linux-kernel - Re: [RESEND] f2fs: add sanity compress level check for compressed file

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Date:   Tue, 4 Apr 2023 09:16:30 +0800
From:   Chao Yu <chao@...nel.org>
To:     Yangtao Li <frank.li@...o.com>,
        linux-f2fs-devel@...ts.sourceforge.net
Cc:     jaegeuk@...nel.org, linux-kernel@...r.kernel.org, terrelln@...com
Subject: Re: [RESEND] f2fs: add sanity compress level check for compressed
 file

On 2023/4/3 21:33, Yangtao Li wrote:
> Hi Chao,
> 
>> Why not zstd_max_clevel()?
> 
> zstd_max_clevel() is only defined when CONFIG_F2FS_FS_ZSTD is enabled,
> using zstd_max_clevel() will result in compile errors otherwise.
> 
> If using the following code,
> 
> ----------------------------------------------------------------------------
>          switch (ri->i_compress_algorithm) {
>          case COMPRESS_LZO:
>          case COMPRESS_LZORLE:
>                  if (compress_level)
>                          goto err;
>                  break;
>          case COMPRESS_LZ4:
>                  if ((compress_level && compress_level < LZ4HC_MIN_CLEVEL) ||
>                                  compress_level > LZ4HC_MAX_CLEVEL)
>                          goto err;
>                  break;
> #ifdef CONFIG_F2FS_FS_ZSTD
>          case COMPRESS_ZSTD:

Hi Yangtao,

How about:

#ifdef CONFIG_F2FS_FS_ZSTD
	if (!compress_level || compress_level > zstd_max_clevel())
		goto err;
#endif
	break;

>                  if (!compress_level || compress_level > zstd_max_clevel())
>                          goto err;
>                  break;
> #endif
>          default:
>                  goto err;
>          }
> ----------------------------------------------------------------------------
> 
> then we will get this result:
> 
> 	F2FS-fs (loop0): sanity_check_compress_inode: inode (ino=4) has
> 			unsupported compress level: 0, run fsck to fix
> 
> Another way is to use the following code, which ignores the check for
> level when CONFIG_F2FS_FS_ZSTD is not enabled.
> 
> ----------------------------------------------------------------------------
>          switch (ri->i_compress_algorithm) {
>          case COMPRESS_LZO:
>          case COMPRESS_LZORLE:
>                  if (compress_level)
>                          goto err;
>                  break;
>          case COMPRESS_LZ4:
>                  if ((compress_level && compress_level < LZ4HC_MIN_CLEVEL) ||
>                                  compress_level > LZ4HC_MAX_CLEVEL)
>                          goto err;
>                  break;
>          case COMPRESS_ZSTD:
> #ifdef CONFIG_F2FS_FS_ZSTD
>                  if (!compress_level || compress_level > zstd_max_clevel())
>                          goto err;
>                  break;
> #else
>                  return true;
> #endif
>          default:
>                  goto err;
>          }
> ----------------------------------------------------------------------------
> 
> Perhaps exporting ZSTD_MAX_CLEVEL is a better choice?
> 
> Thx,
> Yangtao