trivial: fix a pdlfush -> pdflush typo in comment

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index e3fe991..99903ab 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -420,7 +420,7 @@
  * 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.