Re: [PATCH v2 1/4] iotests/109: Don't mirror with mismatched size

[Max Reitz <mreitz@redhat.com>]

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On 11.05.20 17:29, Kevin Wolf wrote:
> Am 11.05.2020 um 17:08 hat Max Reitz geschrieben:
>> On 11.05.20 15:58, Kevin Wolf wrote:
>>> This patch makes the raw image the same size as the file in a different
>>> format that is mirrored as raw to it to avoid errors when mirror starts
>>> to enforce that source and target are the same size.
>>>
>>> We check only that the first 512 bytes are zeroed (instead of 64k)
>>> because some image formats create image files that are smaller than 64k,
>>> so trying to read 64k would result in I/O errors. Apart from this, 512
>>> is more appropriate anyway because the raw format driver protects
>>> specifically the first 512 bytes.
>>>
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>>  tests/qemu-iotests/109           | 10 ++---
>>>  tests/qemu-iotests/109.out       | 74 +++++++++++++-------------------
>>>  tests/qemu-iotests/common.filter |  5 +++
>>>  3 files changed, 41 insertions(+), 48 deletions(-)
>>>
>>> diff --git a/tests/qemu-iotests/109 b/tests/qemu-iotests/109
>>> index 5bc2e9b001..3ffeaf3c55 100755
>>> --- a/tests/qemu-iotests/109
>>> +++ b/tests/qemu-iotests/109
>>> @@ -77,14 +77,14 @@ for fmt in qcow qcow2 qed vdi vmdk vpc; do
>>>      echo "=== Writing a $fmt header into raw ==="
>>>      echo
>>>  
>>> -    _make_test_img 64M
>>>      TEST_IMG="$TEST_IMG.src" IMGFMT=$fmt _make_test_img 64M
>>> +    _make_test_img $(du -b "$TEST_IMG.src" | cut -f1) | _filter_img_create_size
>>
>> Why du and not the file length (stat -c '%s')?
> 
> Because the test from which I copied had 'du' and the internet claimed
> that 'stat -c' isn't portable. Now I see that we do use it in other test
> cases, so I guess it would have been fine, too. Is there a good reason
> why 'stat' would be better?

Oh, I didn’t know that du -b reports the file length.  Well, then that
works, too.  (I’ve never seen du used for anything but getting the,
well, disk usage.)

(I figured -b would just report the size in bytes.)

Then:

Reviewed-by: Max Reitz <mreitz@redhat.com>


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