+ /*
+ * We need this before the filemap_fdatawrite() so that it can
+ * transfer the dirty bit from the PTE to the
+ * page. Unfortunately this means that even for EX->PR
+ * downconverts, we'll lose our mappings and have to build
+ * them up again.
+ */
+ unmap_mapping_range(mapping, 0, 0, 0);
+