mm: keep page cache radix tree nodes in check

[cascardo/linux.git] / mm / truncate.c

diff --git a/mm/truncate.c b/mm/truncate.c
index 0db9258..e5cc39a 100644 (file)
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -25,6 +25,9 @@
 static void clear_exceptional_entry(struct address_space *mapping,
                                    pgoff_t index, void *entry)
 {
+       struct radix_tree_node *node;
+       void **slot;
+
        /* Handled by shmem itself */
        if (shmem_mapping(mapping))
                return;
@@ -35,8 +38,27 @@ static void clear_exceptional_entry(struct address_space *mapping,
         * without the tree itself locked.  These unlocked entries
         * need verification under the tree lock.
         */
-       if (radix_tree_delete_item(&mapping->page_tree, index, entry) == entry)
-               mapping->nrshadows--;
+       if (!__radix_tree_lookup(&mapping->page_tree, index, &node, &slot))
+               goto unlock;
+       if (*slot != entry)
+               goto unlock;
+       radix_tree_replace_slot(slot, NULL);
+       mapping->nrshadows--;
+       if (!node)
+               goto unlock;
+       workingset_node_shadows_dec(node);
+       /*
+        * Don't track node without shadow entries.
+        *
+        * Avoid acquiring the list_lru lock if already untracked.
+        * The list_empty() test is safe as node->private_list is
+        * protected by mapping->tree_lock.
+        */
+       if (!workingset_node_shadows(node) &&
+           !list_empty(&node->private_list))
+               list_lru_del(&workingset_shadow_nodes, &node->private_list);
+       __radix_tree_delete_node(&mapping->page_tree, node);
+unlock:
        spin_unlock_irq(&mapping->tree_lock);
 }