mm/slub: add slub_get_cpu_partial() helper

Add slub_get_cpu_partial() and dummy function to help improve
get_partial_node(). It can help remove #ifdef of CONFIG_SLUB_CPU_PARTIAL
and improve filling cpu partial logic.
Signed-off-by: Xiongwei Song <xiongwei.song@windriver.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

mm/slub.c

@@ -604,11 +604,21 @@ static void slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects)
 	nr_slabs = DIV_ROUND_UP(nr_objects * 2, oo_objects(s->oo));
 	s->cpu_partial_slabs = nr_slabs;
 }
+
+static inline unsigned int slub_get_cpu_partial(struct kmem_cache *s)
+{
+	return s->cpu_partial_slabs;
+}
 #else
 static inline void
 slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects)
 {
 }
+
+static inline unsigned int slub_get_cpu_partial(struct kmem_cache *s)
+{
+	return 0;
+}
 #endif /* CONFIG_SLUB_CPU_PARTIAL */
 
 /*