Btrfs: fix ->iterate_shared() by upgrading i_rwsem for delayed nodes

[cascardo/linux.git] / fs / btrfs / delayed-inode.c

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 61561c2..d3aaabb 100644 (file)
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1606,15 +1606,23 @@ int btrfs_inode_delayed_dir_index_count(struct inode *inode)
        return 0;
 }
 
-void btrfs_get_delayed_items(struct inode *inode, struct list_head *ins_list,
-                            struct list_head *del_list)
+bool btrfs_readdir_get_delayed_items(struct inode *inode,
+                                    struct list_head *ins_list,
+                                    struct list_head *del_list)
 {
        struct btrfs_delayed_node *delayed_node;
        struct btrfs_delayed_item *item;
 
        delayed_node = btrfs_get_delayed_node(inode);
        if (!delayed_node)
-               return;
+               return false;
+
+       /*
+        * We can only do one readdir with delayed items at a time because of
+        * item->readdir_list.
+        */
+       inode_unlock_shared(inode);
+       inode_lock(inode);
 
        mutex_lock(&delayed_node->mutex);
        item = __btrfs_first_delayed_insertion_item(delayed_node);
@@ -1641,10 +1649,13 @@ void btrfs_get_delayed_items(struct inode *inode, struct list_head *ins_list,
         * requeue or dequeue this delayed node.
         */
        atomic_dec(&delayed_node->refs);
+
+       return true;
 }
 
-void btrfs_put_delayed_items(struct list_head *ins_list,
-                            struct list_head *del_list)
+void btrfs_readdir_put_delayed_items(struct inode *inode,
+                                    struct list_head *ins_list,
+                                    struct list_head *del_list)
 {
        struct btrfs_delayed_item *curr, *next;
 
@@ -1659,6 +1670,12 @@ void btrfs_put_delayed_items(struct list_head *ins_list,
                if (atomic_dec_and_test(&curr->refs))
                        kfree(curr);
        }
+
+       /*
+        * The VFS is going to do up_read(), so we need to downgrade back to a
+        * read lock.
+        */
+       downgrade_write(&inode->i_rwsem);
 }
 
 int btrfs_should_delete_dir_index(struct list_head *del_list,