linux-kernel - Re: [PATCH v5 8/9] ovl: Check for casefold consistency when creating new dentries

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Message-ID: <CAOQ4uxg6HDTCNKzp=wTKP4CaLVojzZNb61Wp4xgikYZiWK1TMQ@mail.gmail.com>
Date: Thu, 14 Aug 2025 20:54:09 +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 v5 8/9] ovl: Check for casefold consistency when creating
 new dentries

On Thu, Aug 14, 2025 at 7:22 PM André Almeida <andrealmeid@...lia.com> wrote:
>
> In a overlayfs with casefold enabled, all new dentries should have
> casefold enabled as well. Check this at ovl_create_real().
>
> Signed-off-by: André Almeida <andrealmeid@...lia.com>
> ---
> Changes from v4:
> - Add pr_warn()
>
> Changes from v3:
> - New patch
> ---
>  fs/overlayfs/dir.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
> index 70b8687dc45e8e33079c865ae302ac58464224a6..88e888ed8696363d6cde39817f6c21e795f0760a 100644
> --- a/fs/overlayfs/dir.c
> +++ b/fs/overlayfs/dir.c
> @@ -187,6 +187,12 @@ struct dentry *ovl_create_real(struct ovl_fs *ofs, struct dentry *parent,
>                         /* mkdir is special... */
>                         newdentry =  ovl_do_mkdir(ofs, dir, newdentry, attr->mode);
>                         err = PTR_ERR_OR_ZERO(newdentry);
> +                       /* expect to inherit casefolding from workdir/upperdir */
> +                       if (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) {
> +                               pr_warn_ratelimited("dentry wrong casefold inheritance");

pr_warn_ratelimited("wrong inherited casefold (%pd2)\n", newdentry);

No need to report.
I can fix that on commit.

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


Thanks,
Amir.