On Friday 03 December 2010 19:09:35 Xiaoguang Chen wrote:
> Hi
> We have an issue when mounting yaffs image on onenand with kernel 35, after
> mount, only "lost+found" in the mounted directory. 

Is there anything inside lost+found?

> We tried to add new 
> files in the mounted directory, and checked the new file is indeed written
> to onenand flash. But after umount and mount again, the new file is lost
> and again "lost + found" is the only thing . 

If you just write the file then read it back then the file is most likely just 
being read from the page cache and not from nand.

You can clear out the cache as follows:

.. write files..
echo 3 > /proc/sys/vm/drop_caches
.. read files


> We suspect whether it's 
> onenand driver's problem or yaffs's problem. so we tried to replace all
> yaffs files in drivers/fs/yaffs2 in kernel 35 with kernel 32 yaffs files,
> and this time the mount has no problem at all. Mount/umount both will
> succeed. So maybe it's something that yaffs changed from .32 to .35,  but
> we didn't noticed. 

Yaffs is not really connected to a Linux version. There have been some changes 
in that timeframe which make a difference.

The older code will use file headers that had ECC errors where the newer code 
will reject those headers. 

I suggest you have a very good look at the mtd layer to ensure that you are 
not getting ECC corruptions. THat is the most likely cause of problems of 
this sort.

-- CHarles