[CentOS] ISCSI help

I am fairly new to ISCSI and SAN technology but having recently invested
in the technology I am trying to find out exactly what can and can not
be manipulated, filesystem wise, without requiring a reboot. I am using
the inbuilt software ISCSI initiator and multipathing in CentOS 5.1.

My steps so far.

Create 10GB volume on SAN
# iscsiadm -m session -R
# fdisk /dev/mapper/mpath0
# kpartx -a /dev/mapper/mpath0
# mke2fs -j /dev/mapper/mpath0p1
# mount /dev/mapper/mpath0p1 /test-mount <--works fine to here-->

Now I want to extend the volume on the SAN to 15GB run fdisk and use
resize2fs to extend the filesystem, is this possible without a reboot?
Currently, I don't seem to be able to get fdisk to see the new disk size
after extending the volume. I know this can be done using LVM if I
created 2 volumes rather than extending but I am curious to know if it
can be done without LVM.

Any other tips about what can be done with ISCSI would be welcome.

Thanks

Dean