+
+ /*
+ * Set the "writeback" flag, and clear "dirty" in the radix tree.
+ *
+ * A writepage() implementation always needs to do either this,
+ * or re-dirty the page with "redirty_page_for_writepage()" in
+ * the case of a failure.
+ *
+ * Just unlocking the page will cause the radix tree tag-bits
+ * to fail to update with the state of the page correctly.
+ */
+ set_page_writeback(page);