code: func validatePodSecurityPolicyVolumes(fldPath *field.Path, volumes []policy.FSType) field.ErrorList {
  	allErrs := field.ErrorList{}
  	allowed := psputil.GetAllFSTypesAsSet()
  	// add in the * value since that is a pseudo type that is not included by default
  	allowed.Insert(string(policy.All))
  	for _, v := range volumes {
  		if !allowed.Has(string(v)) {
  			allErrs = append(allErrs, field.NotSupported(fldPath.Child("volumes"), v, allowed.List()))
  		}
  	}
  	return allErrs
  }
docs: // validatePodSecurityPolicyVolumes validates the volume fields of PodSecurityPolicy.