Re: [f2fs-dev] [PATCH v3] f2fs: compress: Allow modular (de)compression algorithms

[Chao Yu]

On 2021/2/26 23:51, Geert Uytterhoeven wrote:
> If F2FS_FS is modular, enabling the compressions options
> F2FS_FS_{LZ4,LZ4HZ,LZO,LZORLE,ZSTD} will make the (de)compression
> algorithms {LZ4,LZ4HC,LZO,ZSTD}_{,DE}COMPRESS builtin instead of
> modular, as the former depend on an intermediate boolean
> F2FS_FS_COMPRESSION, which in-turn depends on tristate F2FS_FS.
>
> Indeed, if a boolean symbol A depends directly on a tristate symbol B
> and selects another tristate symbol C:
>
>      tristate B
>
>      tristate C
>
>      bool A
>        depends on B
>        select C
>
> and B is modular, then C will also be modular.
>
> However, if there is an intermediate boolean D in the dependency chain
> between A and B:
>
>      tristate B
>
>      tristate C
>
>      bool D
>        depends on B
>
>      bool A
>        depends on D
>        select C
>
> then the modular state won't propagate from B to C, and C will be
> builtin instead of modular.
>
> As modular dependency propagation through intermediate symbols is
> obscure, fix this in a robust way by moving the selection of tristate
> (de)compression algorithms from the boolean compression options to the
> tristate main F2FS_FS option.
>
> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>

Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>

Thanks,