SUNRPC: Move definition of XDR_UNIT

Clean up: The unit of XDR alignment is defined by RFC 4506,
not as part of the RPC message header. Thus it belongs in
include/linux/sunrpc/xdr.h.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

include/linux/sunrpc/msg_prot.h

@@ -10,9 +10,6 @@
 
 #define RPC_VERSION 2
 
-/* size of an XDR encoding unit in bytes, i.e. 32bit */
-#define XDR_UNIT	(4)
-
 /* spec defines authentication flavor as an unsigned 32 bit integer */
 typedef u32	rpc_authflavor_t;
 

include/linux/sunrpc/xdr.h

@@ -19,6 +19,13 @@
 struct bio_vec;
 struct rpc_rqst;
 
+/*
+ * Size of an XDR encoding unit in bytes, i.e. 32 bits,
+ * as defined in Section 3 of RFC 4506. All encoded
+ * XDR data items are aligned on a boundary of 32 bits.
+ */
+#define XDR_UNIT		sizeof(__be32)
+
 /*
  * Buffer adjustment
  */
@@ -330,7 +337,7 @@ ssize_t xdr_stream_decode_string_dup(struct xdr_stream *xdr, char **str,
 static inline size_t
 xdr_align_size(size_t n)
 {
-	const size_t mask = sizeof(__u32) - 1;
+	const size_t mask = XDR_UNIT - 1;
 
 	return (n + mask) & ~mask;
 }
@@ -360,7 +367,7 @@ static inline size_t xdr_pad_size(size_t n)
  */
 static inline ssize_t xdr_stream_encode_item_present(struct xdr_stream *xdr)
 {
-	const size_t len = sizeof(__be32);
+	const size_t len = XDR_UNIT;
 	__be32 *p = xdr_reserve_space(xdr, len);
 
 	if (unlikely(!p))
@@ -379,7 +386,7 @@ static inline ssize_t xdr_stream_encode_item_present(struct xdr_stream *xdr)
  */
 static inline int xdr_stream_encode_item_absent(struct xdr_stream *xdr)
 {
-	const size_t len = sizeof(__be32);
+	const size_t len = XDR_UNIT;
 	__be32 *p = xdr_reserve_space(xdr, len);
 
 	if (unlikely(!p))