Re: [PATCH 08/17] nvme: enable passthrough with fixed-buffer

[Christoph Hellwig <hch@lst.de>]

On Tue, Mar 08, 2022 at 08:50:56PM +0530, Kanchan Joshi wrote:
> +/* Unlike blk_rq_map_user () this is only for fixed-buffer async passthrough. */
> +int blk_rq_map_user_fixedb(struct request_queue *q, struct request *rq,
> +		     u64 ubuf, unsigned long len, gfp_t gfp_mask,
> +		     struct io_uring_cmd *ioucmd)
> +{

This doesn't belong into a patch title nvme.  Also please add a proper
kernel-doc comment.

> +EXPORT_SYMBOL(blk_rq_map_user_fixedb);

EXPORT_SYMBOL_GPL, please.

> +static inline bool nvme_is_fixedb_passthru(struct io_uring_cmd *ioucmd)
> +{
> +	return ((ioucmd) && (ioucmd->flags & IO_URING_F_UCMD_FIXEDBUFS));
> +}

No need for the outer and first set of inner braces.

> +
>  static int nvme_submit_user_cmd(struct request_queue *q,
> -		struct nvme_command *cmd, void __user *ubuffer,
> +		struct nvme_command *cmd, u64 ubuffer,
>  		unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
>  		u32 meta_seed, u64 *result, unsigned timeout,
>  		struct io_uring_cmd *ioucmd)
> @@ -152,8 +157,12 @@ static int nvme_submit_user_cmd(struct request_queue *q,
>  	nvme_req(req)->flags |= NVME_REQ_USERCMD;
>  
>  	if (ubuffer && bufflen) {
> -		ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
> -				GFP_KERNEL);
> +		if (likely(nvme_is_fixedb_passthru(ioucmd)))
> +			ret = blk_rq_map_user_fixedb(q, req, ubuffer, bufflen,
> +					GFP_KERNEL, ioucmd);
> +		else
> +			ret = blk_rq_map_user(q, req, NULL, nvme_to_user_ptr(ubuffer),

Overly long line.