Re: [PATCH 2/7] sd: implement ->get_unique_id

[Hannes Reinecke <hare@suse.de>]

On 10/12/21 2:04 PM, Christoph Hellwig wrote:
> Add the method to query for a uniqueue ID of a given type by looking
> it up in the cached device identification VPD page.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/scsi/sd.c | 37 +++++++++++++++++++++++++++++++++++++
>   1 file changed, 37 insertions(+)
> 
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index d8f6add416c0a..ea1489d3e8497 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -1757,6 +1757,42 @@ static void sd_rescan(struct device *dev)
>   	sd_revalidate_disk(sdkp->disk);
>   }
>   
> +static int sd_get_unique_id(struct gendisk *disk, u8 id[16], u8 type)
> +{
> +	struct scsi_device *sdev = scsi_disk(disk)->device;
> +	const struct scsi_vpd *vpd;
> +	const unsigned char *d;
> +	int len = -ENXIO;
> +
> +	rcu_read_lock();
> +	vpd = rcu_dereference(sdev->vpd_pg83);
> +	if (!vpd)
> +		goto out_unlock;
> +
> +	len = -EINVAL;
> +	for (d = vpd->data + 4; d < vpd->data + vpd->len; d += d[3] + 4) {
> +		/* we only care about designators with LU association */
> +		if (((d[1] >> 4) & 0x3) != 0x00)
> +			continue;
> +		if ((d[1] & 0xf) != type)
> +			continue;
> +
> +		/*
> +		 * Only exit early if a 16-byte descriptor was found.  Otherwise
> +		 * keep looking as one with more entropy might still show up.
> +		 */
> +		len = d[3];
> +		if (len != 8 && len != 12 && len != 16)
> +			continue;
> +		memcpy(id, d + 4, len);
> +		if (len == 16)
> +			break;
> +	}
> +out_unlock:
> +	rcu_read_unlock();
> +	return len;
> +}
> +
>   static char sd_pr_type(enum pr_type type)
>   {
>   	switch (type) {
> @@ -1861,6 +1897,7 @@ static const struct block_device_operations sd_fops = {
>   	.check_events		= sd_check_events,
>   	.unlock_native_capacity	= sd_unlock_native_capacity,
>   	.report_zones		= sd_zbc_report_zones,
> +	.get_unique_id		= sd_get_unique_id,
>   	.pr_ops			= &sd_pr_ops,
>   };
>   
> 
Errm.

What's wrong with scsi_vpd_lun_id() ?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer