Changes for Linux 5.1: - Fix online fsck to handle inode btrees correctly on 64k block filesystems. - Teach online fsck to check directory and attribute names for invalid characters. - Miscellanous fixes for online fsck. - Introduce a new panic mask so that we can halt immediately on metadata corruption (for debugging purposes) - Fix a block mapping race during writeback. - Cache unlinked inode list backrefs in memory to speed up list processing. - Separate the bnobt/cntbt and inobt/finobt buffer verifiers so that we can detect crosslinked btrees. - Refactor magic number verification so that we can standardize it. - Strengthen ondisk metadata structure offset build time verification. - Fix a memory corruption problem in the listxattr code. - Fix a shutdown problem during log recovery due to unreserved finobt expansion. - Fix a referential integrity problem where O_TMPFILE inodes were put on the unlinked list with nlink > 0 which would cause asserts during log recovery if the system went down immediately. - Refactor the delayed allocation allocator to be more clever about the possibility that its mapping might be stale. - Various fixes to the copy on write mechanism. - Make CoW preallocation suitable for use even with writes that wouldn't otherwise require it. - Refactor an internal API. - Fix some statx implementation bugs. - Fix miscellaneous compiler and static checker complaints.