extend reiserfs filesystem size

I have a VM server with an extra disk mounted on it. I have increased size on it from VMWare. The disk uses reiserfs file system.

 /dev/sdb1 /data/mysql_data reiserfs rw,relatime 0 0 

After expanding disk size, I run this

# fdisk -l
Disk /dev/sdb: 39.3 GB, 39322648576 bytes
255 heads, 63 sectors/track, 4780 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        2611    20971488+  83  Linux

After this, I run

# resize_reiserfs -f /dev/sdb1
resize_reiserfs 3.6.21 (2009 www.namesys.com)

/dev/sdb1 already is of the needed size. Nothing to be done

and then df -h but still file system size hasn't increased.

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_0-lv_root
                       21G   12G  7.9G  60% /
tmpfs                1004M     0 1004M   0% /dev/shm
/dev/sda1             485M  156M  305M  34% /boot
/dev/sdb1              20G   15G  5.6G  73% /data/mysql_data

At the moment, my partition table says this

# cat ~/sfdisk_sdb.txt 
# partition table of /dev/sdb
unit: sectors

/dev/sdb1 : start=       63, size= 41942977, Id=83
/dev/sdb2 : start=        0, size=        0, Id= 0
/dev/sdb3 : start=        0, size=        0, Id= 0
/dev/sdb4 : start=        0, size=        0, Id= 0

So, what am I doing wrong?