diff --git a/drivers/md/md.h b/drivers/md/md.h
index 4ba93af36126d..de6dadb9a40b0 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -746,6 +746,9 @@ struct md_personality
 	void *(*takeover) (struct mddev *mddev);
 	/* Changes the consistency policy of an active array. */
 	int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
+	/* convert io ranges from array to bitmap */
+	void (*bitmap_sector)(struct mddev *mddev, sector_t *offset,
+			      unsigned long *sectors);
 };
 
 struct md_sysfs_entry {