Merge pull request #52260 from andyzhangx/azuremounter-issue

Automatic merge from submit-queue (batch tested with PRs 52452, 52115, 52260, 52290)

fix azure disk mounter issue

**What this PR does / why we need it**:
fix azure disk mounter issue, it's a P1 bug, it exists in 1.7, 1.8 release, should cherry pick to 1.7, 1.8

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
fixes #52261 

consider following issue: 
1) A pod mounting an azure disk in a k8s agent
2) The kubelet is restarted in that k8s agent
3) The pod could not start up, it always reports error as following:

  4d            1m              3065    kubelet, 14777acs9000                   Warning         FailedMount     MountVolume.SetUp failed for volume "pvc-7a0cdeb9-92c7-11e7-b86b-000d3a36d70c" : azureDisk - No
t a mounting point for disk andykubewin175-dynamic-pvc-7a0cdeb9-92c7-11e7-b86b-000d3a36d70c on \var\lib\kubelet\pods\d146c023-92c7-11e7-b86b-000d3a36d70c\volumes\kubernetes.io~azure-disk\pvc-7a0cdeb9-92c7-11
e7-b86b-000d3a36d70c
  4d            1m              3157    kubelet, 14777acs9000                   Warning         FailedMount     Error syncing pod

**Special notes for your reviewer**:
If you take a look at following implementation of vsphere or gce, it will return nil instead of error:
https://github.com/kubernetes/kubernetes/blob/master/pkg/volume/vsphere_volume/vsphere_volume.go#L217-L220
https://github.com/kubernetes/kubernetes/blob/master/pkg/volume/gce_pd/gce_pd.go#L273-L275

The logic of return info parsing here, it's wrong to return error
https://github.com/kubernetes/kubernetes/blob/master/pkg/volume/util/operationexecutor/operation_generator.go#L469-L475

**Release note**:

```release-note
```
This commit is contained in:
Kubernetes Submit Queue 2017-09-15 02:00:03 -07:00 committed by GitHub
commit b7953a787e

View File

@ -80,7 +80,8 @@ func (m *azureDiskMounter) SetUpAt(dir string, fsGroup *int64) error {
return err
}
if !mountPoint {
return fmt.Errorf("azureDisk - Not a mounting point for disk %s on %s", diskName, dir)
glog.V(4).Infof("azureDisk - already mounted to target %s", dir)
return nil
}
if runtime.GOOS != "windows" {