linux-kernel - Re: [PATCH] block: respect virtual boundary mask in bvecs

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Message-ID: <a97f3d77-d23b-b418-abce-2d93ed725bdb@acm.org>
Date:   Tue, 6 Nov 2018 06:53:16 -0800
From:   Bart Van Assche <bvanassche@....org>
To:     Johannes Thumshirn <jthumshirn@...e.de>, Jens Axboe <axboe@...com>
Cc:     Linux Block Layer Mailinglist <linux-block@...r.kernel.org>,
        Hannes Reinecke <hare@...e.de>,
        Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>,
        Jan Kara <jack@...e.cz>, Sagi Grimberg <sagi@...mberg.me>
Subject: Re: [PATCH] block: respect virtual boundary mask in bvecs

On 11/5/18 2:23 AM, Johannes Thumshirn wrote:
> @@ -169,7 +169,7 @@ static inline bool biovec_phys_mergeable(struct request_queue *q,
>   static inline bool __bvec_gap_to_prev(struct request_queue *q,
>   		struct bio_vec *bprv, unsigned int offset)
>   {
> -	return offset ||
> +	return (offset & queue_virt_boundary(q)) ||
>   		((bprv->bv_offset + bprv->bv_len) & queue_virt_boundary(q));
>   }

How about changing that expression into the following to make it easier 
for the compiler to optimize this code?

(offset | (bprv->bv_offset + bprv->bv_len)) & queue_virt_boundary(q)

Thanks,

Bart.