From 1ed8d48c57bf7400eac7b8dc622ab0413715cafb Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 18 Aug 2015 14:54:52 -0700 Subject: writeback: bdi_for_each_wb() iteration is memcg ID based not blkcg wb's (bdi_writeback's) are currently keyed by memcg ID; however, in an earlier implementation, wb's were keyed by blkcg ID. bdi_for_each_wb() walks bdi->cgwb_tree in the ascending ID order and allows iterations to start from an arbitrary ID which is used to interrupt and resume iterations. Unfortunately, while changing wb to be keyed by memcg ID instead of blkcg, bdi_for_each_wb() was missed and is still assuming that wb's are keyed by blkcg ID. This doesn't affect iterations which don't get interrupted but bdi_split_work_to_wbs() makes use of iteration resuming on allocation failures and thus may incorrectly skip or repeat wb's. Fix it by changing bdi_for_each_wb() to take memcg IDs instead of blkcg IDs and updating bdi_split_work_to_wbs() accordingly. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/fs-writeback.c') diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 518c6294bf6c..c9def2115aca 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -839,7 +839,7 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, bool skip_if_busy) { long nr_pages = base_work->nr_pages; - int next_blkcg_id = 0; + int next_memcg_id = 0; struct bdi_writeback *wb; struct wb_iter iter; @@ -849,14 +849,14 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, return; restart: rcu_read_lock(); - bdi_for_each_wb(wb, bdi, &iter, next_blkcg_id) { + bdi_for_each_wb(wb, bdi, &iter, next_memcg_id) { if (!wb_has_dirty_io(wb) || (skip_if_busy && writeback_in_progress(wb))) continue; base_work->nr_pages = wb_split_bdi_pages(wb, nr_pages); if (!wb_clone_and_queue_work(wb, base_work)) { - next_blkcg_id = wb->blkcg_css->id + 1; + next_memcg_id = wb->memcg_css->id + 1; rcu_read_unlock(); wb_wait_for_single_work(bdi, base_work); goto restart; -- cgit v1.2.3