writeback: pass in '0' for nr_pages writeback in laptop mode

Laptop mode really wants to writeback the number of dirty
pages and inodes. Instead of calculating this in the caller,
just pass in 0 and let wakeup_flusher_threads() handle it.

Use the new wakeup_flusher_threads_bdi() instead of rolling
our own.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Chris Mason <clm@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index dede533..8d1fc59 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1980,23 +1980,8 @@ int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
 void laptop_mode_timer_fn(unsigned long data)
 {
        struct request_queue *q = (struct request_queue *)data;
-       int nr_pages = global_node_page_state(NR_FILE_DIRTY) +
-               global_node_page_state(NR_UNSTABLE_NFS);
-       struct bdi_writeback *wb;
 
-       /*
-        * We want to write everything out, not just down to the dirty
-        * threshold
-        */
-       if (!bdi_has_dirty_io(q->backing_dev_info))
-               return;
-
-       rcu_read_lock();
-       list_for_each_entry_rcu(wb, &q->backing_dev_info->wb_list, bdi_node)
-               if (wb_has_dirty_io(wb))
-                       wb_start_writeback(wb, nr_pages,
-                                               WB_REASON_LAPTOP_TIMER);
-       rcu_read_unlock();
+       wakeup_flusher_threads_bdi(q->backing_dev_info, WB_REASON_LAPTOP_TIMER);
 }
 
 /*