Merge pull request #971 from jeffhostetler/jeffhostetler/add_preload_fscache

add: use preload-index and fscache for performance

builtin/add.c

@@ -593,6 +593,10 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 	die_in_unpopulated_submodule(&the_index, prefix);
 	die_path_inside_submodule(&the_index, &pathspec);
 
+	enable_fscache(1);
+	/* We do not really re-read the index but update the up-to-date flags */
+	preload_index(&the_index, &pathspec, 0);
+
 	if (add_new_files) {
 		int baselen;
 
@@ -695,6 +699,7 @@ finish:
 		die(_("Unable to write new index file"));
 
 	dir_clear(&dir);
+	enable_fscache(0);
 	UNLEAK(pathspec);
 	return exit_status;
 }