eth/downloader: make syncing error more obvious (#19413)

eth/downloader/statesync.go

@@ -302,7 +302,7 @@ func (s *stateSync) loop() (err error) {
 			return errCancelStateFetch
 
 		case <-s.d.cancelCh:
-			return errCancelStateFetch
+			return errCanceled
 
 		case req := <-s.deliver:
 			// Response, disconnect or timeout triggered, drop the peer if stalling
@@ -317,6 +317,16 @@ func (s *stateSync) loop() (err error) {
 					req.peer.log.Warn("Downloader wants to drop peer, but peerdrop-function is not set", "peer", req.peer.id)
 				} else {
 					s.d.dropPeer(req.peer.id)
+
+					// If this peer was the master peer, abort sync immediately
+					s.d.cancelLock.RLock()
+					master := req.peer.id == s.d.cancelPeer
+					s.d.cancelLock.RUnlock()
+
+					if master {
+						s.d.cancel()
+						return errTimeout
+					}
 				}
 			}
 			// Process all the received blobs and check for stale delivery