jffs2 save new firmware or data backup.
In an telnet session:
Remount read only / and /home

# mount / -o remount,ro
# mount /home -o remount,ro
mount: /home is busy (if you cannot remount)
# fuser -m /home
from here you can see the n. of PID and kill (maybe you need kill 2 times the pid, so first and second pid)
# kill -9 81
# mount /home -o remount,ro
Verify with mount thath /dev/root on / show ro
Verify with mount thath /dev/mtdblock8 on /home show ro
Now save mtd8 and mtd9 with dd (use option conv=sync) mtd8 it is /home mtd9 it is /
dd if=/dev/mtd8 of=/mmc/mmca1/mtd8.bin conv=sync (write 23,1mb in sd)
dd if=/dev/mtd9 of=/mmc/mmca1/mtd9.bin conv=sync (write 38,1mb in sd)
After remount in swrite / and /home
# mount / -o remount,rw
# mount /home -o remount,rw
Now rename mtd8.bin (23,1mb) in CG35.smg 
Now rename mtd9.bin (38,1mb) in CG41.smg
Now with ezxcodec open the firmware original -> extract you will see CG35.smg e CG41.smg
Rename and replace with the new. Now -> compile and save the new firmware in .sbf

p.s.: if you share the new firmware before saving mtd you need remove your personal data (sms, mms, contacts, your history... all will be saved).