Re: [PATCH 8/8] dm-mpath: do not activate failed paths

[Hannes Reinecke <hare@suse.de>]

On 02/28/2014 03:22 PM, Mike Snitzer wrote:
[ .. ]
> 
> FYI, I still intend to review/take your "accept failed paths" patch.
> Would be helpful if any rebase is needed for that patch that you do so
> and re-post.
> 
> One thing I noticed is you're only converting MAJ:MIN paths to devices.
> I think we should factor a helper out of DM core that does the full path
> lookup check from dm_get_device() -- rather than you open coding an
> older version of the MAJ:MIN device path processing.
> 
> But is there a reason for not using lookup_bdev()?  Because the device
> is failed it cannot be found using lookup_bdev()?
> 
Yes, that's precisely it.
When setting dev_loss_tmo very aggressively (to, say, 10 or even 5
seconds) it might well be that multipathd won't be able to keep up
with the events in time.
So by the time multipathd tries to push a new table into the kernel
(which contains major:minor numbers only) those devices are already
gone. So lookup_bdev() won't be able to find them, either.

Not sure if factoring things out from dm_get_device() would help
here ...

But I'll be sending an updated patch, which'll apply on top of the
'push back' patchset.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
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