Disclosed are various examples for downloading data objects by enforcing a threshold amount of allocated data. A file sync application determines which data objects to download to the client device such that the total amount of downloaded data meets or falls below the threshold amount of allocated data. File system entries for undownloaded data objects are also downloaded and stored in a file system of the client device. If a process attempts to access an undownloaded data object, the file sync application downloads the data object and evicts another data object, if necessary, according to the threshold amount of allocated data.