writeback: track if we're sleeping on progress in balance_dirty_pages()

Note in the bdi_writeback structure whenever a task ends up sleeping
waiting for progress. We can use that information in the lower layers
to increase the priority of writes.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>

1 files changed, 1 insertions, 0 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 8fde443f36d7..3bfed5ab2475 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -310,6 +310,7 @@ static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
         spin_lock_init(&wb->work_lock);
         INIT_LIST_HEAD(&wb->work_list);
         INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
+        wb->dirty_sleep = jiffies;
 
         wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
         if (!wb->congested)