EROFS (Enhanced Read-Only File System) is a lightweight read-only
file system with modern designs (e.g. no buffer heads, inline
xattrs/data, chunk-based deduplication, multiple devices, etc.) for
scenarios which need high-performance read-only solutions, e.g.
smartphones with Android OS, LiveCDs and high-density hosts with
numerous containers;

It also provides transparent compression and deduplication support to
improve storage density and maintain relatively high compression
ratios, and it implements in-place decompression to temporarily reuse
page cache for compressed data using proper strategies, which is
quite useful for ensuring guaranteed end-to-end runtime decompression
performance under extreme memory pressure without extra cost.

See the documentation at <file:Documentation/filesystems/erofs.rst>
and the web pages at <https://erofs.docs.kernel.org> for more details.

If unsure, say N.

source code:

fs/erofs/