[PATCH 0/5] erofs: basic sub-page compressed data support

[Gao Xiang]

Hi folks,

Recently, there are two new cases so that we need to add a preliminary
sub-page block support for compressed files;

 - As Android folks requested, Android ecosystem itself is now switching
   to 16k page size for their arm64 devices.  They needs an option of
   4k-block image compatibility on their new 16k devices;

 - Some arm64 cloud servers use 64k page size for their optimized
   workloads, but 4k-block EROFS container images need to be parsed too.

So this patchset mainly addresses the requirements above with a very
very simple approach as a start: just allocate short-lived temporary
buffers all the time to keep compressed data if sub-page blocks are
identified.  In other words, no inplace/cache decompression for
the preliminary support.

This patchset survives EROFS stress test on my own testfarms.

Thanks,
Gao Xiang

Gao Xiang (5):
  erofs: support I/O submission for sub-page compressed blocks
  erofs: record `pclustersize` in bytes instead of pages
  erofs: fix up compacted indexes for block size < 4096
  erofs: refine z_erofs_transform_plain() for sub-page block support
  erofs: enable sub-page compressed block support

 fs/erofs/decompressor.c |  81 +++++++++------
 fs/erofs/inode.c        |   6 +-
 fs/erofs/zdata.c        | 224 ++++++++++++++++++----------------------
 fs/erofs/zmap.c         |  32 +++---
 4 files changed, 169 insertions(+), 174 deletions(-)

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2.39.3