Re: [Qemu-devel] [PATCH v2] vmdk: Set vmdk parent backing_format to vmdk

[Sam]

Thanks Thomas, Thanks Max

So how do you want to proceed?

Apply Max’s RFC from here 
(http://lists.nongnu.org/archive/html/qemu-block/2019-04/msg00442.html 
<http://lists.nongnu.org/archive/html/qemu-block/2019-04/msg00442.html>) and 
add the commit id which is stable now?
Or should I resubmit my fix (which is very similar to what Max did) without the 
original change?

Sam

> On 3 May 2019, at 17:32, Max Reitz <address@hidden> wrote:
> 
> On 03.05.19 13:34, Thomas Huth wrote:
>> Hi Sam,
>> 
>> On 02/05/2019 15.08, Sam Eiderman wrote:
>>> Commit b69864e ("vmdk: Support version=3 in VMDK descriptor files")
>>> fixed the probe function to correctly guess vmdk descriptors with
>>> version=3.
>>> 
>>> This solves the issue where vmdk snapshot with parent vmdk descriptor
>>> containing "version=3" would be treated as raw instead vmdk.
>>> 
>>> In the future case where a new vmdk version is introduced, we will again
>>> experience this issue, even if the user will provide "-f vmdk" it will
>>> only apply to the tip image and not to the underlying "misprobed" parent
>>> image.
>>> 
>>> The code in vmdk.c already assumes that the backing file of vmdk must be
>>> vmdk (see vmdk_is_cid_valid which returns 0 if backing file is not
>>> vmdk).
>>> 
>>> So let's make it official by supplying the backing_format as vmdk.
>>> 
>>> Reviewed-by: Mark Kanda <address@hidden>
>>> Reviewed-By: Liran Alon <address@hidden>
>>> Reviewed-by: Arbel Moshe <address@hidden>
>>> Signed-off-by: Shmuel Eiderman <address@hidden>
>>> ---
>>> block/vmdk.c           | 2 ++
>>> tests/qemu-iotests/110 | 6 +++---
>>> tests/qemu-iotests/126 | 4 ++--
>>> 3 files changed, 7 insertions(+), 5 deletions(-)
>>> 
>>> diff --git a/block/vmdk.c b/block/vmdk.c
>>> index 8dec6ef767..de8cb859f8 100644
>>> --- a/block/vmdk.c
>>> +++ b/block/vmdk.c
>>> @@ -397,6 +397,8 @@ static int vmdk_parent_open(BlockDriverState *bs)
>>>         pstrcpy(bs->auto_backing_file, end_name - p_name + 1, p_name);
>>>         pstrcpy(bs->backing_file, sizeof(bs->backing_file),
>>>                 bs->auto_backing_file);
>>> +        pstrcpy(bs->backing_format, sizeof(bs->backing_format),
>>> +                "vmdk");
>>>     }
>> 
>> Your patch with this change has already been merged into the QEMU master
>> branch...
>> 
>>> diff --git a/tests/qemu-iotests/110 b/tests/qemu-iotests/110
>>> index fad672c1ae..982569dbc5 100755
>>> --- a/tests/qemu-iotests/110
>>> +++ b/tests/qemu-iotests/110
>>> @@ -54,7 +54,7 @@ _make_test_img -b "$TEST_IMG_REL.base" 64M
>>> # qemu should be able to reconstruct the filename, so relative backing names
>>> # should work
>>> TEST_IMG="json:{'driver':'$IMGFMT','file':{'driver':'file','filename':'$TEST_IMG'}}"
>>>  \
>>> -    _img_info | _filter_img_info
>>> +    _img_info | _filter_img_info | grep -v "backing file format"
>>> 
>>> echo
>>> echo '=== Non-reconstructable filename ==='
>>> @@ -78,7 +78,7 @@ TEST_IMG="json:{
>>>             }
>>>         ]
>>>     }
>>> -}" _img_info | _filter_img_info
>>> +}" _img_info | _filter_img_info | grep -v "backing file format"
>>> 
>>> echo
>>> echo '=== Backing name is always relative to the backed image ==='
>>> @@ -110,7 +110,7 @@ TEST_IMG="json:{
>>>             }
>>>         ]
>>>     }
>>> -}" _img_info | _filter_img_info
>>> +}" _img_info | _filter_img_info | grep -v "backing file format"
>>> 
>>> 
>>> # success, all done
>>> diff --git a/tests/qemu-iotests/126 b/tests/qemu-iotests/126
>>> index 96dc048d59..1f7618c8a5 100755
>>> --- a/tests/qemu-iotests/126
>>> +++ b/tests/qemu-iotests/126
>>> @@ -63,7 +63,7 @@ TEST_IMG=$BASE_IMG _make_test_img 64M
>>> TEST_IMG=$TOP_IMG _make_test_img -b ./image:base.$IMGFMT
>>> 
>>> # The default cluster size depends on the image format
>>> -TEST_IMG=$TOP_IMG _img_info | grep -v 'cluster_size'
>>> +TEST_IMG=$TOP_IMG _img_info | grep -v 'cluster_size\|backing file format'
>>> 
>>> _rm_test_img "$BASE_IMG"
>>> _rm_test_img "$TOP_IMG"
>>> @@ -79,7 +79,7 @@ TOP_IMG="file:image:top.$IMGFMT"
>>> TEST_IMG=$BASE_IMG _make_test_img 64M
>>> TEST_IMG=$TOP_IMG _make_test_img -b "$BASE_IMG"
>>> 
>>> -TEST_IMG=$TOP_IMG _img_info | grep -v 'cluster_size'
>>> +TEST_IMG=$TOP_IMG _img_info | grep -v 'cluster_size\|backing file format'
>>> 
>>> _rm_test_img "$BASE_IMG"
>>> _rm_test_img "image:top.$IMGFMT"
>>> 
>> 
>> ... so please just send a patch with these fixes!
> 
> I already did, it's here:
> 
> http://lists.nongnu.org/archive/html/qemu-block/2019-04/msg00442.html 
> <http://lists.nongnu.org/archive/html/qemu-block/2019-04/msg00442.html>
> 
> Max