Filesystems that need to deal with the super block encoding need to use
a if IS_ENABLED(CONFIG_UNICODE) around it because this struct member is
not declared otherwise. In order to move this if/endif guards outside of
the filesytem code and make it simpler, create a new function that
returns the s_encoding member of struct super_block if Unicode is
enabled, and return NULL otherwise.

Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: André Almeida <andrealmeid@igalia.com>
---
Changes from v3:
- New patch
---
 include/linux/fs.h | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 796319914b0a063642c2bd0c0140697a0eb651f6..20102d81e18a59d5daaed06855d1f168979b4fa7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3739,15 +3739,20 @@ static inline bool generic_ci_validate_strict_name(struct inode *dir, struct qst
 }
 #endif
 
-static inline bool sb_has_encoding(const struct super_block *sb)
+static inline struct unicode_map *sb_encoding(const struct super_block *sb)
 {
 #if IS_ENABLED(CONFIG_UNICODE)
-	return !!sb->s_encoding;
+	return sb->s_encoding;
 #else
-	return false;
+	return NULL;
 #endif
 }
 
+static inline bool sb_has_encoding(const struct super_block *sb)
+{
+	return !!sb_encoding(sb);
+}
+
 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

On Thu, Aug 14, 2025 at 12:37 AM André Almeida <andrealmeid@igalia.com> wrote:
>
> Filesystems that need to deal with the super block encoding need to use
> a if IS_ENABLED(CONFIG_UNICODE) around it because this struct member is
> not declared otherwise. In order to move this if/endif guards outside of
> the filesytem code and make it simpler, create a new function that
> returns the s_encoding member of struct super_block if Unicode is
> enabled, and return NULL otherwise.
>
> Suggested-by: Amir Goldstein <amir73il@gmail.com>
> Signed-off-by: André Almeida <andrealmeid@igalia.com>

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

Andre,

I know I suggested starting the series with ofs->casefold patch,
but I meant the ovl patches series.

The two vfs helper patches should come before the ovl patches,
because Christian might prefer to carry them separately via vfs tree.

Thanks,
Amir.

> ---
> Changes from v3:
> - New patch
> ---
>  include/linux/fs.h | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 796319914b0a063642c2bd0c0140697a0eb651f6..20102d81e18a59d5daaed06855d1f168979b4fa7 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3739,15 +3739,20 @@ static inline bool generic_ci_validate_strict_name(struct inode *dir, struct qst
>  }
>  #endif
>
> -static inline bool sb_has_encoding(const struct super_block *sb)
> +static inline struct unicode_map *sb_encoding(const struct super_block *sb)
>  {
>  #if IS_ENABLED(CONFIG_UNICODE)
> -       return !!sb->s_encoding;
> +       return sb->s_encoding;
>  #else
> -       return false;
> +       return NULL;
>  #endif
>  }
>
> +static inline bool sb_has_encoding(const struct super_block *sb)
> +{
> +       return !!sb_encoding(sb);
> +}
> +
>  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
>