From 87a32bfef4f9b4c3594d20dac22d0e8cf60db341 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Wed, 19 May 2021 10:02:01 -0700
Subject: [PATCH] avoid possible nil when node is disconnected from its parent

fix https://github.com/chrislusf/seaweedfs/issues/2073
---
 weed/topology/data_node.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/weed/topology/data_node.go b/weed/topology/data_node.go
index 69f739dd5..2813f7b45 100644
--- a/weed/topology/data_node.go
+++ b/weed/topology/data_node.go
@@ -177,7 +177,13 @@ func (dn *DataNode) GetVolumesById(id needle.VolumeId) (vInfo storage.VolumeInfo
 
 func (dn *DataNode) GetDataCenter() *DataCenter {
 	rack := dn.Parent()
+	if rack == nil {
+		return nil
+	}
 	dcNode := rack.Parent()
+	if dcNode == nil {
+		return nil
+	}
 	dcValue := dcNode.GetValue()
 	return dcValue.(*DataCenter)
 }