Re: [Qemu-devel] [PATCH v7 11/20] dirty-bitmap: Change bdrv_dirty_iter_next() to report byte offset

[John Snow <jsnow@redhat.com>]

On 09/14/2017 07:58 AM, Eric Blake wrote:
> On 09/13/2017 07:15 PM, John Snow wrote:
>>
>>
>> On 09/12/2017 04:31 PM, Eric Blake wrote:
>>> Thanks to recent cleanups, most callers were scaling a return value
>>> of sectors into bytes (the exception, in qcow2-bitmap, will be
>>> converted to byte-based iteration later).  Update the interface to
>>> do the scaling internally instead.
>>>
>>> In qcow2-bitmap, the code was specifically checking for an error
>>> to be -1; it is more robust to treat all negative values as an
>>> error, but at the same time it is also easy enough to ensure we
>>> return -1 (and not -512) on error.
>>>
>>> Signed-off-by: Eric Blake <eblake@redhat.com>
>>>
>>
>> This patch now smells like a bugfix and a separate incremental feature
>> enhancement.
> 
> There is no bug without this patch; more of a fix to avoid a latent

Ah, you're right, I see. Please take the RB.

> regression from happening in further changes.  In v6, I (accidentally)
> had bdrv_dirty_iter_next() temporarily returning -512 instead of -1 on
> failure; changing the qcow2 code to treat all negatives instead of
> precisely -1 as error is enough to avoid that regression, but so also is
> fixing bdrv_dirty_iter_next() to always return -1 on failure.  This
> patch does both, rather than either fix in isolation, but that means we
> don't need a backport.
> 
>>
>> Do we need to backport the error-checking to a possible 2.10.1?
>>
>> If no:
>>
>> Reviewed-by: John Snow <jsnow@redhat.com>
>>
>