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

From: Laurent Vivier
Date: Wed Nov 04 2015 - 06:46:47 EST




On 04/11/2015 12:16, Hannes Reinecke wrote:
> 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.

So you are saying we can remove the line ?

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

There is no issue with QEMU. QEMU can manage more than "8" LUNs, and
we'd like to.

Laurent
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