memcg: convert to use cgroup id

Use cgroup id instead of css id. This is a preparation to kill css id.

Note, as memcg treat 0 as an invalid id, while cgroup id starts with 0,
we define memcg_id == cgroup_id + 1.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index aa8363ef381cc799a3c7679c7b507d8813f20a44..404a13a09efa0ee17f268aec1075e80b6eb1f488 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -488,6 +488,23 @@ static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
        return (memcg == root_mem_cgroup);
 }
 
+static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
+{
+       /*
+        * The ID of the root cgroup is 0, but memcg treat 0 as an
+        * invalid ID, so we return (cgroup_id + 1).
+        */
+       return memcg->css.cgroup->id + 1;
+}
+
+static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
+{
+       struct cgroup_subsys_state *css;
+
+       css = css_from_id(id - 1, &mem_cgroup_subsys);
+       return mem_cgroup_from_css(css);
+}
+
 /* Writing them here to avoid exposing memcg's inner layout */
 #if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
 
@@ -2709,15 +2726,10 @@ static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
  */
 static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
 {
-       struct cgroup_subsys_state *css;
-
        /* ID 0 is unused ID */
        if (!id)
                return NULL;
-       css = css_lookup(&mem_cgroup_subsys, id);
-       if (!css)
-               return NULL;
-       return mem_cgroup_from_css(css);
+       return mem_cgroup_from_id(id);
 }
 
 struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
@@ -4232,7 +4244,7 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
         * css_get() was called in uncharge().
         */
        if (do_swap_account && swapout && memcg)
-               swap_cgroup_record(ent, css_id(&memcg->css));
+               swap_cgroup_record(ent, mem_cgroup_id(memcg));
 }
 #endif
 
@@ -4284,8 +4296,8 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry,
 {
        unsigned short old_id, new_id;
 
-       old_id = css_id(&from->css);
-       new_id = css_id(&to->css);
+       old_id = mem_cgroup_id(from);
+       new_id = mem_cgroup_id(to);
 
        if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
                mem_cgroup_swap_statistics(from, false);
@@ -6325,7 +6337,7 @@ static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
        }
        /* There is a swap entry and a page doesn't exist or isn't charged */
        if (ent.val && !ret &&
-                       css_id(&mc.from->css) == lookup_swap_cgroup_id(ent)) {
+           mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
                ret = MC_TARGET_SWAP;
                if (target)
                        target->ent = ent;