[PATCH 2/6] zsmalloc/zram: pass zspage order to zs_create_pool()

[Sergey Senozhatsky]

Allow zsmalloc pool owner to specify max zspage (during
pool creation), so that different pools can have different
characteristics.

Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
 drivers/block/zram/zram_drv.c |  3 ++-
 include/linux/zsmalloc.h      |  2 +-
 mm/zsmalloc.c                 | 11 ++++++++---
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 364323713393..e3ef542f9618 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1253,7 +1253,8 @@ static bool zram_meta_alloc(struct zram *zram, u64 disksize)
 	if (!zram->table)
 		return false;
 
-	zram->mem_pool = zs_create_pool(zram->disk->disk_name);
+	zram->mem_pool = zs_create_pool(zram->disk->disk_name,
+					ZS_DEFAULT_PAGE_ORDER);
 	if (!zram->mem_pool) {
 		vfree(zram->table);
 		return false;
diff --git a/include/linux/zsmalloc.h b/include/linux/zsmalloc.h
index 2110b140e0fa..4a92c5e186ad 100644
--- a/include/linux/zsmalloc.h
+++ b/include/linux/zsmalloc.h
@@ -53,7 +53,7 @@ struct zs_pool_stats {
 
 struct zs_pool;
 
-struct zs_pool *zs_create_pool(const char *name);
+struct zs_pool *zs_create_pool(const char *name, u32 zspage_order);
 void zs_destroy_pool(struct zs_pool *pool);
 
 unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t flags);
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 6ffa32b8b6c8..fa55e0c66f8d 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -369,7 +369,7 @@ static void *zs_zpool_create(const char *name, gfp_t gfp,
 	 * different contexts and its caller must provide a valid
 	 * gfp mask.
 	 */
-	return zs_create_pool(name);
+	return zs_create_pool(name, ZS_DEFAULT_PAGE_ORDER);
 }
 
 static void zs_zpool_destroy(void *pool)
@@ -2177,6 +2177,7 @@ static int zs_register_shrinker(struct zs_pool *pool)
 /**
  * zs_create_pool - Creates an allocation pool to work from.
  * @name: pool name to be created
+ * @zspage_order: maximum order of zspage
  *
  * This function must be called before anything when using
  * the zsmalloc allocator.
@@ -2184,17 +2185,21 @@ static int zs_register_shrinker(struct zs_pool *pool)
  * On success, a pointer to the newly created pool is returned,
  * otherwise NULL.
  */
-struct zs_pool *zs_create_pool(const char *name)
+struct zs_pool *zs_create_pool(const char *name, u32 zspage_order)
 {
 	int i;
 	struct zs_pool *pool;
 	struct size_class *prev_class = NULL;
 
+	if (WARN_ON(zspage_order < ZS_MIN_PAGE_ORDER ||
+		    zspage_order > ZS_MAX_PAGE_ORDER))
+		return NULL;
+
 	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
 	if (!pool)
 		return NULL;
 
-	pool->max_pages_per_zspage = 1U << ZS_MIN_PAGE_ORDER;
+	pool->max_pages_per_zspage = 1U << zspage_order;
 	/* min_alloc_size must be multiple of ZS_ALIGN */
 	pool->min_alloc_size = (pool->max_pages_per_zspage << PAGE_SHIFT) >>
 		OBJ_INDEX_BITS;
-- 
2.38.0.135.g90850a2211-goog