Re: [Qemu-block] [PATCH for-4.1 2/2] iotests: Test backup job with two guest writes

[Max Reitz]

On 01.08.19 18:03, Vladimir Sementsov-Ogievskiy wrote:
> 01.08.2019 18:12, Max Reitz wrote:
>> Perform two guest writes to not yet backed up areas of an image, where
>> the former touches an inner area of the latter.
>>
>> Before HEAD^, copy offloading broke this in two ways:
>> (1) The output differs from the reference output (what the source was
>>      before the guest writes).
>> (2) But you will not see that in the failing output, because the job
>>      offset is reported as being greater than the job length.  This is
>>      because one cluster is copied twice, and thus accounted for twice,
>>      but of course the job length does not increase.
>>
>> Signed-off-by: Max Reitz <address@hidden>
>> ---
>>   tests/qemu-iotests/056     | 34 ++++++++++++++++++++++++++++++++++
>>   tests/qemu-iotests/056.out |  4 ++--
>>   2 files changed, 36 insertions(+), 2 deletions(-)
>>
>> diff --git a/tests/qemu-iotests/056 b/tests/qemu-iotests/056
>> index f40fc11a09..d7198507f5 100755
>> --- a/tests/qemu-iotests/056
>> +++ b/tests/qemu-iotests/056
>> @@ -133,6 +133,7 @@ class BackupTest(iotests.QMPTestCase):
>>           self.vm = iotests.VM()
>>           self.test_img = img_create('test')
>>           self.dest_img = img_create('dest')
>> +        self.ref_img = img_create('ref')
>>           self.vm.add_drive(self.test_img)
>>           self.vm.launch()
>>   
>> @@ -140,6 +141,7 @@ class BackupTest(iotests.QMPTestCase):
>>           self.vm.shutdown()
>>           try_remove(self.test_img)
>>           try_remove(self.dest_img)
>> +        try_remove(self.ref_img)
>>   
>>       def hmp_io_writes(self, drive, patterns):
>>           for pattern in patterns:
>> @@ -177,6 +179,38 @@ class BackupTest(iotests.QMPTestCase):
>>               self.assert_qmp(event, 'data/error', qerror)
>>               return False
>>   
>> +    def test_overlapping_writes(self):
>> +        # Write something to back up
>> +        self.hmp_io_writes('drive0', [('42', '0M', '2M')])
>> +
>> +        # Create a reference backup
>> +        self.qmp_backup_and_wait(device='drive0', format=iotests.imgfmt,
>> +                                 sync='full', target=self.ref_img)
>> +
>> +        # Now to the test backup: We simulate the following guest
>> +        # writes:
>> +        # (1) [1M + 64k, 1M + 128k): Afterwards, everything in that
>> +        #     area should be in the target image, and we must not copy
>> +        #     it again (because the source image has changed now)
>> +        #     (64k is the job's cluster size)
>> +        # (2) [1M, 2M): The backup job must not get overeager.  It
>> +        #     must copy [1M, 1M + 64k) and [1M + 128k, 2M) separately,
>> +        #     but not the area in between.
>> +
>> +        self.qmp_backup(device='drive0', format=iotests.imgfmt, sync='full',
>> +                        target=self.dest_img, speed=1)
>> +
>> +        self.hmp_io_writes('drive0', [('23', '%ik' % (1024 + 64), '64k'),
>> +                                      ('66', '1M', '1M')])
>> +
>> +        # Let the job complete
>> +        res = self.vm.qmp('block-job-set-speed', device='drive0', speed=0)
>> +        self.assert_qmp(res, 'return', {})
>> +        self.qmp_backup_wait('drive0')
>> +
>> +        self.assertTrue(iotests.compare_images(self.ref_img, self.dest_img),
>> +                        'target image does not match reference image')
>> +
>>       def test_dismiss_false(self):
>>           res = self.vm.qmp('query-block-jobs')
>>           self.assert_qmp(res, 'return', [])
>> diff --git a/tests/qemu-iotests/056.out b/tests/qemu-iotests/056.out
>> index dae404e278..36376bed87 100644
>> --- a/tests/qemu-iotests/056.out
>> +++ b/tests/qemu-iotests/056.out
>> @@ -1,5 +1,5 @@
>> -.........
>> +..........
>>   ----------------------------------------------------------------------
>> -Ran 9 tests
>> +Ran 10 tests
>>   
>>   OK
>>
> 
> Failed for me:
> -..........
> +qemu-img: Could not open 
> '/work/src/qemu/master/tests/qemu-iotests/scratch/dest.qcow2': Failed to get 
> shared "write" lock
> +Is another process using the image 
> [/work/src/qemu/master/tests/qemu-iotests/scratch/dest.qcow2]?
> +......F...
> +======================================================================
> +FAIL: test_overlapping_writes (__main__.BackupTest)
> +----------------------------------------------------------------------
> +Traceback (most recent call last):
> +  File "056", line 212, in test_overlapping_writes
> +    'target image does not match reference image')
> +AssertionError: False is not true : target image does not match reference 
> image
> +
>   ----------------------------------------------------------------------
>   Ran 10 tests
> 
> -OK
> +FAILED (failures=1)

Hm.  I hoped seeing BLOCK_JOB_COMPLETED would be enough.

> So, with applied
> 
> @@ -207,6 +207,7 @@ class BackupTest(iotests.QMPTestCase):
>           res = self.vm.qmp('block-job-set-speed', device='drive0', speed=0)
>           self.assert_qmp(res, 'return', {})
>           self.qmp_backup_wait('drive0')
> +        self.vm.shutdown()
> 
>           self.assertTrue(iotests.compare_images(self.ref_img, self.dest_img),
>                           'target image does not match reference image')

I’d personally prefer auto_dismiss=False and then block-job-dismiss.
Although I can’t give a reason why.

> Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> Tested-by: Vladimir Sementsov-Ogievskiy <address@hidden>

In any case, thanks!

Max

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