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	Fri, 04 Oct 2024 22:23:24 +0000
Date: Fri, 4 Oct 2024 23:23:23 +0100
From: Al Viro <viro@zeniv.linux.org.uk>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
	Christian Brauner <brauner@kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org
Subject: Re: [PATCH 3/4] ovl: convert ovl_real_fdget_meta() callers to
 ovl_real_file_meta()
Message-ID: <20241004222323.GS4017910@ZenIV>
References: <20241004102342.179434-1-amir73il@gmail.com>
 <20241004102342.179434-4-amir73il@gmail.com>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Fri, Oct 04, 2024 at 12:23:41PM +0200, Amir Goldstein wrote:

>  	if (upper_meta) {
>  		ovl_path_upper(dentry, &realpath);
>  		if (!realpath.dentry)
> -			return 0;
> +			return NULL;
>  	} else {
>  		/* lazy lookup and verify of lowerdata */
>  		err = ovl_verify_lowerdata(dentry);
>  		if (err)
> -			return err;
> +			return ERR_PTR(err);

Ugh...  That kind of calling conventions is generally a bad idea.

> +	return realfile;

... especially since it's NULL/ERR_PTR()/pointer to object.


> +	realfile = ovl_real_file_meta(file, !datasync);
> +	if (IS_ERR_OR_NULL(realfile))
> +		return PTR_ERR(realfile);

Please, don't.  IS_ERR_OR_NULL is bogus 9 times out of 10 (at least).
And you still have breakage in llseek et.al.