linux-kernel - Re: [PATCH v2 2/4] fs/sysv: Change the signature of dir_get

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Message-ID: <4773794.GXAFRqVoOG@suse>
Date:   Thu, 12 Jan 2023 21:15:24 +0100
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Christoph Hellwig <hch@...radead.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Ira Weiny <ira.weiny@...el.com>,
        Dan Carpenter <error27@...il.com>
Subject: Re: [PATCH v2 2/4] fs/sysv: Change the signature of dir_get_page()

On mercoledì 11 gennaio 2023 03:34:47 CET Al Viro wrote:
> On Mon, Jan 09, 2023 at 06:06:37PM +0100, Fabio M. De Francesco wrote:
> > -struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
> > +struct sysv_dir_entry *sysv_dotdot(struct inode *dir, struct page **p)
> > 
> >  {
> > 
> > -	struct page *page = dir_get_page(dir, 0);
> > -	struct sysv_dir_entry *de = NULL;
> > +	struct page *page = NULL;
> > +	struct sysv_dir_entry *de = dir_get_page(dir, 0, &page);
> > 
> > -	if (!IS_ERR(page)) {
> > -		de = (struct sysv_dir_entry*) page_address(page) + 1;
> > +	if (!IS_ERR(de)) {
> > 
> >  		*p = page;
> > 
> > +		return (struct sysv_dir_entry *)page_address(page) + 1;
> > 
> >  	}
> > 
> > -	return de;
> > +	return NULL;
> > 
> >  }
> 
> Would be better off with
> 
> 	struct sysv_dir_entry *de = dir_get_page(dir, 0, p);
> 
> 	if (!IS_ERR(de))
> 		return de + 1;	// ".." is the second directory entry
> 	return NULL;
> 
> IMO...

I totally agree with you...

1) This comment is a good way to explain why we return "de + 1".
2) "*p = page" is redundant, so it's not necessary because we assign the out 
argument in dir_get_page() if and only if read_mapping_page() doesn't fail.

I will send v3 asap.

Thanks for your suggestions.

Fabio