[PATCH -mm 09/14] memcg: rename some cache id related variables

[Vladimir Davydov <vdavydov@parallels.com>]

memcg_limited_groups_array_size, which defines the size of memcg_caches
arrays, sounds rather cumbersome. Also it doesn't point anyhow that it's
related to kmem/caches stuff. So let's rename it to memcg_max_cache_ids.
It's concise and points us directly to memcg_cache_id.

Also, rename kmem_limited_groups to memcg_cache_ida, because it's not a
container for groups, but the memcg_cache_id allocator.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
---
 include/linux/memcontrol.h |    9 ++++++++-
 mm/memcontrol.c            |   19 +++++++++----------
 mm/slab_common.c           |    4 ++--
 3 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e57a097cf393..7c1bf0a84950 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -415,7 +415,12 @@ static inline void sock_release_memcg(struct sock *sk)
 #ifdef CONFIG_MEMCG_KMEM
 extern struct static_key memcg_kmem_enabled_key;
 
-extern int memcg_limited_groups_array_size;
+/*
+ * The maximal number of kmem-active memory cgroups that can exist on the
+ * system. May grow, but never shrinks. The value returned by memcg_cache_id()
+ * is always less.
+ */
+extern int memcg_max_cache_ids;
 
 static inline bool memcg_kmem_enabled(void)
 {
@@ -545,6 +550,8 @@ memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
 	return __memcg_kmem_get_cache(cachep, gfp);
 }
 #else
+#define memcg_max_cache_ids 0
+
 static inline bool memcg_kmem_enabled(void)
 {
 	return false;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d665d715090b..0020824dee96 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -615,12 +615,11 @@ static void disarm_sock_keys(struct mem_cgroup *memcg)
  *  memcgs, and none but the 200th is kmem-limited, we'd have to have a
  *  200 entry array for that.
  *
- * The current size of the caches array is stored in
- * memcg_limited_groups_array_size.  It will double each time we have to
- * increase it.
+ * The current size of the caches array is stored in memcg_max_cache_ids. It
+ * will double each time we have to increase it.
  */
-static DEFINE_IDA(kmem_limited_groups);
-int memcg_limited_groups_array_size;
+static DEFINE_IDA(memcg_cache_ida);
+int memcg_max_cache_ids;
 
 /*
  * MIN_SIZE is different than 1, because we would like to avoid going through
@@ -2926,12 +2925,12 @@ static int memcg_alloc_cache_id(void)
 	int id, size;
 	int err;
 
-	id = ida_simple_get(&kmem_limited_groups,
+	id = ida_simple_get(&memcg_cache_ida,
 			    0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);
 	if (id < 0)
 		return id;
 
-	if (id < memcg_limited_groups_array_size)
+	if (id < memcg_max_cache_ids)
 		return id;
 
 	/*
@@ -2950,7 +2949,7 @@ static int memcg_alloc_cache_id(void)
 	mutex_unlock(&memcg_slab_mutex);
 
 	if (err) {
-		ida_simple_remove(&kmem_limited_groups, id);
+		ida_simple_remove(&memcg_cache_ida, id);
 		return err;
 	}
 	return id;
@@ -2959,7 +2958,7 @@ static int memcg_alloc_cache_id(void)
 
 static void memcg_free_cache_id(int id)
 {
-	ida_simple_remove(&kmem_limited_groups, id);
+	ida_simple_remove(&memcg_cache_ida, id);
 }
 
 /*
@@ -2969,7 +2968,7 @@ static void memcg_free_cache_id(int id)
  */
 void memcg_update_array_size(int num)
 {
-	memcg_limited_groups_array_size = num;
+	memcg_max_cache_ids = num;
 }
 
 static void memcg_register_cache(struct mem_cgroup *memcg,
diff --git a/mm/slab_common.c b/mm/slab_common.c
index d4add958843c..cc6e18437f6c 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -98,7 +98,7 @@ static int memcg_alloc_cache_params(struct mem_cgroup *memcg,
 
 	if (!memcg) {
 		size = offsetof(struct memcg_cache_params, memcg_caches);
-		size += memcg_limited_groups_array_size * sizeof(void *);
+		size += memcg_max_cache_ids * sizeof(void *);
 	} else
 		size = sizeof(struct memcg_cache_params);
 
@@ -138,7 +138,7 @@ static int memcg_update_cache_params(struct kmem_cache *s, int num_memcgs)
 
 	cur_params = s->memcg_params;
 	memcpy(new_params->memcg_caches, cur_params->memcg_caches,
-	       memcg_limited_groups_array_size * sizeof(void *));
+	       memcg_max_cache_ids * sizeof(void *));
 
 	new_params->is_root_cache = true;
 	INIT_LIST_HEAD(&new_params->memcg_caches_list);
-- 
1.7.10.4