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

[Thomas Huth]

 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!

 Thanks,
  Thomas