When the attach/detach controller crashes and a pod with attached PV is deleted
afterwards the controller will never detach the pod's attached volumes. To
prevent this the controller should try to recover the state from the nodes
status.
Automatic merge from submit-queue
Remove unused method from operation_generator
This is only a removal of the GerifyVolumeIsSafeToDetach [sic] method from operation_executor. The method is not called from anywhere, moreover there is a private method named verifyVolumeIsSafeToDetach (which is being used). This looks like a cut&paste mistake that deserves to be cleaned.
```release-note
NONE
```
Automatic merge from submit-queue (batch tested with PRs 42522, 42545, 42556, 42006, 42631)
Fixes MountVolume.NewMounter errors not displayed to users via describe events
Fixes#42004
This fixes the problem of mount errors being eaten and not displayed to users again. Specifically erros caught in MountVolume.NewMounter (like missing endpoints, etc...)
Current behavior for any mount failure:
```
Events:
FirstSeen LastSeen Count From SubObjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
12m 12m 1 default-scheduler Normal Scheduled Successfully assigned glusterfs-bb-pod1 to 127.0.0.1
10m 1m 5 kubelet, 127.0.0.1 Warning FailedMount Unable to mount volumes for pod "glusterfs-bb-pod1_default(67c9dfa7-f9f5-11e6-aee2-5254003a59cf)": timeout expired waiting for volumes to attach/mount for pod "default"/"glusterfs-bb-pod1". list of unattached/unmounted volumes=[glusterfsvol]
10m 1m 5 kubelet, 127.0.0.1 Warning FailedSync Error syncing pod, skipping: timeout expired waiting for volumes to attach/mount for pod "default"/"glusterfs-bb-pod1". list of unattached/unmounted volumes=[glusterfsvol]
```
New Behavior:
For example on glusterfs - deliberately didn't create endpoints, now correct message is displayed:
```
Events:
FirstSeen LastSeen Count From SubObjectPath Type Reason Message
--------- -------- ----- ---- ------------- -------- ------ -------
2m 2m 1 default-scheduler Normal Scheduled Successfully assigned glusterfs-bb-pod1 to 127.0.0.1
54s 54s 1 kubelet, 127.0.0.1 Warning FailedMount Unable to mount volumes for pod "glusterfs-bb-pod1_default(8edd2c25-fa09-11e6-92ae-5254003a59cf)": timeout expired waiting for volumes to attach/mount for pod "default"/"glusterfs-bb-pod1". With error timed out waiting for the condition. list of unattached/unmounted volumes=[glusterfsvol]
54s 54s 1 kubelet, 127.0.0.1 Warning FailedSync Error syncing pod, skipping: timeout expired waiting for volumes to attach/mount for pod "default"/"glusterfs-bb-pod1". With error timed out waiting for the condition. list of unattached/unmounted volumes=[glusterfsvol]
2m 6s 814 kubelet, 127.0.0.1 Warning FailedMount MountVolume.NewMounter failed for volume "kubernetes.io/glusterfs/8edd2c25-fa09-11e6-92ae-5254003a59cf-glusterfsvol" (spec.Name: "glusterfsvol") pod "8edd2c25-fa09-11e6-92ae-5254003a59cf" (UID: "8edd2c25-fa09-11e6-92ae-5254003a59cf") with: endpoints "glusterfs-cluster" not found
```
This implements Bulk volume polling using ideas presented by
justin in https://github.com/kubernetes/kubernetes/pull/39564
But it changes the implementation to use an interface
and doesn't affect other implementations.
