rpc: change comments to assertions

Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/xdr.c

@@ -619,7 +619,8 @@ void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
 	buf->len -= fraglen;
 	if (tail->iov_len) {
 		xdr->p = tail->iov_base + tail->iov_len;
-		/* xdr->end, xdr->iov should be set already */
+		WARN_ON_ONCE(!xdr->end);
+		WARN_ON_ONCE(!xdr->iov);
 		return;
 	}
 	WARN_ON_ONCE(fraglen);
@@ -635,7 +636,7 @@ void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
 		xdr->p = page_address(*xdr->page_ptr);
 		xdr->end = (void *)xdr->p + PAGE_SIZE;
 		xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
-		/* xdr->iov should already be NULL */
+		WARN_ON_ONCE(xdr->iov);
 		return;
 	}
 	if (fraglen) {