The shrinking code used btrfs_next_leaf to find the next item, but
this does not cow the blocks it touches.  This fix calls search_slot after
finding the next item to do appropriate cow and balancing.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
                                break;
                        }
                        leaf = path->nodes[0];
-                       nritems = btrfs_header_nritems(leaf);
+                       btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+                       /*
+                        * btrfs_next_leaf doesn't cow buffers, we have to
+                        * do the search again
+                        */
+                       memcpy(&key, &found_key, sizeof(key));
+                       btrfs_release_path(root, path);
+                       continue;
                }
 
                btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);