vfs: nuke pdflush from comments

The pdflush thread is long gone, so this patch removes references to pdflush
from vfs comments.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/bio.c b/fs/bio.c
index 73922ab..5eaa70c 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1312,7 +1312,7 @@
  * Note that this code is very hard to test under normal circumstances because
  * direct-io pins the pages with get_user_pages().  This makes
  * is_page_cache_freeable return false, and the VM will not clean the pages.
- * But other code (eg, pdflush) could clean the pages if they are mapped
+ * But other code (eg, flusher threads) could clean the pages if they are mapped
  * pagecache.
  * Simply disabling the call to bio_set_pages_dirty() is a good way to test the
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index c66fe33..50c3e8f 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -104,7 +104,6 @@
 	wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
  * mm/page-writeback.c