Re: [PATCH] Sanitize PQ3 device handling

[Christoph Hellwig <hch@infradead.org>]

>  	res = scsi_probe_and_add_lun(starget, 0, &bflags, &sdev, rescan, NULL);
> -	if (res == SCSI_SCAN_LUN_PRESENT) {
> -		if (scsi_report_lun_scan(sdev, bflags, rescan) != 0)
> +	if (res != SCSI_SCAN_NO_RESPONSE) {
> +		if (scsi_report_lun_scan(sdev, bflags, rescan) != 0) {
>  			/*
>  			 * The REPORT LUN did not scan the target,
>  			 * do a sequential scan.
>  			 */
> +			if (res == SCSI_SCAN_TARGET_PRESENT)
> +				/*
> +				 * There's a target here, but lun 0 is 
> +				 * offline so we can't use the report_lun
> +				 * scan.  Fall back to a sequential lun scan
> +				 * with a bflags of SPARSELUN.
> +				 *
> +				 * The old code also used a default scsi level
> +				 * of SCSI_2 which seems a bit spurious. Any
> +				 * misbehaving device should rather be added
> +				 * to the blacklist.
> +				 */
> +				bflags |= BLIST_SPARSELUN;
> +
>  			scsi_sequential_lun_scan(starget, bflags,
>  				       	res, sdev->scsi_level, rescan);

If scsi_probe_and_add_lun returns SCSI_SCAN_TARGET_PRESENT sdev isn't valid at
this point.  You should probably default to SCSI_2 for that case.