1 files changed, 32 insertions, 10 deletions

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index e9dfd6a826f4..060739144552 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -132,6 +132,33 @@ rpcrdma_tail_pullup(struct xdr_buf *buf)
 	return tlen;
 }
 
+/* Split "vec" on page boundaries into segments. FMR registers pages,
+ * not a byte range. Other modes coalesce these segments into a single
+ * MR when they can.
+ */
+static int
+rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg,
+		     int n, int nsegs)
+{
+	size_t page_offset;
+	u32 remaining;
+	char *base;
+
+	base = vec->iov_base;
+	page_offset = offset_in_page(base);
+	remaining = vec->iov_len;
+	while (remaining && n < nsegs) {
+		seg[n].mr_page = NULL;
+		seg[n].mr_offset = base;
+		seg[n].mr_len = min_t(u32, PAGE_SIZE - page_offset, remaining);
+		remaining -= seg[n].mr_len;
+		base += seg[n].mr_len;
+		++n;
+		page_offset = 0;
+	}
+	return n;
+}
+
 /*
  * Chunk assembly from upper layer xdr_buf.
  *
@@ -150,11 +177,10 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
 	int page_base;
 	struct page **ppages;
 
-	if (pos == 0 && xdrbuf->head[0].iov_len) {
-		seg[n].mr_page = NULL;
-		seg[n].mr_offset = xdrbuf->head[0].iov_base;
-		seg[n].mr_len = xdrbuf->head[0].iov_len;
-		++n;
+	if (pos == 0) {
+		n = rpcrdma_convert_kvec(&xdrbuf->head[0], seg, n, nsegs);
+		if (n == nsegs)
+			return -EIO;
 	}
 
 	len = xdrbuf->page_len;
@@ -192,13 +218,9 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
 		 * xdr pad bytes, saving the server an RDMA operation. */
 		if (xdrbuf->tail[0].iov_len < 4 && xprt_rdma_pad_optimize)
 			return n;
+		n = rpcrdma_convert_kvec(&xdrbuf->tail[0], seg, n, nsegs);
 		if (n == nsegs)
-			/* Tail remains, but we're out of segments */
 			return -EIO;
-		seg[n].mr_page = NULL;
-		seg[n].mr_offset = xdrbuf->tail[0].iov_base;
-		seg[n].mr_len = xdrbuf->tail[0].iov_len;
-		++n;
 	}
 
 	return n;