vSphere. ([#59328](https://github.com/kubernetes/kubernetes/pull/59328), [@divyenpatel](https://github.com/divyenpatel))

* Emit number of bound and unbound persistent volumes as Metrics. This PR adds four kinds of Volume Metrics for kube-controller-manager: bound PVC numbers, unbound PVC numbers, bound PV numbers and unbound PV numbers. The PVC metrics use namespace as dimension and the PV metrics use StorageClassName as its dimension. With these metrics we can better monitor the use...

* kubeadm: Fixed support of node certificates when joining a cluster ([#69328](https://github.com/kubernetes/kubernetes/pull/69328), [@bart0sh](https://github.com/bart0sh))
* Fix an issue where filesystems are not unmounted when a backend is not reachable and returns EIO. ([#67097](https://github.com/kubernetes/kubernetes/pull/67097), [@chakri-nelluri](https://github.com/chakri-nelluri))

## Changelog since v1.18.8

## Changes by Kind

### Bug or Regression

- "unbound immediate PersistentVolumeClaims" causes UnschedulableAndUnresolvable status rather than an Error in the scheduler. ([#93892](https://github.com/kubernetes/kubernetes/pull/93892), [@ahg-g](https://github.com/ahg-g)) [SIG Apps and Storage]

- Content-type and verb for request metrics are now bounded to a known set. ([#89451](https://github.com/kubernetes/kubernetes/pull/89451), [@logicalhan](https://github.com/logicalhan)) [SIG API Machinery and Instrumentation]

* Check if pathExists before performing Unmount ([#39311](https://github.com/kubernetes/kubernetes/pull/39311), [@rkouj](https://github.com/rkouj))
* Unmount operation should not fail if volume is already unmounted ([#38547](https://github.com/kubernetes/kubernetes/pull/38547), [@rkouj](https://github.com/rkouj))

* Check if pathExists before performing Unmount ([#39311](https://github.com/kubernetes/kubernetes/pull/39311), [@rkouj](https://github.com/rkouj))
* Unmount operation should not fail if volume is already unmounted ([#38547](https://github.com/kubernetes/kubernetes/pull/38547), [@rkouj](https://github.com/rkouj))

- Fixed a bug in block volume expansion. ([#77317](https://github.com/kubernetes/kubernetes/pull/77317), [@gnufied](https://github.com/gnufied))
- Count PVCs that are unbound towards attach limit. ([#73863](https://github.com/kubernetes/kubernetes/pull/73863), [@gnufied](https://github.com/gnufied))

### VMware

// Node annotation with key scheduler.alpha.kubernetes.io/preferAvoidPods and
// will eventually become a field of NodeStatus.
message AvoidPods {
  // Bounded-sized list of signatures of pods that should avoid this node, sorted
  // in timestamp order from oldest to newest. Size of the slice is unspecified.
  // +optional
  repeated PreferAvoidPodsEntry preferAvoidPods = 1;
}

* Fix potential panic when getting azure load balancer status ([#68609](https://github.com/kubernetes/kubernetes/pull/68609), [@feiskyer](https://github.com/feiskyer))
* Fix an issue where filesystems are not unmounted when a backend is not reachable and returns EIO. ([#67097](https://github.com/kubernetes/kubernetes/pull/67097), [@chakri-nelluri](https://github.com/chakri-nelluri))

- Unmounted volumes correctly for reconstructed volumes even if mount operation fails after kubelet restart. ([#110670](https://github.com/kubernetes/kubernetes/pull/110670), [@gnufied](https://github.com/gnufied))