On Fri, Apr 26, 2019 at 07:45:07AM -0700, Darrick J. Wong wrote: > Hmmm, this lease interface still doesn't support COW, right? > > (Right, xfs_pnfs.c bails out with -ENXIO for reflink files) Yes, but that is because no one bothered to do the work. pNFS/block and pNFS/scsi explicitly support a compatbile COW scheme, it is just that no implemented it yet (at all I think, not just for Linux..).