Re: [PATCH 00/10] erofs: 48-bit layout support

From: Gao Xiang
Date: Thu Mar 13 2025 - 08:34:29 EST




On 2025/3/13 20:06, Chao Yu wrote:
On 2025/3/10 17:54, Gao Xiang wrote:
Hi folks,

The current 32-bit block addressing limits EROFS to a 16TiB maximum
volume size with 4KiB blocks.  However, several new use cases now
require larger capacity support:
  - Massive datasets for model training to boost random sampling
    performance for each epoch;
  - Object storage clients using EROFS direct passthrough.

This extends core on-disk structures to support 48-bit block addressing,
such as inodes, device slots, and inode chunks.

In addition, it introduces an mtime field to 32-byte compact inodes for
basic timestamp support, as well as expands the superblock root NID to
an 8-byte rootnid_8b for out-of-place update incremental builds.

In order to support larger images beyond 32-bit block addressing and
efficient indexing of large compression units for compressed data, and
to better support popular compression algorithms (mainly Zstd) that
still lack native fixed-sized output compression support, introduce
byte-oriented encoded extents, so that these compressors are allowed
to retain their current methods.

Therefore, it speeds up Zstd image building a lot by using:
Processor: Intel(R) Xeon(R) Platinum 8163 CPU @ 2.50GHz * 96
Dataset: enwik9
Build time Size Type Command Line
3m52.339s 266653696 FO -C524288 -zzstd,22
3m48.549s 266174464 FO -E48bit -C524288 -zzstd,22
0m12.821s 272134144 FI -E48bit -C1048576 --max-extent-bytes=1048576 -zzstd,22

It has been stress-tested on my local setup for a while without any
strange happens.

Cool, good work! For this serial,

Acked-by: Chao Yu <chao@xxxxxxxxxx>

Hoping to grab continuous free slots to check the details, then we can
change it to rvb status before merge window. :)

Thanks, I don't find any issue so far and users would like to
get 48-bit addressing and quick Zstd compression. It's not a
complex update anyway.

Thanks,
Gao Xiang