writeback: get rid to incorrect references to pdflush in comments

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3c78fc3..8bef063 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -58,7 +58,7 @@
 /* The following parameters are exported via /proc/sys/vm */
 
 /*
- * Start background writeback (via pdflush) at this percentage
+ * Start background writeback (via writeback threads) at this percentage
  */
 int dirty_background_ratio = 10;
 
@@ -477,8 +477,8 @@
  * balance_dirty_pages() must be called by processes which are generating dirty
  * data.  It looks at the number of dirty pages in the machine and will force
  * the caller to perform writeback if the system is over `vm_dirty_ratio'.
- * If we're over `background_thresh' then pdflush is woken to perform some
- * writeout.
+ * If we're over `background_thresh' then the writeback threads are woken to
+ * perform some writeout.
  */
 static void balance_dirty_pages(struct address_space *mapping,
 				unsigned long write_chunk)
@@ -582,7 +582,7 @@
 		bdi->dirty_exceeded = 0;
 
 	if (writeback_in_progress(bdi))
-		return;		/* pdflush is already working this queue */
+		return;
 
 	/*
 	 * In laptop mode, we wait until hitting the higher threshold before
diff --git a/mm/shmem.c b/mm/shmem.c
index b206a7a..aa94811 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1046,8 +1046,9 @@
 	 * sync from ever calling shmem_writepage; but a stacking filesystem
 	 * may use the ->writepage of its underlying filesystem, in which case
 	 * tmpfs should write out to swap only in response to memory pressure,
-	 * and not for pdflush or sync.  However, in those cases, we do still
-	 * want to check if there's a redundant swappage to be discarded.
+	 * and not for the writeback threads or sync.  However, in those cases,
+	 * we do still want to check if there's a redundant swappage to be
+	 * discarded.
 	 */
 	if (wbc->for_reclaim)
 		swap = get_swap_page();
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 613e89f..359c3c5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1709,10 +1709,10 @@
  *
  * If the caller is !__GFP_FS then the probability of a failure is reasonably
  * high - the zone may be full of dirty or under-writeback pages, which this
- * caller can't do much about.  We kick pdflush and take explicit naps in the
- * hope that some of these pages can be written.  But if the allocating task
- * holds filesystem locks which prevent writeout this might not work, and the
- * allocation attempt will fail.
+ * caller can't do much about.  We kick the writeback threads and take explicit
+ * naps in the hope that some of these pages can be written.  But if the
+ * allocating task holds filesystem locks which prevent writeout this might not
+ * work, and the allocation attempt will fail.
  *
  * returns:	0, if no pages reclaimed
  * 		else, the number of pages reclaimed