01.08.2019 20:43, Vladimir Sementsov-Ogievskiy wrote:
> 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 <mre...@redhat.com>
>>>>>> ---
>>>>>> 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...
>
>
But BlockJob.nodes are removed at very-end from block_job_free, so it seems to
be another reference to target,
which is still alive when event is sent.
>
>>
>>>>> 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 <vsement...@virtuozzo.com>
>>>>> Tested-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
>>>>
>>>> In any case, thanks!
>>>>
>>>> Max
>>>>
>>>
>>>
>>
>>
>
>
--
Best regards,
Vladimir
