Re: Supporting reflinked/cow files in coreutils

[Jim Meyering]

Philipp Thomas wrote:
> * Pádraig Brady (address@hidden) [20110414 17:30]:
>
>> I don't think there is anything else you could do,
>> like minimizing reads from a set of files with
>> shared extents, as there is no way to ID the extent.
>> Oh I suppose you could by using device_id, physical_offset.
>> You could extend the di_set stuff we have for matching
>> hardlinks to do that I suppose. But then one can currently
>> only clone a file, not an extent (on BTRFS at least).
>> What is your use case exactly?
>
> As far as I understood the request, it's for reflink support in du so that
> it's possible to see the space savings reflinks give you. Given your hint
> I'll have a look at the di_set stuff to see how this can possibly be
> extended to use the FIEMAP info.
>
>> Also it would be better to send details to address@hidden
>> as others might have suggestions.
>
> Which I'm doing hereby. BTW, could somebody point me to the documents for
> copyright assignment? I have one on file for GCC but now I'd need one for
> coreutils.

Sure:

    http://git.sv.gnu.org/cgit/coreutils.git/tree/HACKING#n429