dax: New fault locking

[sfrench/cifs-2.6.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index f2479af09da91ae8767b009c294bef2e3e75fc2e..7b9a4b180cae2a8ae3c4d24e17a27db03e1f91fd 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -160,13 +160,15 @@ static void page_cache_tree_delete(struct address_space *mapping,
                        return;
 
        /*
-        * Track node that only contains shadow entries.
+        * Track node that only contains shadow entries. DAX mappings contain
+        * no shadow entries and may contain other exceptional entries so skip
+        * those.
         *
         * Avoid acquiring the list_lru lock if already tracked.  The
         * list_empty() test is safe as node->private_list is
         * protected by mapping->tree_lock.
         */
-       if (!workingset_node_pages(node) &&
+       if (!dax_mapping(mapping) && !workingset_node_pages(node) &&
            list_empty(&node->private_list)) {
                node->private_data = mapping;
                list_lru_add(&workingset_shadow_nodes, &node->private_list);
@@ -597,14 +599,24 @@ static int page_cache_tree_insert(struct address_space *mapping,
                if (!radix_tree_exceptional_entry(p))
                        return -EEXIST;
 
-               if (WARN_ON(dax_mapping(mapping)))
-                       return -EINVAL;
-
-               if (shadowp)
-                       *shadowp = p;
                mapping->nrexceptional--;
-               if (node)
-                       workingset_node_shadows_dec(node);
+               if (!dax_mapping(mapping)) {
+                       if (shadowp)
+                               *shadowp = p;
+                       if (node)
+                               workingset_node_shadows_dec(node);
+               } else {
+                       /* DAX can replace empty locked entry with a hole */
+                       WARN_ON_ONCE(p !=
+                               (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY |
+                                        RADIX_DAX_ENTRY_LOCK));
+                       /* DAX accounts exceptional entries as normal pages */
+                       if (node)
+                               workingset_node_pages_dec(node);
+                       /* Wakeup waiters for exceptional entry lock */
+                       dax_wake_mapping_entry_waiter(mapping, page->index,
+                                                     false);
+               }
        }
        radix_tree_replace_slot(slot, page);
        mapping->nrpages++;