Grow file num_maps to unsigned long

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/file.h b/file.h
index b3ff051..67ef24f 100644
--- a/file.h
+++ b/file.h
@@ -107,9 +107,9 @@
 	 * block map for random io
 	 */
 	unsigned long *file_map;
-	unsigned int num_maps;
-	unsigned int last_free_lookup;
-	unsigned int failed_rands;
+	unsigned long num_maps;
+	unsigned long last_free_lookup;
+	unsigned failed_rands;
 
 	int references;
 	enum fio_file_flags flags;