修复磁盘空间可能为0的情形

internal/nodes/node_status_executor.go

@@ -264,7 +264,9 @@ func (this *NodeStatusExecutor) updateDisk(status *nodeconfigs.NodeStatus) {
 		}
 	}
 	status.DiskTotal = total
+	if total > 0 {
 		status.DiskUsage = float64(totalUsage) / float64(total)
+	}
 	status.DiskMaxUsage = maxUsage / 100
 
 	// 记录监控数据