Re: [PATCH 0/2][RESEND] scsi_transport_fc: LUN masking

[Hannes Reinecke <hare@suse.de>]

On 03/02/2016 03:54 AM, Ewan Milne wrote:
> On Tue, 2016-02-23 at 18:21 +0800, Hannes Reinecke wrote:
>> On 02/22/2016 07:39 PM, Seymour, Shane M wrote:
>>> Hi Hannes,
>>>
>>> How do you know that a request for an async scan is complete (I'm assuming
>>> that you get add or change udev events)? Assuming that someone has
manually
>>> started a scan on something (e.g. some newly presented devices after
boot)
>>> and all scans are going to be async how do you know when it is complete
>>> rather than waiting in a work queue? An example may be a sysfs
>>> file that contains unscanned, pending, scanning, scanned so you know
>>> when it's complete at the appropriate level in sysfs (the hba and the rports)
>>> so you know when can continue if you're polling the status (e.g.
checking
>>> as part of system admin work with newly
>>> presented rports so you can then do something with them).
>>>
>> Thing is, I don't.
>>
>> We have had a similar discussion with the IBM zfcp folks, that it would
>> be desirable to have a marker in sysfs telling us that the rport is
>> stable (ie no scanning in progress).
>> However, this cannot be at the rport level (as the rport itself might be
>> going away), but rather at some higher level (eg fc_host).
> 
> I am not sure this really helps.  If another process initiates a scan
> then sysfs might report that the scanning was still in progress.  If
> scans are initiated often enough, you might never observe a stable state.
> 
True.

Which is one of the reasons why this particular item hasn't made any
progress yet.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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