Add field accessibility_requirements to ControllerModifyVolumeTopology

Author: iltyty

csi.proto

@@ -1075,6 +1075,20 @@ message ControllerModifyVolumeTopologyRequest {
   // on the absence of keys, only keys that are specified should result
   // in modifications to the volume.
   map<string, string> mutable_parameters = 3;
+
+  // Specifies where (regions, zones, racks, etc.) the
+  // volume MUST be accessible from after modification.
+  // COs SHALL only specify topological accessibility
+  // information supported by the SP.
+  // This field is OPTIONAL.
+  // This field SHALL NOT be specified unless the SP has the
+  // VOLUME_ACCESSIBILITY_CONSTRAINTS plugin capability and the
+  // MODIFY_VOLUME_TOPOLOGY controller capability.
+  // If this field is not specified and the SP has the
+  // VOLUME_ACCESSIBILITY_CONSTRAINTS plugin capability and the
+  // MODIFY_VOLUME_TOPOLOGY controller capability, the SP MAY
+  // modify the volume topology according to the mutable_parameters.
+  TopologyRequirement accessibility_requirements = 4;
 }
 
 message ControllerModifyVolumeTopologyResponse {