diff -Nru xfsprogs-4.9.0+nmu1/io/copy_file_range.c xfsprogs-4.9.0+nmu2/io/copy_file_range.c
--- xfsprogs-4.9.0+nmu1/io/copy_file_range.c
+++ xfsprogs-4.9.0+nmu2/io/copy_file_range.c
@@ -42,8 +42,12 @@
 "));
 }
 
+/*
+ * Issue a raw copy_file_range syscall; for our test program we don't want the
+ * glibc buffered copy fallback.
+ */
 static loff_t
-copy_file_range(int fd, loff_t *src, loff_t *dst, size_t len)
+copy_file_range_cmd(int fd, loff_t *src, loff_t *dst, size_t len)
 {
 	loff_t ret;
 
@@ -127,7 +131,7 @@
 		copy_dst_truncate();
 	}
 
-	ret = copy_file_range(fd, &src, &dst, len);
+	ret = copy_file_range_cmd(fd, &src, &dst, len);
 	close(fd);
 	return ret;
 }