Function vmem_alloc

kernel/oswrapper/vspace.cc:246–290

}

vaddr_t vmem_alloc(size_t size) {
  lock_allocator();
  size_t alloc_size = size + offsetof(Block, data);
  int level = find_level(alloc_size);
  int flevel = level;
  while (flevel < LOG2_SEGMENT_SIZE && vmem.freelist[flevel] == VADDR_NULL)
    flevel++;
  if (vmem.freelist[flevel] == VADDR_NULL) {
    vmem.add_segment();
  }
  vmem.ensure_is_mapped(vmem.freelist[flevel]);
  while (flevel > level) {
    // get and split a block
    vaddr_t blockaddr = vmem.freelist[flevel];
    assert((blockaddr & ((1 << flevel) - 1)) == 0);
    Block *block = vmem.block_ptr(blockaddr);
    vmem.freelist[flevel] = block->next;
    if (vmem.freelist[flevel] != VADDR_NULL)
      vmem.block_ptr(vmem.freelist[flevel])->prev = VADDR_NULL;
    vaddr_t blockaddr2 = blockaddr + (1 << (flevel - 1));
    Block *block2 = vmem.block_ptr(blockaddr2);
    flevel--;
    block2->next = vmem.freelist[flevel];
    block2->prev = blockaddr;
    block->next = blockaddr2;
    block->prev = VADDR_NULL;
    // block->prev == VADDR_NULL already.
    vmem.freelist[flevel] = blockaddr;
  }
  assert(vmem.freelist[level] != VADDR_NULL);
  Block *block = vmem.block_ptr(vmem.freelist[level]);
  vaddr_t vaddr = vmem.freelist[level];
  #if defined(__GNUC__) && (__GNUC__>11)
  vaddr_t result = vaddr + (sizeof(vaddr_t)*2);
  #else
  vaddr_t result = vaddr + offsetof(Block, data);
  #endif
  vmem.freelist[level] = block->next;
  if (block->next != VADDR_NULL)
    vmem.block_ptr(block->next)->prev = VADDR_NULL;
  block->mark_as_allocated(vaddr, level);
  unlock_allocator();
  memset(block->data, 0, size);
  return result;
}

void init_flock_struct(
    struct flock &lock_info, size_t offset, size_t len, bool lock) {