linux-kernel - Re: [PATCH] block: remove the boring judgment in blk_rq_map_bio

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Message-ID: <2d73aaa4-9718-4285-ab3f-85e1fa3b40fa@kernel.dk>
Date: Thu, 15 Jan 2026 10:18:33 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Chaohai Chen <wdhh6@...yun.com>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] block: remove the boring judgment in
 blk_rq_map_bio_alloc()

On 1/15/26 4:43 AM, Chaohai Chen wrote:
> There is no need to check the return value of bio_alloc_bioset().

Boring judgement? I'm very confused, what on earth does that mean.

> diff --git a/block/blk-map.c b/block/blk-map.c
> index 4533094d9458..f95b07ec3b88 100644
> --- a/block/blk-map.c
> +++ b/block/blk-map.c
> @@ -46,14 +46,8 @@ static struct bio *blk_rq_map_bio_alloc(struct request *rq,
>  		unsigned int nr_vecs, gfp_t gfp_mask)
>  {
>  	struct block_device *bdev = rq->q->disk ? rq->q->disk->part0 : NULL;
> -	struct bio *bio;
>  
> -	bio = bio_alloc_bioset(bdev, nr_vecs, rq->cmd_flags, gfp_mask,
> -				&fs_bio_set);
> -	if (!bio)
> -		return NULL;
> -
> -	return bio;
> +	return bio_alloc_bioset(bdev, nr_vecs, rq->cmd_flags, gfp_mask, &fs_bio_set);
>  }

Presumably this means that nobody ever calls blk_rq_map_bio_alloc()
without __GFP_WAIT set in gfp_mask? Because otherwise this would be
broken. And this then further means that this should most likely be
checked.

All of this is absent from the commit message, which has zero details.

-- 
Jens Axboe