SUNRPC: Add encoders for list item discriminators

Clean up. These are taken from the client-side RPC/RDMA transport
to a more global header file so they can be used elsewhere.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

include/linux/sunrpc/xdr.h

@@ -315,6 +315,44 @@ static inline size_t xdr_pad_size(size_t n)
 	return xdr_align_size(n) - n;
 }
 
+/**
+ * xdr_stream_encode_item_present - Encode a "present" list item
+ * @xdr: pointer to xdr_stream
+ *
+ * Return values:
+ *   On success, returns length in bytes of XDR buffer consumed
+ *   %-EMSGSIZE on XDR buffer overflow
+ */
+static inline ssize_t xdr_stream_encode_item_present(struct xdr_stream *xdr)
+{
+	const size_t len = sizeof(__be32);
+	__be32 *p = xdr_reserve_space(xdr, len);
+
+	if (unlikely(!p))
+		return -EMSGSIZE;
+	*p = xdr_one;
+	return len;
+}
+
+/**
+ * xdr_stream_encode_item_absent - Encode a "not present" list item
+ * @xdr: pointer to xdr_stream
+ *
+ * Return values:
+ *   On success, returns length in bytes of XDR buffer consumed
+ *   %-EMSGSIZE on XDR buffer overflow
+ */
+static inline int xdr_stream_encode_item_absent(struct xdr_stream *xdr)
+{
+	const size_t len = sizeof(__be32);
+	__be32 *p = xdr_reserve_space(xdr, len);
+
+	if (unlikely(!p))
+		return -EMSGSIZE;
+	*p = xdr_zero;
+	return len;
+}
+
 /**
  * xdr_stream_encode_u32 - Encode a 32-bit integer
  * @xdr: pointer to xdr_stream

net/sunrpc/xprtrdma/rpc_rdma.c

@@ -275,32 +275,6 @@ rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
 	return n;
 }
 
-static inline int
-encode_item_present(struct xdr_stream *xdr)
-{
-	__be32 *p;
-
-	p = xdr_reserve_space(xdr, sizeof(*p));
-	if (unlikely(!p))
-		return -EMSGSIZE;
-
-	*p = xdr_one;
-	return 0;
-}
-
-static inline int
-encode_item_not_present(struct xdr_stream *xdr)
-{
-	__be32 *p;
-
-	p = xdr_reserve_space(xdr, sizeof(*p));
-	if (unlikely(!p))
-		return -EMSGSIZE;
-
-	*p = xdr_zero;
-	return 0;
-}
-
 static void
 xdr_encode_rdma_segment(__be32 *iptr, struct rpcrdma_mr *mr)
 {
@@ -414,7 +388,7 @@ static int rpcrdma_encode_read_list(struct rpcrdma_xprt *r_xprt,
 	} while (nsegs);
 
 done:
-	return encode_item_not_present(xdr);
+	return xdr_stream_encode_item_absent(xdr);
 }
 
 /* Register and XDR encode the Write list. Supports encoding a list
@@ -453,7 +427,7 @@ static int rpcrdma_encode_write_list(struct rpcrdma_xprt *r_xprt,
 	if (nsegs < 0)
 		return nsegs;
 
-	if (encode_item_present(xdr) < 0)
+	if (xdr_stream_encode_item_present(xdr) < 0)
 		return -EMSGSIZE;
 	segcount = xdr_reserve_space(xdr, sizeof(*segcount));
 	if (unlikely(!segcount))
@@ -480,7 +454,7 @@ static int rpcrdma_encode_write_list(struct rpcrdma_xprt *r_xprt,
 	*segcount = cpu_to_be32(nchunks);
 
 done:
-	return encode_item_not_present(xdr);
+	return xdr_stream_encode_item_absent(xdr);
 }
 
 /* Register and XDR encode the Reply chunk. Supports encoding an array
@@ -507,14 +481,14 @@ static int rpcrdma_encode_reply_chunk(struct rpcrdma_xprt *r_xprt,
 	__be32 *segcount;
 
 	if (wtype != rpcrdma_replych)
-		return encode_item_not_present(xdr);
+		return xdr_stream_encode_item_absent(xdr);
 
 	seg = req->rl_segments;
 	nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf, 0, wtype, seg);
 	if (nsegs < 0)
 		return nsegs;
 
-	if (encode_item_present(xdr) < 0)
+	if (xdr_stream_encode_item_present(xdr) < 0)
 		return -EMSGSIZE;
 	segcount = xdr_reserve_space(xdr, sizeof(*segcount));
 	if (unlikely(!segcount))