On Wed, Jan 17, 2018 at 11:42:39PM -0800, Darrick J. Wong wrote:

From: Darrick J. Wong <redacted>

Try to unshare an extent before granting a lease to pnfs; if this isn't
possible, then bail out.

I don't like this at all.  The block and scsi layout protocols actually
have support for reflinks, someone just needs to implement it..

But until that is implemented I'd rather fail getting a layout than
starting a potentially very long running unshare.