On Fri, Aug 8, 2025 at 10:59 PM André Almeida <andrealmeid@igalia.com> wrote:
>
> For cases where a file lookup can go to different mount points (like in
s/can go to different mount points/can look in different filesystems/
> overlayfs), both super blocks must have the same encoding and the same
> flags. To help with that, create a sb_same_encoding() function.
>
> Signed-off-by: André Almeida <andrealmeid@igalia.com>
With wording fixed feel free to add:
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Thanks,
Amir.
> ---
> Changes from v2:
> - Simplify the code. Instead of `if (cond) return true`, just do `return
> cond`;
> ---
> include/linux/fs.h | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index db49a17376d124785b87dd7f35672fc6e5434f47..d1fe69f233c046a960a60072d5ac3f6286d32c17 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3746,6 +3746,25 @@ static inline bool sb_has_encoding(const struct super_block *sb)
> #endif
> }
>
> +/*
> + * 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 *);
>
> --
> 2.50.1
>