Re: BTRFS crash on mount with 3.4.4

[Marc MERLIN <marc@merlins.org>]

On Thu, Aug 02, 2012 at 03:40:03PM +0200, David Sterba wrote:
> On Tue, Jul 31, 2012 at 06:01:04PM -0700, Marc MERLIN wrote:
> > On Tue, Jul 31, 2012 at 11:04:12AM -0700, Marc MERLIN wrote:
> > > My kernel crashed for some other reason, and now I can't mount my btrfs
> > > filesystem.
> > > I don't care about the data, it's backed up.
> > > 
> > > I'll compile a 3.5 kernel, but is there any info you'd like off that
> > > filesystem to see why btrfs is crashing on mount?
> > 
> > On the plus side, 3.5 mounted the filesystem:
> > [  183.069179] device label btrfs_pool1 devid 1 transid 20769 /dev/mapper/test
> > [  183.087805] btrfs: disk space caching is enabled
> > [  183.224784] btrfs: no dev_stats entry found for device /dev/mapper/test (devid 1) (OK on first mount after mkfs)
> > [  186.277795] Btrfs detected SSD devices, enabling SSD mode
> > [  188.477443] btrfs: unlinked 6 orphans
> > [  188.477451] btrfs: truncated 1 orphans
> > [  411.837015] btrfs: unlinked 13 orphans
> > [  414.373500] btrfs: unlinked 35 orphans
> 
> there's this commit in 3.5 that looks like it fixed the problem:
> 
> Author:     Josef Bacik <jbacik@fusionio.com>
> AuthorDate: Wed Jun 27 15:10:56 2012 -0400
> 
>     Btrfs: fix tree log remove space corner case
> 
>     The tree log stuff can have allocated space that we end up having split
>     across a bitmap and a real extent.  The free space code does not deal with
>     this, it assumes that if it finds an extent or bitmap entry that the entire
>     range must fall within the entry it finds.  This isn't necessarily the case,
>     so rework the remove function so it can handle this case properly.  This
>     fixed two panics the user hit, first in the case where the space was
>     initially in a bitmap and then in an extent entry, and then the reverse
>     case.  Thanks,

Indeed. Thanks for finding this David and thanks for writing this Josef :)

Marc
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