[Yaffs] loopback , power-off, and data is lost

Hi,

I am using yaffs2 on a 2.6.20.
On the yaffs2 partition we mount a FAT fs with loopback. If we modify files in
the FAT partition, umount it and do a sync. The data is lost after a unclean
unmount.

For example if yaffs2 partition is mount in /mnt and /mnt/media is a file
containing a FAT fs.

# mount /mnt/media /media/fat -o loop
# cp /somefile /media/frame/somefile
# umount /media/frame
# sync
<--- wait 10 seconds
<--- power-off and power-on without umount
# mount /mnt/media /media/fat -o loop
# md5sum /somefile /media/frame/somefile
7fbf15f115bdbe93c3466b595a926b5e /somefile
6a7cfc972547b2385e97a4af3d854444 /media/frame/somefile


There is no such problem if I write the file in the yaffs2 partition instead of
FAT fs.


Matthieu