Add volume capability to volume expansion calls

Update specs and add new error code for invalid capabilities

Author: gnufied

csi.proto

@@ -1066,6 +1066,15 @@ message ControllerExpandVolumeRequest {
   // Secrets required by the plugin for expanding the volume.
   // This field is OPTIONAL.
   map<string, string> secrets = 3 [(csi_secret) = true];
+
+  // Volume capability describing how the CO intends to use this volume.
+  // This allows SP to determine if volume is being used as a block
+  // device or mounted file system. For example - if volume is
+  // being used as a block device - the SP MAY set
+  // node_expansion_required to false in ControllerExpandVolumeResponse
+  // to skip invocation of NodeExpandVolume on the node by the CO.
+  // This is an OPTIONAL field.
+  VolumeCapability volume_capability = 4;
 }
 
 message ControllerExpandVolumeResponse {
@@ -1341,6 +1350,17 @@ message NodeExpandVolumeRequest {
   // filesystem of the process serving this request.
   // This field is OPTIONAL.
   string staging_path = 4;
+
+  // Volume capability describing how the CO intends to use this volume.
+  // This allows SP to determine if volume is being used as a block
+  // device or mounted file system. For example - if volume is being
+  // used as a block device the SP MAY choose to skip expanding the
+  // filesystem in NodeExpandVolume implementation but still perform
+  // rest of the housekeeping needed for expanding the volume. If
+  // volume_capability is omitted the SP MAY determine
+  // access_type from given volume_path for the volume and perform
+  // node expansion. This is an OPTIONAL field.
+  VolumeCapability volume_capability = 5;
 }
 
 message NodeExpandVolumeResponse {