Changes for 4.13: - Avoid quotacheck deadlocks - Fix transaction overflows when bunmapping fragmented files - Refactor directory readahead - Allow admin to configure if ASSERT is fatal - Improve transaction usage detail logging during overflows - Minor cleanups - Don't leak log items when the log shuts down - Remove double-underscore typedefs - Various preparation for online scrubbing - Introduce new error injection configuration sysfs knobs - Refactor dq_get_next to use extent map directly