diff --git a/ircd/aio.cc b/ircd/aio.cc
index 47c2331e8..7b8b79580 100644
--- a/ircd/aio.cc
+++ b/ircd/aio.cc
@@ -16,6 +16,7 @@
 namespace ircd::fs::aio
 {
 	static int reqprio(int);
+	static size_t bytes(const vector_view<const struct ::iovec> &);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -191,6 +192,16 @@ ircd::fs::aio::prefetch(const fd &fd,
 // internal util
 //
 
+size_t
+ircd::fs::aio::bytes(const vector_view<const struct ::iovec> &iov)
+{
+	return std::accumulate(begin(iov), end(iov), size_t(0), []
+	(auto ret, const auto &iov)
+	{
+		return ret += iov.iov_len;
+	});
+}
+
 int
 ircd::fs::aio::reqprio(int input)
 {