Hi, This patchset implements metadata compression since many users are interested in smaller image sizes (even at the cost of some I/O latency).
In short, it uses a special "metabox" inode to gather all inode metadata and then compresses it. Since EROFS supports multiple algorithms, you can select a faster algorithm (e.g., LZ4) from the one used for data compression (e.g., LZMA). Also see the detailed commit messages for more details. Here are some preliminary numbers: Command line: -zlzma,6 -Efragments,ztailpacking -C1048576 ______________________________________________________________ | |_______ Vanilla _______|___ 2554769408 (2437MiB) ___| | Fedora |_______ `-m4096` ______|___ 2524504064 (2408MiB) ___| |_________|_ `-m4096` (lz4hc,12) _|___ 2527326208 (2411MiB) ___| | |_______ Vanilla _______|___ 378634240 ( 362MiB) ___| | AOSP |_______ `-m4096` ______|___ 377856000 ( 361MiB) ___| |_________|_ `-m4096` (lz4hc,12) _|___ 377942016 ( 361MiB) ___| Thanks, Gao Xiang v2: https://lore.kernel.org/r/20250711094004.2488-1-liub...@inspur.com Changes since v2: - refine the ondisk format and implementation. Bo Liu (1): erofs: implement metadata compression Gao Xiang (1): erofs: add on-disk definition for metadata compression fs/erofs/data.c | 59 +++++++++++++++++++++++++---------------- fs/erofs/decompressor.c | 2 +- fs/erofs/erofs_fs.h | 15 ++++++++--- fs/erofs/fileio.c | 2 +- fs/erofs/inode.c | 5 ++-- fs/erofs/internal.h | 19 ++++++++++--- fs/erofs/super.c | 22 +++++++++++++-- fs/erofs/xattr.c | 20 +++++++++----- fs/erofs/zdata.c | 5 +++- fs/erofs/zmap.c | 16 ++++++----- 10 files changed, 115 insertions(+), 50 deletions(-) -- 2.43.5
