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

[Chao Yu]

Hi Geert,

On 2021/2/23 15:42, Geert Uytterhoeven wrote:
> > I checked the code in menu_finalize(), and this seems to work like this.
> >
> > I discussed the oddity of the select behavior before
> > (https://lore.kernel.org/linux-kbuild/e1a6228d-1341-6264-d97a-e2bd52a65c82@xxxxxxxxxxxxx/),
> > but I was not confident about what the right direction was.
> >
> >
> > Anyway, the behavior is obscure from the current code.
> >
> > If you want to make this more robust,
> > you can write as follows:
> >
> > config F2FS_FS
> >          tristate "F2FS filesystem support"
> >          depends on BLOCK
> >          select NLS
> >          select CRYPTO
> >          select CRYPTO_CRC32
> >          select F2FS_FS_XATTR if FS_ENCRYPTION
> >          select FS_ENCRYPTION_ALGS if FS_ENCRYPTION
> >          select LZO_COMPRESS if F2FS_FS_LZO
> >          select LZO_DECOMPRESS if F2FS_FS_LZO
> >          select LZ4_COMPRESS if F2FS_FS_LZ4
> >          select LZ4_DECOMPRESS if F2FS_FS_LZ4
> >          select LZ4HC_COMPRESS if F2FS_FS_LZ4HC
> >          select ZSTD_COMPRESS if F2FS_FS_ZSTD
> >          select ZSTD_DECOMPRESS if F2FS_FS_ZSTD
> >
> > The code is a bit clumsy, but it is clear
> > that the module (F2FS_FS) is selecting the
> > compress/decompress libraries.
> Actually the above is what I tried first ;-)  Works fine.
>
> Then I started to look for similar cases in other file systems (e.g.
> EROFS_FS_ZIP), and discovered the issue doesn't happen there, which
> sparked my investigation.  So I settled on the direct dependency,
> because it keeps all compression-related logic together.

It looks above way is more explicit, how about using your previous implementation?

Thank,

> Gr{oetje,eeting}s,