Function watch_one_event 

async fn watch_one_event(
    dir_path: &str,
    watch_tree: bool,
    filter: u32,
    cancel: &mut Receiver<Status>,
) -> Result<Vec<(u32, String)>, Status>

Await the first inotify event on dir_path (mapped from the SMB completion filter) or a cancellation. When watch_tree is set, subdirectories are watched too and the reported name is relative to dir_path. Returns the (action, name) list on an event, or Err(status) carrying the completion status on cancel/handle-close/setup error.