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Date: Mon, 11 Mar 2024 22:36:37 -0400
From: Johannes Weiner <hannes@cmpxchg.org>
To: Yosry Ahmed <yosryahmed@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Nhat Pham <nphamcs@gmail.com>,
	Chengming Zhou <zhouchengming@bytedance.com>, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm: zpool: return pool size in pages
Message-ID: <20240312023637.GB22705@cmpxchg.org>
References: <20240311161214.1145168-1-hannes@cmpxchg.org>
 <20240311161214.1145168-2-hannes@cmpxchg.org>
 <Ze-Bsr8lfC1lm1u7@google.com>
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In-Reply-To: <Ze-Bsr8lfC1lm1u7@google.com>

On Mon, Mar 11, 2024 at 10:12:02PM +0000, Yosry Ahmed wrote:
> On Mon, Mar 11, 2024 at 12:12:14PM -0400, Johannes Weiner wrote:
> > 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.
> 
> Nice. Although I would prefer renaming the zpool interface to
> total_pages and renaming the zpool backends functions as well to use
> pages rather than size.

Ha, I was on the fence, since it's kind of churny. But if you don't
mind, then it works for me as well.

> Either way:
> Acked-by: Yosry Ahmed <yosryahmed@google.com>

Thanks.

diff --git a/include/linux/zpool.h b/include/linux/zpool.h
index 3296438eec06..a67d62b79698 100644
--- a/include/linux/zpool.h
+++ b/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);
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 9bacacd4168c..2ebfed32871b 100644
--- a/mm/z3fold.c
+++ b/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);
+	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");
diff --git a/mm/zbud.c b/mm/zbud.c
index b7d8a22bbf5f..e9836fff9438 100644
--- a/mm/zbud.c
+++ b/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);
+	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");
diff --git a/mm/zpool.c b/mm/zpool.c
index 410808aee7fe..b9fda1fa857d 100644
--- a/mm/zpool.c
+++ b/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 pages of the pool.
  *
  * 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);
 }
 
 /**
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 398f3856817f..b42d3545ca85 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -399,7 +399,7 @@ 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);
 }
@@ -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");
diff --git a/mm/zswap.c b/mm/zswap.c
index 7ed79caf1e1e..9fdf4c76d5ea 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -519,7 +519,7 @@ unsigned long zswap_total_pages(void)
 		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();