illegal path parameter value: /path-not-on-host. it must be a directory

[89yanyu]

Issue Description

Type: bug report

Describe what happened (or what feature you want)

I try to create the pod-disk fill injection using url and it is created failed.

curl -v http://11.140.167.216:9526/chaosblade?cmd=create%20k8s%20pod-disk%20fill%20--path%20/path-not-on-host%20--names%20chaos-test%20--namespace%20default%20--kubeconfig%20/root/.kube/config%20--percent%2020

{
    "code": 54000,
    "success": false,
    "error": "illegal `path` parameter value: `/path-not-on-host`. it must be a directory",
    "result": {
        "error": "illegal `path` parameter value: `/path-not-on-host`. it must be a directory",
        "statuses": [
            {
                "error": "illegal `path` parameter value: `/path-not-on-host`. it must be a directory",
                "identifier": "default/11.140.167.216/chaos-test/chaos-test/180df34b3c94/docker",
                "kind": "pod",
                "state": "Error",
                "success": false
            }
        ],
        "success": false,
        "uid": "56f1e63091f5ac86"
    }
}

and I checked path which I injected:

# kubectl exec -it chaos-test -- ls /
bin               lib64             path-not-on-host  sys
dev               linuxrc           proc              tmp
etc               media             root              usr
home              mnt               run               var
lib               opt               sbin

Describe what you expected to happen

Inject succeefully and disk will be filled to 20%

How to reproduce it (as minimally and precisely as possible)

1. prepare kubernetes enviroment
2. install chaosblade-operator
3. create a pod with volume and the mount path have to be not same as host path

apiVersion: v1
kind: Pod
metadata:
  name: chaos-test
  namespace: default
spec:
  restartPolicy: Never
  volumes:
  - name: vol
    hostPath:
      path: /data
  containers:
  - name: chaos-test
    image: "registry.k8s.io/busybox"
    command: ["/bin/sh", "-c", "while true; do sleep 1000; done"]
    volumeMounts:
    - name: vol
      mountPath: /path-not-on-host

5. use the url above to inject and error will be got

Tell us your environment

CentOS8
chaosblade-operator 1.7.2

Anything else we need to know?

I checked source code with 1.7.2. I found that pod-disk fill will check whether the path is a directory out of namespace.
source code

[xcaspar]

The current implementation logic is to use cgroup to execute commands on the node, so it will look for the corresponding directory on the node. If it does not exist, this error will be reported. This can be solved by mounting this directory on the node. We plan to solve this problem by the end of August.