block: null_blk: only set set->nr_maps as 3 if active poll_queues is > 0

It isn't correct to set set->nr_maps as 3 if g_poll_queues is > 0 since
we can change it via configfs for null_blk device created there, so only
set it as 3 if active poll_queues is > 0.

Fixes divide zero exception reported by Shinichiro.

Fixes: 2bfdbe8b7ebd ("null_blk: allow zero poll queues")
Reported-by: Shinichiro Kawasaki <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Reviewed-by: Shin'ichiro Kawasaki <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions