Just sharing an issue I've run across in this domain.
There is a difference between a new file appearing on disk and when the file has been filled and is whole. For example if a file is FTP'd to a directory there is a period of time where the new file exists, however it has a zero byte size or partial byte size.
There are various ways to get around this depending on your circumstances, but it's dangerous to assume that the file system performs atomic operations on disk.
Still looking. Still searching.