[libvirt] [PATCH] check "fc_host" and "vport_ops" capabilities in SCSI host nodedevs

[Shivaprasad bhat]

On Wed, Feb 4, 2015 at 7:25 PM, John Ferlan <jferlan at redhat.com> wrote:
>
>
> On 02/03/2015 03:59 PM, John Ferlan wrote:
>>
>>
>> On 02/03/2015 06:55 AM, Shivaprasad G Bhat wrote:
>>> fc_host & vport_ops devices are SCSI devices with additional capabilities.
>>> Mere string comparison of basic types is not sufficient in this case. This
>>> patch introduces additional capability checks for SCSI devices if the user
>>> is looking to list 'fc_host' or 'vport_ops' devices.
>>>
>>> Signed-off-by: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
>>> ---
>>>  src/conf/node_device_conf.c |    8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>>
>>
>> While this does work and more or less follows what was done for
>> virNodeDeviceCapMatch, I'm wondering if the 'fc_host' and 'vports_ops'
>> capabilities need to also be returned in a "list" of capabilities for a
>> node device
>>
>> That is I see that virNodeDeviceListCaps() seems to be only returning 1
>> capability for every device. However, for the scsi_host, it has those
>> additional fc_host and vport_ops capabilities which if returned in the
>> list would then be "found" by the python listDevices code which for some
>> devices (like the scsi_host here) there may be more than one way to "get
>> at" the information.
>>
>> I'm investigating whether modifying nodeDeviceListCaps() in
>> src/node_device/node_device_driver.c to add "fc_host" and "vport_ops" to
>> the return caps_list will resolve the issue...  This also means
>> virNodeDeviceNumOfCaps() (and it's driver API nodeDeviceNumOfCaps) will
>> need some tweaking too.
>>
>> Another option would be to fix the libvirt-python code to use
>> ListAllDevices with the flags argument like virsh does.
>>
>> John
> <...snip...>
>
> As it turns out your patch will be required in order to cover the
> virNodeListDevices case as well as the attached patch in order to cover
> the virNodeDeviceNumOfCaps and virNodeDeviceListCaps cases.
>

You are right, The listDevices doesn't use either of these APIs.

> Could you take a look at the attached code and try it out on your system
> to make sure it does what I expect (the system I use to test these types
> of checks is unavailable at the moment).  What should happen is for
> 'scsi_host' devices with 'fc_host' and/or 'vports' capability types -
> the cap_list returned will be larger than 1. The code currently only has
> ever returned 1 element. The patch also lists the sample python which
> should work.
>
> With your successful test, I'll push the patches (although I'm tweaking
> your commit message a bit - it'll be very similar to the attached patch
> commit message).
>

Thanks John. I agree with your changes for virNodeDeviceListCaps
and virNodeDeviceNumOfCaps. I too don't have systems for verifying the
patch for now. Let me see if I can catch hold of a system tomorrow.

> Thanks -
>
> John
>
>