> Can you think of anywhere else we can store the data?

5) in another file in the lower-level filesystem, possibly indexed by
inode number.  This is akin to the LFS "ifile", as well as how AFS
stores some of its metadata.

Yes, AFS also wants to stuff 16 bytes in the inode (it wants 5
longwords, but one of them is essentially the same as the generation
number, and it can make do with less, stuffing the extra in a separate
file); also, higher-level structures like volumes are built out of
additional inodes, which also contain acls.

					- Bill