In one embodiment, non-transitory computer-readable medium stores instructions for implementing a file system, which include operations for acquiring an exclusive lock on a first node in an ordered tree data-structure, and adding an identifier and index of the first node to a path data structure. If the value of the index in the first node is non-zero, then each exclusive lock acquired between the first node and the root of the tree data structure is released. In any case, the operation proceeds to a second node, which is addressed at the index on the first node. In one embodiment, operations further include acquiring an exclusive lock on the second node, and, if the second node is a leaf node, performing updates to the second node, and then releasing each exclusive lock in the data-structure.