There 'rv' tests were confused and sometimes wrong.
This resulted in not writing the second bsb.
Also fix the test script so the the critical section is long enough
that we have some hope of interrupting it.
Signed-off-by: NeilBrown <neilb@suse.de>
This seems more appropriate for current (and recent) model drives than
64K.
64K is still the default for '--build' as changing that could corrupt
data.
64K is also the default rounding for 'linear' on kernels older than
2.6.16.
Signed-off-by: NeilBrown <neilb@suse.de>