Brainstorming:
Datalogging system will write to a buffer that's the size of one flash page. When the buffer is full, its contents are written to flash.
File system is flat: every file is in the root directory. When a new file is created, it is written to the first available page, and as the file grows, its contents are written in the next available pages. When flash is full, the oldest file is deleted.
Pages are linked together?