EROFS (Enhanced Read-Only File System) is a modern, lightweight,
secure read-only filesystem for various use cases, such as immutable
system images, container images, application sandboxes, and datasets.

EROFS uses a flexible, hierarchical on-disk design so that features
can be enabled on demand: the core on-disk format is block-aligned in
order to perform optimally on all kinds of devices, including block
and memory-backed devices; the format is easy to parse and has zero
metadata redundancy, unlike generic filesystems, making it ideal for
filesystem auditing and remote access; inline data, random-access
friendly directory data, inline/shared extended attributes and
chunk-based deduplication ensure space efficiency while maintaining
high performance.

Optionally, it supports multiple devices to reference external data,
enabling data sharing for container images.

It also has advanced encoded on-disk layouts, particularly for data
compression and fine-grained deduplication. It utilizes fixed-size
output compression to improve storage density while keeping relatively
high compression ratios. Furthermore, it implements in-place
decompression to reuse file pages to keep compressed data temporarily
with proper strategies, which ensures guaranteed end-to-end runtime
performance under extreme memory pressure without extra cost.

For more details, see the web pages at <https://erofs.docs.kernel.org>
and the documentation at <a href="https://www.kernel.org/doc/Documentation/filesystems/erofs.rst">Documentation/filesystems/erofs.rst</a>.

To compile EROFS filesystem support as a module, choose M here. The
module will be called erofs.

If unsure, say N.

source code:

fs/erofs/