Re: [PATCH v2 1/1] block: centralize PI remapping logic to the block layer

[Christoph Hellwig <hch@lst.de>]

On Wed, Sep 04, 2019 at 07:27:32PM +0300, Max Gurtovoy wrote:
> @@ -1405,6 +1406,11 @@ bool blk_update_request(struct request *req, blk_status_t error,
>  	if (!req->bio)
>  		return false;
>  
> +	if (blk_integrity_rq(req) && req_op(req) == REQ_OP_READ &&
> +	    error == BLK_STS_OK)
> +		t10_pi_complete(req,
> +			nr_bytes >> blk_integrity_interval_shift(req->q));

I think it would be nicer to just pass nr_bytes to t10_pi_complete and 
do the calculation internally.  That keeps the caller a littler cleaner.

> -void t10_pi_prepare(struct request *rq, u8 protection_type)
> +void t10_pi_prepare(struct request *rq)
>  {
> +	u8 protection_type = rq->rq_disk->protection_type;

The protection_type variable is only used once, so we might as well
remove it.

> +void t10_pi_complete(struct request *rq, unsigned int intervals)
>  {
> +	u8 protection_type = rq->rq_disk->protection_type;

Same here.

> +static void nvme_set_disk_prot_type(struct nvme_ns *ns, struct gendisk *disk)
> +{
> +	switch (ns->pi_type) {
> +	case NVME_NS_DPS_PI_TYPE1:
> +		disk->protection_type = T10_PI_TYPE1_PROTECTION;
> +		break;
> +	case NVME_NS_DPS_PI_TYPE2:
> +		disk->protection_type = T10_PI_TYPE2_PROTECTION;
> +		break;
> +	case NVME_NS_DPS_PI_TYPE3:
> +		disk->protection_type = T10_PI_TYPE3_PROTECTION;
> +		break;
> +	default:
> +		disk->protection_type = T10_PI_TYPE0_PROTECTION;
> +		break;
> +	}
> +}

We just passed the value in direttly before, so I think we can keep
it that way.  In fact it might make sense to just remove the
NVME_NS_DPS_PI_TYPE* values entirely (in a separate patch).

But I think we should remove the pi_type field in struct nvme_ns here,
just like in sd.