Added VolumeMarkWritable and VolumeStatus grpc methods

This is necessary for copy to mark as read-only and then restore the
original state afterwards.

weed/pb/volume_server.proto

@@ -37,8 +37,12 @@ service VolumeServer {
     }
     rpc VolumeMarkReadonly (VolumeMarkReadonlyRequest) returns (VolumeMarkReadonlyResponse) {
     }
+    rpc VolumeMarkWritable (VolumeMarkWritableRequest) returns (VolumeMarkWritableResponse) {
+    }
     rpc VolumeConfigure (VolumeConfigureRequest) returns (VolumeConfigureResponse) {
     }
+    rpc VolumeStatus (VolumeStatusRequest) returns (VolumeStatusResponse) {
+    }
 
     // copy the .idx .dat files, and mount this volume
     rpc VolumeCopy (VolumeCopyRequest) returns (VolumeCopyResponse) {
@@ -200,6 +204,12 @@ message VolumeMarkReadonlyRequest {
 message VolumeMarkReadonlyResponse {
 }
 
+message VolumeMarkWritableRequest {
+    uint32 volume_id = 1;
+}
+message VolumeMarkWritableResponse {
+}
+
 message VolumeConfigureRequest {
     uint32 volume_id = 1;
     string replication = 2;
@@ -208,6 +218,13 @@ message VolumeConfigureResponse {
     string error = 1;
 }
 
+message VolumeStatusRequest {
+    uint32 volume_id = 1;
+}
+message VolumeStatusResponse {
+    bool is_read_only = 1;
+}
+
 message VolumeCopyRequest {
     uint32 volume_id = 1;
     string collection = 2;