upgrade cramfs rootfs while running

[ganesh subramonian]

i have a cramfs image, which is my rootfs(/ partition)
on flash. in an earlier thread i found some replies
saying that upgrading it while mounted was prone to
errors. however if i am doing the upgrade only in my
shutdown scripts (so that most applications are killed
by this time) like this:
mount -o loop -t cramfs rootfs.img /tmp/somedir
eraseall /dev/mtd2
cp rootfs.img /dev/mtd2
export PATH=/tmp/somedir/bin:/tmp/somedir/sbin...
export LD_LIBRARY_PATH=/tmp/somedir/lib
reboot
is there anything that could go wrong? All further
programs(with their libs) should be executed from the
loop mounted rootfs. 
or else can i do something like
mount -o loop ...
cd /tmp/somedir
pivot_root . tmp
eraseall, copy
reboot
Since i am upgrading just before reboot only these
scripts would be running. Is there a risk in
either/both of these methods.

Thanks
Ganesh

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