root@OpenWrt:/# mount
rootfs on / type rootfs (rw)
/dev/root on /rom type ext2 (rw)
none on /proc type proc (rw)
none on /sys type sysfs (rw)
none on /tmp type tmpfs (rw,nosuid,nodev)
tmpfs on /dev type tmpfs (rw)
none on /dev/pts type devpts (rw)
/dev/mtdblock3 on /jffs type jffs2 (rw)
mini_fo:/jffs on / type mini_fo (rw)
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root@OpenWrt:/# df -h
Filesystem                Size      Used Available Use% Mounted on
/dev/mtdblock3           11.5M    672.0k     10.8M   6% /jffs
mini_fo:/jffs             4.6G     10.4M      4.3G   0% /

root@OpenWrt:/# dd if=/dev/zero of=/TEST.bin

root@OpenWrt:/# df -h
Filesystem                Size      Used Available Use% Mounted on
/dev/mtdblock3           11.5M    708.0k     10.8M   6% /jffs
mini_fo:/jffs             4.6G     10.4M      4.3G   0% /
root@OpenWrt:/#