Fixes #893. Check if the target fs exists.

[ioggstream]

Running this role on a node which already has a device mounted on the
target mountpoint results in an error. This check makes the role
to understand that everything is fine.

What does this PR do?

Check if the target filesystem on the given device / mountpoint is present

How should this be manually tested?

Create the following playbook and run it twice.

cat > /tmp/test.yml <<EOF
---
- hosts: nodes
  roles:
  - openshift-volume-quota
EOF

ansible-playbook /tmp/test.yml

ansible-playbook /tmp/test.yml

Is there a relevant Issue open for this?

#893

Who would you like to review this?

cc: @tomassedovic PTAL

[openshift-bot]

Can one of the admins verify this patch?
I understand the following commands:

• bot, add author to whitelist
• bot, test pull request
• bot, test pull request once

[openshift-bot]

Can one of the admins verify this patch?
I understand the following commands:

• bot, add author to whitelist
• bot, test pull request
• bot, test pull request once

[openshift-bot]

Can one of the admins verify this patch?
I understand the following commands:

• bot, add author to whitelist
• bot, test pull request
• bot, test pull request once

[openshift-bot]

Can one of the admins verify this patch?
I understand the following commands:

• bot, add author to whitelist
• bot, test pull request
• bot, test pull request once

[openshift-bot]

Issues go stale after 90d of inactivity.

Mark the issue as fresh by commenting /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.
Exclude this issue from closing by commenting /lifecycle frozen.

If this issue is safe to close now please do so with /close.

/lifecycle stale

[ioggstream]

/lifecycle frozen