Re: BTRFS constantly reports "No space left on device" even with a huge unallocated space

From: Chris Murphy <lists@colorremedies.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Ronan Arraes Jardim Chagas <ronisbr@gmail.com>,
	Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: BTRFS constantly reports "No space left on device" even with a huge unallocated space
Date: Fri, 12 Aug 2016 14:34:31 -0600	[thread overview]
Message-ID: <CAJCQCtS51syrzxvpZXGzS=Ge=rW1iEfZDj6VrVmON39ww-Hmdg@mail.gmail.com> (raw)
In-Reply-To: <CAJCQCtTrEqR=UNpHp7ApbdBkwRRT6U5tiSHcs2y4N-P_G5u=Fw@mail.gmail.com>

On Fri, Aug 12, 2016 at 1:37 PM, Chris Murphy <lists@colorremedies.com> wrote:
> On Fri, Aug 12, 2016 at 1:00 PM, Ronan Arraes Jardim Chagas
> <ronisbr@gmail.com> wrote:

>
> d. Run journalctl -f from a 2nd computer.

Hopefully it's obvious I mean run journalctl -f on the affected
computer remotely via ssh.

>
>> Do you
>> think that if I reinstall my openSUSE it will be fixed?
>
> Probably but the nature of this probem isn't well understood as far as
> I know. It's not that common or it'd be easy for a dev to reproduce
> and then figure out what's going on.

Since this file system has relatively small metadata size, just under
2GiB, it might be useful to take a btrfs-image of it and put it up
somewhere like a google drive, or wherever it can remain for a while.
Options -t 4 -c9 -s are fairly standard and sanitize file names. Data
itself is not included in the image. From this I think a dev might be
able to figure out what's unique about this file system that results
in the bogus enospc. If you do this, I recommend filing a
bugzilla.kernel.org bug and include URL to the image and URL to this
thread, and then the bugzilla URL in a post on this thread that way
everything is cross referenced.

-- 
Chris Murphy