/// <summary>Rename the given snapshot</summary>
/// <param name="oldSnapshotName">Old name of the snapshot</param>
/// <param name="newSnapshotName">New name of the snapshot</param>
/// <exception cref="System.IO.IOException">
/// Throw IOException when 1) the given path does not lead to an
/// existing snapshottable directory, and/or 2) the snapshot with the
/// old name does not exist for the directory, and/or 3) there exists
/// a snapshot with the new name for the directory
/// </exception>
public virtual void RenameSnapshot(INodesInPath iip, string snapshotRoot, string
oldSnapshotName, string newSnapshotName)
{
INodeDirectory srcRoot = GetSnapshottableRoot(iip);
srcRoot.RenameSnapshot(snapshotRoot, oldSnapshotName, newSnapshotName);
}