Re: Fsck, parent transid verify failed

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

Excerpts from Tom Kuther's message of 2010-12-09 11:21:03 -0500:
> Chris Mason <chris.mason <at> oracle.com> writes:
> 
> > [...]
> > Build the latest tools, then:
> > 
> > btrfsck -s 1 /dev/xxx
> > btrfsck -s 2 /dev/xxx
> > 
> > If either of these work we have an easy way to get it mounted.  Just let
> > me know.
> > 
> 
> Hello,
> 
> I get those "parent transid verify failed" errors too after a system failure.
> 
> # btrfsck -s 1 /dev/md0 
> using SB copy 1, bytenr 67108864
> found 1954912653312 bytes used err is 0
> total csum bytes: 1892054684
> total tree bytes: 3455627264
> total fs tree bytes: 1082691584
> btree space waste bytes: 584155173
> file data blocks allocated: 12808940421120
>  referenced 1933520879616
> Btrfs v0.19-35-g1b444cd-dirty
> # btrfsck -s 2 /dev/md0 
> using SB copy 2, bytenr 274877906944
> found 1954912653312 bytes used err is 0
> -snip-
> 
> Both seem to work.
> What would be the steps to get it mounted?

If btrfsck -s is able to find a good super, I've setup a tool that will
copy the good super over into the default super.  It is currently
sitting in the next branch of the btrfs-progs-unstable repo.

git clone git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs-unstable.git next

(or git pull into your existing checkout)

Then

make btrfs-select-super
./btrfs-selects-super -s 1 /dev/xxx

After this you'll want to do a full backup and make sure things are
working properly.

-chris