Dear all,
During a move of some 60GB of data from an ext4 partition to a btrfs
partition, both on the same disk, the following happened:
- my window manager froze;
- the move suspended, i.e., no more data was written to the destination
or deleted from the source;
- part of top output: (sorry for possible wrapping; sending this from
webmail)
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
13610 root 20 0 0 0 0 D 26 0.0 299:45.87
btrfs-cache-279
1566 root 20 0 0 0 0 S 22 0.0 218:30.86
btrfs-endio-met
(there were also a firefox instance and an npviewer.bin process still
consuming CPU time, but I guess this was some flash movie happily
playing along during the freeze);
- those two btrfs processes could not be terminated, not even by kill
-9;
- "lsof 1566" output (similar for the other process):
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
btrfs-end 1566 root cwd DIR 8,6 4096 2 /
btrfs-end 1566 root rtd DIR 8,6 4096 2 /
btrfs-end 1566 root txt unknown /proc/1566/exe
After a reboot, I am able to mount the btrfs filesystem, and read data
from it, but as soon as I try any write operation (even a simple touch),
that command hangs, and there are two btrfs processes hanging around,
just as above; dmesg gives lots of "parent transid failed" messages.
My kernel is 2.6.36 (with gentoo patches).
So, the questions:
1) Is this a known problem? If so, is it fixed in a newer version?
In the archive of this list, I read about others with "parent transid
failed" errors, and a recovery operation (suggested by Chris Mason),
using btrfs-select-super
<http://www.spinics.net/lists/linux-btrfs/msg07572.html>.
2) Should I try this procedure to fix my filesystem? Is there any debug
information I should collect first? (I can recreate the two "spinning"
processes by rebooting and writing to the filesystem.)
I am saddened by this failure, as this data move was actually part of
an operation to switch over to btrfs completely, after using it without
problems for quite a while.
Thanks for any help. Keep up the good work.
Regards,
Arie Peterson
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