mm: try_to_free_swap replaces remove_exclusive_swap_page

[mv-sheeva.git] / mm / swapfile.c

diff --git a/mm/swapfile.c b/mm/swapfile.c
index bfd4ee59cb88d7ce10162bfcf3209701bdbc3bce..f436018276073b0e7633514ec1f31943a5bfd51d 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -348,68 +348,23 @@ int reuse_swap_page(struct page *page)
 }
 
 /*
- * Work out if there are any other processes sharing this
- * swap cache page. Free it if you can. Return success.
+ * If swap is getting full, or if there are no more mappings of this page,
+ * then try_to_free_swap is called to free its swap space.
  */
-static int remove_exclusive_swap_page_count(struct page *page, int count)
+int try_to_free_swap(struct page *page)
 {
-       int retval;
-       struct swap_info_struct * p;
-       swp_entry_t entry;
-
        VM_BUG_ON(!PageLocked(page));
 
        if (!PageSwapCache(page))
                return 0;
        if (PageWriteback(page))
                return 0;
-       if (page_count(page) != count) /* us + cache + ptes */
-               return 0;
-
-       entry.val = page_private(page);
-       p = swap_info_get(entry);
-       if (!p)
+       if (page_swapcount(page))
                return 0;
 
-       /* Is the only swap cache user the cache itself? */
-       retval = 0;
-       if (p->swap_map[swp_offset(entry)] == 1) {
-               /* Recheck the page count with the swapcache lock held.. */
-               spin_lock_irq(&swapper_space.tree_lock);
-               if ((page_count(page) == count) && !PageWriteback(page)) {
-                       __delete_from_swap_cache(page);
-                       SetPageDirty(page);
-                       retval = 1;
-               }
-               spin_unlock_irq(&swapper_space.tree_lock);
-       }
-       spin_unlock(&swap_lock);
-
-       if (retval) {
-               swap_free(entry);
-               page_cache_release(page);
-       }
-
-       return retval;
-}
-
-/*
- * Most of the time the page should have two references: one for the
- * process and one for the swap cache.
- */
-int remove_exclusive_swap_page(struct page *page)
-{
-       return remove_exclusive_swap_page_count(page, 2);
-}
-
-/*
- * The pageout code holds an extra reference to the page.  That raises
- * the reference count to test for to 2 for a page that is only in the
- * swap cache plus 1 for each process that maps the page.
- */
-int remove_exclusive_swap_page_ref(struct page *page)
-{
-       return remove_exclusive_swap_page_count(page, 2 + page_mapcount(page));
+       delete_from_swap_cache(page);
+       SetPageDirty(page);
+       return 1;
 }
 
 /*
@@ -436,13 +391,12 @@ void free_swap_and_cache(swp_entry_t entry)
                spin_unlock(&swap_lock);
        }
        if (page) {
-               int one_user;
-
-               one_user = (page_count(page) == 2);
-               /* Only cache user (+us), or swap space full? Free it! */
-               /* Also recheck PageSwapCache after page is locked (above) */
+               /*
+                * Not mapped elsewhere, or swap space full? Free it!
+                * Also recheck PageSwapCache now page is locked (above).
+                */
                if (PageSwapCache(page) && !PageWriteback(page) &&
-                                       (one_user || vm_swap_full())) {
+                               (!page_mapped(page) || vm_swap_full())) {
                        delete_from_swap_cache(page);
                        SetPageDirty(page);
                }