linux-ext4 - Re: [PATCH v2 2/8] fscrypt: Drop d

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Date: Tue, 19 Dec 2023 16:00:29 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: Gabriel Krisman Bertazi <krisman@...e.de>
Cc: viro@...iv.linux.org.uk, jaegeuk@...nel.org, tytso@....edu,
	linux-f2fs-devel@...ts.sourceforge.net, linux-ext4@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2 2/8] fscrypt: Drop d_revalidate if key is available

On Fri, Dec 15, 2023 at 04:16:02PM -0500, Gabriel Krisman Bertazi wrote:
> fscrypt dentries are always valid once the key is available.  Since the
> key cannot be removed without evicting the dentry, we don't need to keep
> retrying to revalidate it.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@...e.de>

IIUC, this patch minimizes the overhead of fscrypt_d_revalidate() both for
encrypted and unencrypted dentries.  That's what's needed (seeing as this series
makes fscrypt_d_revalidate be installed on unencrypted dentries), but the commit
message only mentions the encrypted case.  It would be helpful to mention both.

> ---
>  fs/crypto/fname.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
> index 7b3fc189593a..0457ba2d7d76 100644
> --- a/fs/crypto/fname.c
> +++ b/fs/crypto/fname.c
> @@ -591,8 +591,15 @@ int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
>  	 * reverting to no-key names without evicting the directory's inode
>  	 * -- which implies eviction of the dentries in the directory.
>  	 */
> -	if (!(dentry->d_flags & DCACHE_NOKEY_NAME))
> +	if (!(dentry->d_flags & DCACHE_NOKEY_NAME)) {
> +		/*
> +		 * If fscrypt is the only feature requiring
> +		 * revalidation for this dentry, we can just disable it.
> +		 */
> +		if (dentry->d_op->d_revalidate == &fscrypt_d_revalidate)

No need for the & in &fscrypt_d_revalidate.

- Eric