[PATCH] mempool: add page allocator

This will be used by the next patch in the series to replace duplicate
mempool-backed page allocators in 2 places in the kernel.  It is also likely
that there will be more users in the future.

Signed-off-by: Matthew Dobson <colpatch@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/mempool.h

@@ -38,4 +38,16 @@ extern void mempool_free(void *element, mempool_t *pool);
 void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data);
 void mempool_free_slab(void *element, void *pool_data);
 
+/*
+ * A mempool_alloc_t and mempool_free_t for a simple page allocator that
+ * allocates pages of the order specified by pool_data
+ */
+void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data);
+void mempool_free_pages(void *element, void *pool_data);
+static inline mempool_t *mempool_create_page_pool(int min_nr, int order)
+{
+	return mempool_create(min_nr, mempool_alloc_pages, mempool_free_pages,
+			      (void *)(long)order);
+}
+
 #endif /* _LINUX_MEMPOOL_H */

mm/mempool.c

@@ -289,3 +289,21 @@ void mempool_free_slab(void *element, void *pool_data)
 	kmem_cache_free(mem, element);
 }
 EXPORT_SYMBOL(mempool_free_slab);
+
+/*
+ * A simple mempool-backed page allocator that allocates pages
+ * of the order specified by pool_data.
+ */
+void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
+{
+	int order = (int)(long)pool_data;
+	return alloc_pages(gfp_mask, order);
+}
+EXPORT_SYMBOL(mempool_alloc_pages);
+
+void mempool_free_pages(void *element, void *pool_data)
+{
+	int order = (int)(long)pool_data;
+	__free_pages(element, order);
+}
+EXPORT_SYMBOL(mempool_free_pages);