mm: swap: zswap: maybe_preload & refactoring

[mirror_ubuntu-zesty-kernel.git] / mm / zswap.c

diff --git a/mm/zswap.c b/mm/zswap.c
index 2d5727baed5988c23ca4252a601ebaf734820b04..09208c7c86f3e010b91ce9c5f10cd29241c76d41 100644 (file)
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -446,75 +446,14 @@ enum zswap_get_swap_ret {
 static int zswap_get_swap_cache_page(swp_entry_t entry,
                                struct page **retpage)
 {
-       struct page *found_page, *new_page = NULL;
-       struct address_space *swapper_space = swap_address_space(entry);
-       int err;
+       bool page_was_allocated;
 
-       *retpage = NULL;
-       do {
-               /*
-                * First check the swap cache.  Since this is normally
-                * called after lookup_swap_cache() failed, re-calling
-                * that would confuse statistics.
-                */
-               found_page = find_get_page(swapper_space, entry.val);
-               if (found_page)
-                       break;
-
-               /*
-                * Get a new page to read into from swap.
-                */
-               if (!new_page) {
-                       new_page = alloc_page(GFP_KERNEL);
-                       if (!new_page)
-                               break; /* Out of memory */
-               }
-
-               /*
-                * call radix_tree_preload() while we can wait.
-                */
-               err = radix_tree_preload(GFP_KERNEL);
-               if (err)
-                       break;
-
-               /*
-                * Swap entry may have been freed since our caller observed it.
-                */
-               err = swapcache_prepare(entry);
-               if (err == -EEXIST) { /* seems racy */
-                       radix_tree_preload_end();
-                       continue;
-               }
-               if (err) { /* swp entry is obsolete ? */
-                       radix_tree_preload_end();
-                       break;
-               }
-
-               /* May fail (-ENOMEM) if radix-tree node allocation failed. */
-               __set_page_locked(new_page);
-               SetPageSwapBacked(new_page);
-               err = __add_to_swap_cache(new_page, entry);
-               if (likely(!err)) {
-                       radix_tree_preload_end();
-                       lru_cache_add_anon(new_page);
-                       *retpage = new_page;
-                       return ZSWAP_SWAPCACHE_NEW;
-               }
-               radix_tree_preload_end();
-               ClearPageSwapBacked(new_page);
-               __clear_page_locked(new_page);
-               /*
-                * add_to_swap_cache() doesn't return -EEXIST, so we can safely
-                * clear SWAP_HAS_CACHE flag.
-                */
-               swapcache_free(entry);
-       } while (err != -ENOMEM);
-
-       if (new_page)
-               page_cache_release(new_page);
-       if (!found_page)
+       *retpage = __read_swap_cache_async(entry, GFP_KERNEL,
+                       NULL, 0, &page_was_allocated);
+       if (page_was_allocated)
+               return ZSWAP_SWAPCACHE_NEW;
+       if (!*retpage)
                return ZSWAP_SWAPCACHE_FAIL;
-       *retpage = found_page;
        return ZSWAP_SWAPCACHE_EXIST;
 }