linux-kernel - Re: [PATCH v4 6/9] ovl: Set case-insensitive dentry operations for ovl sb

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Message-ID: <CAOQ4uxjQkF2qa_DWCDY=1QLZCUq6rJbK_HTv2iuz0+O+rnRsRw@mail.gmail.com>
Date: Thu, 14 Aug 2025 14:57:19 +0200
From: Amir Goldstein <amir73il@...il.com>
To: André Almeida <andrealmeid@...lia.com>
Cc: Miklos Szeredi <miklos@...redi.hu>, Theodore Tso <tytso@....edu>, 
	Gabriel Krisman Bertazi <krisman@...nel.org>, linux-unionfs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	kernel-dev@...lia.com
Subject: Re: [PATCH v4 6/9] ovl: Set case-insensitive dentry operations for
 ovl sb

On Thu, Aug 14, 2025 at 12:37 AM André Almeida <andrealmeid@...lia.com> wrote:
>
> For filesystems with encoding (i.e. with case-insensitive support), set
> the dentry operations for the super block as ovl_dentry_ci_operations.
>
> Signed-off-by: André Almeida <andrealmeid@...lia.com>
Reviewed-by: Amir Goldstein <amir73il@...il.com>

> ---
> Changes from v3:
> - new helper ovl_set_d_op()
> - encoding flags are now set in a step earlier
>
> Changes from v2:
> - Create ovl_dentry_ci_operations to not override dentry ops set by
>   ovl_dentry_operations
> - Create a new function for this
> - Instead of setting encoding just when there's a upper layer, set it
>   for any first layer (ofs->fs[0].sb), regardless of it being upper or
>   not.
> ---
>  fs/overlayfs/super.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index b1dbd3c79961094d00c7f99cc622e515d544d22f..a99c77802efa1a6d96c43019728d3517fccdc16a 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -161,6 +161,16 @@ static const struct dentry_operations ovl_dentry_operations = {
>         .d_weak_revalidate = ovl_dentry_weak_revalidate,
>  };
>
> +#if IS_ENABLED(CONFIG_UNICODE)
> +static const struct dentry_operations ovl_dentry_ci_operations = {
> +       .d_real = ovl_d_real,
> +       .d_revalidate = ovl_dentry_revalidate,
> +       .d_weak_revalidate = ovl_dentry_weak_revalidate,
> +       .d_hash = generic_ci_d_hash,
> +       .d_compare = generic_ci_d_compare,
> +};
> +#endif
> +
>  static struct kmem_cache *ovl_inode_cachep;
>
>  static struct inode *ovl_alloc_inode(struct super_block *sb)
> @@ -1332,6 +1342,19 @@ static struct dentry *ovl_get_root(struct super_block *sb,
>         return root;
>  }
>
> +static void ovl_set_d_op(struct super_block *sb)
> +{
> +       struct ovl_fs *ofs = sb->s_fs_info;
> +
> +#if IS_ENABLED(CONFIG_UNICODE)
> +       if (ofs->casefold) {
> +               set_default_d_op(sb, &ovl_dentry_ci_operations);
> +               return;
> +       }
> +#endif
> +       set_default_d_op(sb, &ovl_dentry_operations);
> +}
> +
>  int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
>  {
>         struct ovl_fs *ofs = sb->s_fs_info;
> @@ -1443,6 +1466,8 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
>         if (IS_ERR(oe))
>                 goto out_err;
>
> +       ovl_set_d_op(sb);
> +
>         /* If the upper fs is nonexistent, we mark overlayfs r/o too */
>         if (!ovl_upper_mnt(ofs))
>                 sb->s_flags |= SB_RDONLY;
>
> --
> 2.50.1
>