mm: memcontrol: rename shrinker_map to shrinker_info

The following patch is going to add nr_deferred into shrinker_map, the
change will make shrinker_map not only include map anymore, so rename it
to "memcg_shrinker_info".  And this should make the patch adding
nr_deferred cleaner and readable and make review easier.  Also remove the
"memcg_" prefix.

Link: https://lkml.kernel.org/r/20210311190845.9708-7-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index aa99a83..518084c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -192,16 +192,16 @@ static inline int shrinker_map_size(int nr_items)
 	return (DIV_ROUND_UP(nr_items, BITS_PER_LONG) * sizeof(unsigned long));
 }
 
-static int expand_one_shrinker_map(struct mem_cgroup *memcg,
-				   int size, int old_size)
+static int expand_one_shrinker_info(struct mem_cgroup *memcg,
+				    int size, int old_size)
 {
-	struct memcg_shrinker_map *new, *old;
+	struct shrinker_info *new, *old;
 	struct mem_cgroup_per_node *pn;
 	int nid;
 
 	for_each_node(nid) {
 		pn = memcg->nodeinfo[nid];
-		old = rcu_dereference_protected(pn->shrinker_map, true);
+		old = rcu_dereference_protected(pn->shrinker_info, true);
 		/* Not yet online memcg */
 		if (!old)
 			return 0;
@@ -214,17 +214,17 @@ static int expand_one_shrinker_map(struct mem_cgroup *memcg,
 		memset(new->map, (int)0xff, old_size);
 		memset((void *)new->map + old_size, 0, size - old_size);
 
-		rcu_assign_pointer(pn->shrinker_map, new);
+		rcu_assign_pointer(pn->shrinker_info, new);
 		kvfree_rcu(old, rcu);
 	}
 
 	return 0;
 }
 
-void free_shrinker_maps(struct mem_cgroup *memcg)
+void free_shrinker_info(struct mem_cgroup *memcg)
 {
 	struct mem_cgroup_per_node *pn;
-	struct memcg_shrinker_map *map;
+	struct shrinker_info *info;
 	int nid;
 
 	if (mem_cgroup_is_root(memcg))
@@ -232,15 +232,15 @@ void free_shrinker_maps(struct mem_cgroup *memcg)
 
 	for_each_node(nid) {
 		pn = memcg->nodeinfo[nid];
-		map = rcu_dereference_protected(pn->shrinker_map, true);
-		kvfree(map);
-		rcu_assign_pointer(pn->shrinker_map, NULL);
+		info = rcu_dereference_protected(pn->shrinker_info, true);
+		kvfree(info);
+		rcu_assign_pointer(pn->shrinker_info, NULL);
 	}
 }
 
-int alloc_shrinker_maps(struct mem_cgroup *memcg)
+int alloc_shrinker_info(struct mem_cgroup *memcg)
 {
-	struct memcg_shrinker_map *map;
+	struct shrinker_info *info;
 	int nid, size, ret = 0;
 
 	if (mem_cgroup_is_root(memcg))
@@ -249,20 +249,20 @@ int alloc_shrinker_maps(struct mem_cgroup *memcg)
 	down_write(&shrinker_rwsem);
 	size = shrinker_map_size(shrinker_nr_max);
 	for_each_node(nid) {
-		map = kvzalloc_node(sizeof(*map) + size, GFP_KERNEL, nid);
-		if (!map) {
-			free_shrinker_maps(memcg);
+		info = kvzalloc_node(sizeof(*info) + size, GFP_KERNEL, nid);
+		if (!info) {
+			free_shrinker_info(memcg);
 			ret = -ENOMEM;
 			break;
 		}
-		rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, map);
+		rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info);
 	}
 	up_write(&shrinker_rwsem);
 
 	return ret;
 }
 
-static int expand_shrinker_maps(int new_id)
+static int expand_shrinker_info(int new_id)
 {
 	int size, old_size, ret = 0;
 	int new_nr_max = new_id + 1;
@@ -282,7 +282,7 @@ static int expand_shrinker_maps(int new_id)
 	do {
 		if (mem_cgroup_is_root(memcg))
 			continue;
-		ret = expand_one_shrinker_map(memcg, size, old_size);
+		ret = expand_one_shrinker_info(memcg, size, old_size);
 		if (ret) {
 			mem_cgroup_iter_break(NULL, memcg);
 			goto out;
@@ -298,13 +298,13 @@ static int expand_shrinker_maps(int new_id)
 void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
 {
 	if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
-		struct memcg_shrinker_map *map;
+		struct shrinker_info *info;
 
 		rcu_read_lock();
-		map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map);
+		info = rcu_dereference(memcg->nodeinfo[nid]->shrinker_info);
 		/* Pairs with smp mb in shrink_slab() */
 		smp_mb__before_atomic();
-		set_bit(shrinker_id, map->map);
+		set_bit(shrinker_id, info->map);
 		rcu_read_unlock();
 	}
 }
@@ -335,7 +335,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker)
 		goto unlock;
 
 	if (id >= shrinker_nr_max) {
-		if (expand_shrinker_maps(id)) {
+		if (expand_shrinker_info(id)) {
 			idr_remove(&shrinker_idr, id);
 			goto unlock;
 		}
@@ -665,7 +665,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
 static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 			struct mem_cgroup *memcg, int priority)
 {
-	struct memcg_shrinker_map *map;
+	struct shrinker_info *info;
 	unsigned long ret, freed = 0;
 	int i;
 
@@ -675,12 +675,12 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 	if (!down_read_trylock(&shrinker_rwsem))
 		return 0;
 
-	map = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_map,
-					true);
-	if (unlikely(!map))
+	info = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info,
+					 true);
+	if (unlikely(!info))
 		goto unlock;
 
-	for_each_set_bit(i, map->map, shrinker_nr_max) {
+	for_each_set_bit(i, info->map, shrinker_nr_max) {
 		struct shrink_control sc = {
 			.gfp_mask = gfp_mask,
 			.nid = nid,
@@ -691,7 +691,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 		shrinker = idr_find(&shrinker_idr, i);
 		if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) {
 			if (!shrinker)
-				clear_bit(i, map->map);
+				clear_bit(i, info->map);
 			continue;
 		}
 
@@ -702,7 +702,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 
 		ret = do_shrink_slab(&sc, shrinker, priority);
 		if (ret == SHRINK_EMPTY) {
-			clear_bit(i, map->map);
+			clear_bit(i, info->map);
 			/*
 			 * After the shrinker reported that it had no objects to
 			 * free, but before we cleared the corresponding bit in