writeback: Fix some comment errors

Signed-off-by: NWanpeng Li <liwp@linux.vnet.ibm.com>
Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>

fs/fs-writeback.c

@@ -628,8 +628,8 @@ static long writeback_sb_inodes(struct super_block *sb,
 		}
 
 		/*
-		 * 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);

fs/super.c

@@ -318,7 +318,7 @@ static int grab_super(struct super_block *s) __releases(sb_lock)
 
 /*
  *	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

fs/sync.c

@@ -92,7 +92,7 @@ static void sync_filesystems(int wait)
 }
 
 /*
- * 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)

mm/page-writeback.c

@@ -946,7 +946,7 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
 	 *	bdi->dirty_ratelimit = balanced_dirty_ratelimit;
 	 *
 	 * However to get a more stable dirty_ratelimit, the below elaborated
-	 * code makes use of task_ratelimit to filter out sigular points and
+	 * code makes use of task_ratelimit to filter out singular points and
 	 * limit the step size.
 	 *
 	 * The below code essentially only uses the relative value of
@@ -969,7 +969,7 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
 	 * feel and care are stable dirty rate and small position error.
 	 *
 	 * |task_ratelimit - dirty_ratelimit| is used to limit the step size
-	 * and filter out the sigular points of balanced_dirty_ratelimit. Which
+	 * and filter out the singular points of balanced_dirty_ratelimit. Which
 	 * keeps jumping around randomly and can even leap far away at times
 	 * due to the small 200ms estimation period of dirty_rate (we want to
 	 * keep that period small to reduce time lags).