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Date:   Thu, 23 Dec 2021 14:18:40 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 05/48] pagevec: Add folio_batch
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On Wed, Dec 22, 2021 at 10:54:27PM -0800, Christoph Hellwig wrote:
> On Wed, Dec 08, 2021 at 04:22:13AM +0000, Matthew Wilcox (Oracle) wrote:
> > +static inline void folio_batch_release(struct folio_batch *fbatch)
> > +{
> > +	pagevec_release((struct pagevec *)fbatch);
> > +}
> > +
> > +static inline void folio_batch_remove_exceptionals(struct folio_batch *fbatch)
> > +{
> > +	pagevec_remove_exceptionals((struct pagevec *)fbatch);
> > +}
> 
> I think these casts need documentation, both here and at the
> struct folio_batch and struct pagevec definitions.
> 
> Alternatively I wonder if a union in stuct pagevec so that it can store
> folios or pages might be the better option.

I tried that way first, but then the caller & callee need to agree
whether they're storing folios or pages in the pagevec.  And that's kind
of why we have types.

pagevec_remove_exceptionals() goes away by the end of this series.
pagevec_release() will take longer to remove.  What documentation
do you want to see?