[RFC PATCH v0 0/3] erofs-utils: support multiple block compression

[Gao Xiang via Linux-erofs <linux-erofs@lists.ozlabs.org>]

From: Gao Xiang <hsiangkao@aol.com>

Hi folks,

This is the first RFC patch of multiple block compression (including
erofsfuse) after I carefully think over the on-disk design to support
multiblock in-place decompression.

Compression ratio results (POC, lz4hc, lz4-1.9.3, not final result):
	1000000000		enwik9
		621211648	enwik9_4k.squashfs.img
	 557858816      	enwik9_4k.erofs.img
		556191744	enwik9_8k.squashfs.img
		502661120	enwik9_16k.squashfs.img
	 500723712		enwik9_8k.erofs.img
		458784768	enwik9_32k.squashfs.img
	 453971968		enwik9_16k.erofs.img
		422318080	enwik9_64k.squashfs.img
	 416686080		enwik9_32k.erofs.img
		398204928	enwik9_128k.squashfs.img
	 395276288		enwik9_64k.erofs.img

TODO:
	- support compact indexes for multiple block compression **;
	- support multithread compression (keep compressed data in memory);
	- carefully design kernel optimized paths to maximize runtime performance;
	- widely testing.

If you think that'd be useful for your products and you also have interest
in development, feel free to follow that as well since I don't have abundant
free time so the progress might be somewhat slow (I tend to finish them all before
the next LTS).

Thanks,
Gao Xiang

Gao Xiang (3):
  erofs-utils: add -C# for the maximum size of pclusters
  erofs-utils: mkfs: support multiple block compression
  erofs-utils: fuse: support multiple block compression

 include/erofs/config.h   |  2 ++
 include/erofs/internal.h |  1 +
 include/erofs_fs.h       | 19 ++++++++---
 lib/compress.c           | 70 ++++++++++++++++++++++++--------------
 lib/config.c             |  1 +
 lib/data.c               |  4 +--
 lib/zmap.c               | 72 ++++++++++++++++++++++++++++++++++++----
 mkfs/main.c              | 14 +++++++-
 8 files changed, 146 insertions(+), 37 deletions(-)

-- 
2.24.0