Re: [RFC PATCH 0/5] btrfs-progs: snapshot diff function

[Jie Liu <jeff.liu@oracle.com>]

On 08/25/12 14:23, Alexander Block wrote:
> On Fri, Aug 24, 2012 at 4:15 PM, Jeff Liu <jeff.liu@oracle.com> wrote:
>> Hi Alex,
>>
>> Thanks for taking a look.
>>
>> On 08/24/2012 09:09 PM, Alex Lyakas wrote:
>>
>>> Hi Jeff,
>>> how do you see this snapshot-diff functionality vs the send/receive
>>> functionality that was recently added? I think that the binary stream
>>> that the send code produces, can be interpreted by printing out text
>>> messages, which will essentially give the same information (although
>>> much more detailed) as your snapshot-diff tool.
>> send/receive has not yet implemented when I working on this feature(back to the end of last year).
>> looks there really has some duplicate efforts.
>>
>> Just as you said, the produced stream of send need to interpret to show readable info, if the binary stream is
>> became huge enough, maybe that will make some silly user crying like me :).
>> Also, it is mainly focus on backup purpose IMHO, please correct me if I missing something in this point.
>>
>> The diff utility is designed to list any changes between two snapshots in a straightforward way consider the command interface,
>> it also can be improved to show the differences at a given time range.
>>
>> But sure, send/receive is just awesome, if we can introduce a interpreted script which do same thing to
>> make end user's life easier, that would be fine.
>>
>> Thanks,
>> -Jeff
>>
>>> Apologies if I somehow misunderstood what your snapshot-diff code does.
>>>
>>> Thanks,
>>> Alex.
>>>
>>>
>>> On Tue, Aug 7, 2012 at 11:56 AM, Jeff Liu <jeff.liu@oracle.com> wrote:
>>>> Hello,
>>>>
>>>> I've done a prototype implementation of snapshot diff utility many months ago.
>>>> It was originally meant to analyze the differences between two snapshots which are
>>>> inherited from the same subvolume/snapshot.

>>>> My idea was to introduce new "instructions" to the stream later which
>>>> could be activated using a flag in the ioctl structure. These
>>>> instructions would not be real instruction but diff statements. They
>>>> would contain the plain results as given by btrfs_compare_trees. So we
>>>> would have the information which tree items were
>>>> added/removed/changed. As an alternative, this could be a new ioctl.
Sound interesting.
The performance of interpret huge streams from the user land could
resolved in this way, am looking forward to see that become true so. :)

Thanks,
-Jeff
>
> Greetings from Ko Tao :)
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