Execute sync before taking the snapshot

[mauriciopoppe]

What type of PR is this?

/kind bug
/kind failing-test
/kind flake

What this PR does / why we need it:

From the last CI runs of PD CSI Driver it looks like sometimes data is not flushed to disk, after the echo command is execute we flush the data with the sync command.

Does this PR introduce a user-facing change?

NONE

/cc @jingxu97

[k8s-ci-robot]

@mauriciopoppe: This issue is currently awaiting triage.

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[mauriciopoppe]

/retest

[mauriciopoppe]

/hold

Sync isn't working in the agnhost image:

PS C:\> echo 'hi' > hi; sync
sync : The term 'sync' is not recognized as the name of a cmdlet, function, script file, or operable program.
Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:17
+ echo 'hi' > hi; sync
+                 ~~~~
+ CategoryInfo          : ObjectNotFound: (sync:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException

[mauriciopoppe]

/hold cancel

I tried with this manifest and sync is available here, it was a problem on my end.

# A multi-arch Windows container that runs an HTTP server on port
# 9376 that serves the container's hostname.
#   curl -s http://<pod_ip>:9376
apiVersion: apps/v1
kind: Deployment
metadata:
  name: windows-agnhost
  labels:
    app: agnhost
spec:
  replicas: 1
  selector:
    matchLabels:
      app: agnhost
  template:
    metadata:
      labels:
        app: agnhost
    spec:
      containers:
      - name: agnhost
        image: k8s.gcr.io/e2e-test-images/agnhost:2.33
        args:
        - serve-hostname
      nodeSelector:
        kubernetes.io/os: windows
      tolerations:
      - effect: NoSchedule
        key: node.kubernetes.io/os
        operator: Equal
        value: windows

[msau42]

Does sync also have to be added in https://github.com/kubernetes/kubernetes/blob/227da7b0534d344a4a41ad2041b92a601e9765df/test/e2e/storage/testsuites/snapshottable.go#L145?

[mauriciopoppe]

good catch, added sync there too

[mauriciopoppe]

/test pull-kubernetes-e2e-gce-storage-slow

[jingxu97]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jingxu97, mauriciopoppe

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[gnufied]

@mauriciopoppe can you cherry-pick this to 1.23 also btw? It looks like these tests can fail there too.