1 files changed, 67 insertions, 11 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 66b567216432..5e7cbdaf725d 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -156,6 +156,25 @@ static bool swap_is_has_cache(struct swap_info_struct *si,
 	return true;
 }
 
+static bool swap_is_last_map(struct swap_info_struct *si,
+		unsigned long offset, int nr_pages, bool *has_cache)
+{
+	unsigned char *map = si->swap_map + offset;
+	unsigned char *map_end = map + nr_pages;
+	unsigned char count = *map;
+
+	if (swap_count(count) != 1)
+		return false;
+
+	while (++map < map_end) {
+		if (*map != count)
+			return false;
+	}
+
+	*has_cache = !!(count & SWAP_HAS_CACHE);
+	return true;
+}
+
 /*
  * returns number of pages in the folio that backs the swap entry. If positive,
  * the folio was reclaimed. If negative, the folio was not reclaimed. If 0, no
@@ -1469,6 +1488,53 @@ static unsigned char __swap_entry_free(struct swap_info_struct *si,
 	return usage;
 }
 
+static bool __swap_entries_free(struct swap_info_struct *si,
+		swp_entry_t entry, int nr)
+{
+	unsigned long offset = swp_offset(entry);
+	unsigned int type = swp_type(entry);
+	struct swap_cluster_info *ci;
+	bool has_cache = false;
+	unsigned char count;
+	int i;
+
+	if (nr <= 1 || swap_count(data_race(si->swap_map[offset])) != 1)
+		goto fallback;
+	/* cross into another cluster */
+	if (nr > SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER)
+		goto fallback;
+
+	ci = lock_cluster_or_swap_info(si, offset);
+	if (!swap_is_last_map(si, offset, nr, &has_cache)) {
+		unlock_cluster_or_swap_info(si, ci);
+		goto fallback;
+	}
+	for (i = 0; i < nr; i++)
+		WRITE_ONCE(si->swap_map[offset + i], SWAP_HAS_CACHE);
+	unlock_cluster_or_swap_info(si, ci);
+
+	if (!has_cache) {
+		for (i = 0; i < nr; i++)
+			zswap_invalidate(swp_entry(si->type, offset + i));
+		spin_lock(&si->lock);
+		swap_entry_range_free(si, entry, nr);
+		spin_unlock(&si->lock);
+	}
+	return has_cache;
+
+fallback:
+	for (i = 0; i < nr; i++) {
+		if (data_race(si->swap_map[offset + i])) {
+			count = __swap_entry_free(si, swp_entry(type, offset + i));
+			if (count == SWAP_HAS_CACHE)
+				has_cache = true;
+		} else {
+			WARN_ON_ONCE(1);
+		}
+	}
+	return has_cache;
+}
+
 /*
  * Drop the last HAS_CACHE flag of swap entries, caller have to
  * ensure all entries belong to the same cgroup.
@@ -1792,11 +1858,9 @@ void free_swap_and_cache_nr(swp_entry_t entry, int nr)
 {
 	const unsigned long start_offset = swp_offset(entry);
 	const unsigned long end_offset = start_offset + nr;
-	unsigned int type = swp_type(entry);
 	struct swap_info_struct *si;
 	bool any_only_cache = false;
 	unsigned long offset;
-	unsigned char count;
 
 	if (non_swap_entry(entry))
 		return;
@@ -1811,15 +1875,7 @@ void free_swap_and_cache_nr(swp_entry_t entry, int nr)
 	/*
 	 * First free all entries in the range.
 	 */
-	for (offset = start_offset; offset < end_offset; offset++) {
-		if (data_race(si->swap_map[offset])) {
-			count = __swap_entry_free(si, swp_entry(type, offset));
-			if (count == SWAP_HAS_CACHE)
-				any_only_cache = true;
-		} else {
-			WARN_ON_ONCE(1);
-		}
-	}
+	any_only_cache = __swap_entries_free(si, entry, nr);
 
 	/*
 	 * Short-circuit the below loop if none of the entries had their