msg/async: print error log if add_event fail

Signed-off-by: mychoxin <mychoxin@gmail.com>

src/msg/async/Event.cc

@@ -230,6 +230,8 @@ int EventCenter::create_file_event(int fd, int mask, EventCallbackRef ctxt)
     // Actually we don't allow any failed error code, caller doesn't prepare to
     // handle error status. So now we need to assert failure here. In practice,
     // add_event shouldn't report error, otherwise it must be a innermost bug!
+    lderr(cct) << __func__ << " add event failed, ret=" << r << " fd=" << fd
+               << " mask=" << mask << " original mask is " << event->mask << dendl;
     assert(0 == "BUG!");
     return r;
   }

src/os/bluestore/KernelDevice.cc

@@ -362,17 +362,17 @@ void KernelDevice::_aio_thread()
 	io_since_flush.store(true);
 
 	int r = aio[i]->get_return_value();
-	dout(10) << __func__ << " finished aio " << aio[i] << " r " << r
-		 << " ioc " << ioc
-		 << " with " << (ioc->num_running.load() - 1)
-		 << " aios left" << dendl;
 	if (r < 0) {
 	  derr << __func__ << " finished aio " << aio[i] << " r " << r
 	       << " ioc " << ioc
 	       << " with " << (ioc->num_running.load() - 1)
 	       << " aios left" << dendl;
 	  assert(r >= 0);
-    }
+	}
+	dout(10) << __func__ << " finished aio " << aio[i] << " r " << r
+		 << " ioc " << ioc
+		 << " with " << (ioc->num_running.load() - 1)
+		 << " aios left" << dendl;
 
 	// NOTE: once num_running and we either call the callback or
 	// call aio_wake we cannot touch ioc or aio[] as the caller