Abe wrote on 2016/01/07 17:39 +0100:
No wonder why chunck-recover crashed, superblocks are valid but they all
contain a bogus chunk_root, it exceeds the total_bytes !
So all I need it to find where that btree root is on disk, right?
Problem is almost every tool from btrfs-progs is unusuable because they
try to read the chunck root at first. Do you know of any alternative
tool that could scan devices and find where roots might be?
First, you're wrong about the total_bytes and chunk_root bytenr.
Chunk_root bytenr is btrfs *logical* bytenr.
It is completely OK for logical bytenr to beyond total bytenr,
So the problem is not here.
The real problem for chunk recovery to segfault, would be that, in your
cmds-check.c:5013, the leaf->data could be empty.
But you did give enough info or checked *leaf, so I can't determine now.
To recovery your RAID6, the possible chance lies in your superblock.
Please use run btrfs-show-super with -f -a to get full backup roots output.
Which may have a good old chunk root.
Thanks,
Qu
All superblock copies for all devices look like this :
# ./btrfs-show-super /dev/sdb1
superblock: bytenr=65536, device=/dev/sdb1
---------------------------------------------------------
csum 0x938855ef [match]
bytenr 65536
flags 0x1
( WRITTEN )
magic _BHRfS_M [match]
fsid bec7b9a0-c56c-494e-8631-072d3f89c0c9
label hive
generation 34245
root 6766859681792
sys_array_size 321
chunk_root_generation 32751
root_level 1
chunk_root 4415566151680 <--- Impossible Offset
chunk_root_level 1
log_root 0
log_root_transid 0
log_root_level 0
total_bytes 4096872997376 <---
bytes_used 2438972817408
sectorsize 4096
nodesize 16384
leafsize 16384
stripesize 4096
root_dir 6
num_devices 8
compat_flags 0x0
compat_ro_flags 0x0
incompat_flags 0x1e1
( MIXED_BACKREF |
BIG_METADATA |
EXTENDED_IREF |
RAID56 |
SKINNY_METADATA )
csum_type 0
csum_size 4
cache_generation 34245
uuid_tree_generation 34245
dev_item.uuid ea4a089b-c88c-4a6c-80e5-b2c93f0613f5
dev_item.fsid bec7b9a0-c56c-494e-8631-072d3f89c0c9 [match]
dev_item.type 0
dev_item.total_bytes 512109125120
dev_item.bytes_used 349754621952
dev_item.io_align 4096
dev_item.io_width 4096
dev_item.sector_size 4096
dev_item.devid 5
dev_item.dev_group 0
dev_item.seek_speed 0
dev_item.bandwidth 0
dev_item.generation 0
Best regards,
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