Every directory-state lookup went through path2inode, the map that holds one
full path per inode in the table, and then through dirStates. Directories now
carry their own path and are indexed by it directly.
There are orders of magnitude fewer directories than files, so this map stays
small whatever the mount holds, and it is what a file needs before it can stop
carrying a full path of its own: a child's path is its parent's plus its name.
No behavior change - the two indexes are asserted to agree.
Chris LuandGitHub
fc97f8ea8f