linux-kernel - [PATCH] mm: Extend 'usage' parameter so that cluster_swap_free

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Message-Id: <20240708061502.9006-1-21cnbao@gmail.com>
Date: Mon,  8 Jul 2024 18:15:02 +1200
From: Barry Song <21cnbao@...il.com>
To: akpm@...ux-foundation.org,
	linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org,
	Barry Song <v-songbaohua@...o.com>,
	"Huang, Ying" <ying.huang@...el.com>,
	Chris Li <chrisl@...nel.org>,
	Ryan Roberts <ryan.roberts@....com>,
	Kairui Song <kasong@...cent.com>,
	David Hildenbrand <david@...hat.com>,
	Chuanhua Han <hanchuanhua@...o.com>
Subject: [PATCH] mm: Extend 'usage' parameter so that cluster_swap_free_nr() can be reused

From: Barry Song <v-songbaohua@...o.com>

Extend a usage parameter so that cluster_swap_free_nr() can be reused by
both swapcache_clear() and swap_free().
__swap_entry_free() is quite similar but more tricky as it requires the
return value of __swap_entry_free_locked() which cluster_swap_free_nr()
doesn't support.

Cc: "Huang, Ying" <ying.huang@...el.com>
Cc: Chris Li <chrisl@...nel.org>
Cc: Ryan Roberts <ryan.roberts@....com>
Cc: Kairui Song <kasong@...cent.com>
Cc: David Hildenbrand <david@...hat.com>
Cc: Chuanhua Han <hanchuanhua@...o.com>
Signed-off-by: Barry Song <v-songbaohua@...o.com>
---
 mm/swapfile.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index f7224bc1320c..70c4a9132672 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1352,7 +1352,8 @@ static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry)
 }
 
 static void cluster_swap_free_nr(struct swap_info_struct *sis,
-		unsigned long offset, int nr_pages)
+		unsigned long offset, int nr_pages,
+		unsigned char usage)
 {
 	struct swap_cluster_info *ci;
 	DECLARE_BITMAP(to_free, BITS_PER_LONG) = { 0 };
@@ -1363,7 +1364,7 @@ static void cluster_swap_free_nr(struct swap_info_struct *sis,
 		nr = min(BITS_PER_LONG, nr_pages);
 		for (i = 0; i < nr; i++) {
 			if (!__swap_entry_free_locked(sis, offset + i, 1))
-				bitmap_set(to_free, i, 1);
+				bitmap_set(to_free, i, usage);
 		}
 		if (!bitmap_empty(to_free, BITS_PER_LONG)) {
 			unlock_cluster_or_swap_info(sis, ci);
@@ -1396,7 +1397,7 @@ void swap_free_nr(swp_entry_t entry, int nr_pages)
 
 	while (nr_pages) {
 		nr = min_t(int, nr_pages, SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER);
-		cluster_swap_free_nr(sis, offset, nr);
+		cluster_swap_free_nr(sis, offset, nr, 1);
 		offset += nr;
 		nr_pages -= nr;
 	}
@@ -3492,15 +3493,9 @@ int swapcache_prepare(swp_entry_t entry)
 
 void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry)
 {
-	struct swap_cluster_info *ci;
 	unsigned long offset = swp_offset(entry);
-	unsigned char usage;
 
-	ci = lock_cluster_or_swap_info(si, offset);
-	usage = __swap_entry_free_locked(si, offset, SWAP_HAS_CACHE);
-	unlock_cluster_or_swap_info(si, ci);
-	if (!usage)
-		free_swap_slot(entry);
+	cluster_swap_free_nr(si, offset, 1, SWAP_HAS_CACHE);
 }
 
 struct swap_info_struct *swp_swap_info(swp_entry_t entry)
-- 
2.39.2