Re: btrfs-image gets stuck, using 100%, looping on bad file descriptor

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

Timothy Normand Miller wrote on 2015/08/18 22:55 -0400:
> On Tue, Aug 18, 2015 at 10:48 PM, Qu Wenruo <quwenruo@cn.fujitsu.com> wrote:
>>
>>
>> Timothy Normand Miller wrote on 2015/08/18 22:46 -0400:
>>>
>>> On Tue, Aug 18, 2015 at 9:32 PM, Qu Wenruo <quwenruo@cn.fujitsu.com>
>>> wrote:
>>>>
>>>> Hi Timothy,
>>>>
>>>> Although I have replied to the bugzilla, IMHO it's more appropriate to
>>>> discuss it in mail list, as it's not a kernel bug.
>>>>
>>>
>>> All four devices were online.  The "missing" one was a drive that
>>> died, which was replaced by a new one, but btrfs wouldn't finish the
>>> deletion of the missing device.
>>>
>> By replaced, did you mean "btrfs replace"? Or just change the physical disk
>> without using "btrfs replace"?
>
> Here's what happened:
>
> - A drive started throwing bad sectors.  Somehow this caused metadata
> on other drives to get messed up.

Did that cause any huge damage?

> - I took that drive offline and mounted degraded (it's a 4-drive RAID1)
> - I did a "btrfs add" on a new drive and then a "btrfs delete missing"
> - The replacement drive failed during the replacement operation, and
> everything went to crap.
> - With some help, I got a kernel patch that allowed me to mount the
> original three drives with TWO missing devices.

So the original 3 drives are still OK,
original bad one is missing, and the newly add one is also missing?

That sounds quite repairable.

> - I added a brand new drive and then did "delete missing" again.  This
> time, the first "delete missing" was successful, but it didn't fully
> balance the drives, and there was another missing device, so I had to
> do a "delete missing" again, and that failed.
>
> I wanted to get this back online and restored from a backup, but I was
> willing to keep it this way if people wanted to probe at, in case we
> can uncover any btrfs bugs.  So it was suggested to get a metadata
> image, but that ran into some kind of bug in btrfs-image.
If btrfs-image doesn't work, you can also try btrfs-debug-tree.
IIRC, debug-tree should be more robust than btrfs-image.

BTW, have you tried btrfsck on it? Does it also cause the infinite loop?

I'll also try to reproduce it and investigate the codes directly.

Thanks,
Qu
>
> Currently, I'm restoring from backup, but I have at least a partial
> metadata dump.
>
>