feat(io.cost): adding rollback method

Signed-off-by: Robin Lu <robin.lu@bytedance.com>

pkg/agent/qrm-plugins/io/handlers/iocost/iocost_linux.go

@@ -120,8 +120,7 @@ func reportDevicesIOCostVrate(emitter metrics.MetricEmitter) {
 }
 
 func disableIOCost(conf *config.Configuration) {
-	if !conf.EnableSettingIOCost {
-		general.Infof("IOCostSetting disabled, skip disableIOCost")
+	if !cgcommon.CheckCgroup2UnifiedMode() {
 		return
 	}
 
@@ -267,13 +266,12 @@ func SetIOCost(conf *coreconfig.Configuration,
 	}
 
 	// EnableSettingIOCost featuregate.
-	if !conf.EnableSettingIOCost {
-		general.Infof("SetIOCost disabled")
-		return
-	}
-
-	if !conf.EnableSettingIOCostHDDOnly {
-		general.Infof("SetIOCostHDDOnly disabled. For now, only HDD supported")
+	if !conf.EnableSettingIOCost || !conf.EnableSettingIOCostHDDOnly {
+		general.Infof("SetIOCost disabled. For now, only HDD supported.")
+		// If EnableSettingIOCost was disabled, we should never enable io.cost.
+		initializeOnce.Do(func() {
+			disableIOCost(conf)
+		})
 		return
 	}