1 files changed, 4 insertions, 1 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index f5a04eb9a2ac..81123277c2b8 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -206,10 +206,11 @@ int add_extent_mapping(struct extent_map_tree *tree,
         struct extent_map *merge = NULL;
         struct rb_node *rb;
 
+        BUG_ON(spin_trylock(&tree->lock));
         rb = tree_insert(&tree->map, em->start, &em->rb_node);
         if (rb) {
-                merge = rb_entry(rb, struct extent_map, rb_node);
                 ret = -EEXIST;
+                free_extent_map(merge);
                 goto out;
         }
         atomic_inc(&em->refs);
@@ -268,6 +269,7 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
         struct rb_node *next = NULL;
         u64 end = range_end(start, len);
 
+        BUG_ON(spin_trylock(&tree->lock));
         em = tree->last;
         if (em && end > em->start && start < extent_map_end(em))
                 goto found;
@@ -318,6 +320,7 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
 {
         int ret = 0;
 
+        BUG_ON(spin_trylock(&tree->lock));
         rb_erase(&em->rb_node, &tree->map);
         em->in_tree = 0;
         if (tree->last == em)