Re: [PATCH 1/2] block: introduce and export blk_rq_map_user_vec

[Christoph Hellwig <hch@lst.de>]

On Thu, Jan 27, 2022 at 01:55:35PM +0530, Kanchan Joshi wrote:
> Similiar to blk_rq_map_user except that it operates on iovec.
> This is a prep patch.
> 
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
> ---
>  block/blk-map.c        | 19 +++++++++++++++++++
>  include/linux/blk-mq.h |  2 ++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/block/blk-map.c b/block/blk-map.c
> index 4526adde0156..7fe45df3e580 100644
> --- a/block/blk-map.c
> +++ b/block/blk-map.c
> @@ -577,6 +577,25 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
>  }
>  EXPORT_SYMBOL(blk_rq_map_user);
>  
> +int blk_rq_map_user_vec(struct request_queue *q, struct request *rq,
> +		    struct rq_map_data *map_data, void __user *uvec,
> +		    unsigned long nr_vecs, gfp_t gfp_mask)
> +{
> +	struct iovec fast_iov[UIO_FASTIOV];
> +	struct iovec *iov = fast_iov;
> +	struct iov_iter iter;
> +	int ret;
> +
> +	ret = import_iovec(rq_data_dir(rq), uvec, nr_vecs, UIO_FASTIOV, &iov, &iter);
> +	if (unlikely(ret < 0))
> +		return ret;
> +	ret = blk_rq_map_user_iov(q, rq, NULL, &iter, gfp_mask);
> +	kfree(iov);
> +
> +	return ret;

I see very little point in adding this function vs just open coding it.

Also please don't add overly long lines.