Re: AW: ext4 filesystem bad extent error review

[Eric Sandeen <sandeen@redhat.com>]

On 1/3/14, 10:29 AM, Juergens Dirk (CM-AI/ECO2) wrote:
> So, I think there _might_ be a kernel bug, but it could be also a problem 
> related to the particular type of eMMC. We did not observe the same issue
> in previous tests with another type of eMMC from another supplier, but this
> was with an older kernel patch level and with another HW design.
> 
> Regarding a possible kernel bug: Is there any chance that the invalid 
> ee_len or ee_start are returned by, e.g., the block allocator ?
> If so, can we try to instrument the code to get suitable traces ?
> Just to see or to exclude that the corrupted inode is really written
> to the eMMC ?

>From your description it does sound possible that it's a kernel bug.
Adding testcases to the code to catch it before it hits the journal
might be helpful - but then maybe this is something getting overwritten
after the fact - hard to say.

Can you share more details of the test you are running?  Or maybe even
the test itself?

I've used a test framework in the past to simulate resets w/o needing
to reset the box, and do many journal replays very quickly.  It'd be
interesting to run it using your testcase.

Thanks,
-Eric