sys/dev/disk/dm: Fix sanity checks for striped target [2/4]
Target specific args for striped is redundant in the sense
that it has an arg for # of stripes other than the args for
actual stripe devices. These two must meet below.
((argc - 2) / 2) == # of stripe devices.
e.g.
--table '0 100 stripe1 3 10 /dev/da3 0 /dev/da4 0 /dev/da5 0'
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 8 target args
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 6 device args
^ # of stripe devices
((8 - 2) / 2) = 6/2 = 3
-> 3 stripe devices (/dev/da[345])