Re: can't read superblock (but could mount)

[Chris Mason <chris.mason@oracle.com>]

On Fri, Feb 10, 2012 at 05:18:42PM -0500, Chris Mason wrote:
> On Fri, Feb 10, 2012 at 08:30:51PM +0100, btrfs@nentwig.biz wrote:
> > Hi!
> > 
> > I used to have arch linux running on 1 btrfs partition (sda1, incl. /boot).
> > When switching to 3.2.5 recently the system fails to boot:
> > 
> > (after udevd)
> > /etc/rc.sysinit: line 15: 117 Bus error  mountpoint -q /proc
> > and so on, no idea.
> > 
> > It used to boot with 3.2.4, but
> > 
> > 1) I obviously had some corruption in the tree, when I tried to delete a
> > certain file I hit e.g. "kernel BUG at fs/btrfs/extent-tree.c" message.
> > 
> > 2) Even while running 3.2.4 I was unable to mount the partition from a
> > parallel gentoo or live USB install and I still am:
> > 
> > # mount /dev/sda1 /mnt/arch/
> > mount: /dev/sda1: can't read superblock
> > 
> > The strange thing is: when trying to boot from the partition the
> > boot loader (syslinux) is
> > obviously still able load the kernel from that partition.
> > 
> > Tried btrfs-zero-log and some deperate other things. Result: I can
> > now actually
> > execute btrfsck which previously used to fail:
> 
> Ok, step one:
> 
> Pull down the dangerdonteveruse branch of btrfs-progs:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs.git dangerdonteveruse
> 
> Run btrfs-debug-tree -r /dev/sda1 and send the output here please.

Sorry, that's btrfs-debug-tree -R /dev/sda1

-chris