linux-kernel - Re: [RFC PATCH 2/3] mpage: use bio_for_each_folio_all in mpage_end

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Date:   Wed, 15 Mar 2023 16:08:46 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Hannes Reinecke <hare@...e.de>
Cc:     Pankaj Raghav <p.raghav@...sung.com>, hubcap@...ibond.com,
        senozhatsky@...omium.org, martin@...ibond.com, minchan@...nel.org,
        viro@...iv.linux.org.uk, brauner@...nel.org, axboe@...nel.dk,
        akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, gost.dev@...sung.com, mcgrof@...nel.org,
        devel@...ts.orangefs.org
Subject: Re: [RFC PATCH 2/3] mpage: use bio_for_each_folio_all in
 mpage_end_io()

On Wed, Mar 15, 2023 at 03:52:15PM +0100, Hannes Reinecke wrote:
> On 3/15/23 13:32, Pankaj Raghav wrote:
> > Use bio_for_each_folio_all to iterate through folios in a bio so that
> > the folios can be directly passed to the folio_endio() function.
> > +	bio_for_each_folio_all(fi, bio)
> > +		folio_endio(fi.folio, bio_op(bio),
> > +			    blk_status_to_errno(bio->bi_status));
> >   	bio_put(bio);
> >   }
> 
> Ah. Here it is.
> 
> I would suggest merge these two patches.

The right way to have handled this patch series was:

1. Introduce a new folio_endio() [but see Christoph's mail on why we
shouldn't do that]
2-n convert callers to use folios directly
n+1 remove page_endio() entirely.

Note that patch n+1 might not be part of this patch series; sometimes
it takes a while to convert all callers to use folios.

I very much dislike the way this was done by pushing the page_folio()
call into each of the callers because it makes the entire series hard to
review.