The “Experimental” tag has just been removed from XFS upstream, for kernel 4.16.
1e369b0 xfs: remove experimental tag for reflinks
(Removal of experimental pretty much means “deemed stable and ready.”)
It would be really great to get xfs reflink support into urbackup, please let me know if I can help. (I’m an XFS developer, and actually shopping for a backup strategy, and would love to try urbackup + xfs reflinks!)
Thanks,
-Eric