+ clear_page_dirty_for_io(page);
+ /*
+ * We have to be very careful here! Nothing protects writeback path
+ * against i_size changes and the page can be writeably mapped into
+ * page tables. So an application can be growing i_size and writing
+ * data through mmap while writeback runs. clear_page_dirty_for_io()
+ * write-protects our page in page tables and the page cannot get
+ * written to again until we release page lock. So only after
+ * clear_page_dirty_for_io() we are safe to sample i_size for
+ * ext4_bio_write_page() to zero-out tail of the written page. We rely
+ * on the barrier provided by TestClearPageDirty in
+ * clear_page_dirty_for_io() to make sure i_size is really sampled only
+ * after page tables are updated.
+ */
+ size = i_size_read(mpd->inode);