Re: Massive filesystem corruption after balance + fstrim on Linux 5.1.2

From: "Michael Laß" <bevan@bi-co.net>
To: Chris Murphy <lists@colorremedies.com>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: Massive filesystem corruption after balance + fstrim on Linux 5.1.2
Date: Sat, 18 May 2019 11:18:31 +0200	[thread overview]
Message-ID: <AD966642-1043-468D-BABF-8FC9AF514D36@bi-co.net> (raw)
In-Reply-To: <CAJCQCtTZWXUgUDh8vn0BFeEbAdKToDSVYYw4Q0bt0rECQr9nxQ@mail.gmail.com>

> Am 18.05.2019 um 06:09 schrieb Chris Murphy <lists@colorremedies.com>:
> 
> On Fri, May 17, 2019 at 11:37 AM Michael Laß <bevan@bi-co.net> wrote:
>> 
>> 
>> I tried to reproduce this issue: I recreated the btrfs file system, set up a minimal system and issued fstrim again. It printed the following error message:
>> 
>> fstrim: /: FITRIM ioctl failed: Input/output error
> 
> Huh. Any kernel message at the same time? I would expect any fstrim
> user space error message to also have a kernel message. Any i/o error
> suggests some kind of storage stack failure - which could be hardware
> or software, you can't know without seeing the kernel messages.

I missed that. The kernel messages are:

attempt to access beyond end of device
sda1: rw=16387, want=252755893, limit=250067632
BTRFS warning (device dm-5): failed to trim 1 device(s), last error -5

Here are some more information on the partitions and LVM physical segments:

fdisk -l /dev/sda:

Device     Boot Start       End   Sectors   Size Id Type
/dev/sda1  *     2048 250069679 250067632 119.2G 8e Linux LVM

pvdisplay -m:

  --- Physical volume ---
  PV Name               /dev/sda1
  VG Name               vg_system
  PV Size               119.24 GiB / not usable <22.34 MiB
  Allocatable           yes (but full)
  PE Size               32.00 MiB
  Total PE              3815
  Free PE               0
  Allocated PE          3815
  PV UUID               mqCLFy-iDnt-NfdC-lfSv-Maor-V1Ih-RlG8lP

  --- Physical Segments ---
  Physical extent 0 to 1248:
    Logical volume	/dev/vg_system/btrfs
    Logical extents	2231 to 3479
  Physical extent 1249 to 1728:
    Logical volume	/dev/vg_system/btrfs
    Logical extents	640 to 1119
  Physical extent 1729 to 1760:
    Logical volume	/dev/vg_system/grml-images
    Logical extents	0 to 31
  Physical extent 1761 to 2016:
    Logical volume	/dev/vg_system/swap
    Logical extents	0 to 255
  Physical extent 2017 to 2047:
    Logical volume	/dev/vg_system/btrfs
    Logical extents	3480 to 3510
  Physical extent 2048 to 2687:
    Logical volume	/dev/vg_system/btrfs
    Logical extents	0 to 639
  Physical extent 2688 to 3007:
    Logical volume	/dev/vg_system/btrfs
    Logical extents	1911 to 2230
  Physical extent 3008 to 3320:
    Logical volume	/dev/vg_system/btrfs
    Logical extents	1120 to 1432
  Physical extent 3321 to 3336:
    Logical volume	/dev/vg_system/boot
    Logical extents	0 to 15
  Physical extent 3337 to 3814:
    Logical volume	/dev/vg_system/btrfs
    Logical extents	1433 to 1910

Would btrfs even be able to accidentally trim parts of other LVs or does this clearly hint towards a LVM/dm issue? Is there an easy way to somehow trace the trim through the different layers so one can see where it goes wrong?

Cheers,
Michael

PS: Current state of bisection: It looks like the error was introduced somewhere between b5dd0c658c31b469ccff1b637e5124851e7a4a1c and v5.1.