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* gazillions of Incorrect local/global backref count
@ 2016-09-04  4:50 Christoph Anton Mitterer
  2016-09-04  5:33 ` Paul Jones
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Christoph Anton Mitterer @ 2016-09-04  4:50 UTC (permalink / raw)
  To: linux-btrfs

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Hey.

I just did a btrfs check on my notebooks root fs, with:
$ uname -a
Linux heisenberg 4.7.0-1-amd64 #1 SMP Debian 4.7.2-1 (2016-08-28)
x86_64 GNU/Linux
$ btrfs --version
btrfs-progs v4.7.1



during:
checking extents

it found gazillions of these:
Incorrect local backref count on 1107980288 root 257 owner 17807428
offset 13568135168 found 2 wanted 3 back 0x2d69990
Incorrect local backref count on 1107980288 root 257 owner 14055042
offset 13568135168 found 2 wanted 3 back 0x2d69930
Incorrect global backref count on 1107980288 found 4 wanted 6
backpointer mismatch on [1107980288 61440]
Incorrect local backref count on 1108049920 root 257 owner 17807428
offset 13568262144 found 2 wanted 5 back 0x2d69ac0
Incorrect local backref count on 1108049920 root 257 owner 14055042
offset 13568262144 found 2 wanted 5 back 0x2d69b20
Incorrect global backref count on 1108049920 found 4 wanted 10
backpointer mismatch on [1108049920 77824]

See stdout/err[0] logfiles from the check.


What do they mean?

And does this now mean that data is corrupted and I should try to
recover that from a backup?
And if so... how to I map the affected addresses above back to files?

Or can I somehow simply (and foremost cleanly/perfectly) correct these
errors?


Thanks in advance,
Chris.


[0] http://christoph.anton.mitterer.name/tmp/public/dbf3aee0-725a-11e6-8fd0-0019dbacbbbf/

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^ permalink raw reply	[flat|nested] 6+ messages in thread
* RE: gazillions of Incorrect local/global backref count
  2016-09-04  4:50 gazillions of Incorrect local/global backref count Christoph Anton Mitterer
@ 2016-09-04  5:33 ` Paul Jones
  2016-09-04  6:33   ` Christoph Anton Mitterer
  2016-09-04 22:41 ` Chris Murphy
  2016-09-05  7:27 ` David Sterba
  2 siblings, 1 reply; 6+ messages in thread
From: Paul Jones @ 2016-09-04  5:33 UTC (permalink / raw)
  To: Christoph Anton Mitterer, linux-btrfs@vger.kernel.org

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> -----Original Message-----
> From: linux-btrfs-owner@vger.kernel.org [mailto:linux-btrfs-
> owner@vger.kernel.org] On Behalf Of Christoph Anton Mitterer
> Sent: Sunday, 4 September 2016 2:51 PM
> To: linux-btrfs@vger.kernel.org
> Subject: gazillions of Incorrect local/global backref count
> 
> Hey.
> 
> I just did a btrfs check on my notebooks root fs, with:
> $ uname -a
> Linux heisenberg 4.7.0-1-amd64 #1 SMP Debian 4.7.2-1 (2016-08-28)
> x86_64 GNU/Linux
> $ btrfs --version
> btrfs-progs v4.7.1
> 
> 
> 
> during:
> checking extents
> 
> it found gazillions of these:
> Incorrect local backref count on 1107980288 root 257 owner 17807428
> offset 13568135168 found 2 wanted 3 back 0x2d69990
> Incorrect local backref count on 1107980288 root 257 owner 14055042
> offset 13568135168 found 2 wanted 3 back 0x2d69930
> Incorrect global backref count on 1107980288 found 4 wanted 6
> backpointer mismatch on [1107980288 61440]
> Incorrect local backref count on 1108049920 root 257 owner 17807428
> offset 13568262144 found 2 wanted 5 back 0x2d69ac0
> Incorrect local backref count on 1108049920 root 257 owner 14055042
> offset 13568262144 found 2 wanted 5 back 0x2d69b20
> Incorrect global backref count on 1108049920 found 4 wanted 10
> backpointer mismatch on [1108049920 77824]
> 
> See stdout/err[0] logfiles from the check.
> 
> 
> What do they mean?
> 
> And does this now mean that data is corrupted and I should try to
> recover that from a backup?
> And if so... how to I map the affected addresses above back to files?
> 
> Or can I somehow simply (and foremost cleanly/perfectly) correct these
> errors?

The errors are wrong. I nearly ruined my filesystem a few days ago by trying to repair similar errors, thankfully all seems ok.
Check again with btrfs-progs 4.6.1 and see if the errors go away, mine did.
See open bug https://bugzilla.kernel.org/show_bug.cgi?id=155791 for more details.

Cheers,
Paul.




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^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: gazillions of Incorrect local/global backref count
  2016-09-04  5:33 ` Paul Jones
@ 2016-09-04  6:33   ` Christoph Anton Mitterer
  0 siblings, 0 replies; 6+ messages in thread
From: Christoph Anton Mitterer @ 2016-09-04  6:33 UTC (permalink / raw)
  To: Paul Jones, linux-btrfs@vger.kernel.org

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On Sun, 2016-09-04 at 05:33 +0000, Paul Jones wrote:
> The errors are wrong. I nearly ruined my filesystem a few days ago by
> trying to repair similar errors, thankfully all seems ok.
> Check again with btrfs-progs 4.6.1 and see if the errors go away,
> mine did.
> See open bug https://bugzilla.kernel.org/show_bug.cgi?id=155791 for
> more details.

Thanks for the pointer :)
I can at least confirm that my system seems to work normal, scrub
didn't bring any errors either, nor are there any kernel messages...

The interesting thing... I have some pretty large btrfs on those 8TiB
seagate disks (nearly full with some million files)... which I have
also scanned with v4.7... and no errors.
Only my system fs seems to be "affected".


Well it's not my first case of false positives in btrfs check (https://
www.mail-archive.com/linux-btrfs@vger.kernel.org/msg48325.html)... so I
was more relaxed this time (at least a bit ;-) ).

Cheers,
Chris.

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^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: gazillions of Incorrect local/global backref count
  2016-09-04  4:50 gazillions of Incorrect local/global backref count Christoph Anton Mitterer
  2016-09-04  5:33 ` Paul Jones
@ 2016-09-04 22:41 ` Chris Murphy
  2016-09-05  7:27 ` David Sterba
  2 siblings, 0 replies; 6+ messages in thread
From: Chris Murphy @ 2016-09-04 22:41 UTC (permalink / raw)
  To: Christoph Anton Mitterer; +Cc: Btrfs BTRFS

On Sat, Sep 3, 2016 at 10:50 PM, Christoph Anton Mitterer
<calestyo@scientia.net> wrote:
> Hey.
>
> I just did a btrfs check on my notebooks root fs, with:
> $ uname -a
> Linux heisenberg 4.7.0-1-amd64 #1 SMP Debian 4.7.2-1 (2016-08-28)
> x86_64 GNU/Linux
> $ btrfs --version
> btrfs-progs v4.7.1
>
>
>
> during:
> checking extents
>
> it found gazillions of these:
> Incorrect local backref count on 1107980288 root 257 owner 17807428
> offset 13568135168 found 2 wanted 3 back 0x2d69990
> Incorrect local backref count on 1107980288 root 257 owner 14055042
> offset 13568135168 found 2 wanted 3 back 0x2d69930
> Incorrect global backref count on 1107980288 found 4 wanted 6
> backpointer mismatch on [1107980288 61440]
> Incorrect local backref count on 1108049920 root 257 owner 17807428
> offset 13568262144 found 2 wanted 5 back 0x2d69ac0
> Incorrect local backref count on 1108049920 root 257 owner 14055042
> offset 13568262144 found 2 wanted 5 back 0x2d69b20
> Incorrect global backref count on 1108049920 found 4 wanted 10
> backpointer mismatch on [1108049920 77824]
>
> See stdout/err[0] logfiles from the check.
>
>
> What do they mean?

https://bugzilla.kernel.org/show_bug.cgi?id=155791
http://www.spinics.net/lists/linux-btrfs/msg58142.html


-- 
Chris Murphy

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: gazillions of Incorrect local/global backref count
  2016-09-04  4:50 gazillions of Incorrect local/global backref count Christoph Anton Mitterer
  2016-09-04  5:33 ` Paul Jones
  2016-09-04 22:41 ` Chris Murphy
@ 2016-09-05  7:27 ` David Sterba
  2016-09-05 14:33   ` Christoph Anton Mitterer
  2 siblings, 1 reply; 6+ messages in thread
From: David Sterba @ 2016-09-05  7:27 UTC (permalink / raw)
  To: Christoph Anton Mitterer; +Cc: linux-btrfs

On Sun, Sep 04, 2016 at 06:50:53AM +0200, Christoph Anton Mitterer wrote:
> Hey.
> 
> I just did a btrfs check on my notebooks root fs, with:
> $ uname -a
> Linux heisenberg 4.7.0-1-amd64 #1 SMP Debian 4.7.2-1 (2016-08-28)
> x86_64 GNU/Linux
> $ btrfs --version
> btrfs-progs v4.7.1

As others replied, it's a false positive. There's a fix on the way, once
it's done I'll release 4.7.2.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: gazillions of Incorrect local/global backref count
  2016-09-05  7:27 ` David Sterba
@ 2016-09-05 14:33   ` Christoph Anton Mitterer
  0 siblings, 0 replies; 6+ messages in thread
From: Christoph Anton Mitterer @ 2016-09-05 14:33 UTC (permalink / raw)
  To: linux-btrfs

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On Mon, 2016-09-05 at 09:27 +0200, David Sterba wrote:
> As others replied, it's a false positive. There's a fix on the way,
> once
> it's done I'll release 4.7.2.
Yeah... thanks again for confirming... and sorry that I've missed the
obvious earlier post :-/

Best wishes,
Chris.

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^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-09-05 14:33 UTC | newest]

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2016-09-04  4:50 gazillions of Incorrect local/global backref count Christoph Anton Mitterer
2016-09-04  5:33 ` Paul Jones
2016-09-04  6:33   ` Christoph Anton Mitterer
2016-09-04 22:41 ` Chris Murphy
2016-09-05  7:27 ` David Sterba
2016-09-05 14:33   ` Christoph Anton Mitterer

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