writeback: Fix some comment errors

Signed-off-by: Wanpeng Li <liwp@linux.vnet.ibm.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 41a3ccf..0b2c87e 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -628,8 +628,8 @@
 		}
 
 		/*
-		 * Don't bother with new inodes or inodes beeing freed, first
-		 * kind does not need peridic writeout yet, and for the latter
+		 * Don't bother with new inodes or inodes being freed, first
+		 * kind does not need periodic writeout yet, and for the latter
 		 * kind writeout is handled by the freer.
 		 */
 		spin_lock(&inode->i_lock);
diff --git a/fs/super.c b/fs/super.c
index cf00177..3d65443 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -318,7 +318,7 @@
 
 /*
  *	grab_super_passive - acquire a passive reference
- *	@s: reference we are trying to grab
+ *	@sb: reference we are trying to grab
  *
  *	Tries to acquire a passive reference. This is used in places where we
  *	cannot take an active reference but we need to ensure that the
diff --git a/fs/sync.c b/fs/sync.c
index 11e3d1c..1830704 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -92,7 +92,7 @@
 }
 
 /*
- * sync everything.  Start out by waking pdflush, because that writes back
+ * sync everything.  Start out by waking flusher, because that writes back
  * all queues in parallel.
  */
 SYSCALL_DEFINE0(sync)