linux-ext4 - Re: [PATCH v4 2/7] fs: Add DCACHE_CASEFOLDED

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Date:   Fri, 28 Jul 2023 21:34:22 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Gabriel Krisman Bertazi <krisman@...e.de>
Cc:     viro@...iv.linux.org.uk, brauner@...nel.org, tytso@....edu,
        jaegeuk@...nel.org, linux-fsdevel@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
        Gabriel Krisman Bertazi <krisman@...labora.com>
Subject: Re: [PATCH v4 2/7] fs: Add DCACHE_CASEFOLDED_NAME flag

On Thu, Jul 27, 2023 at 01:28:38PM -0400, Gabriel Krisman Bertazi wrote:
> From: Gabriel Krisman Bertazi <krisman@...labora.com>
> 
> This flag marks a negative or positive dentry as being created after a
> case-insensitive lookup operation.  It is useful to differentiate
> dentries this way to detect whether the negative dentry can be trusted
> during a case-insensitive lookup.
> 
> Reviewed-by: Theodore Ts'o <tytso@....edu>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>
> 
> ---
> Changes since v2:
>   -  Rename DCACHE_CASEFOLD_LOOKUP -> DCACHE_CASEFOLDED_NAME (Eric)
> ---
>  fs/dcache.c            | 8 ++++++++
>  include/linux/dcache.h | 8 ++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/fs/dcache.c b/fs/dcache.c
> index 98521862e58a..5791489b589f 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -1958,6 +1958,14 @@ void d_set_fallthru(struct dentry *dentry)
>  }
>  EXPORT_SYMBOL(d_set_fallthru);
>  
> +void d_set_casefold_lookup(struct dentry *dentry)
> +{
> +	spin_lock(&dentry->d_lock);
> +	dentry->d_flags |= DCACHE_CASEFOLDED_NAME;
> +	spin_unlock(&dentry->d_lock);
> +}
> +EXPORT_SYMBOL(d_set_casefold_lookup);

d_set_casefolded_name()

> +static inline bool d_is_casefold_lookup(const struct dentry *dentry)
> +{
> +	return dentry->d_flags & DCACHE_CASEFOLDED_NAME;
> +}

d_is_casefolded_name().  Or even better, just write 'dentry->d_flags &
DCACHE_CASEFOLDED_NAME' directly in the one place that actually needs this?

- Eric