NFSv4: Record the OPEN create mode used in the nfs4_opendata structure

If we're doing NFSv4.1 against a server that has persistent sessions,
then we should not need to call SETATTR in order to reset the file
attributes immediately after doing an exclusive create.

Note that since the create mode depends on the type of session that
has been negotiated with the server, we should not choose the
mode until after we've got a session slot.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/nfs_xdr.h

@@ -349,6 +349,7 @@ struct nfs_openargs {
 	const u32 *		bitmask;
 	const u32 *		open_bitmap;
 	__u32			claim;
+	enum createmode4	createmode;
 };
 
 struct nfs_openres {