EROFS Adds Sub-Page Compressed Data Support To Help Out Android & ARM64 Servers

The read-only EROFS open-source file-system continues to prove quite popular for Android mobile devices as well as containerized environments. With the in-development Linux 6.8 kernel EROFS adds initial support for sub-page compressed data support.

EROFS in Linux 6.8 has some bug fixes and other minor work but its main feature addition this kernel cycle is basic support for sub-page compressed data support. This feature is about allowing compressed data for block sizes smaller than the system's configured page size.

Motivating this sub-page compressed data support for EROFS is Google moving to a 16k page size for their AArch64 devices moving forward. With the Android ecosystem transitioning from 4k to 16k page sizes, 4k-block image compatibility is necessary.

In addition to the 16k page size transition for Android, more AArch64 cloud servers are beginning to use a 64k page size for various purposes and there is a desire to continue to support 4k-block EROFS container images.

For this initial support in Linux 6.8, there isn't in-place/cache decompression but otherwise is enough to get sub-page compressed block support started. More details for those interested via this pull request.