linux-kernel - Re: [PATCH] btrfs: remove dead assignment in prepare_one

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Message-ID: <CALUEkOes_HJnWDbM0wHOiU6s0VVL3twQUwkxg+yzt4-OBz1YMw@mail.gmail.com>
Date: Thu, 4 Dec 2025 21:51:00 +0100
From: Massimiliano Pellizzer <mpellizzer.dev@...il.com>
To: Boris Burkov <boris@....io>
Cc: clm@...com, dsterba@...e.com, linux-btrfs@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btrfs: remove dead assignment in prepare_one_folio()

On Wed, Dec 3, 2025 at 10:21 PM Boris Burkov <boris@....io> wrote:
>
> On Fri, Nov 28, 2025 at 05:47:55PM +0000, Massimiliano Pellizzer wrote:
> > In the error path of prepare_one_folio(), we assign ret = 0
> > before jumping to the again label to retry the operation.
> > However, ret is immediately overwritten by
> > ret = set_folio_extent_mapped(folio).
> >
> > The zero assignment is never observerd by any code path,
> > therefore it can be safely removed.
> >
> > No functional change.
>
> This looks fine to me. But given the fact that we are setting ret = 0
> before entering the again: loop, this code is maintaining that
> (unneeded) invariant. So I think we should remove both or neither.
>
> I would lean towards removing both, but I don't feel strongly about it.
>
> Thanks,
> Boris
>

Hi Boris,

Good point. You are right, both assignments serve no purpose
since ret is immediately overwritten after the again label.

I'll send a v2 that removes both the initialization and the assignment
before the goto.

Thanks for the review,
Massimiliano

> >
> > Signed-off-by: Massimiliano Pellizzer <mpellizzer.dev@...il.com>
> > ---
> >  fs/btrfs/file.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> > index 7a501e73d880..7d875aa261d1 100644
> > --- a/fs/btrfs/file.c
> > +++ b/fs/btrfs/file.c
> > @@ -877,7 +877,6 @@ static noinline int prepare_one_folio(struct inode *inode, struct folio **folio_
> >               /* The folio is already unlocked. */
> >               folio_put(folio);
> >               if (!nowait && ret == -EAGAIN) {
> > -                     ret = 0;
> >                       goto again;
> >               }
> >               return ret;
> > --
> > 2.51.0
> >