Method create_volume

src/iocore/cache/CacheDisk.cc:253–345

size is in store blocks */

/* size is in store blocks */
DiskStripeBlock *
CacheDisk::create_volume(int number, off_t size_in_blocks, int scheme)
{
  if (size_in_blocks == 0) {
    return nullptr;
  }

  DiskStripeBlockQueue *q             = free_blocks->dpb_queue.head;
  DiskStripeBlockQueue *closest_match = q;

  if (!q) {
    return nullptr;
  }

  off_t max_blocks = MAX_STRIPE_SIZE >> STORE_BLOCK_SHIFT;
  size_in_blocks   = (size_in_blocks <= max_blocks) ? size_in_blocks : max_blocks;

  int blocks_per_vol = STORE_BLOCKS_PER_STRIPE;
  //  ink_assert(!(size_in_blocks % blocks_per_vol));
  DiskStripeBlock *p = nullptr;
  for (; q; q = q->link.next) {
    if (static_cast<off_t>(q->b->len) >= size_in_blocks) {
      p            = q->b;
      q->new_block = 1;
      break;
    } else {
      if (closest_match->b->len < q->b->len) {
        closest_match = q;
      }
    }
  }

  if (!p && closest_match) {
    /* allocate from the closest match */
    q            = closest_match;
    p            = q->b;
    q->new_block = 1;
    ink_assert(size_in_blocks > (off_t)p->len);
    /* allocate in 128 megabyte chunks. The Remaining space should
       be thrown away */
    size_in_blocks  = (p->len - (p->len % blocks_per_vol));
    wasted_space   += p->len % blocks_per_vol;
  }

  free_blocks->dpb_queue.remove(q);
  free_space        -= p->len;
  free_blocks->size -= p->len;

  size_t new_size = p->len - size_in_blocks;
  if (new_size >= static_cast<size_t>(blocks_per_vol)) {
    /* create a new volume */
    DiskStripeBlock *dpb  = &header->vol_info[header->num_diskvol_blks];
    *dpb                  = *p;
    dpb->len             -= size_in_blocks;
    dpb->offset          += (size_in_blocks * STORE_BLOCK_SIZE);

    DiskStripeBlockQueue *new_q = new DiskStripeBlockQueue();
    new_q->b                    = dpb;