Is any technical documentation available for Apple's new File System. By technical, I mean File System's internal structures, File allocation block etc. If Apple has not released any documentation, did someone tried to reverse engineer it?
Apple File System is a new, modern file system for iOS, macOS, tvOS, and watchOS. It is optimized for Flash/SSD storage and features strong encryption, copy-on-write metadata, space sharing, cloning for files and directories, snapshots, fast directory sizing, atomic safe-save primitives, and improved file system fundamentals.
See also Apple's File System Programming Guide.
Apple has released documentation for APFS. It's a little sparse, but most of the critical information should be there.