[PATCH 1/2 v3] memcg: rename do_flush_stats and add force flag

[JP Kobryn <inwardvessel@gmail.com>]

Change the name to something more consistent with others in the file and
use double unders to signify it is associated with the
mem_cgroup_flush_stats() API call. Additionally include a new flag that
call sites use to indicate a forced flush; skipping checks and flushing
unconditionally. There are no changes in functionality.

Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
---
 mm/memcontrol.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 18c3f513d766..59f6f247fc13 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -588,8 +588,11 @@ static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val)
 	}
 }
 
-static void do_flush_stats(struct mem_cgroup *memcg)
+static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force)
 {
+	if (!force && !memcg_vmstats_needs_flush(memcg->vmstats))
+		return;
+
 	if (mem_cgroup_is_root(memcg))
 		WRITE_ONCE(flush_last_time, jiffies_64);
 
@@ -613,8 +616,7 @@ void mem_cgroup_flush_stats(struct mem_cgroup *memcg)
 	if (!memcg)
 		memcg = root_mem_cgroup;
 
-	if (memcg_vmstats_needs_flush(memcg->vmstats))
-		do_flush_stats(memcg);
+	__mem_cgroup_flush_stats(memcg, false);
 }
 
 void mem_cgroup_flush_stats_ratelimited(struct mem_cgroup *memcg)
@@ -630,7 +632,7 @@ static void flush_memcg_stats_dwork(struct work_struct *w)
 	 * Deliberately ignore memcg_vmstats_needs_flush() here so that flushing
 	 * in latency-sensitive paths is as cheap as possible.
 	 */
-	do_flush_stats(root_mem_cgroup);
+	__mem_cgroup_flush_stats(root_mem_cgroup, true);
 	queue_delayed_work(system_unbound_wq, &stats_flush_dwork, FLUSH_TIME);
 }
 
@@ -5281,11 +5283,8 @@ bool obj_cgroup_may_zswap(struct obj_cgroup *objcg)
 			break;
 		}
 
-		/*
-		 * mem_cgroup_flush_stats() ignores small changes. Use
-		 * do_flush_stats() directly to get accurate stats for charging.
-		 */
-		do_flush_stats(memcg);
+		/* Force flush to get accurate stats for charging */
+		__mem_cgroup_flush_stats(memcg, true);
 		pages = memcg_page_state(memcg, MEMCG_ZSWAP_B) / PAGE_SIZE;
 		if (pages < max)
 			continue;
-- 
2.47.0