Problem mounting a UBIFS volume

[Bruce_Leonard at selinc.com]

Artem,

Sorry for the delay in replying, I was on holiday for a couple of weeks 
and it's taken me a while to get my brain wrapped back around what I was 
working on when I left :).

Artem Bityutskiy <dedekind at infradead.org> wrote on 07/04/2008 06:02:29 AM:

> 
> On Wed, 2008-07-02 at 22:18 -0700, Bruce_Leonard at selinc.com wrote:
> > UBIFS error (pid 842): check_lpt_crc:invalid crc in LPT node: crc 2bbb 

> > calc a5a5
> > UBIFS error (pid 842): ubifs_read_nnode: error -22 reading nnode at 
8:6150
> > mount: wrong fs type, bad option, bad superblock on ubi0:bob,
> >        missing codepage or other error
> >        In some cases useful info is found in syslog - try
> >        dmesg | tail  or so
> 
> AFAIU, you still use a small flash and small image. So the only change
> was your MTD change. Are you sure it is not the MTD change which is to
> blame? Can you reproduce this error without your MTD change?
> 

Yes I can and here's what I've found.  I pulled the latest vanilla kernel 
from Linus' tree (congratulations on getting UBIFS in BTW, very cool), 
pulled the latest mkfs.ubifs, and did an entirely new clone of mtd-utils 
(I wanted to get rid of my modifications).  So there are NONE of my MTD 
changes in any of the code I'm currently using.  I also reset my driver to 
only recognize 2GiB of NAND.  Before I left I was starting to get 
suspicious of mkfs.ubifs, so I ran the following experiment this morning. 
I used mkfs.ubifs to create two different images of the same filesystem 
(one for up to 2GiB devices and one for up to 8GiB devices) as follows:

$ mkfs.ubifs -r x103/ -m 2048 -e 129024 -c 16384 -o x103.img
$ mkfs.ubifs -r x103/ -m 2048 -e 129024 -c 65536 -o x103_large.img

If I understand things right (which usually isn't the case :-\), these 
should be more or less the same, because the -c option is just specifying 
a MAXIMUM volume size the image can be put onto.  An ls -l command gives 
the following:

-rw-r--r--  1 root root  29159424 Jul 23 13:31 x103.img
-rw-r--r--  1 root root  30449664 Jul 23 14:08 x103_large.img

So they match pretty close in size.  I can burn both images to my NAND 
without errors by:

$ ubiupdatevol /dev/ubi0_0 x103*.img

When I try to mount the filesystem that comes from x103.img (the one for 
the 'smaller' NAND flash) it mounts just fine, I can cd to it, create 
directories/files, etc.  However, when I try to mount the filesystem from 
x103_large.img, it fails with the following errors:

UBIFS error (pid 863): check_lpt_crc: invalid crc in LPT node: crc f486 
calc e0b
UBIFS error (pid 863): ubifs_read_nnode: error -22 reading nnode at 8:1356

mount: wrong fs type, bad option, bad superblock on ubi0:bob,
       missing codepage or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

So, here's a couple of questions?  Does mkfs.ubifs and UBIFS calculate the 
CRC identically or could there be a difference that's causing the problem? 
 Does ubiupdatevol touch the CRC and that's what's causing the problem?  A 
complicating factor, I'm running on an MPC8349E, which is big endian and I 
know we've tripped across an endian issue in the past.  I've tried 
eliminating endian issues by compiling and running all tools native on the 
8347, but could that be a factor?

I'm going to start by digging into mkfs.ubifs on the assumption that the 
large -c parameter is causing it to some how miscalculate the CRC, but any 
pointers of where else the problem could be are greatly appreciated.

Bruce