-----Original Message-----
From: Mike Christie <[email protected]>
Date: Thursday 27 December 2012 5:14 AM
To: "[email protected]" <[email protected]>
Cc: Vikas <[email protected]>, Lalit Chandivade
<[email protected]>, Ravi Anand <[email protected]>, Adheer
Chandravanshi <[email protected]>, Poornima Vonti
<[email protected]>, Manish Rangankar <[email protected]>
Subject: Re: [RFC_V3 PATCH 1/2] scsi_transport_iscsi: Add flash target
mgmt support through sysfs
>>>>>>
>>>>>> This patch allows iscsiadm to manage iSCSI target information stored
>>>>>> on
>>>>>> adapter flash on per host basis.
>>>>>>
>>>>>> The sysfs entries will look as cited below:
>>>>>> /sys/class/iscsi_flash_tgt/tgt-<host_no>-<target_no>/
>>>>>>
>>>>>> Eg:
>>>>>> /sys/class/iscsi_flash_tgt/tgt-1-0/apply
>>>>>> /sys/class/iscsi_flash_tgt/tgt-1-0/login
>>>>>> /sys/class/iscsi_flash_tgt/tgt-1-0/logout
>>>>>> /sys/class/iscsi_flash_tgt/tgt-1-0/<Target attributes>
>>>>>>
>>>>>
>>>>> I was more asking if we could just work off the existing layout. When
>>>>> you write to /sys/class/iscsi_host/host1/add_flash_tgt, it would
>>>>>create
>>>>> a new /sys/class/iscsi_session/session-X entry. Then you would cd
>>>>>there
>>>>> and write to the files to set the values you wanted to use. Then
>>>>>write
>>>>> to a /sys/class/iscsi_session/session-X/login file to initiate login.
>>>>>
>>>>> Was it too difficult to modify the existing
>>>>> iscsi_cls_session/iscsi_cls_conn code for this?
>>>>
>>>> We want to keep both things separate because:
>>>> 1. What we are exporting in "/sys/class/iscsi_flash_tgt" is flash
>>>>target
>>>> entry (persistent data) and
>>>> what gets exported in "/sys/class/iscsi_session / connection" is ram
>>>> copy
>>>> (running copy) of that entry.
>>>>
>>>> 2. As per current implementation the session and connection objects
>>>>are
>>>> created only after a target is logged in.
>>>> They are not present by default. So, for all the target entries in
>>>> "/sys/class/iscsi_flash_tgt" corresponding session and connection
>>>> class objects are created after that entry is logged in.
>>>> Also, exporting flash target entries enables user to see all the
>>>> persistent target entries even if they are not logged in.
>>>
>>> Ok. Just to make sure we are on the same page then, the flash dirs will
>>> only present the info in flash. It will not present any of the running
>>> info? If so then 1 and 2 make sense.
>>>
>>
>> Yes, flash dirs will only present info in flash.
>> Just want to confirm are you ok with exporting flash target data in
>> "/sys/class/iscsi_flash_tgt"
>
>
>Yeah, that seems fine.
>
>
>>
>>>
>>>
>>>>
>>>>
>>>>
>>>>> But a second question I have is why are you using sysfs for this when
>>>>> for the iface stuff you used netlink?
>>>>
>>>> In case of iface we maintain all configuration in userspace file and
>>>> then
>>>> pass it down to kernel via netlink but for flash target entries
>>>> we do not want to use netlink because we do not want to maintain files
>>>> for
>>>> each flash target entry.
>>>>
>>>
>>> Netlink does not require you to store in files though. It was just due
>>> to your implementation of the iface stuff. For the qla4xxx iface stuff
>>>I
>>> said to not use the iface files at all, and just pass everything on the
>>> command line.
>>
>>
>> Do you want us to change write path to use Netlink interface and keep
>> "/sys/class/iscsi_flash_tgt" as it is?
>>
>
>I think so. That would be how we do other things, right. We mostly
>export info through sysfs (the chap table is a exception as you know),
>then for these operations where we want to set settings we have been
>using netlink.
We modified patches to use Netlink interface for write path.
I am sending following updated patches in next email:
[RFC_V4 PATCH 1/2] scsi_transport_iscsi: Add flash target mgmt support
[RFC_V4 PATCH 2/2] qla4xxx: Add flash target mgmt support
[RFC_V4 PATCH] iscsiadm: Add flash target mgmt support.
Thanks,
Vikas.
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