For the last couple of weeks, I’ve been playing on a PoC implementation of a file system for the Linux kernel. The goal is to address a fundamental limitation in how container images are stored: the existing overlay model deduplicates at the layer level, but once you want per-file deduplication — so that identical files across different images share a single copy on disk and in the page cache — the current architecture gets in the way and requires awkward workarounds involving hard links or filesystem-specific reflinks.