From d866dbf6178713e37d2fec2870af00b345684e1a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 24 Jul 2019 10:37:22 -0700 Subject: blkcg: rename blkcg->cgwb_refcnt to ->online_pin and always use it blkcg->cgwb_refcnt is used to delay blkcg offlining so that blkgs don't get offlined while there are active cgwbs on them. However, it ends up making offlining unordered sometimes causing parents to be offlined before children. To fix it, we want child blkcgs to pin the parents' online states turning the refcnt into a more generic online pinning mechanism. In prepartion, * blkcg->cgwb_refcnt -> blkcg->online_pin * blkcg_cgwb_get/put() -> blkcg_pin/unpin_online() * Take them out of CONFIG_CGROUP_WRITEBACK Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- mm/backing-dev.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm/backing-dev.c') diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 62f05f605fb5..c81b4f3a7268 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -491,8 +491,8 @@ static void cgwb_release_workfn(struct work_struct *work) css_put(wb->blkcg_css); mutex_unlock(&wb->bdi->cgwb_release_mutex); - /* triggers blkg destruction if cgwb_refcnt becomes zero */ - blkcg_cgwb_put(blkcg); + /* triggers blkg destruction if no online users left */ + blkcg_unpin_online(blkcg); fprop_local_destroy_percpu(&wb->memcg_completions); percpu_ref_exit(&wb->refcnt); @@ -592,7 +592,7 @@ static int cgwb_create(struct backing_dev_info *bdi, list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); list_add(&wb->memcg_node, memcg_cgwb_list); list_add(&wb->blkcg_node, blkcg_cgwb_list); - blkcg_cgwb_get(blkcg); + blkcg_pin_online(blkcg); css_get(memcg_css); css_get(blkcg_css); } -- cgit v1.2.3