“FailedMount：没有卷的挂起工作负载 Pod”是什么意思？

在k3s集群（具有多个控制平面节点）和安装了Rancher Longhorn 的情况下，对于具有默认longhorn存储类的 pvc 的 pod，我观察到以下警告（输出为kubectl get events,wrapped 以提高可读性）：

LAST SEEN   TYPE      REASON        OBJECT                      
113s        Warning   FailedMount   pod/grafana-6756f6587b-rv2xj

   MESSAGE
   MountVolume.SetUp failed for volume "pvc-7b6d12e3-132d-4af1-99c0-920ac5af0687" :
     rpc error:
       code = Aborted
       desc = no Pending workload pods for volume pvc-7b6d12e3-132d-4af1-99c0-920ac5af0687
              to be mounted: map[Running:[grafana-6756f6587b-rv2xj]]

这个反复出现的警告意味着什么以及需要采取什么措施来解决它？

至少从我在 Pod 容器中看到的情况来看，该卷已安装。我已经尝试重新启动 Pod 并重新创建 Pod，但警告仍然存在。longhorn 仪表板也没有显示任何问题。

请参阅下面的 pvc 和部署资源定义：

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: grafana-pvc
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  storageClassName: longhorn
  resources:
    requests:
      storage: 1Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: grafana
  namespace: monitoring
  labels:
    app: grafana
spec:
  selector:
    matchLabels:
      app: grafana
  template:
    metadata:
      labels:
        app: grafana
    spec:
      securityContext:
        fsGroup: 472
        supplementalGroups:
          - 0
      containers:
        - name: grafana
          image: grafana/grafana:latest
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 3000
              name: http-grafana
              protocol: TCP
          readinessProbe:
            failureThreshold: 3
            httpGet:
              path: /robots.txt
              port: 3000
              scheme: HTTP
            initialDelaySeconds: 10
            periodSeconds: 30
            successThreshold: 1
            timeoutSeconds: 2
          livenessProbe:
            failureThreshold: 3
            initialDelaySeconds: 30
            periodSeconds: 10
            successThreshold: 1
            tcpSocket:
              port: 3000
            timeoutSeconds: 1
          resources:
            requests:
              cpu: 250m
              memory: 750Mi
          volumeMounts:
            - mountPath: /var/lib/grafana
              name: grafana-pv
      volumes:
        - name: grafana-pv
          persistentVolumeClaim:
            claimName: grafana-pvc