+/*
+ * Currently used to update mapped file statistics, but the routine can be
+ * generalized to update other statistics as well.
+ */
+void mem_cgroup_update_mapped_file_stat(struct page *page, int val)
+{
+ struct mem_cgroup *mem;
+ struct mem_cgroup_stat *stat;
+ struct mem_cgroup_stat_cpu *cpustat;
+ int cpu;
+ struct page_cgroup *pc;
+
+ if (!page_is_file_cache(page))
+ return;
+
+ pc = lookup_page_cgroup(page);
+ if (unlikely(!pc))
+ return;
+
+ lock_page_cgroup(pc);
+ mem = pc->mem_cgroup;
+ if (!mem)
+ goto done;
+
+ if (!PageCgroupUsed(pc))
+ goto done;
+
+ /*
+ * Preemption is already disabled, we don't need get_cpu()
+ */
+ cpu = smp_processor_id();
+ stat = &mem->stat;
+ cpustat = &stat->cpustat[cpu];
+
+ __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_MAPPED_FILE, val);
+done:
+ unlock_page_cgroup(pc);
+}