[PATCH 1/3] mm: shrinker: introduce new function get_shrinker_id()

[Haifeng Xu]

Use get_shrinker_id() to retrieve the id of shrinker. No functional change.

Signed-off-by: Haifeng Xu <haifeng.xu@xxxxxxxxxx>
---
 mm/shrinker.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/mm/shrinker.c b/mm/shrinker.c
index 7b61fc0ee78f..f0c6dfa026b0 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -193,6 +193,11 @@ static inline int calc_shrinker_id(int index, int offset)
 	return index * SHRINKER_UNIT_BITS + offset;
 }
 
+static inline int get_shrinker_id(struct mem_cgroup *memcg, struct shrinker *shrinker)
+{
+	return shrinker->id;
+}
+
 void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
 {
 	if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
@@ -255,11 +260,13 @@ static long xchg_nr_deferred_memcg(int nid, struct shrinker *shrinker,
 	struct shrinker_info *info;
 	struct shrinker_info_unit *unit;
 	long nr_deferred;
+	int id;
 
 	rcu_read_lock();
+	id = get_shrinker_id(memcg, shrinker);
 	info = rcu_dereference(memcg->nodeinfo[nid]->shrinker_info);
-	unit = info->unit[shrinker_id_to_index(shrinker->id)];
-	nr_deferred = atomic_long_xchg(&unit->nr_deferred[shrinker_id_to_offset(shrinker->id)], 0);
+	unit = info->unit[shrinker_id_to_index(id)];
+	nr_deferred = atomic_long_xchg(&unit->nr_deferred[shrinker_id_to_offset(id)], 0);
 	rcu_read_unlock();
 
 	return nr_deferred;
@@ -271,12 +278,14 @@ static long add_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker,
 	struct shrinker_info *info;
 	struct shrinker_info_unit *unit;
 	long nr_deferred;
+	int id;
 
 	rcu_read_lock();
+	id = get_shrinker_id(memcg, shrinker);
 	info = rcu_dereference(memcg->nodeinfo[nid]->shrinker_info);
-	unit = info->unit[shrinker_id_to_index(shrinker->id)];
+	unit = info->unit[shrinker_id_to_index(id)];
 	nr_deferred =
-		atomic_long_add_return(nr, &unit->nr_deferred[shrinker_id_to_offset(shrinker->id)]);
+		atomic_long_add_return(nr, &unit->nr_deferred[shrinker_id_to_offset(id)]);
 	rcu_read_unlock();
 
 	return nr_deferred;
-- 
2.43.0