From: Anand Jain <anand.jain@oracle.com>
To: Chris Murphy <lists@colorremedies.com>
Cc: Konstantin Svist <fry.kun@gmail.com>,
Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
David Sterba <dsterba@suse.cz>
Subject: Re: "Some devices missing" only while not mounted
Date: Fri, 22 Jan 2016 13:59:30 +0800 [thread overview]
Message-ID: <56A1C542.2050205@oracle.com> (raw)
In-Reply-To: <CAJCQCtTn8KvDRCD2h9aKBaWzYDLJpK6zE-f9AuDcD8zH4+Q_Tg@mail.gmail.com>
On 01/22/2016 12:40 PM, Chris Murphy wrote:
> On Thu, Jan 21, 2016 at 8:55 PM, Anand Jain <anand.jain@oracle.com> wrote:
>
>> 'btrfs dev ready':
>> - cannot be fixed without breaking the API rules.
>> May be we would obsolete this cli to a sysfs interface or
>> something else.
>
>
> Wait, so 'btrfs dev ready' will always exit 1 (not ready) any time a
> device has been made missing or replaced?
> And therefore now the
> system can't boot anymore since udev+systemd won't mount a Btrfs root
> fs that's not ready? That's kindof a nasty bug.
In the case here, its not a problem as kernel doesn't think there
is a missing device. So with that 'btrfs dev ready' should return 0,
unless user is providing a device which was deleted in the btrfs
device tree but failed to wipe the SB in the deleted device.
However there are some cases where 'btrfs dev ready' will never
return 0, especially in the cases of seed/sprout devices. So if
system boot depends on that, then yes boot will fail. (I am not
sure if there are some real use cases).
Next. Even with a missing device some pools are mountable with
degrade option. Discussion on this before preferred boot to
ask for the user choice. Since its alway challenging to know
if the device is really missing OR its just +1s slower than
our timeout in waiting for it.
Thanks, Anand
prev parent reply other threads:[~2016-01-22 5:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-21 19:28 "Some devices missing" only while not mounted Konstantin Svist
2016-01-21 21:25 ` Chris Murphy
2016-01-21 22:27 ` Konstantin Svist
2016-01-21 23:13 ` Chris Murphy
2016-01-22 2:44 ` Konstantin Svist
2016-01-22 3:08 ` Chris Murphy
2016-01-23 23:37 ` Konstantin Svist
2016-01-22 3:55 ` Anand Jain
2016-01-22 4:40 ` Chris Murphy
2016-01-22 5:59 ` Anand Jain [this message]
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