Method ll_write_block

src/client/Client.cc:17177–17230

   buffer was written, return the write length on success. */

int Client::ll_write_block(Inode *in, uint64_t blockid,
			   char* buf, uint64_t offset,
			   uint64_t length, file_layout_t* layout,
			   uint64_t snapseq, uint32_t sync)
{
  vinodeno_t vino = ll_get_vino(in);
  int r = 0;
  std::unique_ptr<C_SaferCond> onsafe = nullptr;

  RWRef_t mref_reader(mount_state, CLIENT_MOUNTING);
  if (!mref_reader.is_state_satisfied())
    return -ENOTCONN;

  if (length == 0) {
    return -EINVAL;
  }
  if (true || sync) {
    /* if write is stable, the epilogue is waiting on
     * flock */
    onsafe.reset(new C_SaferCond("Client::ll_write_block flock"));
  }
  object_t oid = file_object_t(vino.ino, blockid);
  SnapContext fakesnap;
  ceph::bufferlist bl;
  if (length > 0) {
    bl.push_back(buffer::copy(buf, length));
  }

  ldout(cct, 1) << "ll_block_write for " << vino.ino << "." << blockid
		<< dendl;

  fakesnap.seq = snapseq;

  /* lock just in time */
  objecter->write(oid,
		  object_locator_t(layout->pool_id),
		  offset,
		  length,
		  fakesnap,
		  bl,
		  ceph::real_clock::now(),
		  0,
		  onsafe.get());

  if (nullptr != onsafe) {
    r = onsafe->wait();
  }

  if (r < 0) {
    return r;
  } else {
    return length;
  }
}

int Client::ll_commit_blocks(Inode *in,
			     uint64_t offset,