From: Rich Freeman <r-btrfs@thefreemanclan.net>
To: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: btrfs balance segfault, kernel BUG at fs/btrfs/extent-tree.c:7727
Date: Sat, 25 Oct 2014 21:41:27 -0400 [thread overview]
Message-ID: <CAGfcS_kFnqp5aeHMfTLJbTbVx=yobNf+Zp-ECYh1xNRFG7UjaA@mail.gmail.com> (raw)
In-Reply-To: <CAGfcS_nR-MP8VLWanvvs9dMQBi02JoCCUTYd_JwA9tmtPRGmSg@mail.gmail.com>
On Mon, Oct 13, 2014 at 11:12 AM, Rich Freeman
<r-btrfs@thefreemanclan.net> wrote:
> On Thu, Oct 9, 2014 at 10:19 AM, Petr Janecek <janecek@ucw.cz> wrote:
>>
>> I have trouble finishing btrfs balance on five disk raid10 fs.
>> I added a disk to 4x3TB raid10 fs and run "btrfs balance start
>> /mnt/b3", which segfaulted after few hours, probably because of the BUG
>> below. "btrfs check" does not find any errors, both before the balance
>> and after reboot (the fs becomes un-umountable).
>>
>> [22744.238559] WARNING: CPU: 0 PID: 4211 at fs/btrfs/extent-tree.c:876 btrfs_lookup_extent_info+0x292/0x30a [btrfs]()
>>
>> [22744.532378] kernel BUG at fs/btrfs/extent-tree.c:7727!
>
> I am running into something similar. I just added a 3TB drive to my
> raid1 btrfs and started a balance. The balance segfaulted, and I find
> this in dmesg:
I got another one of these crashes during a balance today, and this is
on 3.17.1 with the "Btrfs: race free update of commit root for ro
snapshots" patch. So, there is something else in 3.17.1 that causes
this problem. I did see mention of an extent error of some kind on
the lists and I don't have that patch - I believe it is planned for
3.17.2.
After the crash the filesystem became read-only.
I didn't have any way to easily capture the logs, but I got repeated
crashes when trying to re-mount the filesystem after rebooting. The
dmesg log showed read errors from one of the devices (bdev /dev/sdb2
errs: wr 0, rd 1361, flush 0, corrupt 0, gen 0). When I tried to
btrfs check the filesystem with btrfs-progs 3.17 it abruptly
terminated and output an error mentioning could not find extent items
followed by root and a really large number.
I finally managed to recover by mounting the device with skip_balance
- I suspect that it was crashing due to attempts to restart the
failing balance. Then after letting the filesystem settle down I
unmounted it cleanly and rebooted and everything was back to normal.
However, i'm still getting "bdev /dev/sdb2 errs: wr 0, rd 1361, flush
0, corrupt 0, gen 0" in my dmesg logs. I have tried scrubbing the
device with no errors found.
--
Rich
next prev parent reply other threads:[~2014-10-26 1:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-09 14:19 btrfs balance segfault, kernel BUG at fs/btrfs/extent-tree.c:7727 Petr Janecek
2014-10-13 15:12 ` Rich Freeman
2014-10-26 1:41 ` Rich Freeman [this message]
2014-10-26 1:51 ` Chris Samuel
2014-10-26 2:02 ` Duncan
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