1 files changed, 45 insertions, 0 deletions
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 3bd5bef02996..b45af330f9f3 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -648,6 +648,51 @@ __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
 }
 EXPORT_SYMBOL_GPL(xdr_reserve_space);
 
+
+/**
+ * xdr_reserve_space_vec - Reserves a large amount of buffer space for sending
+ * @xdr: pointer to xdr_stream
+ * @vec: pointer to a kvec array
+ * @nbytes: number of bytes to reserve
+ *
+ * Reserves enough buffer space to encode 'nbytes' of data and stores the
+ * pointers in 'vec'. The size argument passed to xdr_reserve_space() is
+ * determined based on the number of bytes remaining in the current page to
+ * avoid invalidating iov_base pointers when xdr_commit_encode() is called.
+ */
+int xdr_reserve_space_vec(struct xdr_stream *xdr, struct kvec *vec, size_t nbytes)
+{
+	int thislen;
+	int v = 0;
+	__be32 *p;
+
+	/*
+	 * svcrdma requires every READ payload to start somewhere
+	 * in xdr->pages.
+	 */
+	if (xdr->iov == xdr->buf->head) {
+		xdr->iov = NULL;
+		xdr->end = xdr->p;
+	}
+
+	while (nbytes) {
+		thislen = xdr->buf->page_len % PAGE_SIZE;
+		thislen = min_t(size_t, nbytes, PAGE_SIZE - thislen);
+
+		p = xdr_reserve_space(xdr, thislen);
+		if (!p)
+			return -EIO;
+
+		vec[v].iov_base = p;
+		vec[v].iov_len = thislen;
+		v++;
+		nbytes -= thislen;
+	}
+
+	return v;
+}
+EXPORT_SYMBOL_GPL(xdr_reserve_space_vec);
+
 /**
  * xdr_truncate_encode - truncate an encode buffer
  * @xdr: pointer to xdr_stream