xfs_growfs tutorial?

[Artur Makówka <juice@xxxxxxxxxxxxx>]

Hello, is there any xfs_growfs tutorial out there? i can't find it. 
Manual for xfs_growfs doesnt even says how exactly to use it - if mount 
point is the only argument, from where xfs takes free space?
i mean, how exactly it works? lets say i have 3 disks in RAID 5 at 
/dev/md0 and i connected fourth disk to my box. how should i add it to 
xfs? (/dev/md0 is xfs of course)
i found complicated solution to use fdisk and play with partition sizes, 
but its from 2003, maybe something changed?
please CC also to my mail if you don't mind.

Regards