Implement pg_test vector to test for max IO sizes. We calculate
a max_io_size member only once, and cache it in lseg so to not
do so on every page insert.
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
[simplify logic]
Signed-off-by: NBenny Halevy <bhalevy@panasas.com>