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

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Message-ID: <20251203212145.GC3589713@zen.localdomain>
Date: Wed, 3 Dec 2025 13:21:45 -0800
From: Boris Burkov <boris@....io>
To: Massimiliano Pellizzer <mpellizzer.dev@...il.com>
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 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

> 
> 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
>