Re: [PATCH for-next v10 4/7] nvme: refactor nvme_alloc_request

[Christoph Hellwig <hch@lst.de>]

> +	if (!vec)
> +		ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
> +			GFP_KERNEL);
> +	else {
> +		struct iovec fast_iov[UIO_FASTIOV];
> +		struct iovec *iov = fast_iov;
> +		struct iov_iter iter;
> +
> +		ret = import_iovec(rq_data_dir(req), ubuffer, bufflen,
> +				UIO_FASTIOV, &iov, &iter);
> +		if (ret < 0)
>  			goto out;
> +
> +		ret = blk_rq_map_user_iov(q, req, NULL, &iter, GFP_KERNEL);
> +		kfree(iov);
> +	}

As mentioned before this is something that should got into blk-map.c
as a separate helper, and scsi_ioctl.c and sg.c should be switched to
use it as well.

Otherwise this looks good.