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Date: Tue, 1 Apr 2008 16:12:33 +0300
From: "Pekka Enberg" <penberg@cs.helsinki.fi>
To: "Artem Bityutskiy" <dedekind@yandex.ru>
Subject: Re: [RFC PATCH 20/26] UBIFS: add VFS operations
Cc: "Artem Bityutskiy" <Artem.Bityutskiy@nokia.com>,
       LKML <linux-kernel@vger.kernel.org>,
       "Adrian Hunter" <ext-adrian.hunter@nokia.com>
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Hi Artem,

On Tue, Apr 1, 2008 at 3:42 PM, Artem Bityutskiy <dedekind@yandex.ru> wrote:
> > >  +static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
> > >  +{
> > >  +       /*
> > >  +        * An attempt to release a dirty page without budgeting for it - should
> > >  +        * not happen.
> > >  +        */
> > >  +       ubifs_assert(PageLocked(page));
> > >  +       if (PageWriteback(page))
> > >  +               return 0;
> > >  +       ubifs_assert(PagePrivate(page));
> > >  +       ubifs_assert(0);
> > >  +       ClearPagePrivate(page);
> > >  +       ClearPageChecked(page);
> > >  +       return 1;
> > >  +}
>
>  Yeah, this is also a guarding thing. When a dirty page is released
>  the budget which was allocated for it has to be freed. If this function
>  is called, then the budget was not freed, which must never happen.

So what guarantees that no one calls invalidate_complete_page() or
fallback_migrate_page(), for example?