writeback: get rid of pdflush completely

It is now unused, so kill it off.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7f6dae8..2e601ce 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -30,6 +30,11 @@
 #define inode_to_bdi(inode)	((inode)->i_mapping->backing_dev_info)
 
 /*
+ * We don't actually have pdflush, but this one is exported though /proc...
+ */
+int nr_pdflush_threads;
+
+/*
  * Work items for the bdi_writeback threads
  */
 struct bdi_work {