Re: [PATCH v2 3/3] ibmvscsi: Allow to configure maximum LUN
From: Hannes Reinecke
Date: Thu Nov 05 2015 - 03:51:47 EST
On 11/05/2015 12:06 AM, Brian King wrote:
> On 11/04/2015 07:02 AM, Hannes Reinecke wrote:
>> On 11/04/2015 12:46 PM, Laurent Vivier wrote:
>>>
>>>
>>> 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 ?
>>>
>> Ho-hum. In principle you could, as ibmvscsi is using SRP internally,
>> which does support 64 bit LUNs.
>>
>> However, due to some weird design decisions there is
>> the function 'lun_from_dev()', which mangles the incoming LUN number
>> into something ... else.
>> Which leaves only 4 bits free for the actual LUN number, requiring
>> you to use max_lun = 16.
>>
>> Personally I would just do away with that function and use the
>> incoming LUN numbers as is.
>
> I pulled out my copy of SAM, what lun_from_dev is doing is translating
> the incoming bus / id / LUN to a LUN in the logical unit addressing format,
> as defined in 4.6.9 of SAM-4.
>
> --------------------------------------
> |Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
> --------------------------------------
> | n | (10b) | Target |
> --------------------------------------
> | n+1| Bus | LUN |
> --------------------------------------
>
> So this means, in the current implementation, we have 6 bits for target (max=63),
> 3 bits for bus (max=7), and 5 bits for LUN (max=31).
>
> It might not be a bad idea to enforce these limits on the module parameters. Otherwise
> we'll have a mess when we run through lun_from_dev...
>
Correct. With the current implementation we need to set max_lun to 31.
> As far as eliminating lun_from_dev and just passing the LUN through, I don't think we
> can do that. The LUN list returned by Report LUNs to a VSCSI disk assumes we are
> doing the translation above.
>
? How can that be ?
REPORT LUNs will give you a list of available LUNs _from that target_.
As the SCSI stack now moved to handle full 64bit LUNs the values
from REPORT LUNs will be used as-is (well, byte-swapped, but still).
Can you test with the attached patch?
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)
From 42d920e9ff2a4739d4a901e033a93364586c840c Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare@xxxxxxx>
Date: Thu, 5 Nov 2015 09:50:23 +0100
Subject: [PATCH] ibmvscsi: Allow 64bit LUNs
The SRP protocol allows full 64bit LUNs, so there is no need
to mangle the LUNs in the driver.
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
drivers/scsi/ibmvscsi/ibmvscsi.c | 25 ++++++-------------------
1 file changed, 6 insertions(+), 19 deletions(-)
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 6a41c36..0162b1d 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -1019,16 +1019,6 @@ static void handle_cmd_rsp(struct srp_event_struct *evt_struct)
}
/**
- * lun_from_dev: - Returns the lun of the scsi device
- * @dev: struct scsi_device
- *
-*/
-static inline u16 lun_from_dev(struct scsi_device *dev)
-{
- return (0x2 << 14) | (dev->id << 8) | (dev->channel << 5) | dev->lun;
-}
-
-/**
* ibmvscsi_queue: - The queuecommand function of the scsi template
* @cmd: struct scsi_cmnd to be executed
* @done: Callback function to be called when cmd is completed
@@ -1040,7 +1030,6 @@ static int ibmvscsi_queuecommand_lck(struct scsi_cmnd *cmnd,
struct srp_event_struct *evt_struct;
struct srp_indirect_buf *indirect;
struct ibmvscsi_host_data *hostdata = shost_priv(cmnd->device->host);
- u16 lun = lun_from_dev(cmnd->device);
u8 out_fmt, in_fmt;
cmnd->result = (DID_OK << 16);
@@ -1053,7 +1042,7 @@ static int ibmvscsi_queuecommand_lck(struct scsi_cmnd *cmnd,
memset(srp_cmd, 0x00, SRP_MAX_IU_LEN);
srp_cmd->opcode = SRP_CMD;
memcpy(srp_cmd->cdb, cmnd->cmnd, sizeof(srp_cmd->cdb));
- int_to_scsilun(lun, &srp_cmd->lun);
+ int_to_scsilun(cmnd->device->lun, &srp_cmd->lun);
if (!map_data_for_srp_cmd(cmnd, evt_struct, srp_cmd, hostdata->dev)) {
if (!firmware_has_feature(FW_FEATURE_CMO))
@@ -1489,7 +1478,6 @@ static int ibmvscsi_eh_abort_handler(struct scsi_cmnd *cmd)
union viosrp_iu srp_rsp;
int rsp_rc;
unsigned long flags;
- u16 lun = lun_from_dev(cmd->device);
unsigned long wait_switch = 0;
/* First, find this command in our sent list so we can figure
@@ -1529,7 +1517,7 @@ static int ibmvscsi_eh_abort_handler(struct scsi_cmnd *cmd)
/* Set up an abort SRP command */
memset(tsk_mgmt, 0x00, sizeof(*tsk_mgmt));
tsk_mgmt->opcode = SRP_TSK_MGMT;
- int_to_scsilun(lun, &tsk_mgmt->lun);
+ int_to_scsilun(cmnd->device->lun, &tsk_mgmt->lun);
tsk_mgmt->tsk_mgmt_func = SRP_TSK_ABORT_TASK;
tsk_mgmt->task_tag = (u64) found_evt;
@@ -1556,7 +1544,7 @@ static int ibmvscsi_eh_abort_handler(struct scsi_cmnd *cmd)
sdev_printk(KERN_INFO, cmd->device,
"aborting command. lun 0x%llx, tag 0x%llx\n",
- (((u64) lun) << 48), (u64) found_evt);
+ cmd->device->lun, (u64) found_evt);
wait_for_completion(&evt->comp);
@@ -1628,7 +1616,6 @@ static int ibmvscsi_eh_device_reset_handler(struct scsi_cmnd *cmd)
union viosrp_iu srp_rsp;
int rsp_rc;
unsigned long flags;
- u16 lun = lun_from_dev(cmd->device);
unsigned long wait_switch = 0;
spin_lock_irqsave(hostdata->host->host_lock, flags);
@@ -1652,7 +1639,7 @@ static int ibmvscsi_eh_device_reset_handler(struct scsi_cmnd *cmd)
/* Set up a lun reset SRP command */
memset(tsk_mgmt, 0x00, sizeof(*tsk_mgmt));
tsk_mgmt->opcode = SRP_TSK_MGMT;
- int_to_scsilun(lun, &tsk_mgmt->lun);
+ int_to_scsilun(cmnd->device->lun, &tsk_mgmt->lun);
tsk_mgmt->tsk_mgmt_func = SRP_TSK_LUN_RESET;
evt->sync_srp = &srp_rsp;
@@ -1677,7 +1664,7 @@ static int ibmvscsi_eh_device_reset_handler(struct scsi_cmnd *cmd)
}
sdev_printk(KERN_INFO, cmd->device, "resetting device. lun 0x%llx\n",
- (((u64) lun) << 48));
+ cmnd->device->lun);
wait_for_completion(&evt->comp);
@@ -2289,7 +2276,7 @@ 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 = 0xFFFF;
host->max_id = max_id;
host->max_channel = max_channel;
host->max_cmd_len = 16;
--
1.8.5.6