fix: residual fuse mountpoint after graceful shutdown

    1. Case1: Fuse server exits in thread not main. There is possibility
       that process finishes before shutdown of server.
    2. Case2: Fuse server exits in thread of state machine. There is
       possibiltiy that state machine not responses to signal catch
       thread. Then dead lock happens. Process exits before shutdown of
       server.

    This pr aims to seperator shutdown actions from signal catch
    handler. It only notifies controller. Controller exits with
    shutdown of fuse server. No race. No deadlock.

Signed-off-by: 泰友 <[email protected]>

service/src/daemon.rs

@@ -422,13 +422,16 @@ impl DaemonController {
         self.fs_service.lock().unwrap().clone()
     }
 
-    /// Shutdown all services managed by the controller.
-    pub fn shutdown(&self) {
+    /// Notify controller shutdown
+    pub fn notify_shutdown(&self) {
         // Marking exiting state.
         self.active.store(false, Ordering::Release);
         // Signal the `run_loop()` working thread to exit.
         let _ = self.waker.wake();
+    }
 
+    /// Shutdown all services managed by the controller.
+    pub fn shutdown(&self) {
         let daemon = self.daemon.lock().unwrap().take();
         if let Some(d) = daemon {
             if let Err(e) = d.trigger_stop() {

src/bin/nydusd/main.rs

@@ -720,7 +720,7 @@ mod nbd {
 }
 
 extern "C" fn sig_exit(_sig: std::os::raw::c_int) {
-    DAEMON_CONTROLLER.shutdown();
+    DAEMON_CONTROLLER.notify_shutdown();
 }
 
 fn main() -> Result<()> {