Re: [LSF/MM TOPIC] Direct block mapping through fs for device

[Christoph Hellwig]

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..).