 +--
>>  tests/qemu-iotests/060 | 4 ++--
>>  tests/qemu-iotests/062 | 3 ++-
>>  tests/qemu-iotests/066 | 3 ++-
>>  tests/qemu-iotests/068 | 3 ++-
>>  tests/qemu-iotests/098 | 4 ++--
>>  6 files changed, 11 insertions(+), 9 deletions(-)
>>
>> diff --git a/tests/qemu-iotests/036 b/tests/qemu-iotests/036
>> index 5f929ad3be..bbaf0ef45b 100755
>> --- a/tests/qemu-iotests/036
>> +++ b/tests/qemu-iotests/036
>> @@ -43,9 +43,8 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
>>  # This tests qcow2-specific low-level functionality
>>  _supported_fmt qcow2
>>  _supported_proto file
>> -
>>  # Only qcow2v3 and later supports feature bits
>> -IMGOPTS="compat=1.1"
>> +_unsupported_imgopts 'compat=0.10'
>>  
>>  echo
>>  echo === Image with unknown incompatible feature bit ===
>> diff --git a/tests/qemu-iotests/060 b/tests/qemu-iotests/060
>> index b91d8321bb..9c2ef42522 100755
>> --- a/tests/qemu-iotests/060
>> +++ b/tests/qemu-iotests/060
>> @@ -48,6 +48,8 @@ _filter_io_error()
>>  _supported_fmt qcow2
>>  _supported_proto file
>>  _supported_os Linux
>> +# These tests only work for compat=1.1 images with refcount_bits=16
>> +_unsupported_imgopts 'compat=0.10' 'refcount_bits=\([^1]\|.\([^6]\|$\)\)'
> Looks like the reason for that is that the test hardcodes (or guesses that 
> is) various qcow2 structures
> thing I have seen few times already in the iotests.
> Not now but sometime in the future it would be nice to extend qcow2.py (or 
> something
> like that) to dump location of all qcow2 structures so that the guesswork 
> could be eliminated.

With the peek_file* functions we have now it’s actually simple to dump
that location ($(peek_file_be "$TEST_IMG" 48 8) for the refcount table
offset, for example).

But it wouldn’t help, because compat=0.10 or refcount_bits != 16 won’t
change those locations.  So the locations aren’t the reason why we need
to forbid those options here.

The reason we need refcount_bits=16 is that we’re going to directly
manipulate a refcount block.  To do so, we need to know the refcount
width, and I don’t think it’s worth trying to implement something generic.

We need compat=1.1 because compat=0.10 doesn’t have feature bits, so
there’s no “corrupt” bit there.

Max

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