SUNRPC: Refactor xs_sendpages()

Re-locate xs_sendpages() so that it can be shared with server code.

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

include/linux/sunrpc/xdr.h

@@ -188,20 +188,6 @@ extern int xdr_buf_read_mic(struct xdr_buf *, struct xdr_netobj *, unsigned int)
 extern int read_bytes_from_xdr_buf(struct xdr_buf *, unsigned int, void *, unsigned int);
 extern int write_bytes_to_xdr_buf(struct xdr_buf *, unsigned int, void *, unsigned int);
 
-/*
- * Helper structure for copying from an sk_buff.
- */
-struct xdr_skb_reader {
-	struct sk_buff	*skb;
-	unsigned int	offset;
-	size_t		count;
-	__wsum		csum;
-};
-
-typedef size_t (*xdr_skb_read_actor)(struct xdr_skb_reader *desc, void *to, size_t len);
-
-extern int csum_partial_copy_to_xdr(struct xdr_buf *, struct sk_buff *);
-
 extern int xdr_encode_word(struct xdr_buf *, unsigned int, u32);
 extern int xdr_decode_word(struct xdr_buf *, unsigned int, u32 *);
 

net/sunrpc/socklib.c

@@ -14,9 +14,24 @@
 #include <linux/types.h>
 #include <linux/pagemap.h>
 #include <linux/udp.h>
+#include <linux/sunrpc/msg_prot.h>
 #include <linux/sunrpc/xdr.h>
 #include <linux/export.h>
 
+#include "socklib.h"
+
+/*
+ * Helper structure for copying from an sk_buff.
+ */
+struct xdr_skb_reader {
+	struct sk_buff	*skb;
+	unsigned int	offset;
+	size_t		count;
+	__wsum		csum;
+};
+
+typedef size_t (*xdr_skb_read_actor)(struct xdr_skb_reader *desc, void *to,
+				     size_t len);
 
 /**
  * xdr_skb_read_bits - copy some data bits from skb to internal buffer
@@ -186,3 +201,129 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
+
+static inline int xprt_sendmsg(struct socket *sock, struct msghdr *msg,
+			       size_t seek)
+{
+	if (seek)
+		iov_iter_advance(&msg->msg_iter, seek);
+	return sock_sendmsg(sock, msg);
+}
+
+static int xprt_send_kvec(struct socket *sock, struct msghdr *msg,
+			  struct kvec *vec, size_t seek)
+{
+	iov_iter_kvec(&msg->msg_iter, WRITE, vec, 1, vec->iov_len);
+	return xprt_sendmsg(sock, msg, seek);
+}
+
+static int xprt_send_pagedata(struct socket *sock, struct msghdr *msg,
+			      struct xdr_buf *xdr, size_t base)
+{
+	int err;
+
+	err = xdr_alloc_bvec(xdr, GFP_KERNEL);
+	if (err < 0)
+		return err;
+
+	iov_iter_bvec(&msg->msg_iter, WRITE, xdr->bvec, xdr_buf_pagecount(xdr),
+		      xdr->page_len + xdr->page_base);
+	return xprt_sendmsg(sock, msg, base + xdr->page_base);
+}
+
+/* Common case:
+ *  - stream transport
+ *  - sending from byte 0 of the message
+ *  - the message is wholly contained in @xdr's head iovec
+ */
+static int xprt_send_rm_and_kvec(struct socket *sock, struct msghdr *msg,
+				 rpc_fraghdr marker, struct kvec *vec,
+				 size_t base)
+{
+	struct kvec iov[2] = {
+		[0] = {
+			.iov_base	= &marker,
+			.iov_len	= sizeof(marker)
+		},
+		[1] = *vec,
+	};
+	size_t len = iov[0].iov_len + iov[1].iov_len;
+
+	iov_iter_kvec(&msg->msg_iter, WRITE, iov, 2, len);
+	return xprt_sendmsg(sock, msg, base);
+}
+
+/**
+ * xprt_sock_sendmsg - write an xdr_buf directly to a socket
+ * @sock: open socket to send on
+ * @msg: socket message metadata
+ * @xdr: xdr_buf containing this request
+ * @base: starting position in the buffer
+ * @marker: stream record marker field
+ * @sent_p: return the total number of bytes successfully queued for sending
+ *
+ * Return values:
+ *   On success, returns zero and fills in @sent_p.
+ *   %-ENOTSOCK if  @sock is not a struct socket.
+ */
+int xprt_sock_sendmsg(struct socket *sock, struct msghdr *msg,
+		      struct xdr_buf *xdr, unsigned int base,
+		      rpc_fraghdr marker, unsigned int *sent_p)
+{
+	unsigned int rmsize = marker ? sizeof(marker) : 0;
+	unsigned int remainder = rmsize + xdr->len - base;
+	unsigned int want;
+	int err = 0;
+
+	*sent_p = 0;
+
+	if (unlikely(!sock))
+		return -ENOTSOCK;
+
+	msg->msg_flags |= MSG_MORE;
+	want = xdr->head[0].iov_len + rmsize;
+	if (base < want) {
+		unsigned int len = want - base;
+
+		remainder -= len;
+		if (remainder == 0)
+			msg->msg_flags &= ~MSG_MORE;
+		if (rmsize)
+			err = xprt_send_rm_and_kvec(sock, msg, marker,
+						    &xdr->head[0], base);
+		else
+			err = xprt_send_kvec(sock, msg, &xdr->head[0], base);
+		if (remainder == 0 || err != len)
+			goto out;
+		*sent_p += err;
+		base = 0;
+	} else {
+		base -= want;
+	}
+
+	if (base < xdr->page_len) {
+		unsigned int len = xdr->page_len - base;
+
+		remainder -= len;
+		if (remainder == 0)
+			msg->msg_flags &= ~MSG_MORE;
+		err = xprt_send_pagedata(sock, msg, xdr, base);
+		if (remainder == 0 || err != len)
+			goto out;
+		*sent_p += err;
+		base = 0;
+	} else {
+		base -= xdr->page_len;
+	}
+
+	if (base >= xdr->tail[0].iov_len)
+		return 0;
+	msg->msg_flags &= ~MSG_MORE;
+	err = xprt_send_kvec(sock, msg, &xdr->tail[0], base);
+out:
+	if (err > 0) {
+		*sent_p += err;
+		err = 0;
+	}
+	return err;
+}

net/sunrpc/socklib.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 1995-1997 Olaf Kirch <okir@monad.swb.de>
+ * Copyright (C) 2020, Oracle.
+ */
+
+#ifndef _NET_SUNRPC_SOCKLIB_H_
+#define _NET_SUNRPC_SOCKLIB_H_
+
+int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb);
+int xprt_sock_sendmsg(struct socket *sock, struct msghdr *msg,
+		      struct xdr_buf *xdr, unsigned int base,
+		      rpc_fraghdr marker, unsigned int *sent_p);
+
+#endif /* _NET_SUNRPC_SOCKLIB_H_ */

net/sunrpc/svcsock.c

@@ -55,6 +55,7 @@
 #include <linux/sunrpc/stats.h>
 #include <linux/sunrpc/xprt.h>
 
+#include "socklib.h"
 #include "sunrpc.h"
 
 #define RPCDBG_FACILITY	RPCDBG_SVCXPRT