Re: [PATCH for-4.2? v3 0/8] block: Fix resize (extending) of short overlays

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

19.12.2019 13:20, Vladimir Sementsov-Ogievskiy wrote:
> 19.12.2019 13:13, Kevin Wolf wrote:
>> Am 19.12.2019 um 10:24 hat Vladimir Sementsov-Ogievskiy geschrieben:
>>> 10.12.2019 20:46, Kevin Wolf wrote:
>>>> Am 22.11.2019 um 17:05 hat Kevin Wolf geschrieben:
>>>>> See patch 4 for the description of the bug fixed.
>>>>
>>>> I'm applying patches 3 and 5-7 to the block branch because they make
>>>> sense on their own.
>>>>
>>>> The real fix will need another approach because the error handling is
>>>> broken in this one: If zeroing out fails (either because of NO_FALLBACK
>>>> or because of some other I/O error), bdrv_co_truncate() will return
>>>> failure, but the image size has already been increased, with potentially
>>>> incorrect data in the new area.
>>>>
>>>> To fix this, we need to make sure that zeros will be read before we
>>>> commit the new image size to the image file (e.g. qcow2 header) and to
>>>> bs->total_sectors. In other words, it must become the responsibility of
>>>> the block driver.
>>>>
>>>> To this effect, I'm planning to introduce a PREALLOC_MODE_ZERO_INIT flag
>>>> that can be or'ed to the preallocation mode. This will fail by default
>>>> because it looks like just another unimplemented preallocation mode to
>>>> block drivers. It will be requested explicitly by commit jobs and
>>>> automatically added by bdrv_co_truncate() if the backing file would
>>>> become visible (like in this series, but now for all preallocation
>>>> modes). I'm planning to implement it for qcow2 and file-posix for now,
>>>> which should cover most interesting cases.
>>>>
>>>> Does this make sense to you?
>>>
>>> This should work. Do you still have this plan in a timeline?
>>
>> Still planning to do this, but tomorrow is my last working day for this
>> year. So I guess I'll get to it sometime in January.
>>
> 
> Good. Have a nice holiday!
> 
> 

Hi, didn't you forget? I just going to ping (or resend) my related
"[PATCH 0/4] fix & merge block_status_above and is_allocated_above", so,
pinging these patches too...

-- 
Best regards,
Vladimir