get_lock
journal->reap_lock = get_lock(journal, journal->unreapable);
get_lock(journal, header->sequence_number)->recovery_start = recovery_block;
get_lock(journal, header->sequence_number);
lock = get_lock(journal, sequence_number);
struct journal_lock *lock = get_lock(journal, i);
VDO_ASSERT_LOG_ONLY((get_lock(journal, block)->count == 0),