Mike Snitzer wrote:
> 
> On Wed, Sep 22 2010 at  6:13am -0400,
> Hannes Reinecke <hare@suse.de> wrote:
> 
>> Mike Christie wrote:
>>> On 09/21/2010 02:33 PM, Mike Snitzer wrote:
>>>> 2) the patch also modified alua_rtpg() so implicit ALUA would retry
>>>>     (just like explicit ALUA currently does) if TPGS_STATE_TRANSITIONING
>>>>     - so why should we avoid retry for implicit but do it for explicit?
>>> Leaving that for Hannes. I cannot think of a reason. Probably just did
>>> not do it.
>> Finally I got around to answering this.
>>
>> I've attached a patch which I made the other day which seems to work
>> reasonably well.
>> Looks better from my side, so if you agree I'll be sending it
>> upstream properly.
> 
> Looks good for covering this "2)" change above.
> 
> But "1)" change you had concern with (in my previous patch) was that
> alua_prep_fn would return BLKPREP_DEFER if TPGS_STATE_TRANSITIONING.
> This was bad in that FS requests (like the directio path checker) would
> always call ->prep_fn and that if TPGS_STATE_TRANSITIONING the RTPG
> state would never be reevaluated.. leaving us stuck in BLKPREP_DEFER.
> 
> Seems I'm missing a new flow that proves this is no longer a concern.
> 
The device_handler will keep retrying any path in 'transitioning'.
After ALUA_FAILOVER_TIMEOUT the device handler will either have
updated the port state to something other than 'transitioning' or
returned with 'SCSI_DH_RETRY'.
But yes, you are right; we should be setting the port to something
else than 'transitioning' then. Probably 'standby' is a good choice
here.
New patch attached.

Thanks for the review.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
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