Re: BTRFS file clone support for cp

[Giuseppe Scrivano <gscrivano@gnu.org>]

Hi P=C3=A1draig,


P=C3=A1draig Brady <P@draigBrady.com> writes:

> How different exactly?
> OK I tried this myself on F11 with inconclusive results.

I can't replicate it now, all tests I am doing report that blocks used
before and after the clone are the same.  Probably yesterday the
difference I noticed was in reality the original file flushed to the
disk.


> The above suggests that the clone does actually allocate space
> but btrfs isn't reporting it through statvfs correctly?

The same message appeared here too some days ago, though I cloned only
few Kb files, not much to fill the entire partition.


> If the clone does allocate space, then how can one
> clone without allocation which could be very useful
> for snapshotting for example?

I don't know if snapshotting is handled in the same way as a "clone",
but in this case it seems more obvious to me that no additional space
should be reported.


> Also I tried the above twice and both times got:
> http://www.kerneloops.org/submitresult.php?number=3D578993

I didn't get these errors.  I am using the btrfs git version.


Regards,
Giuseppe