linux-kernel - [PATCH v4 1/4] mm: zswap: zswap_is_folio_same

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Message-Id: <20240819021621.29125-2-kanchana.p.sridhar@intel.com>
Date: Sun, 18 Aug 2024 19:16:18 -0700
From: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	hannes@...xchg.org,
	yosryahmed@...gle.com,
	nphamcs@...il.com,
	ryan.roberts@....com,
	ying.huang@...el.com,
	21cnbao@...il.com,
	akpm@...ux-foundation.org
Cc: nanhai.zou@...el.com,
	wajdi.k.feghali@...el.com,
	vinodh.gopal@...el.com,
	kanchana.p.sridhar@...el.com
Subject: [PATCH v4 1/4] mm: zswap: zswap_is_folio_same_filled() takes an index in the folio.

This change is being made so that zswap_store can process mTHP folios.

Modified zswap_is_folio_same_filled() to work for any-order folios,
by accepting an additional "index" parameter to arrive at the
page within the folio to run the same-filled page check.

Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
---
 mm/zswap.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index df66ab102d27..6434e76a4ea3 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1419,14 +1419,14 @@ static void shrink_worker(struct work_struct *w)
 /*********************************
 * same-filled functions
 **********************************/
-static bool zswap_is_folio_same_filled(struct folio *folio, unsigned long *value)
+static bool zswap_is_folio_same_filled(struct folio *folio, long index, unsigned long *value)
 {
 	unsigned long *data;
 	unsigned long val;
 	unsigned int pos, last_pos = PAGE_SIZE / sizeof(*data) - 1;
 	bool ret = false;
 
-	data = kmap_local_folio(folio, 0);
+	data = kmap_local_folio(folio, index * PAGE_SIZE);
 	val = data[0];
 
 	if (val != data[last_pos])
@@ -1496,7 +1496,7 @@ bool zswap_store(struct folio *folio)
 		goto reject;
 	}
 
-	if (zswap_is_folio_same_filled(folio, &value)) {
+	if (zswap_is_folio_same_filled(folio, 0, &value)) {
 		entry->length = 0;
 		entry->value = value;
 		atomic_inc(&zswap_same_filled_pages);
-- 
2.27.0