filelock: SoftReadWriteLock follows a lock tree swapped in after its first acquire and writes lock records into directories of the user running the lock

SoftReadWriteLock and AsyncSoftReadWriteLock, which wraps one checks once per lock object, by name, that .rw, .rw/gen and .rw/holders are real directories and not symbolic links files that redirect to another path. It then keeps only a boolean. Every later record operation resolves the full path...