NAME

       pmem2_vm_reservation_new(), pmem2_vm_reservation_delete() - creates or deletes an instance
       of virtual memory reservation

SYNOPSIS

              #include <libpmem2.h>

              struct pmem2_vm_reservation;
              int pmem2_vm_reservation_new(struct pmem2_vm_reservation **rsv_ptr,
                      void *addr, size_t size);
              int pmem2_vm_reservation_delete(struct pmem2_vm_reservation **rsv_ptr);

DESCRIPTION

       The pmem2_vm_reservation_new() function creates a new blank mapping in the virtual address
       space  of  the  calling  process.   Reservation serves as a placeholder of a given size on
       which sources can be mapped.

       For the function to succeed, the addr must be either aligned to an appropriate  allocation
       granularity  or  NULL,  the  size  always  has  to be aligned to an appropriate allocation
       granularity.

       If the pmem2_vm_reservation_new() succeeds in creating a reservation,  it  instantiates  a
       new  struct  pmem2_vm_reservation  object describing the reservation.  The pointer to this
       object is stored in the user-provided variable via the rsv_ptr pointer.  If  the  function
       fails,  an appropriate error value will be returned.  For a list of possible return values
       please see RETURN VALUE

       After instantiating an object via  the  pmem2_vm_reservation_new()  function,  it  may  be
       disposed of using the pmem2_vm_reservation_delete() function.

       The  pmem2_vm_reservation_delete() function destroys the object describing the reservation
       and unmaps virtual memory region the *struct pmem2_vm_reservation**  had  assigned  during
       the  initialization.   For  the  delete  function  to  succeed,  it  is  required that the
       reservation passed via the rsv_ptr pointer does not contain any mappings.

RETURN VALUE

       The pmem2_vm_reservation_new() and pmem2_vm_reservation_delete()  functions  return  0  on
       success or a negative error code on failure.

       The function returns 0 on success or a negative error code on failure.

ERRORS

       The pmem2_vm_reservation_new() function can fail with the following errors:

       • PMEM2_E_ADDRESS_UNALIGNED  -  argument addr is not aligned to the appropriate allocation
         granularity.

       • PMEM2_E_MAPPING_EXISTS - mapping already exists in the range (addr, addr + size).

       It can also return -EAGAIN, -ENOMEM from the underlying mmap(2) function  and  -ENOMEM  in
       case of insufficient memory to allocate an instance of struct pmem2_vm_reservation.

       The pmem2_vm_reservation_delete() function can fail with the following errors:

       • PMEM2_E_RESERVATION_NOT_EMPTY - reservation contains mappings.

       It can also return errors from the underlying munmap(2) function.

SEE ALSO

       pmem2_config_set_vm_reservation(3), libpmem2(7) and <https://pmem.io>