linux-ext4 - Re: [PATCH v5 01/12] ovl: Reject mounting over case-insensitive directories

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Date: Tue, 30 Jan 2024 16:22:58 -0800
From: Eric Biggers <ebiggers@...nel.org>
To: Gabriel Krisman Bertazi <krisman@...e.de>
Cc: viro@...iv.linux.org.uk, jaegeuk@...nel.org, tytso@....edu,
	amir73il@...il.com, linux-ext4@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v5 01/12] ovl: Reject mounting over case-insensitive
 directories

On Mon, Jan 29, 2024 at 05:43:19PM -0300, Gabriel Krisman Bertazi wrote:
> ovl: Reject mounting over case-insensitive directories

Maybe:

    ovl: Reject mounting over rootdir of case-insensitive capable FS

or:

    ovl: Always reject mounting over case-insensitive directories

... since as your commit message explains, overlayfs already does reject
mounting over case-insensitive directories, just not in all cases.

> Since commit bb9cd9106b22 ("fscrypt: Have filesystems handle their
> d_ops"), we set ->d_op through a hook in ->d_lookup, which
> means the root dentry won't have them, causing the mount to accidentally
> succeed.

But this series changes that.  Doesn't that make this overlayfs fix redundant?
It does improve the error message, which is helpful, but your commit message
makes it sound like it's an actual fix, not just an error message improvement.

- Eric