Move ref counts to their own cacheline - otherwise they pollute and cause
false sharing to fields nearby and cause a lot of cache bouncing between
physical CPUs.
Signed-off-by: Kozlowski Mateusz <mateusz.kozlowski@intel.com>
Volume close should not close underlying device until all
I/O targeting this volume are deallocated. To achieve this
a reference counter is added to volume. Counter value
matches number of I/O objects associated with volume. Counter
is freezed when volume is closed, blocking allocation of new
I/O objects.
Signed-off-by: Adam Rutkowski <adam.j.rutkowski@intel.com>
