Alright, I give up. What does the "i" in "inode" stand for?

Rob Landley (landley@trommello.org)
Thu, 18 Jul 2002 18:33:54 -0400


I've been sitting on this question for years, hoping I'd come across the
answer, and I STILL don't know what the "i" is short for. Somebody here has
got to know this. :)

I know what an inode IS (although it took me almost a year to figure this
out, way back when), but I don't know what the name means.

I've been following this list for years now, and nobody's ever actually said
what the i stands for, and neither do the (sparse) comments in fs/inode.c.
I've read Peter Salus's book "a Quarter Century of Unix". I've read the
history of early unix development on Dennis Richie's home page, and although
it complains that his original notes came back form the dictation service
misspelling "inode" as "eyenode", it doesn't say what the I stands for. I'm
only about a third of the way into "Life with Unix", but it doesn't seem like
a particularly technical history so far...

Another question I'm unclear about is "does every userspace-visible memory
allocation have an inode"? Loaded programs are basically mmaped files, and
shared memory is now its own filesystem out of which you mmap stuff. But I
don't know about a process's stack and heap.

For a while I thought that swap could be thought of as a filesystem out of
which the heaps were mapped as sparse files (this is the only explanation
that made sense in early 2.5 when every page used HAD to have swap backing
store, and taking away the mandatory backing store would just be an exercise
in deferred allocation), but that apparently is not the case and I got
disabused of this notion a while back. Instead I learn what a "classzone"
is. Ok...

Then earlier today I wander across kerneltrap's interview with Larry McVoy,
who espouses the viewpoint that Linux VM design should store statistics in
inodes rather than worrying so much about individual pages, and I get
confused again.

Has each process space's heap got an inode? If so, in what filesystem?

Rob

(Yes, I am breaking the internet convention of posting errors rather than
asking questions if you want people to respond. I can come up with some
errors if you'd like. I'm good at that. :)
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