memcg: writeback: use memcg->cgwb_list directly

mem_cgroup_cgwb_list is a very simple wrapper and it will never be used
outside of code under CONFIG_CGROUP_WRITEBACK.  so use memcg->cgwb_list
directly.

Link: http://lkml.kernel.org/r/1524406173-212182-1-git-send-email-wanglong19@meituan.com
Signed-off-by: Wang Long <wanglong19@meituan.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 8fe3ebd6ac00..347cc834c04a 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -557,7 +557,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
         memcg = mem_cgroup_from_css(memcg_css);
         blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
         blkcg = css_to_blkcg(blkcg_css);
-        memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
+        memcg_cgwb_list = &memcg->cgwb_list;
         blkcg_cgwb_list = &blkcg->cgwb_list;
 
         /* look up again under lock and discard on blkcg mismatch */
@@ -736,7 +736,7 @@ static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
  */
 void wb_memcg_offline(struct mem_cgroup *memcg)
 {
-        struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
+        struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
         struct bdi_writeback *wb, *next;
 
         spin_lock_irq(&cgwb_lock);