Add support for volume expansion to CSI

add support for volume expansion RPC calls.
also add plugin capabilities that allow CO to query
whether volume expansion is supported online or offline.

Author: gnufied

csi.proto

@@ -57,6 +57,9 @@ service Controller {
 
   rpc ListSnapshots (ListSnapshotsRequest)
     returns (ListSnapshotsResponse) {}
+
+  rpc ControllerExpandVolume (ControllerExpandVolumeRequest)
+    returns (ControllerExpandVolumeResponse) {}
 }
 
 service Node {
@@ -75,6 +78,11 @@ service Node {
   rpc NodeGetVolumeStats (NodeGetVolumeStatsRequest)
     returns (NodeGetVolumeStatsResponse) {}
 
+
+  rpc NodeExpandVolume(NodeExpandVolumeRequest)
+    returns (NodeExpandVolumeResponse) {}
+
+
   rpc NodeGetCapabilities (NodeGetCapabilitiesRequest)
     returns (NodeGetCapabilitiesResponse) {}
 
@@ -116,7 +124,6 @@ message PluginCapability {
   message Service {
     enum Type {
       UNKNOWN = 0;
-
       // CONTROLLER_SERVICE indicates that the Plugin provides RPCs for
       // the ControllerService. Plugins SHOULD provide this capability.
       // In rare cases certain plugins MAY wish to omit the
@@ -138,9 +145,55 @@ message PluginCapability {
     Type type = 1;
   }
 
+  message VolumeExpansion {
+    enum Type {
+      UNKNOWN = 0;
+
+      // ONLINE indicates that volumes may be expanded when published to
+      // a node. When a Plugin implements this capability it MUST
+      // implement either the EXPAND_VOLUME controller capability or the
+      // EXPAND_VOLUME node capability or both. When a plugin supports
+      // ONLINE volume expansion and also has the EXPAND_VOLUME
+      // controller capability then the plugin MUST support expansion of
+      // volumes currently published and available on a node. When a
+      // plugin supports ONLINE volume expansion and also has the
+      // EXPAND_VOLUME node capability then the plugin MAY support
+      // expansion of node-published volume via NodeExpandVolume.
+      //
+      // Example 1: Given a shared filesystem volume (e.g. GlusterFs),
+      //   the Plugin may set the ONLINE volume expansion capability and
+      //   implement ControllerExpandVolume but not NodeExpandVolume.
+      //
+      // Example 2: Given a block storage volume type (e.g. EBS), the
+      //   Plugin may set the ONLINE volume expansion capability and
+      //   implement both ControllerExpandVolume and NodeExpandVolume.
+      //
+      // Example 3: Given a Plugin that supports volume expansion only
+      //   upon a node, the Plugin may set the ONLINE volume
+      //   expansion capability and implement NodeExpandVolume but not
+      //   ControllerExpandVolume.
+      ONLINE = 1;
+
+      // OFFLINE indicates that volumes currently published and
+      // available on a node SHALL NOT be expanded via
+      // ControllerExpandVolume. When a plugin supports OFFLINE volume
+      // expansion it MUST implement either the EXPAND_VOLUME controller
+      // capability or both the EXPAND_VOLUME controller capability and
+      // the EXPAND_VOLUME node capability.
+      //
+      // Example 1: Given a block storage volume type (e.g. Azure Disk)
+      //   that does not support expansion of "node-attached" (i.e.
+      //   controller-published) volumes, the Plugin may indicate
+      //   OFFLINE volume expansion support and implement both
+      //   ControllerExpandVolume and NodeExpandVolume.
+      OFFLINE = 2;
+    }
+  }
+
   oneof type {
     // Service that the plugin supports.
     Service service = 1;
+    VolumeExpansion volume_expansion = 2;
   }
 }
 message ProbeRequest {
@@ -817,14 +870,19 @@ message ControllerServiceCapability {
       // snapshot.
       CREATE_DELETE_SNAPSHOT = 5;
       LIST_SNAPSHOTS = 6;
+
       // Plugins supporting volume cloning at the storage level MAY
       // report this capability. The source volume MUST be managed by
       // the same plugin. Not all volume sources and parameters
       // combinations MAY work.
       CLONE_VOLUME = 7;
+
       // Indicates the SP supports ControllerPublishVolume.readonly
       // field.
       PUBLISH_READONLY = 8;
+
+      // See VolumeExpansion for details.
+      EXPAND_VOLUME = 9;
     }
 
     Type type = 1;
@@ -967,6 +1025,28 @@ message ListSnapshotsResponse {
   // An empty string is equal to an unspecified field value.
   string next_token = 2;
 }
+message ControllerExpandVolumeRequest {
+  // The ID of the volume to expand. This field is REQUIRED.
+  string volume_id = 1;
+
+  // This allows CO to specify the capacity requirements of the volume
+  // after expansion. This field is REQUIRED.
+  CapacityRange capacity_range = 2;
+
+  // Secrets required by the plugin for expanding the volume.
+  // This field is OPTIONAL.
+  map<string, string> secrets = 3 [(csi_secret) = true];
+}
+
+message ControllerExpandVolumeResponse {
+  // Capacity of volume after expansion. This field is REQUIRED.
+  int64 capacity_bytes = 1;
+
+  // Whether node expansion is required for the volume. When true
+  // the CO MUST make NodeExpandVolume RPC call on the node. This field
+  // is REQUIRED.
+  bool node_expansion_required = 2;
+}
 message NodeStageVolumeRequest {
   // The ID of the volume to publish. This field is REQUIRED.
   string volume_id = 1;
@@ -1151,6 +1231,8 @@ message NodeServiceCapability {
       // then it MUST implement NodeGetVolumeStats RPC
       // call for fetching volume statistics.
       GET_VOLUME_STATS = 2;
+      // See VolumeExpansion for details.
+      EXPAND_VOLUME = 3;
     }
 
     Type type = 1;
@@ -1201,3 +1283,23 @@ message NodeGetInfoResponse {
   // "Z2".
   Topology accessible_topology = 3;
 }
+message NodeExpandVolumeRequest {
+  // The ID of the volume. This field is REQUIRED.
+  string volume_id = 1;
+
+  // The path on which volume is available. This field is REQUIRED.
+  string volume_path = 2;
+
+  // This allows CO to specify the capacity requirements of the volume
+  // after expansion. If capacity_range is omitted then a plugin MAY
+  // inspect the file system of the volume to determine the maximum
+  // capacity to which the volume can be expanded. In such cases a
+  // plugin MAY expand the volume to its maximum capacity.
+  // This field is OPTIONAL.
+  CapacityRange capacity_range = 3;
+}
+
+message NodeExpandVolumeResponse {
+  // The capacity of the volume in bytes. This field is OPTIONAL.
+  int64 capacity_bytes = 1;
+}