Fix "mount failed: File exists" issue when unmount fails

[fenglixa]

• Fix for mount failed: mkdir: cannot create directory '/mnt/data': File exists #4239

• Why this fix:
  Before the fix, the unmount will be always return success, that will cause: a) unmount err message cannot be reported timely. b) force unmount will be never ran.

The fixes including: a) fix above error b) delete corpse processes before unmount.

• My UT cases: PASS
  case-1: a) minikube mount b) minikube ssh; cd c) Ctrl+c d) 'minikube mount' again.
  case-2: a) minikube mount b) minikube ssh; run script under mount point dir c) Ctrl+c d) 'minikube mount' again.

/assign @tstromberg
Could you please help review? Thanks.

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @fenglixa. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[minikube-bot]

Can one of the admins verify this patch?

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: fenglixa
To fully approve this pull request, please assign additional approvers.
We suggest the following additional approver: tstromberg

If they are not already assigned, you can assign the PR to them by writing /assign @tstromberg in a comment when ready.

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[fenglixa]

Append UT Result:

[RA489]

@minikube-bot ok-to-test

[sharifelgamal]

@minikube-bot OK to test

[fenglixa]

@minikube-bot OK to test

[fenglixa]

/retest

[k8s-ci-robot]

@fenglixa: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[RA489]

/ok-to-test

[medyagh]

/retest this please

[fenglixa]

test timed out after 1h15m0s
/retest please

[fenglixa]

It cannot work when I call "/retest" to trigger integration test. Could anyone (member) help on this?
Thanks very much.

[RA489]

/retest

[tstromberg]

@minikube-bot OK to test

[tstromberg]

FYI - minikube has not moved to prow yet, so /retest does not work. We're still stuck on the old-style Jenkins commands.