[PATCH v3 8/8] mm: swap: replace cluster_swap_free_nr() with swap_entries_put_[map/cache]()

[Kemeng Shi <shikemeng@huaweicloud.com>]

Replace cluster_swap_free_nr() with swap_entries_put_[map/cache]() to
remove repeat code and leverage batch-remove for entries with last flag.
After removing cluster_swap_free_nr, only functions with "_nr" suffix
could free entries spanning cross clusters. Add corresponding description
in comment of swap_entries_put_map_nr() as is first function with "_nr"
suffix and have a non-suffix variant function swap_entries_put_map().

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
---
 mm/swapfile.c | 30 +++++++++++-------------------
 1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 40a7d75c01e8..c46b56d636af 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1512,6 +1512,11 @@ static bool swap_entries_put_map(struct swap_info_struct *si,
 
 }
 
+/*
+ * Only functions with "_nr" suffix are able to free entries spanning
+ * cross multi clusters, so ensure the range is within a single cluster
+ * when freeing entries with functions without "_nr" suffix.
+ */
 static bool swap_entries_put_map_nr(struct swap_info_struct *si,
 				    swp_entry_t entry, int nr)
 {
@@ -1569,21 +1574,6 @@ static void swap_entries_free(struct swap_info_struct *si,
 		partial_free_cluster(si, ci);
 }
 
-static void cluster_swap_free_nr(struct swap_info_struct *si,
-		unsigned long offset, int nr_pages,
-		unsigned char usage)
-{
-	struct swap_cluster_info *ci;
-	unsigned long end = offset + nr_pages;
-
-	ci = lock_cluster(si, offset);
-	do {
-		swap_entry_put_locked(si, ci, swp_entry(si->type, offset),
-				      usage);
-	} while (++offset < end);
-	unlock_cluster(ci);
-}
-
 /*
  * Caller has made sure that the swap device corresponding to entry
  * is still around or has not been recycled.
@@ -1600,7 +1590,7 @@ 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, 1);
+		swap_entries_put_map(sis, swp_entry(sis->type, offset), nr);
 		offset += nr;
 		nr_pages -= nr;
 	}
@@ -3623,11 +3613,13 @@ int swapcache_prepare(swp_entry_t entry, int nr)
 	return __swap_duplicate(entry, SWAP_HAS_CACHE, nr);
 }
 
+/*
+ * Caller should ensure entries belong to the same folio so
+ * the entries won't span cross cluster boundary.
+ */
 void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr)
 {
-	unsigned long offset = swp_offset(entry);
-
-	cluster_swap_free_nr(si, offset, nr, SWAP_HAS_CACHE);
+	swap_entries_put_cache(si, entry, nr);
 }
 
 struct swap_info_struct *swp_swap_info(swp_entry_t entry)
-- 
2.30.0