Re: 8 days looped? (btrfsck --repair --init-extent-tree)

[Martin <m_btrfs@ml1.co.uk>]

On 22/10/13 19:17, Josef Bacik wrote:
> On Tue, Oct 22, 2013 at 06:58:48PM +0100, Martin wrote:
>> Dear list,
>>
>> I've been trying to recover a 2TB single disk btrfs from a good few days
>> ago as already commented on the list. btrfsck complained of an error in
>> the extents and so I tried:
>>
>> btrfsck --repair --init-extent-tree /dev/sdX
>>
>>
>> That was 8 days ago.
>>
>> The btrfs process is still running at 100% cpu but with no disk activity
>> and no visible change in memory usage.
>>
>> Looped?
>>
>> Is there any way to check whether it is usefully doing anything or
>> whether this is a lost cause?
>>
>>
>> The only output it has given, within a few seconds of starting, is:
>>
>>
>> parent transid verify failed on 911904604160 wanted 17448 found 17449
>> parent transid verify failed on 911904604160 wanted 17448 found 17449
>> parent transid verify failed on 911904604160 wanted 17448 found 17449
>> parent transid verify failed on 911904604160 wanted 17448 found 17449
>> Ignoring transid failure
>>
>>
>> Any comment/interest before abandoning?
>>
>> This all started from trying to delete/repair a directory tree of a few
>> MBytes of files...
>>
> 
> Sooo it probably is looped, you should be able to attach gdb to it and run bt to
> see where it is stuck and send that back to the list so we can figure out what
> to do.  Thanks,

OK... But I doubt this helps much:

(gdb) bt
#0  0x000000000042b93f in ?? ()
#1  0x000000000041cf10 in ?? ()
#2  0x000000000041e29d in ?? ()
#3  0x000000000041e8ae in ?? ()
#4  0x0000000000425bf2 in ?? ()
#5  0x0000000000425cae in ?? ()
#6  0x0000000000421e87 in ?? ()
#7  0x0000000000422022 in ?? ()
#8  0x000000000042210c in ?? ()
#9  0x0000000000416b07 in ?? ()
#10 0x00000000004043ad in ?? ()
#11 0x00007f5ba972860d in __libc_start_main () from /lib64/libc.so.6
#12 0x00000000004043dd in ?? ()
#13 0x00007fff7ead12a8 in ?? ()
#14 0x00000000ffffffff in ?? ()
#15 0x0000000000000004 in ?? ()
#16 0x000000000064f4d0 in ?? ()
#17 0x00007fff7ead2469 in ?? ()
#18 0x00007fff7ead2472 in ?? ()
#19 0x00007fff7ead2485 in ?? ()
#20 0x0000000000000000 in ?? ()

At least it stays consistent when repeated!


Recompiling with -ggdb for the symbols and rerunning:

# gdb /sbin/btrfsck 17151
GNU gdb (Gentoo 7.5.1 p2) 7.5.1
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
For bug reporting instructions, please see:
<http://bugs.gentoo.org/>...
Reading symbols from /sbin/btrfsck...Reading symbols from
/usr/lib64/debug/sbin/btrfsck.debug...(no debugging symbols found)...done.
(no debugging symbols found)...done.
Attaching to program: /sbin/btrfsck, process 17151

warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
Reading symbols from /lib64/libuuid.so.1...(no debugging symbols
found)...done.
Loaded symbols for /lib64/libuuid.so.1
Reading symbols from /lib64/libblkid.so.1...(no debugging symbols
found)...done.
Loaded symbols for /lib64/libblkid.so.1
Reading symbols from /lib64/libz.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib64/libz.so.1
Reading symbols from /usr/lib64/liblzo2.so.2...(no debugging symbols
found)...done.
Loaded symbols for /usr/lib64/liblzo2.so.2
Reading symbols from /lib64/libpthread.so.0...(no debugging symbols
found)...done.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Loaded symbols for /lib64/libpthread.so.0
Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols
found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x000000000041e74f in btrfs_search_slot ()
(gdb) bt
#0  0x000000000041e74f in btrfs_search_slot ()
#1  0x00000000004259fa in find_first_block_group ()
#2  0x0000000000425ab4 in btrfs_read_block_groups ()
#3  0x0000000000421c15 in btrfs_setup_all_roots ()
#4  0x0000000000421dce in __open_ctree_fd ()
#5  0x0000000000421ea8 in open_ctree_fs_info ()
#6  0x00000000004169b4 in cmd_check ()
#7  0x000000000040443b in main ()

And over twelve hours later:

(gdb)
#0  0x000000000041e74f in btrfs_search_slot ()
#1  0x00000000004259fa in find_first_block_group ()
#2  0x0000000000425ab4 in btrfs_read_block_groups ()
#3  0x0000000000421c15 in btrfs_setup_all_roots ()
#4  0x0000000000421dce in __open_ctree_fd ()
#5  0x0000000000421ea8 in open_ctree_fs_info ()
#6  0x00000000004169b4 in cmd_check ()
#7  0x000000000040443b in main ()


Any further debug useful?

Regards,
Martin