slub: Update statistics handling for variable order slabs

Change the statistics to consider that slabs of the same slabcache
can have different number of objects in them since they may be of
different order.

Provide a new sysfs field

	total_objects

which shows the total objects that the allocated slabs of a slabcache
could hold.

Add a max field that holds the largest slab order that was ever used
for a slab cache.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

include/linux/slub_def.h

@@ -48,6 +48,7 @@ struct kmem_cache_node {
 	struct list_head partial;
 #ifdef CONFIG_SLUB_DEBUG
 	atomic_long_t nr_slabs;
+	atomic_long_t total_objects;
 	struct list_head full;
 #endif
 };
@@ -79,6 +80,7 @@ struct kmem_cache {
 	struct kmem_cache_node local_node;
 
 	/* Allocation and freeing of slabs */
+	struct kmem_cache_order_objects max;
 	gfp_t allocflags;	/* gfp flags to use on each alloc */
 	int refcount;		/* Refcount for slab cache destroy */
 	void (*ctor)(struct kmem_cache *, void *);