Re: [PATCH 2/2] Drivers: scsi: storvsc: Force discovery of LUNs that may have been removed.

[Mike Christie <michaelc@cs.wisc.edu>]

On 08/27/2014 09:31 AM, Hannes Reinecke wrote:
> On 08/19/2014 07:54 PM, Christoph Hellwig wrote:
>> On Sat, Aug 16, 2014 at 08:09:48PM -0700, K. Y. Srinivasan wrote:
>>> The host asks the guest to scan when a LUN is removed or added.
>>> The only way a guest can identify the removed LUN is when an I/O is
>>> attempted on a removed LUN - the SRB status code indicates that the LUN
>>> is invalid. We currently handle this SRB status and remove the device.
>>>
>>> Rather than waiting for an I/O to remove the device, force the
>>> discovery of
>>> LUNs that may have been removed prior to discovering LUNs that may have
>>> been added.
>>
>> This looks pretty reasonable to me, but I wonder if we should move this
>> up to common code so that it happens for any host rescan triggered by
>> sysfs or other drivers as well.
>>
> Not without proper testing.
> Currently we cannot rescan existing devices; the inquiry string is
> nailed to the sdev structure. The only way to really refresh the
> information is to delete it and rescan it again.

How are distros handling 0x6/0x3f/0x0e (report luns changed) when it
gets passed to userspace? Is everyone kicking off a new full (add and
delete) scan to handle this or logging it? Is the driver returning this
when the LUNs change?

Also is the driver getting a 0x5/0x25/0 (invalid LUN) when the LUN does
not exist, or is it just getting that SRB_STATUS_INVALID_LUN error code?