Partition broken, btrfsck segfaults or asserts

[Dennis Schridde <devurandom@gmx.net>]

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Hello!

I have a serious problem with inaccessible data and segfaulting btrfsck
for the /var partition on my computer.

The reason is not entirely clear to me. The only extraordinary things
happening today were an empty CMOS battery and me accidentally enabling
C1E support when reconfiguring the BIOS. Afterwards the computer did
not boot properly anymore (some GPU lockup thingy and the whole system
locked up hard before X would start) and when I cut the power and setup
the BIOS again (this time without C1E support), /var would be broken in
the state I describe below.

I can mount it, and dmesg says the following, which seems normal:
---
device label var devid 1 transid 393536 /dev/sda7
btrfs: use lzo compression
btrfs: enabling auto defrag
---

When I access certain directories, however, I get a message like this
one:
ls: cannot access /var/log: Stale NFS file handle

When I run btrfsck --repair it asserts, and when I just run btrfsck
without extra options it segfaults. Sadly I do not have debug symbols
installed, so the backtrace is probably useless. I attached the
stdout/err output of both runs to the bugzilla report:
https://bugzilla.kernel.org/show_bug.cgi?id=64411

# btrfs --version
Btrfs v0.20-rc1-358-g194aa4a

# uname -r
3.11.6-gentoo

I would be thankful if you could help me to get as much as possible of
my data back. And please CC me, as I am not subscribed to the list.

Best regards,
Dennis

P.S: I already sent an email yesterday, but it did not arrive in the
archives, so I assume it was blocked by the list for the two ~125kB
attachments.

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