mm: zpool: return pool size in pages

All zswap backends track their pool sizes in pages.  Currently they
multiply by PAGE_SIZE for zswap, only for zswap to divide again in order
to do limit math.  Report pages directly.

Link: https://lkml.kernel.org/r/20240312153901.3441-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/zpool.h

@@ -53,7 +53,7 @@ void *zpool_map_handle(struct zpool *pool, unsigned long handle,
 
 void zpool_unmap_handle(struct zpool *pool, unsigned long handle);
 
-u64 zpool_get_total_size(struct zpool *pool);
+u64 zpool_get_total_pages(struct zpool *pool);
 
 
 /**
@@ -91,7 +91,7 @@ struct zpool_driver {
 				enum zpool_mapmode mm);
 	void (*unmap)(void *pool, unsigned long handle);
 
-	u64 (*total_size)(void *pool);
+	u64 (*total_pages)(void *pool);
 };
 
 void zpool_register_driver(struct zpool_driver *driver);

mm/z3fold.c

@@ -1237,12 +1237,12 @@ static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
 }
 
 /**
- * z3fold_get_pool_size() - gets the z3fold pool size in pages
+ * z3fold_get_pool_pages() - gets the z3fold pool size in pages
  * @pool:	pool whose size is being queried
  *
  * Returns: size in pages of the given pool.
  */
-static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
+static u64 z3fold_get_pool_pages(struct z3fold_pool *pool)
 {
 	return atomic64_read(&pool->pages_nr);
 }
@@ -1402,9 +1402,9 @@ static void z3fold_zpool_unmap(void *pool, unsigned long handle)
 	z3fold_unmap(pool, handle);
 }
 
-static u64 z3fold_zpool_total_size(void *pool)
+static u64 z3fold_zpool_total_pages(void *pool)
 {
-	return z3fold_get_pool_size(pool) * PAGE_SIZE;
+	return z3fold_get_pool_pages(pool);
 }
 
 static struct zpool_driver z3fold_zpool_driver = {
@@ -1417,7 +1417,7 @@ static struct zpool_driver z3fold_zpool_driver = {
 	.free =		z3fold_zpool_free,
 	.map =		z3fold_zpool_map,
 	.unmap =	z3fold_zpool_unmap,
-	.total_size =	z3fold_zpool_total_size,
+	.total_pages =	z3fold_zpool_total_pages,
 };
 
 MODULE_ALIAS("zpool-z3fold");

mm/zbud.c

@@ -365,13 +365,13 @@ static void zbud_unmap(struct zbud_pool *pool, unsigned long handle)
 }
 
 /**
- * zbud_get_pool_size() - gets the zbud pool size in pages
+ * zbud_get_pool_pages() - gets the zbud pool size in pages
  * @pool:	pool whose size is being queried
  *
  * Returns: size in pages of the given pool.  The pool lock need not be
  * taken to access pages_nr.
  */
-static u64 zbud_get_pool_size(struct zbud_pool *pool)
+static u64 zbud_get_pool_pages(struct zbud_pool *pool)
 {
 	return pool->pages_nr;
 }
@@ -410,9 +410,9 @@ static void zbud_zpool_unmap(void *pool, unsigned long handle)
 	zbud_unmap(pool, handle);
 }
 
-static u64 zbud_zpool_total_size(void *pool)
+static u64 zbud_zpool_total_pages(void *pool)
 {
-	return zbud_get_pool_size(pool) * PAGE_SIZE;
+	return zbud_get_pool_pages(pool);
 }
 
 static struct zpool_driver zbud_zpool_driver = {
@@ -425,7 +425,7 @@ static struct zpool_driver zbud_zpool_driver = {
 	.free =		zbud_zpool_free,
 	.map =		zbud_zpool_map,
 	.unmap =	zbud_zpool_unmap,
-	.total_size =	zbud_zpool_total_size,
+	.total_pages =	zbud_zpool_total_pages,
 };
 
 MODULE_ALIAS("zpool-zbud");

mm/zpool.c

@@ -321,16 +321,16 @@ void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
 }
 
 /**
- * zpool_get_total_size() - The total size of the pool
+ * zpool_get_total_pages() - The total size of the pool
  * @zpool:	The zpool to check
  *
- * This returns the total size in bytes of the pool.
+ * This returns the total size in pages of the pool.
  *
- * Returns: Total size of the zpool in bytes.
+ * Returns: Total size of the zpool in pages.
  */
-u64 zpool_get_total_size(struct zpool *zpool)
+u64 zpool_get_total_pages(struct zpool *zpool)
 {
-	return zpool->driver->total_size(zpool->pool);
+	return zpool->driver->total_pages(zpool->pool);
 }
 
 /**

mm/zsmalloc.c

@@ -399,9 +399,9 @@ static void zs_zpool_unmap(void *pool, unsigned long handle)
 	zs_unmap_object(pool, handle);
 }
 
-static u64 zs_zpool_total_size(void *pool)
+static u64 zs_zpool_total_pages(void *pool)
 {
-	return zs_get_total_pages(pool) << PAGE_SHIFT;
+	return zs_get_total_pages(pool);
 }
 
 static struct zpool_driver zs_zpool_driver = {
@@ -414,7 +414,7 @@ static struct zpool_driver zs_zpool_driver = {
 	.free =			  zs_zpool_free,
 	.map =			  zs_zpool_map,
 	.unmap =		  zs_zpool_unmap,
-	.total_size =		  zs_zpool_total_size,
+	.total_pages =		  zs_zpool_total_pages,
 };
 
 MODULE_ALIAS("zpool-zsmalloc");

mm/zswap.c

@@ -513,18 +513,18 @@ static unsigned long zswap_accept_thr_pages(void)
 unsigned long zswap_total_pages(void)
 {
 	struct zswap_pool *pool;
-	u64 total = 0;
+	unsigned long total = 0;
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(pool, &zswap_pools, list) {
 		int i;
 
 		for (i = 0; i < ZSWAP_NR_ZPOOLS; i++)
-			total += zpool_get_total_size(pool->zpools[i]);
+			total += zpool_get_total_pages(pool->zpools[i]);
 	}
 	rcu_read_unlock();
 
-	return total >> PAGE_SHIFT;
+	return total;
 }
 
 /*********************************