Re: [PATCH v6 2/9] fs: Create sb_same_encoding() helper

[Gabriel Krisman Bertazi <gabriel@krisman.be>]

André Almeida <andrealmeid@igalia.com> writes:

> For cases where a file lookup can look in different filesystems (like in
> overlayfs), both super blocks must have the same encoding and the same
> flags. To help with that, create a sb_same_encoding() function.
>
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> Signed-off-by: André Almeida <andrealmeid@igalia.com>


Reviewed-by: Gabriel Krisman Bertazi <gabriel@krisman.be>


> ---
>  include/linux/fs.h | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index a4d353a871b094b562a87ddcffe8336a26c5a3e2..7de9e1e4839a2726f4355ddf20b9babb74cc9681 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3747,6 +3747,24 @@ static inline bool sb_has_encoding(const struct super_block *sb)
>  	return !!sb_encoding(sb);
>  }
>  
> +/*
> + * Compare if two super blocks have the same encoding and flags
> + */
> +static inline bool sb_same_encoding(const struct super_block *sb1,
> +				    const struct super_block *sb2)
> +{
> +#if IS_ENABLED(CONFIG_UNICODE)
> +	if (sb1->s_encoding == sb2->s_encoding)
> +		return true;
> +
> +	return (sb1->s_encoding && sb2->s_encoding &&
> +	       (sb1->s_encoding->version == sb2->s_encoding->version) &&
> +	       (sb1->s_encoding_flags == sb2->s_encoding_flags));
> +#else
> +	return true;
> +#endif
> +}
> +
>  int may_setattr(struct mnt_idmap *idmap, struct inode *inode,
>  		unsigned int ia_valid);
>  int setattr_prepare(struct mnt_idmap *, struct dentry *, struct iattr *);

-- 
Gabriel Krisman Bertazi