UBIFS - strange behaviour after enabling chk_index

[Krzeminski, Marcin (Nokia - PL/Wroclaw)]

Richad,

> -----Original Message-----
> From: Richard Weinberger [mailto:richard at nod.at]
> Sent: Wednesday, September 14, 2016 11:39 PM
> To: Krzeminski, Marcin (Nokia - PL/Wroclaw)
> <marcin.krzeminski at nokia.com>; linux-mtd at lists.infradead.org
> Subject: Re: UBIFS - strange behaviour after enabling chk_index
> 
> Marcin,
> 
> On 14.09.2016 10:28, Krzeminski, Marcin (Nokia - PL/Wroclaw) wrote:
> > (Plain text now)
> >
> > Hi Richard, list
> >
> > During some power-cut tests I accidently came across strange case.
> > The test script is here (I could attach it this in thread later).
> >
> > http://pastebin.com/daNrf6yG
> >
> > Result of running this on HW and Qemu is the same, and it ends like below
> (logs from Qemu).
> >
> > It does not reproduce if I use flash with 256KiB sectors (both Qemu
> > and HW), or do not enable index integrity checks.
> > Could it be real life case?
> 
> Is this the SPI-NOR device you talked about on IRC?
Yes.

> Maybe the check is broken, maybe it uncovers a hard to hit issue on your
> flash. Both could be.
> 
> Do you emulate exactly the same device in qemu?
Yes, this part of HW is virtualized in Qemu, in fact the same SW build runs on Qemu and HW.
Since it reproduce on both it allows to think that this is SW related (at least for now),
but sure does not mean that this is UBI/UBIFS.

Back to problem, it seem that this could be a debug facility issue, since file system and data
are not corrupted. If data on flash are correct (I have done many test and all passed,
so currently I assume that drier is working properly), it could be that data in debug structure
in this case are somehow outdated/bad (d->old_zroot).
In test script, if I copy the same file twice (instead of three times) the problem does not
reproduce. 
I will try to debug this more, maybe you have any inside where to look?

Thanks,
Marcin
> 
> Thanks,
> //richard