The romfs corruption problem after writing mtdblock!

[Kim Moung-Soo]

I'm using uClinux 2.4.22 on ARM board and have a problem with the romfs.
My machine has 4 partitions on the NOR flash memory like below.
mtdblock 1: boot loader
mtdblock 2: 2nd boot loader
mtdblock 3: kernel and root file system(romfs)
mtdblock 4: user data

Everything works fine until I write area of user data, mtdblock 4.
After I write something on mtdblock4, romfs on mtdblock 3 corrupts
sometimes.
The symptom is that some files have gone in the directory or content of
file is wrong.
Even it happens I think the data in flash memory is okay because after
it reboot every thing is in there.
I use open("/dev/mtdblock/4") and write() to access it directly.
Can I use open(), write() function to access mtdblock 4?