From mboxrd@z Thu Jan  1 00:00:00 1970
From: sagi@grimberg.me (Sagi Grimberg)
Date: Wed, 31 Jul 2019 18:13:06 -0700
Subject: [PATCH rfc 1/2] nvme: don't remove namespace if revalidate failed
 because of controller reset
In-Reply-To: <20190731215437.GA15795@localhost.localdomain>
References: <2825eb74-1df5-5dd2-3e90-c696bc7fa3d1@grimberg.me>
 <20190730173048.GC13948@localhost.localdomain>
 <61445d6f-f4ca-f8d4-cef2-5bfe40aa1e7f@suse.de>
 <2f7535ab-3d45-b24d-1512-a937e16e620f@grimberg.me>
 <20190731193257.GB15643@localhost.localdomain>
 <0720636c-8706-e927-3c0b-c2687694664f@grimberg.me>
 <20190731201634.GC15643@localhost.localdomain>
 <cb8a1faf-ea19-06c8-35dc-08cd11180974@grimberg.me>
 <20190731205836.GD15643@localhost.localdomain>
 <68358e82-cbd5-6199-1329-89421c778dc0@grimberg.me>
 <20190731215437.GA15795@localhost.localdomain>
Message-ID: <55631812-bc90-9dc1-53b7-a76696a7140e@grimberg.me>


>> Well, I don't think we should do that. Unlike I/O commands, which can
>> failover to a different path, these admin commands are bound to the
>> specific controller. In case it takes minutes/hours/days for the
>> controller to restore normal operation, it will be unpleasant to say
>> the least to have admin operations get stuck for so long.
> 
> Unpleasant for who? The scan_work is the only thing waiting for these
> commands, no one else should care because you can't run IO if you're
> stuck in very long reset anyway.

The hung task detector would care, and a user who will attempt to issue
a passthru command, and the rest of the system that have one of the
kworkers sacrificed for a significant amount of time...

> I think the main point is that we don't want to take a delete action on
> a transient condition, but sprinkling NVME_CTRL_LIVE checks is open to
> many other races.

Hence I suggested the transport error code...