sunrpc: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage

When transmitting data, call down into TCP using sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced rather than
performing sendpage calls to transmit header, data pages and trailer.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
cc: Trond Myklebust <trond.myklebust@hammerspace.com>
cc: Anna Schumaker <anna@kernel.org>
cc: Jeff Layton <jlayton@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 12 insertions, 26 deletions

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index f77cebe2c071..9d9f522e3ae1 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1203,13 +1203,14 @@ err_noclose:
 static int svc_tcp_send_kvec(struct socket *sock, const struct kvec *vec,
 			      int flags)
 {
-	return kernel_sendpage(sock, virt_to_page(vec->iov_base),
-			       offset_in_page(vec->iov_base),
-			       vec->iov_len, flags);
+	struct msghdr msg = { .msg_flags = MSG_SPLICE_PAGES | flags, };
+
+	iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 1, vec->iov_len);
+	return sock_sendmsg(sock, &msg);
 }
 
 /*
- * kernel_sendpage() is used exclusively to reduce the number of
+ * MSG_SPLICE_PAGES is used exclusively to reduce the number of
  * copy operations in this path. Therefore the caller must ensure
  * that the pages backing @xdr are unchanging.
  *
@@ -1249,28 +1250,13 @@ static int svc_tcp_sendmsg(struct socket *sock, struct xdr_buf *xdr,
 	if (ret != head->iov_len)
 		goto out;
 
-	if (xdr->page_len) {
-		unsigned int offset, len, remaining;
-		struct bio_vec *bvec;
-
-		bvec = xdr->bvec + (xdr->page_base >> PAGE_SHIFT);
-		offset = offset_in_page(xdr->page_base);
-		remaining = xdr->page_len;
-		while (remaining > 0) {
-			len = min(remaining, bvec->bv_len - offset);
-			ret = kernel_sendpage(sock, bvec->bv_page,
-					      bvec->bv_offset + offset,
-					      len, 0);
-			if (ret < 0)
-				return ret;
-			*sentp += ret;
-			if (ret != len)
-				goto out;
-			remaining -= len;
-			offset = 0;
-			bvec++;
-		}
-	}
+	msg.msg_flags = MSG_SPLICE_PAGES;
+	iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, xdr->bvec,
+		      xdr_buf_pagecount(xdr), xdr->page_len);
+	ret = sock_sendmsg(sock, &msg);
+	if (ret < 0)
+		return ret;
+	*sentp += ret;
 
 	if (tail->iov_len) {
 		ret = svc_tcp_send_kvec(sock, tail, 0);