Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/orangefs/orangefs-bufmap.h b/fs/orangefs/orangefs-bufmap.h
index c2c3c5a..75b2d28 100644
--- a/fs/orangefs/orangefs-bufmap.h
+++ b/fs/orangefs/orangefs-bufmap.h
@@ -34,4 +34,6 @@
 			      int buffer_index,
 			      size_t size);
 
+void orangefs_bufmap_page_fill(void *kaddr, int buffer_index, int slot_index);
+
 #endif /* __ORANGEFS_BUFMAP_H */