xl: Avoid called getdents for folders in listing (#19100)

cmd/is-dir-empty_other.go

@@ -0,0 +1,30 @@
+//go:build !linux
+// +build !linux
+
+// Copyright (c) 2015-2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package cmd
+
+// isDirEmpty - returns true if there is no error and no object and prefix inside this directory
+func isDirEmpty(dirname string) bool {
+	entries, err := readDirN(dirname, 1)
+	if err != nil {
+		return false
+	}
+	return len(entries) == 0
+}