linux-kernel - Re: [PATCH 1/2] fscrypt: new helper function

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Date:   Tue, 14 Mar 2023 08:53:51 +0800
From:   Xiubo Li <xiubli@...hat.com>
To:     Eric Biggers <ebiggers@...nel.org>,
        Luís Henriques <lhenriques@...e.de>
Cc:     Jeff Layton <jlayton@...nel.org>,
        "Theodore Y. Ts'o" <tytso@....edu>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Ilya Dryomov <idryomov@...il.com>,
        linux-fscrypt@...r.kernel.org, ceph-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] fscrypt: new helper function -
 fscrypt_prepare_atomic_open()


On 14/03/2023 02:09, Eric Biggers wrote:
> On Mon, Mar 13, 2023 at 12:33:09PM +0000, Luís Henriques wrote:
>> + * The regular open path will use fscrypt_file_open for that, but in the
>> + * atomic open a different approach is required.
> This should actually be fscrypt_prepare_lookup, not fscrypt_file_open, right?
>
>> +int fscrypt_prepare_atomic_open(struct inode *dir, struct dentry *dentry)
>> +{
>> +	int err;
>> +
>> +	if (!IS_ENCRYPTED(dir))
>> +		return 0;
>> +
>> +	err = fscrypt_get_encryption_info(dir, true);
>> +	if (!err && !fscrypt_has_encryption_key(dir)) {
>> +		spin_lock(&dentry->d_lock);
>> +		dentry->d_flags |= DCACHE_NOKEY_NAME;
>> +		spin_unlock(&dentry->d_lock);
>> +	}
>> +
>> +	return err;
>> +}
>> +EXPORT_SYMBOL_GPL(fscrypt_prepare_atomic_open);
> [...]
>> +static inline int fscrypt_prepare_atomic_open(struct inode *dir,
>> +					      struct dentry *dentry)
>> +{
>> +	return -EOPNOTSUPP;
>> +}
> This has different behavior on unencrypted directories depending on whether
> CONFIG_FS_ENCRYPTION is enabled or not.  That's bad.
>
> In patch 2, the caller you are introducing has already checked IS_ENCRYPTED().
>
> Also, your kerneldoc comment for fscrypt_prepare_atomic_open() says it is for
> *encrypted* directories.
>
> So IMO, just remove the IS_ENCRYPTED() check from the CONFIG_FS_ENCRYPTION
> version of fscrypt_prepare_atomic_open().

IMO we should keep this check in fscrypt_prepare_atomic_open() to make 
it consistent with the existing fscrypt_prepare_open(). And we can just 
remove the check from ceph instead.

- Xiubo

> - Eric
>
-- 
Best Regards,

Xiubo Li (李秀波)

Email: xiubli@...hat.com/xiubli@....com
Slack: @Xiubo Li