nfsd41: implement NFS4_SHARE_WANT_NO_DELEG, NFS4_OPEN_DELEGATE_NONE_EXT, why_no_deleg

Respect client request for not getting a delegation in NFSv4.1
Appropriately return delegation "type" NFS4_OPEN_DELEGATE_NONE_EXT
and WND4_NOT_WANTED reason.

[nfsd41: add missing break when encoding op_why_no_deleg]
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index 32345c2..8cdde4d 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -441,7 +441,20 @@
 enum open_delegation_type4 {
 	NFS4_OPEN_DELEGATE_NONE = 0,
 	NFS4_OPEN_DELEGATE_READ = 1,
-	NFS4_OPEN_DELEGATE_WRITE = 2
+	NFS4_OPEN_DELEGATE_WRITE = 2,
+	NFS4_OPEN_DELEGATE_NONE_EXT = 3, /* 4.1 */
+};
+
+enum why_no_delegation4 { /* new to v4.1 */
+	WND4_NOT_WANTED = 0,
+	WND4_CONTENTION = 1,
+	WND4_RESOURCE = 2,
+	WND4_NOT_SUPP_FTYPE = 3,
+	WND4_WRITE_DELEG_NOT_SUPP_FTYPE = 4,
+	WND4_NOT_SUPP_UPGRADE = 5,
+	WND4_NOT_SUPP_DOWNGRADE = 6,
+	WND4_CANCELLED = 7,
+	WND4_IS_DIR = 8,
 };
 
 enum lock_type4 {