pmem2_vm_reservation_get_size() - reads virtual memory reservation size

       The  pmem2_vm_reservation_get_size()  function reads size of the created virtual memory reservation.  The
       rsv  parameter  points  to  the  structure  describing  virtual  memory  reservation  created  using  the
       pmem2_vm_reservation_new(3) function.

pmem2_vm_reservation_get_size() - reads virtual memory reservation size

       The pmem2_vm_reservation_get_size() function returns a size of the virtual reservation area.

pmem2_vm_reservation_new(3), libpmem2(7) and <https://pmem.io>

              #include <libpmem2.h>

              size_t pmem2_vm_reservation_get_size(struct pmem2_vm_reservation *rsv);