Re: [PATCH v5 02/12] crypto: acomp - Define new interfaces for compress/decompress batching.

[Herbert Xu <herbert@gondor.apana.org.au>]

On Sat, Feb 22, 2025 at 07:26:43PM +1300, Barry Song wrote:
>
> After reviewing the zRAM code, I don't see why zram_write_page() needs
> to rely on
> comp_len to call write_incompressible_page().
> 
> zram_write_page()
> {
>         ret = zcomp_compress(zram->comps[ZRAM_PRIMARY_COMP], zstrm,
>                              mem, &comp_len);
>         kunmap_local(mem);
> 
>         if (unlikely(ret)) {
>                 zcomp_stream_put(zstrm);
>                 pr_err("Compression failed! err=%d\n", ret);
>                 return ret;
>         }
> 
>         if (comp_len >= huge_class_size) {
>                 zcomp_stream_put(zstrm);
>                 return write_incompressible_page(zram, page, index);
>         }
> }

Surely any compression error should just be treated as an
incompressible page?

I mean we might wish to report unusual errors in case the
admin or developer can do something about it, but for the
system as a whole it should still continue as if the page
was simply incompressible.

> As long as crypto drivers consistently return -ENOSP or a specific error
> code for dst_buf overflow, we should be able to eliminate the
> 2*PAGE_SIZE buffer.

Yes we could certainly do that.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt