diff -drupN a/fs/yaffs2/yaffs_cache.h b/fs/yaffs2/yaffs_cache.h
--- a/fs/yaffs2/yaffs_cache.h	1970-01-01 03:00:00.000000000 +0300
+++ b/fs/yaffs2/yaffs_cache.h	2022-06-09 05:02:35.000000000 +0300
@@ -0,0 +1,56 @@
+/*
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2018 Aleph One Ltd.
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __YAFFS_CACHE_H__
+#define __YAFFS_CACHE_H__
+
+#include "yaffs_guts.h"
+
+
+/* Does the object have a dirty cache ? */
+int yaffs_obj_cache_dirty(struct yaffs_obj *obj);
+
+/* Flush the cache associated with a file, either discarding or keeping */
+void yaffs_flush_file_cache(struct yaffs_obj *obj, int discard);
+
+/* Flush everything in the cache, either discarding or keeping */
+void yaffs_flush_whole_cache(struct yaffs_dev *dev, int discard);
+
+/* Grab a cache item during read or write. */
+struct yaffs_cache *yaffs_grab_chunk_cache(struct yaffs_dev *dev);
+
+/* Find a cached chunk */
+struct yaffs_cache *yaffs_find_chunk_cache(const struct yaffs_obj *obj,
+						  int chunk_id);
+
+/* Mark the chunk for the least recently used algorithym */
+void yaffs_use_cache(struct yaffs_dev *dev, struct yaffs_cache *cache,
+			    int is_write);
+
+
+/* Invalidate a single cache page. The cache no longer holds valid data. */
+void yaffs_invalidate_chunk_cache(struct yaffs_obj *object,
+					 int chunk_id);
+
+/* Invalidate all the cache pages associated with this object
+ * Do this whenever ther file is deleted or resized.
+ */
+void yaffs_invalidate_file_cache(struct yaffs_obj *in);
+
+
+int yaffs_count_dirty_caches(struct yaffs_dev *dev);
+
+/* Init/deinit. */
+int yaffs_cache_init(struct yaffs_dev *dev);
+void yaffs_cache_deinit(struct yaffs_dev *dev);
+
+#endif