Changes for Linux 5.2: - Fix some more buffer deadlocks when performing an unmount after a hard shutdown. - Fix some minor space accounting issues. - Fix some use after free problems. - Make the (undocumented) FITRIM behavior consistent with other filesystems. - Embiggen the xfs geometry ioctl's data structure. - Introduce a new AG geometry ioctl. - Introduce a new online health reporting infrastructure and ioctl for userspace to query a filesystem's health status. - Enhance online scrub and repair to update the health reports. - Reduce thundering herd problems when writeback io completes. - Fix some transaction reservation type errors. - Fix integer overflow problems with delayed alloc reservation counters. - Fix some problems where we would exit to userspace without unlocking. - Fix inconsistent behavior when finishing deferred ops fails. - Strengthen scrub to check incore data against ondisk metadata. - Remove long-broken mntpt mount option. - Add an online scrub function for the filesystem summary counters, which should make online metadata scrub more or less feature complete for now.