During a system deadlock I was forced to hard shutdown my system while a
`btrfs balance` was ongoing and ctrl+c & `btrfs balance cancel` failed
Since the restart the partition is broken, the kernel fails to mounts it
and btrfs' repair tools exit cause of errors w/o doing anything. The
partition is 20GB, and so got 2 superblocks: both are broken :/
kernel is 3.11.5, btrfs-progs are git ones & distro is gentoo
------------ btrfs output start ------------
# mount /dev/sda2 /mnt/repair
mount: wrong fs type, bad option, bad superblock on /dev/sda2,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
# dmesg | tail
[279861.340796] device label root-x64 devid 1 transid 535462 /dev/sda2
[279861.341416] btrfs: disk space caching is enabled
[279861.342223] attempt to access beyond end of device <------
[279861.342226] sda2: rw=32, want=44040448, limit=41943040 <------
[279861.342236] attempt to access beyond end of device
[279861.342237] sda2: rw=32, want=44302592, limit=41943040
[279861.347811] btrfs: open_ctree failed
# btrfs-show-super /dev/sda2
superblock: bytenr=65536, device=/dev/sda2
---------------------------------------------------------
csum 0xbd53d63e [match]
bytenr 65536
...
total_bytes 21474836480
bytes_used 18661335040
...
dev_item.total_bytes 21474836480
dev_item.bytes_used 22032678912 <--- beyond part size!
...
# btrfs fi show
Label: 'root-x64' uuid: f87210e5-47a9-44af-9797-6afea2cdaae8
Total devices 1 FS bytes used 17.38GB
devid 1 size 20.00GB used 20.52GB path /dev/sda2 <--- again
beyond partsize
Btrfs v0.20-rc1-358-g194aa4a
# btrfsck /dev/sda2
Check tree block failed, want=39317532672, have=0
read block failed check_tree_block
Couldn't setup extent tree
Checking filesystem on /dev/sda2
UUID: f87210e5-47a9-44af-9797-6afea2cdaae8
Critical roots corrupted, unable to fsck the FS
# btrfs restore /dev/sda2 /tmp/fix
Check tree block failed, want=39317532672, have=0
read block failed check_tree_block
Couldn't setup extent tree
Check tree block failed, want=39317532672, have=0
read block failed check_tree_block
Couldn't read fs root: -5
# btrfs-find-root /dev/sda2
Super think's the tree root is at 29556736, chunk root 40659582976
Found tree root at 29556736 gen 535462 level 1
btrfs-debug-tree & `btrfs chunk-recover -v` output a lot stuff but at the
end both fail:
# btrfs-debug-tree /dev/sda2
...
Check tree block failed, want=39317532672, have=0
read block failed check_tree_block
btrfs-debug-tree: btrfs-debug-tree.c:237: main: Assertion `!(ret < 0)'
failed.
Aborted
# btrfs chunk-recover -v /dev/sda2
...
Total Chunks: 31
Heathy: 29
Bad: 2
Orphan Block Groups:
Block Group: start = 37710987264, len = 268435456, flag = 1
Block Group: start = 37979422720, len = 230686720, flag = 1
Block Group: start = 38210109440, len = 33554432, flag = 1
Orphan Device Extents:
Device extent: devid = 1, start = 3527409664, len = 268435456, chunk
offset = 37710987264
Check tree block failed, want=39317532672, have=0
read block failed check_tree_block
Couldn't setup extent tree
open with broken chunk error
Fail to recover the chunk tree.
------------ btrfs output end ------------
Cause btrfs-debug-tree & `btrfs chunk-recover` say there are still chunks,
I have the hope most data is still intact, only btrfs & tools stumble on
some invalid data. Is there any hope to e.g. force btrfs to clamp all data?
Thanks,
Christian Switaiski
PS: I already tried to patch btrfsprogs to not exit after the errors
occurred (it helped with a problem in the past I had) but it just causes
segfaults :/
Also I am bit confused that none of the btrfs progs show a 'beyond
anything' msg like the kernel.
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