memcg: extract mem_group_usage() from mem_cgroup_read()

Helper to get memory or mem+swap usage of the cgroup.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Dan Malek <dan@embeddedalley.com>
Cc: Vladislav Buzov <vbuzov@embeddedalley.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Alexander Shishkin <virtuoso@slind.org>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 32 insertions, 22 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b00ec74a4c18..5f8f93d83edf 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2857,40 +2857,50 @@ mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
         *val = d.val;
 }
 
+static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
+{
+        u64 idx_val, val;
+
+        if (!mem_cgroup_is_root(mem)) {
+                if (!swap)
+                        return res_counter_read_u64(&mem->res, RES_USAGE);
+                else
+                        return res_counter_read_u64(&mem->memsw, RES_USAGE);
+        }
+
+        mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE, &idx_val);
+        val = idx_val;
+        mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS, &idx_val);
+        val += idx_val;
+
+        if (swap) {
+                mem_cgroup_get_recursive_idx_stat(mem,
+                                MEM_CGROUP_STAT_SWAPOUT, &idx_val);
+                val += idx_val;
+        }
+
+        return val << PAGE_SHIFT;
+}
+
 static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 {
         struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
-        u64 idx_val, val;
+        u64 val;
         int type, name;
 
         type = MEMFILE_TYPE(cft->private);
         name = MEMFILE_ATTR(cft->private);
         switch (type) {
         case _MEM:
-                if (name == RES_USAGE && mem_cgroup_is_root(mem)) {
-                        mem_cgroup_get_recursive_idx_stat(mem,
-                                MEM_CGROUP_STAT_CACHE, &idx_val);
-                        val = idx_val;
-                        mem_cgroup_get_recursive_idx_stat(mem,
-                                MEM_CGROUP_STAT_RSS, &idx_val);
-                        val += idx_val;
-                        val <<= PAGE_SHIFT;
-                } else
+                if (name == RES_USAGE)
+                        val = mem_cgroup_usage(mem, false);
+                else
                         val = res_counter_read_u64(&mem->res, name);
                 break;
         case _MEMSWAP:
-                if (name == RES_USAGE && mem_cgroup_is_root(mem)) {
-                        mem_cgroup_get_recursive_idx_stat(mem,
-                                MEM_CGROUP_STAT_CACHE, &idx_val);
-                        val = idx_val;
-                        mem_cgroup_get_recursive_idx_stat(mem,
-                                MEM_CGROUP_STAT_RSS, &idx_val);
-                        val += idx_val;
-                        mem_cgroup_get_recursive_idx_stat(mem,
-                                MEM_CGROUP_STAT_SWAPOUT, &idx_val);
-                        val += idx_val;
-                        val <<= PAGE_SHIFT;
-                } else
+                if (name == RES_USAGE)
+                        val = mem_cgroup_usage(mem, true);
+                else
                         val = res_counter_read_u64(&mem->memsw, name);
                 break;
         default: