NFS: Add COPY nfs operation

This adds the copy_range file_ops function pointer used by the
sys_copy_range() function call.  This patch only implements sync copies,
so if an async copy happens we decode the stateid and ignore it.

Signed-off-by: Anna Schumaker <bjschuma@netapp.com>
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index 0114334..7225094 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -504,6 +504,7 @@
 	NFSPROC4_CLNT_DEALLOCATE,
 	NFSPROC4_CLNT_LAYOUTSTATS,
 	NFSPROC4_CLNT_CLONE,
+	NFSPROC4_CLNT_COPY,
 };
 
 /* nfs41 types */