R/W Filesystem?

After erasing that partition also i'm getting the same errors.

uClinux/Nios II
Altera Nios II support (C) 2004 Microtronix Datacom Ltd.
setup_arch: No persistant network settings signature at 007F0000
Built 1 zonelists
Kernel command line: root=/dev/mtdblock0 ro
PID hash table entries: 128 (order: 7, 2048 bytes)
Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
Memory available: 14364k/16384k RAM, 0k/0k ROM (1506k kernel code, 317k data)
Mount-cache hash table entries: 512 (order: 0, 4096 bytes)
NET: Registered protocol family 16
JFFS2 version 2.2. (C) 2001-2003 Red Hat, Inc.
Serial: JTAG UART driver $Revision: 1.3 $
ttyJ0 at MMIO 0x821208b0 (irq = 1) is a jtag_uart
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
smc_probe: 50000 Khz Nios
SMSC LAN91C111 Driver (v2.1), (Linux Kernel 2.6)
eth0: SMC91C11xFD(rev:1) at 0x82110300 IRQ:6 MEMSIZE:8192b NOWAIT:0 ADDR: 00:07:
ed:00:00:00 
smc_probe: 50000 Khz Nios
Using anticipatory io scheduler
Altera NDK flash (AMD): Found 1 x8 devices at 0x0 in 8-bit bank
 Amd/Fujitsu Extended Query Table at 0x0040
Altera NDK flash (AMD): CFI does not contain boot bank location. Assuming top.
number of CFI chips: 1
cfi_cmdset_0002: Disabling erase-suspend-program due to code brokenness.
cmdlinepart partition parsing not available
RedBoot partition parsing not available
Using Altera NDK partition definition
Creating 5 MTD partitions on "Altera NDK flash (AMD)":
0x00200000-0x00500000 : "romfs/jffs2"
0x00500000-0x00600000 : "rwfs"
0x00000000-0x00200000 : "loader/kernel"
0x00600000-0x00700000 : "User configuration"
0x00700000-0x00800000 : "safe configuration"
NET: Registered protocol family 2
IP: routing cache hash table of 512 buckets, 4Kbytes
TCP: Hash tables configured (established 1024 bind 2048)
NET: Registered protocol family 1
NET: Registered protocol family 17
VFS: Mounted root (romfs filesystem) readonly.
Freeing unused kernel memory: 48k freed (0x11aa000 - 0x11b5000)
expand: from=/ramfs.img to=/dev/ram0
expand: from=/ramfs.img to=/dev/ram1
/etc/issue              www.microtronix.com               July 2004
                   Welcome to Linux on the Nios II
    
Nios2 login: nios
Password:

# mount -t jffs2 /dev/mtdblock0 /mnt/rwfs -n
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000000: 0x722d in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000004: 0x6631 in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000008: 0x2b00 in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0000000c: 0xe310 in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000010: 0x6966 in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000014: 0x7973 in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000018: 0x6d65 in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0000001c: 0x6d6f in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0000003c: 0xffd1 in
stead
jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x00000040: 0x002e in
stead
Further such events for this erase block will not be printed
Old JFFS2 bitmask found at 0x00004434
You cannot use older JFFS2 filesystems with newer kernels
Old JFFS2 bitmask found at 0x00004504
You cannot use older JFFS2 filesystems with newer kernels
Old JFFS2 bitmask found at 0x00004514
You cannot use older JFFS2 filesystems with newer kernels
Old JFFS2 bitmask found at 0x000046b4
You cannot use older JFFS2 filesystems with newer kernels
Old JFFS2 bitmask found at 0x00006398
You cannot use older JFFS2 filesystems with newer kernels
Empty flash at 0x00009a20 ends at 0x00009a24
Empty flash at 0x0000b7c8 ends at 0x0000b7cc
Empty flash at 0x0000b7e0 ends at 0x0000b7e4
Old JFFS2 bitmask found at 0x0000f55c
You cannot use older JFFS2 filesystems with newer kernels
Old JFFS2 bitmask found at 0x0000f62c
You cannot use older JFFS2 filesystems with newer kernels
Old JFFS2 bitmask found at 0x0000f63c
You cannot use older JFFS2 filesystems with newer kernels
Old JFFS2 bitmask found at 0x0000f7dc
You cannot use older JFFS2 filesystems with newer kernels