ubifs wear leveling across entire device

[twebb]

I'm confused about how wear leveling occurs across the entire device
in the following example.  Could someone help me understand what I'm
missing?

4 GiB flash device (nand MLC):
4 MTD partitions defined:
0 - "p1" - 0x00000000 - 0x00800000
1 - "p2" - 0x00800000 - 0x10000000
2 - "p3" - 0x10000000 - 0x80000000
3 - "p4" - 0x80000000 - 0x100000000

kernel args specify 3 ubi volumes:
ubi.mtd=p1 ubi.mtd=p2 ubi.mtd=p3
(p4 is reserved and no volumes or filesystems sit on top of it)

The "vol_size" for each of the ubi volumes (as specified in the
ubinize cfg file) is slightly less than the corresponding mtd
partition size.  The volumes are specified as dynamic because they
need to be RW.

Thanks,
twebb