linux-kernel - Re: [PATCH] blk_types.h: Use REQ_OP_WRITE in op_is

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Date:   Fri, 11 Jan 2019 02:09:50 -0800
From:   Omar Sandoval <osandov@...ndov.com>
To:     Marcos Paulo de Souza <marcos.souza.org@...il.com>
Cc:     linux-kernel@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        Tejun Heo <tj@...nel.org>, Josef Bacik <jbacik@...com>,
        Mike Snitzer <snitzer@...hat.com>,
        Michael Callahan <michaelcallahan@...com>,
        Omar Sandoval <osandov@...com>,
        Mikulas Patocka <mpatocka@...hat.com>,
        Keith Busch <keith.busch@...el.com>,
        Ming Lei <ming.lei@...hat.com>,
        "Dennis Zhou (Facebook)" <dennisszhou@...il.com>
Subject: Re: [PATCH] blk_types.h: Use REQ_OP_WRITE in op_is_write

On Sat, Dec 22, 2018 at 08:03:54AM -0200, Marcos Paulo de Souza wrote:
> Instead of just using plain '1', as it improves readability.
> 
> Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@...il.com>
> ---
>  include/linux/blk_types.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 1dcf652ba0aa..905c666a0101 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -377,7 +377,7 @@ static inline void bio_set_op_attrs(struct bio *bio, unsigned op,
>  
>  static inline bool op_is_write(unsigned int op)
>  {
> -	return (op & 1);
> +	return (op & REQ_OP_WRITE);
>  }
>  
>  /*

Nak. Conceptually, an operation is a write if the least significant bit
is set. The 1 here doesn't mean REQ_OP_WRITE, it means the least
significant bit.