In a shortened session in the filesystem track at the 2026 <a
href="https://events.linuxfoundation.org/lsfmmbpf/">Linux Storage,
Filesystem, Memory Management, and BPF Summit</a>, Amir Goldstein gave an
update on the <a href="https://docs.kernel.org/filesystems/overlayfs.html">overlayfs
union filesystem</a>. There are some new features over the last few years
that he wanted to mention, along with looking at the status of nesting
overlayfs layers. The <a href="https://lwn.net/Articles/922851/">composefs use case</a>
that was <a href="https://lwn.net/Articles/933616/">discussed at the summit in 2023</a>
has led to some interesting changes to overlayfs.