* If older_than_this is non-NULL, then only write out inodes which
* had their first dirtying at a time earlier than *older_than_this.
*
- * If we're a pdlfush thread, then implement pdflush collision avoidance
+ * If we're a pdflush thread, then implement pdflush collision avoidance
* against the entire list.
*
* If `bdi' is non-zero then we're being asked to writeback a specific queue.