### Volumes
* StorageClass pre-installed and set as default on Azure, AWS, GCE, OpenStack, and vSphere.
  * This is something to pay close attention to if you’ve been using Kubernetes for a while, because it changes the default behavior of PersistentVolumeClaim objects on these clouds.

* [stable] You can now specify the World Wide Identifier (WWID) for the volume identifier in the Fibre Channel volume plugin.

* [beta] Reclaim policy in StorageClass

  * You can now configure the reclaim policy in StorageClass, instead of defaulting to `delete` for dynamically provisioned volumes.

* [alpha] Volume resizing

  * You can now increase the size of a volume by calling the Kubernetes API.

- `diskformat` storage class parameter for in-tree vSphere volume plugin is deprecated as of v1.21 release. Please consider updating storageclass and remove `diskformat` parameter. vSphere CSI Driver does not support diskformat storageclass parameter.
  
  vSphere releases less than 67u3 are deprecated as of v1.21. Please consider upgrading vSphere to 67u3 or above. vSphere CSI Driver requires minimum vSphere 67u3.

  // +optional
  optional string persistentVolumeReclaimPolicy = 5;

  // storageClassName is the name of StorageClass to which this persistent volume belongs. Empty value
  // means that this volume does not belong to any StorageClass.
  // +optional
  optional string storageClassName = 6;

  // mountOptions is the list of mount options, e.g. ["ro", "soft"]. Not validated - mount will

- If more than one StorageClass is designated as default (via the "storageclass.kubernetes.io/is-default-class" annotation), choose the newest one instead of throwing an error. ([#110559](https://github.com/kubernetes/kubernetes/pull/110559), [@danishprakash](https://github.com/danishprakash))

* Portworx volume driver no longer has to run on the master. ([#45518](https://github.com/kubernetes/kubernetes/pull/45518), [@harsh-px](https://github.com/harsh-px))

* Default behavior in Cinder storageclass is changed. If availability is not specified, the zone is chosen by algorithm. It makes possible to spread stateful pods across many zones. ([#44798](https://github.com/kubernetes/kubernetes/pull/44798), [@zetaab](https://github.com/zetaab))

* PodSecurityPolicy now supports restricting hostPath volume mounts to be readOnly and under specific path prefixes ([#58647](https://github.com/kubernetes/kubernetes/pull/58647), [@jhorwit2](https://github.com/jhorwit2))
* Added StorageClass API to restrict topologies of dynamically provisioned volumes. ([#63233](https://github.com/kubernetes/kubernetes/pull/63233), [@lichuqiang](https://github.com/lichuqiang))

* fix formatAndMount func issue on Windows ([#63248](https://github.com/kubernetes/kubernetes/pull/63248), [@andyzhangx](https://github.com/andyzhangx))
* Fixes an issue where Portworx PVCs remain in pending state when created using a StorageClass with empty parameters ([#64895](https://github.com/kubernetes/kubernetes/pull/64895), [@harsh-px](https://github.com/harsh-px))

    * [fluentd-gcp addon] Bump prometheus-to-sd to v0.5.0 to pick up security fixes.
    * [metatada-proxy addon] Bump prometheus-to-sd v0.5.0 to pick up security fixes.
* Fixed parsing of fsType in AWS StorageClass parameters ([#75944](https://github.com/kubernetes/kubernetes/pull/75944), [@jsafrane](https://github.com/jsafrane))

  * Also, if the value of adminId in the in-tree Storageclass is different from admin, the adminSecretName mentioned in the in-tree Storageclass has...