From mboxrd@z Thu Jan  1 00:00:00 1970
From: kbusch@kernel.org (Keith Busch)
Date: Wed, 31 Jul 2019 14:16:34 -0600
Subject: [PATCH rfc 1/2] nvme: don't remove namespace if revalidate
 failed because of controller reset
In-Reply-To: <0720636c-8706-e927-3c0b-c2687694664f@grimberg.me>
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 <2825eb74-1df5-5dd2-3e90-c696bc7fa3d1@grimberg.me>
 <20190730173048.GC13948@localhost.localdomain>
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On Wed, Jul 31, 2019@01:08:05PM -0700, Sagi Grimberg wrote:
> 
> > > I think I asked this but was not answered, why are we removing
> > > the namespace at all? do others do the same thing (remove the
> > > disk if revalidation fails)?
> > 
> > If a namespace no longer exists,
> 
> Why is it no longer exists? it failed revalidate..

One way it fails to validate is if it doesn't exist, i.e., the
controller returned an error when attempting to identify it.

The other way it may fail to revalidate is if its identify has changed
since we last discovered it, so removal is better than data corruption.

Either scenario could happen from administrative namespace management
commands to any controller in the subsystem.
 
> > what do you want to do with it instead of removing it?
> 
> Well, I don't see anyone else even checking the return
> status of revalidate_disk.. Perhaps Hannes can share more
> on how scsi handles this?

Other drivers may have a different path to this, but I'd imagine they
handle a LUN deletion somehow.