Thread (14 messages) 14 messages, 2 authors, 2012-02-17

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

From: Chris Mason <hidden>
Date: 2012-02-10 23:39:59

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:
quoted
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
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