=== Terminal output ==# mount -o recovery /dev/md0 /mnt/root
mount: wrong fs type, bad option, bad superblock on /dev/md0,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
# dmesg | tail
[58290.395538] device label root devid 1 transid 250160 /dev/md0
[58290.395891] btrfs: enabling auto recovery
[58290.395895] btrfs: disk space caching is enabled
[58290.396388] btrfs bad tree block start 0 139264
[58290.396401] btrfs: failed to read chunk root on md0
[58290.396660] btrfs: open_ctree failed
# btrfsck /dev/md0
Check tree block failed, want=139264, have=0
Check tree block failed, want=139264, have=0
Check tree block failed, want=139264, have=0
read block failed check_tree_block
Couldn''t read chunk root
Segmentation fault
======================
I''m having some problems with my btrfs partition. It showed up around
the same time a disk got ejected from a RAID5 mdadm array, so the two
are probably related. The array seems to be working properly now (or
thinks it is), having rebuilt itself and completed a full integrity
check However, the array lists 1196 events and found 180156080
mismatches on the integrity check, so it may be serious issues with my
old disks from a Sun array. Even if my data is completely ruined
(e.g. `dd if=/dev/urandom of=/dev/md0`), btrfsck should not segfault.
Running `btrfs-show-super -a /dev/md0` appears to work fine, except
"chunk_root_generation" is 12 lower than "generation" and
"dev_item.generation" is 0, but I''m not sure how significant
that is.
I''m running 64-bit Linux Mint 14 KDE (Ubuntu 12.10 based), upgraded to
the 3.9-rc1 kernel and latest git pull of the official btrfs-progs as
of March 13, 2013. It uses gcc 4.7.2 (Ubuntu/Linaro 4.7.2-2ubuntu1).
I have attached my backtrace (with commands I used to generate it). I
could not find a debug version of libuuid to show where that is
crashing.
P.S.
Is there any hope for my data? I have at least 1 small subvolume I''d
really like to recover. Most of the rest is either backed up, copies
of media, or stuff I can download. If it''s all gone, I need to move
on with rebuilding, so I can get back to my normal work environment.
P.P.S.
Sorry if anyone is getting this twice. The first message (with a core
dump included) did not get a reply, nor was it on the mailing list
archive.