A storage layer is configured to implement efficient open-close consistency operations. Open close consistency may comprise preserving the original state of a file until the file is closed. The storage layer may be configured to clone a file in response to a file open request. Cloning the file may comprise referencing file data by two separate sets of identifiers. One set may be configured to reflect file modifications, and the other set may be configured to preserve the original state of the file. Subsequent operations configured to modify the file may be performed in reference to one of the sets of identifiers, while the storage layer provides access to the unmodified file through the other set of identifiers. Closing the file may comprise merging the sets of identifiers according to a merge policy.