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Date:   Thu, 13 Jul 2023 22:31:35 -0700
From:   Eric Biggers <ebiggers@kernel.org>
To:     Gabriel Krisman Bertazi <krisman@suse.de>
Cc:     viro@zeniv.linux.org.uk, brauner@kernel.org, tytso@mit.edu,
        jaegeuk@kernel.org, linux-fsdevel@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH v2 4/7] libfs: Support revalidation of encrypted
 case-insensitive dentries
Message-ID: <20230714053135.GD913@sol.localdomain>
References: <20230422000310.1802-1-krisman@suse.de>
 <20230422000310.1802-5-krisman@suse.de>
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On Fri, Apr 21, 2023 at 08:03:07PM -0400, Gabriel Krisman Bertazi wrote:
> From: Gabriel Krisman Bertazi <krisman@collabora.com>
> 
> Preserve the existing behavior for encrypted directories, by rejecting
> negative dentries of encrypted+casefolded directories.  This allows
> generic_ci_d_revalidate to be used by filesystems with both features
> enabled, as long as the directory is either casefolded or encrypted, but
> not both at the same time.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> ---
>  fs/libfs.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/libfs.c b/fs/libfs.c
> index f8881e29c5d5..0886044db593 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -1478,6 +1478,9 @@ static inline int generic_ci_d_revalidate(struct dentry *dentry,
>  		const struct inode *dir = READ_ONCE(parent->d_inode);
>  
>  		if (dir && needs_casefold(dir)) {
> +			if (IS_ENCRYPTED(dir))
> +				return 0;
> +

Why not allow negative dentries in case-insensitive encrypted directories?
I can't think any reason why it wouldn't just work.

- Eric