Re: [PATCH v2 3/3] ibmvscsi: Allow to configure maximum LUN

[Hannes Reinecke]

On 11/04/2015 11:20 AM, Laurent Vivier wrote:
> QEMU allows until 32 LUNs.
> 
> Signed-off-by: Laurent Vivier <lvivier@xxxxxxxxxx>
> ---
>  drivers/scsi/ibmvscsi/ibmvscsi.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
> index 04de287..4480d3e 100644
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -84,6 +84,7 @@
>   */
>  static int max_id = 64;
>  static int max_channel = 3;
> +static int max_lun = 8;
>  static int init_timeout = 300;
>  static int login_timeout = 60;
>  static int info_timeout = 30;
> @@ -117,6 +118,8 @@ module_param_named(fast_fail, fast_fail, int, S_IRUGO | S_IWUSR);
>  MODULE_PARM_DESC(fast_fail, "Enable fast fail. [Default=1]");
>  module_param_named(client_reserve, client_reserve, int, S_IRUGO );
>  MODULE_PARM_DESC(client_reserve, "Attempt client managed reserve/release");
> +module_param(max_lun, int, S_IRUGO);
> +MODULE_PARM_DESC(max_lun, "Maximum LUN value [Default=8]");
>  
>  static void ibmvscsi_handle_crq(struct viosrp_crq *crq,
>  				struct ibmvscsi_host_data *hostdata);
> @@ -2289,7 +2292,7 @@ static int ibmvscsi_probe(struct vio_dev *vdev, const struct vio_device_id *id)
>  		goto init_pool_failed;
>  	}
>  
> -	host->max_lun = 8;
> +	host->max_lun = max_lun;
>  	host->max_id = max_id;
>  	host->max_channel = max_channel;
>  	host->max_cmd_len = 16;
> 
Please, don't do this.

'max_lun' should only be set if the HBA / transport has some hard
limitations on the number of bytes it can use.
Otherwise the scanning algorithm in scsi_scan.c should do the
correct thing, independent on the 'max_lun' setting.

If qemu has some issues here someone should rather fix qemu ...

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@xxxxxxx			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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