[gegl] file backend: Explicitly cancel file monitor

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 1d530816266b52c8788bbe1504c5b2d6eceba036
Author: Simon McVittie <smcv debian org>
Date:   Wed Mar 18 10:00:26 2020 +0000

    file backend: Explicitly cancel file monitor
    
    If we don't cancel it before unreffing it, its last-unref might happen
    on the worker thread, which can lead to a deadlock.
    
    Workaround for <https://gitlab.gnome.org/GNOME/glib/issues/1941>.
    
    Signed-off-by: Simon McVittie <smcv debian org>
    Resolves: https://gitlab.gnome.org/GNOME/gegl/issues/226
    Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=954197

 gegl/buffer/gegl-tile-backend-file-async.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/gegl/buffer/gegl-tile-backend-file-async.c b/gegl/buffer/gegl-tile-backend-file-async.c
index 937c9a40d..67165c4b6 100644
--- a/gegl/buffer/gegl-tile-backend-file-async.c
+++ b/gegl/buffer/gegl-tile-backend-file-async.c
@@ -981,7 +981,10 @@ gegl_tile_backend_file_finalize (GObject *object)
     }
 
   if (self->monitor)
-    g_object_unref (self->monitor);
+    {
+      g_file_monitor_cancel (self->monitor);
+      g_object_unref (self->monitor);
+    }
 
   if (self->file)
     g_object_unref (self->file);