On 7/17/25 15:08, Gao Xiang wrote: > Filesystem metadata has a high degree of redundancy, so it should > compress well in the general case. > > Although metadata compression can increase overall I/O latency, many > users care more about minimized image sizes than extreme runtime > performance. Let's implement metadata compression in response to user > requests [1]. > > Actually, it's quite simple to implement metadata compression: since > EROFS already supports per-inode compression, we can simply treat a > special inode (called `the metabox inode`) as a container for compressed > inode metadata. Since EROFS supports multiple algorithms, users can > even specify LZ4 for metadata and LZMA for data. > > To better support incremental builds, the MSB of NIDs indicates where > the inode metadata is located: if bit 63 is set, the inode itself should > be read from `the metabox inode`. > > Optionally, shared xattrs can also be kept in `the metabox inode` if > COMPAT_SHARED_EA_IN_METABOX is set. > > [1] https://issues.redhat.com/browse/RHEL-75783 > Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com>
Acked-by: Chao Yu <c...@kernel.org> Thanks,
