Red Hat Bugzilla – Bug 596009
Possible ext4 anomalies
Last modified: 2011-02-15 16:57:18 EST
Description of problem:
I have had my FC12 system installed since February this year and have
experienced this particular problem twice so far. The problem does NOT
happen frequently... Just long enough for me to become complacent that
it was a fluke.
Files in /root have become empty, 141 of them this time. Their update
dates are all the same, about 2 minutes before I noticed the problem
Version-Release number of selected component (if applicable):
This has happened with older kernels as well but I do not know their version information.
Current kernel=18.104.22.168-115.fc12.i686.PAE #1 SMP Fri Apr 30 20:14:08 UTC 2010 i686 i686 i386 GNU/Linux
This has happened twice since February 2010.
Steps to Reproduce:
This time, 141 files have become 0 length.
I am EXTREMELY reluctant to claim that this is anyone's programming error. Are there traps that can be placed that would give more information? The only way I know to cause this problem is by taking specific steps like "cat /dev/null > filename" or editing the files but just these specific files, deleting all their data and then saving the file. I assure you that I would not do such a thing. None of these files have anything specific in common except that they're all in /root (same as last time) AND fstype = ext4; OS=FC12.
The system is more up to date than the first failure and there are different rpms as well.
Possible clue? I have a script in /root that I make a soft link in / named poweroff (cd /;ln -s /root/poweroff .). I can make the link and reboot the system and the link will disappear.
Have you had crashes or powerlosses before you saw this happen? Or the machine has been up this whole time and you suddenly have the content lost?
What does poweroff do? :)
Does the root fs fsck cleanly? (touch /.forcefsck will make it check next boot, IIRC)
No crashes or power losses.
I'll give your /.forcefsck trick and reboot in a while. Does this work on all file systems?
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I'd like to leave this open just in case. I'll be migrating to FC13 in the near future. So far, the problem has not happened again.
If you MUST close it then please feel free to do so.
I just got the same error in F14. My wife was using OpenOffice writer - she saves regularly.
Then suddenly we had power outage.
After it the document she was working on for the last 5 hours and was saving regularly was gone and empty.
OpenOffice writer was not able to recover it.
Before F14 we used ext3 for /home - never had problems like this - OO always was able to recover.
With F14 we are using ext4 - I guess this might be ext4 bug.
I have not seen this problem other than the two times on FC12. I have one system at FC12 and one at FC14. I'll keep my eyes on what's going on on this system that might provide clues to this behavior and, of course, report them immediately.
Is this the right place for FC14 bugs?
ext3 essentially syncs every 5s - data=ordered (default) + 5s journal commit pushes file data out more often than "normal"
It is most likely that the application is not doing proper data integrity management... even in the case of a manual save, it matters what OO is doing during periodic saves, etc.
I'm not aware of any deficiencies in ext4's fsync/data integrity handling...
In each specific case here it would be good to do something like strace OO, and see what file IO calls it's doing (writes, truncates, opens, closes, renames, fsyncs, etc...)
George, are you still seeing these issues? If not I don't know where to go with this bug...
Jacek, losing buffered data after a power loss sounds like a different issue, and more likely related to OO doing something bad with data integrity.
I'll probably close this bug unless the mystery George reported is still being mysterious...
I think we can close this one. I have not (so far) seen any problems like this. I'm on fc14 now... It's rough... KDE/X11 are having serious problems... a whole slew of other X11 stuff's failing... I use startx > startx.log 2>&1 and it's horrible... + X11 dumps core when you exit KDE... I have not made many bugs yet... but will.
Regards and thanks for your patience.
Current release seems to work, so closing.