[PATCH] erofs: add error log in erofs_fc_parse_param

[Gao Xiang]

Hi Linxuan,

On 2025/1/17 16:52, Chen Linxuan wrote:
> While reading erofs code, I notice that `erofs_fc_parse_param` will
> return -ENOPARAM, which means that erofs do not support this option,
> without report anything when `fs_parse` return an unknown `opt`.
> 
> But if an option is unknown to erofs, I mean that option not in
> `erofs_fs_parameters` at all, `fs_parse` will return -ENOPARAM,
> which means that `erofs_fs_parameters` should has returned earlier.
> 
> Entering `default` means `fs_parse` return something we unexpected.
> I am not sure about it but I think we should return -EINVAL here,
> just like `xfs_fs_parse_param`.
> 
> Signed-off-by: Chen Linxuan <chenlinxuan at uniontech.com>

I think the default branch is actually deadcode here, see
erofs_fc_parse_param() -> fs_parse() -> fs_lookup_key() -> -ENOPARAM

then vfs_parse_fs_param() will show "Unknown parameter".

Maybe we could just kill `default:` branch...

Thanks,
Gao Xiang


> ---
>   fs/erofs/super.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index 1fc5623c3a4d..67fc4c1deb98 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -509,7 +509,8 @@ static int erofs_fc_parse_param(struct fs_context *fc,
>   #endif
>   		break;
>   	default:
> -		return -ENOPARAM;
> +		errorfc(fc, "%s option not supported", param->key);
> +		return -EINVAL;
>   	}
>   	return 0;
>   }