Re: [PATCH 08/14] iotests/common.rc: _make_test_img(): smarter compressiont_type handling

[Max Reitz]

Subject: s/compressiont_type/compression_type/

On 05.07.21 11:15, Vladimir Sementsov-Ogievskiy wrote:
> Like it is done in iotests.py in qemu_img_create_prepare_args(), let's
> not follow compression_type=zstd of IMGOPTS if test creates image in
> old format.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>   tests/qemu-iotests/common.rc | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/tests/qemu-iotests/common.rc b/tests/qemu-iotests/common.rc
> index cbbf6d7c7f..4cae5b2d70 100644
> --- a/tests/qemu-iotests/common.rc
> +++ b/tests/qemu-iotests/common.rc
> @@ -438,6 +438,14 @@ _make_test_img()
>               backing_file=$param
>               continue
>           elif $opts_param; then
> +            if [[ "$param" == *"compat=0"* ]]; then

Like in patch 2, probably should be 0.10, and account for “v2”.

> +                # If user specified zstd compression type in IMGOPTS, this will
> +                # just not work. So, let's imply forcing zlib compression when
> +                # test creates image in old version of the format.
> +                # Similarly works qemu_img_create_prepare_args() in iotests.py
> +                optstr=$(echo "$optstr" | $SED -e 's/compression_type=\w\+//')

What about the surrounding comma, if compression_type is just one option 
among others?  Do we need something like

$SED -e 's/,compression_type=\w\+//' -e 's/compression_type=\w\+,\?//'

?

> +                optstr=$(_optstr_add "$optstr" "compression_type=zlib")

As the comment says, this is for compression_type in $IMGOPTS and then 
compat=0.10 in the parameters.  It won’t work if you have e.g. 
“_make_test_img -o compat=0.10,compression_type=zstd”, because then this 
generates the optstr 
“$IMGOPTS,compression_type=zlib,compat=0.10,compression_type=zstd”. Not 
sure if we want to care about this case, but, well...

Then there’s the case where I have compat=0.10 in $IMGOPTS, and the test 
wants to use compression_type=zstd.  I think it’s correct not to replace 
compression_type=zstd then, because the test should be skipped for 
compat=0.10 in $IMGOPTS.  But that’s not what happens in the iotest.py 
version (qemu_img_create_prepare_args()), so I wonder whether the latter 
should be made to match this behavior here, if in any way possible.

Now that I think about it more, I begin to wonder more...

So this code doesn’t explicitly handle compression_type only in 
$IMGOPTS.  If you have

_make_test_img -o compression_type=zstd,compat=0.10

It’ll still keep the compression_type=zstd.  However, for

_make_test_img -o compression_type=zstd -o compat=0.10

It’ll replace it by zlib.

So perhaps we should explicitly scan for compression_type only in 
$IMGOPTS and then drop it from the optstr if compat=0.10 is in the 
_make_test_img's -o options.

But thinking further, this is not how $IMGOPTS work.  So far they aren’t 
advisory, they are mandatory.  If a test cannot work with something in 
$IMGOPTS, it has to be skipped.  Like, when you have compat=0.10 in 
$IMGOPTS, I don’t want to run tests that use v3 features and have them 
just create v3 images for those tests.

So my impression is that you’re giving compression_type special 
treatment here, and I don’t know why exactly.  Tests that create v2 
images should just have compression_type be an unsupported_imgopt.

Max

> +            fi
>               optstr=$(_optstr_add "$optstr" "$param")
>               opts_param=false
>               continue