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

[Vladimir Sementsov-Ogievskiy]

01.08.2019 20:35, Max Reitz wrote:
> On 01.08.19 19:25, Vladimir Sementsov-Ogievskiy wrote:
>> 01.08.2019 20:06, Max Reitz wrote:
>>> 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.
>>
>> The problem is higher: "Failed to get shared "write" lock". Because of this 
>> iotests.compare_images
>> can't work. So, because of locking, we need to shutdown qemu before starting 
>> qemu-img.
>> And it's done so in test_complete_top() (I just looked at it as it's the 
>> only other user of compare_images
>> in 056)
> 
> The destination image shouldn’t be in use by qemu after the block job is
> done, though.  Therefore, there shouldn’t be a lock issue.  That’s what
> I meant.
> 

Ah, understand. Hmm, then it's strange that I see that error..

Clearly, in job_finalize_single(), job_clean() is called first, which should 
call backup_clean to unref target,
then job_event_completed() is called...



> 
>>>> 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
>>>
>>
>>
> 
> 


-- 
Best regards,
Vladimir