EROFS to support XZ compressed file

[Gao Xiang]

Hi Vu,

On Wed, Nov 20, 2019 at 11:52:04AM -0500, Vu Tran wrote:
> Hi,
> 
> In my understanding, the work for having EROFS to support XZ (in both
> kernel and userspace utils) is actively developing.  Is it possible to know
> the timeline for when the feature will be available for end users to try
> out?

Streamed-based XZ decompression is not hard for the kernel part. I've talked
to Chao about this offline, he will work on this. (AFAIK, Currently he's busy
in other stuffs.). It can be tried out when this part is ready.

For mkfs part, The problem of fitblk-like XZ compressor is compression time.
Developping a multi-threaded mkfs is not hard even for fixed-sized output
compression (segment-based compression), hacking LZMA2 compressor is more
preferred. Finally I decided to take some time on this (I'm taking much
time on LZMA format and (its entropy coding) range coder now.)

We also hope other forks could join us as well, either filesystem guys
or compression experts... It will be of great help...

Thanks,
Gao Xiang

> 
> Thank you very much and Best Regards,
> Vu Tran