btrfs check --repair crash, and btrfs-cleaner crash

[Marc MERLIN <marc@merlins.org>]

myth:~# btrfs check --repair /dev/mapper/crypt_sdd1 
enabling repair mode
Checking filesystem on /dev/mapper/crypt_sdd1
UUID: 024ba4d0-dacb-438d-9f1b-eeb34083fe49
checking extents
cmds-check.c:4486: add_data_backref: Assertion `back->bytes != max_size` failed.
btrfs[0x8066a73]
btrfs[0x8066aa4]
btrfs[0x8067991]
btrfs[0x806b4ab]
btrfs[0x806b9a3]
btrfs[0x806c5b2]
btrfs(cmd_check+0x1088)[0x806eddf]
btrfs(main+0x153)[0x80557c6]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb75064d3]
btrfs[0x80557ec]

myth:~# btrfs --version
btrfs-progs v4.0

Is anyone interested in getting data off this filesystem or having me
try newer code/a patch?

filesystem is 10TB-ish, so sending an image isn't going to be easy though.

I can mount with -o ro without it crashing, but if I drop ro, it then
tries to do something and crashes, and unfortunately the error doesn't
make it to syslog

Screenshot: http://marc.merlins.org/tmp/btrfs_crash.jpg

Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/                         | PGP 1024R/763BE901