linux-kernel - [RFC PATCH 3/9] mm: zswap: refactor limit checking from zswap

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Message-ID: <20240325235018.2028408-4-yosryahmed@google.com>
Date: Mon, 25 Mar 2024 23:50:11 +0000
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Johannes Weiner <hannes@...xchg.org>, Nhat Pham <nphamcs@...il.com>, 
	Chengming Zhou <chengming.zhou@...ux.dev>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	Yosry Ahmed <yosryahmed@...gle.com>
Subject: [RFC PATCH 3/9] mm: zswap: refactor limit checking from zswap_store()

Refactor limit and acceptance threshold checking outside of
zswap_store(). This code will be moved around in a following patch, so
it would be cleaner to move a function call around.

Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
---
 mm/zswap.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index ff1975afb7e3d..6b890c8590ef7 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1415,6 +1415,21 @@ static void zswap_fill_page(void *ptr, unsigned long value)
 	memset_l(page, value, PAGE_SIZE / sizeof(unsigned long));
 }
 
+static bool zswap_check_limit(void)
+{
+	unsigned long cur_pages = zswap_total_pages();
+	unsigned long thr = zswap_accept_thr_pages();
+	unsigned long max_pages = zswap_max_pages();
+
+	if (cur_pages >= max_pages) {
+		zswap_pool_limit_hit++;
+		zswap_pool_reached_full = true;
+	} else if (zswap_pool_reached_full && cur_pages <= thr) {
+		zswap_pool_reached_full = false;
+	}
+	return !zswap_pool_reached_full;
+}
+
 bool zswap_store(struct folio *folio)
 {
 	swp_entry_t swp = folio->swap;
@@ -1422,7 +1437,6 @@ bool zswap_store(struct folio *folio)
 	struct xarray *tree = swap_zswap_tree(swp);
 	struct obj_cgroup *objcg = NULL;
 	struct mem_cgroup *memcg = NULL;
-	unsigned long max_pages, cur_pages;
 	struct zswap_entry *entry;
 
 	VM_WARN_ON_ONCE(!folio_test_locked(folio));
@@ -1446,22 +1460,8 @@ bool zswap_store(struct folio *folio)
 		mem_cgroup_put(memcg);
 	}
 
-	/* Check global limits */
-	cur_pages = zswap_total_pages();
-	max_pages = zswap_max_pages();
-
-	if (cur_pages >= max_pages) {
-		zswap_pool_limit_hit++;
-		zswap_pool_reached_full = true;
+	if (!zswap_check_limit())
 		goto reject;
-	}
-
-	if (zswap_pool_reached_full) {
-		if (cur_pages > zswap_accept_thr_pages())
-			goto reject;
-		else
-			zswap_pool_reached_full = false;
-	}
 
 	/* allocate entry */
 	entry = zswap_entry_cache_alloc(GFP_KERNEL, folio_nid(folio));
-- 
2.44.0.396.g6e790dbe36-goog