[PATCH 37/49] writeback: make laptop_mode_timer_fn() handle multiple bdi_writeback's

Tejun Heo
2015-04-06T20:13:05Z

For cgroup writeback support, all bdi-wide operations should be
distributed to all its wb's (bdi_writeback's).

This patch updates laptop_mode_timer_fn() so that it invokes
wb_start_writeback() on all wb's rather than just the root one. As
the intent is writing out all dirty data, there's no reason to split
the number of pages to write.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
---
mm/page-writeback.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3b6d79a..5458762 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1723,14 +1723,20 @@ void laptop_mode_timer_fn(unsigned long data)
struct request_queue *q = (struct request_queue *)data;
int nr_pages = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
+ struct bdi_writeback *wb;
+ struct wb_iter iter;

/*
* We want to write everything out, not just down to the dirty
* threshold
*/
- if (bdi_has_dirty_io(&q->backing_dev_info))
- wb_start_writeback(&q->backing_dev_info.wb, nr_pages, true,
- WB_REASON_LAPTOP_TIMER);
+ if (!bdi_has_dirty_io(&q->backing_dev_info))
+ return;
+
+ bdi_for_each_wb(wb, &q->backing_dev_info, &iter, 0)
+ if (wb_has_dirty_io(wb))
+ wb_start_writeback(wb, nr_pages, true,
+ WB_REASON_LAPTOP_TIMER);
}

/*
--
2.1.0