Method _queue_discard

src/blk/kernel/KernelDevice.cc:872–903

this is private and is expected that the caller checks that discard threads are running via _discard_started()

// this is private and is expected that the caller checks that discard
// threads are running via _discard_started()
bool KernelDevice::_queue_discard(interval_set<uint64_t> &to_release)
{
  if (to_release.empty())
    return false;

  auto max_pending = cct->_conf->bdev_async_discard_max_pending;

  std::lock_guard l(discard_lock);

  if (max_pending > 0 && discard_queued.num_intervals() >= max_pending) {
    discard_cond.notify_one();
    return false;
  }

  if(discard_queue_bytes >= cct->_conf->bdev_discard_max_bytes) {
    discard_cond.notify_one();
    return false;
  }

  discard_queued.insert(to_release);

  size_t discarded_bytes = 0;
  for(auto p = to_release.begin(); p != to_release.end(); ++p){
    discarded_bytes += p.get_len();
  }
  discard_queue_bytes += discarded_bytes;

  discard_queue_length = discard_queued.num_intervals();

  discard_cond.notify_one();
  return true;
}

// return true only if discard was queued, so caller won't have to do
// alloc->release, otherwise return false