linux-kernel - Re: [PATCH v2] page cache: Store only head pages in i

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Message-ID: <20190214162741.GA23000@quack2.suse.cz>
Date:   Thu, 14 Feb 2019 17:27:41 +0100
From:   Jan Kara <jack@...e.cz>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Jan Kara <jack@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hugh Dickins <hughd@...gle.com>,
        William Kucharski <william.kucharski@...cle.com>
Subject: Re: [PATCH v2] page cache: Store only head pages in i_pages

On Wed 13-02-19 12:17:15, Matthew Wilcox wrote:
> > > -		pages[ret] = page;
> > > +		pages[ret] = find_subpage(page, xas.xa_index);
> > >  		if (++ret == nr_pages) {
> > >  			*start = page->index + 1;
> > >  			goto out;
> > >  		}
> > 
> > So this subtly changes the behavior because now we will be returning in
> > '*start' a different index. So you should rather use 'pages[ret]->index'
> > instead.
> 
> You're right, I made a mistake there.  However, seeing this:
> https://lore.kernel.org/lkml/20190110030838.84446-1-yuzhao@google.com/
> 
> makes me think that I should be using xa_index + 1 there.

Yeah, you're right. Thanks!

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR