From: Jeff Mahoney <jeffm@suse.de>
To: Chris Mason <chris.mason@oracle.com>,
Roman Mamedov <rm@romanrm.ru>,
dave@jikos.cz, dima <dolenin@parallels.com>,
linux-btrfs@vger.kernel.org
Subject: Re: NOCOW + compress-force = bug
Date: Tue, 13 Mar 2012 14:11:05 -0400 [thread overview]
Message-ID: <4F5F8DB9.40208@suse.de> (raw)
In-Reply-To: <20120216175815.GM21896@shiny>
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On 02/16/2012 12:58 PM, Chris Mason wrote:
> On Thu, Feb 16, 2012 at 07:55:15PM +0600, Roman Mamedov wrote:
>> Hello,
>>
>> Please be aware that there seems to be a possible problem with
>> using NOCOW flag on files situated on a filesystem mounted with
>> compress-force(=lzo, in my case).
>>
>> Since experimenting with NOCOW, I started regularly hitting this
>> BUG at extent-tree.c:5813
>>
>> 5813 BUG_ON(!(flags &
>> BTRFS_BLOCK_FLAG_FULL_BACKREF));
>>
>> I was unable to make netconsole work over a bridged interface, so
>> can only post screenshots of this OOPS:
>> http://romanrm.ru/pics/2012/2012-02-16-btrfs-bug-1.jpg
>> http://romanrm.ru/pics/2012/2012-02-16-btrfs-bug-2.jpg
>>
>> This happened four times already, and always on snapshot creation
>> (but not every case). I have hourly snapshots in crontab, and
>> only one case out of about ten fails with this problem. Did not
>> try to deliberately reproduce it yet by manually making snapshots
>> very often, etc.
>
> Interesting, NOCOW and compression don't really mix. We always cow
> for compression. I'll try to reproduce it.
I hit this one today without nocow or compression. The only thing
non-default was that I mounted with -ossd. The backing store was a 1GB
non-sparse loopback file on tmpfs.
I had kdump enabled and with 16GB, I wasn't waiting around for the
dump to complete. If it happens again, I'll have a full stack trace.
My test case was filling the disk while making snapshots.
- -Jeff
- --
Jeff Mahoney
SUSE Labs
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next prev parent reply other threads:[~2012-03-13 18:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-13 7:17 Set nodatacow per file? Ralf-Peter Rohbeck
2012-02-13 7:34 ` Chester
2012-02-13 8:10 ` Liu Bo
2012-02-13 7:40 ` dima
2012-02-13 8:09 ` Roman Mamedov
2012-02-13 8:40 ` dima
2012-02-13 13:42 ` dima
2012-02-13 13:51 ` Roman Mamedov
2012-02-13 14:31 ` Dmitry Olenin
2012-02-13 14:10 ` David Sterba
2012-02-13 14:21 ` Timo Witte
2012-02-13 15:10 ` dima
2012-02-16 13:55 ` NOCOW + compress-force = bug Roman Mamedov
2012-02-16 14:30 ` David Sterba
2012-02-16 17:58 ` Chris Mason
2012-03-13 18:11 ` Jeff Mahoney [this message]
2012-03-13 18:36 ` Jeff Mahoney
2012-02-29 15:09 ` Set nodatacow per file? Kyle Gates
2012-02-29 15:34 ` cwillu
2012-02-24 5:22 ` dima
2012-02-27 13:54 ` dima
2012-02-27 22:10 ` Chester
2012-02-28 0:51 ` dima
2012-03-02 3:28 ` dima
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