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From: Chris Murphy <>
To: Lee Fleming <>,
	Btrfs BTRFS <>
Cc: Chris Murphy <>
Subject: Re: Unbootable root btrfs
Date: Fri, 17 May 2019 22:06:17 -0600
Message-ID: <> (raw)
In-Reply-To: <>

On Fri, May 17, 2019 at 2:18 AM Lee Fleming <> wrote:
> I didn't see that particular warning. I did see a warning that it could cause damage and should be tried after trying some other things which I did. The data on this drive isn't important. I just wanted to see if it could be recovered before reinstalling.
> There was no crash, just a reboot. I was setting up KVM and I rebooted into a different kernel to see if some performance problems were kernel related. And it just didn't boot.

OK the corrupted Btrfs volume is a guest file system?

That's unexpected. There must be some configuration specific issue
that's instigating this. I've done quite a lot of Btrfs testing in
qemu-kvm including the virtioblk devices using unsafe caching, and I
do vile things with the VM's intentionally trying to blow up Btrfs
including force quitting the VM while it's writing. And I haven't
gotten any corruptions.

All I can recommend is to try to reproduce it again and this next time
try to keep track of the exact steps such that anyone can try to
reproduce it. It might be a bug you've found. But we need a
reproducer. Is it using QCOW2 or RAW file backing, or LVM, or plain
partition? What is the qemu command for the VM? You can get that with
'ps -aux | grep qemu' and it should show all the options used
including the kind of block devices and caching. And then what is the
workload inside the VM?

Chris Murphy

  parent reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-16 10:36 Lee Fleming
2019-05-16 21:39 ` Chris Murphy
     [not found]   ` <>
2019-05-18  4:06     ` Chris Murphy [this message]
2019-05-18  4:39       ` Robert White
2019-05-18 19:28         ` Chris Murphy
2019-05-18 19:43           ` Lee Fleming

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