[PATCH 1/2] erofs-utils: lib: fix up compact indexes for block size < 4096

[Yue Hu]

On Thu, 23 Nov 2023 13:22:44 +0800
Gao Xiang <hsiangkao at linux.alibaba.com> wrote:

> Previously, the block size always equaled to PAGE_SIZE in kernel,
> therefore `lclusterbits` couldn't be less than 12.
> 
> Since sub-page compressed blocks are now considered, `lobits` for
> a lcluster in each pack of compact indexes cannot always be
> `lclusterbits` as before.  Otherwise, there is no enough room for
> the special value `Z_EROFS_LI_D0_CBLKCNT`.
> 
> To support smaller block sizes, `lobits` for each compacted lcluster is
> now calculated as:
>    lobits = max(lclusterbits, ilog2(Z_EROFS_LI_D0_CBLKCNT) + 1)
> 
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Reviewed-by: Yue Hu <huyue2 at coolpad.com>