Filesystem does not recognizing extended disk space?

Issue

After extending SAN LUN from HP EVA(From SAN side) from 1.5 TB to 1.8 TB and rescanning iSCSI bus multipath is recognizing the extended space but its not getting reflect in filesystem,

u_04 (3600508b40006c21100006000078a0000) dm-8 HP,HSV210
[size=1.8T][features=1 queue_if_no_path][hwhandler=0][rw]  <==
\_ round-robin 0 [prio=200][active]
 \_ 1:0:2:4 sdi        8:128  [active][ready]
 \_ 0:0:2:4 sdm        8:192  [active][ready]
 \_ 0:0:3:4 sdy        65:128 [active][ready]
 \_ 1:0:3:4 sdz        65:144 [active][ready]
\_ round-robin 0 [prio=40][enabled]
 \_ 1:0:4:4 sdam       66:96  [active][ready]
 \_ 0:0:4:4 sdan       66:112 [active][ready]
 \_ 1:0:5:4 sdaz       67:48  [active][ready]
  \_ 0:0:5:4 sdbb       67:80  [active][ready]

Have performed following steps to get recognize the disk space by system,

1. umount the volume.
2. Run e2fsck -f on the device.
3. Run resize2fs to expand the LUN partition.

But it still shows the older values,

/dev/mapper/u_04      1.5T  1.4T   20G  99% /u04