mm/swapfile: remove page_swapcount()

By restructuring folio_swapped(), it can use swap_swapcount() instead of
page_swapcount().  It's even a little more efficient.

Link: https://lkml.kernel.org/r/20220902194653.1739778-10-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 469d9af86be2f11b6f3d8cb9bc337f2e491dd097..e0aaeac5c829d68f4c8026988c33dbbc3052ae54 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1431,30 +1431,6 @@ void swapcache_free_entries(swp_entry_t *entries, int n)
                spin_unlock(&p->lock);
 }
 
-/*
- * How many references to page are currently swapped out?
- * This does not give an exact answer when swap count is continued,
- * but does include the high COUNT_CONTINUED flag to allow for that.
- */
-static int page_swapcount(struct page *page)
-{
-       int count = 0;
-       struct swap_info_struct *p;
-       struct swap_cluster_info *ci;
-       swp_entry_t entry;
-       unsigned long offset;
-
-       entry.val = page_private(page);
-       p = _swap_info_get(entry);
-       if (p) {
-               offset = swp_offset(entry);
-               ci = lock_cluster_or_swap_info(p, offset);
-               count = swap_count(p->swap_map[offset]);
-               unlock_cluster_or_swap_info(p, ci);
-       }
-       return count;
-}
-
 int __swap_count(swp_entry_t entry)
 {
        struct swap_info_struct *si;
@@ -1469,11 +1445,16 @@ int __swap_count(swp_entry_t entry)
        return count;
 }
 
+/*
+ * How many references to @entry are currently swapped out?
+ * This does not give an exact answer when swap count is continued,
+ * but does include the high COUNT_CONTINUED flag to allow for that.
+ */
 static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
 {
-       int count = 0;
        pgoff_t offset = swp_offset(entry);
        struct swap_cluster_info *ci;
+       int count;
 
        ci = lock_cluster_or_swap_info(si, offset);
        count = swap_count(si->swap_map[offset]);
@@ -1574,17 +1555,16 @@ unlock_out:
 
 static bool folio_swapped(struct folio *folio)
 {
-       swp_entry_t entry;
-       struct swap_info_struct *si;
+       swp_entry_t entry = folio_swap_entry(folio);
+       struct swap_info_struct *si = _swap_info_get(entry);
+
+       if (!si)
+               return false;
 
        if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!folio_test_large(folio)))
-               return page_swapcount(&folio->page) != 0;
+               return swap_swapcount(si, entry) != 0;
 
-       entry = folio_swap_entry(folio);
-       si = _swap_info_get(entry);
-       if (si)
-               return swap_page_trans_huge_swapped(si, entry);
-       return false;
+       return swap_page_trans_huge_swapped(si, entry);
 }
 
 /*