On Thu, Jan 9, 2020 at 8:15 PM Al Viro [off-list ref] wrote:

quoted

Hmm. If that's the case, maybe they should be marked implicitly as
O_PATH when opened?

I thought you wanted O_PATH as starting point to have mounts traversed?
Confused...

No, I'm confused.  I meant "non-O_PATH", just got the rules reversed in my mind.

So cwd/root would always act as it non-O_PATH, and only using an
actual fd would look at the O_PATH flag, and if it was set would walk
the mountpoints.

<grabs Bach> Right, he simply transcribes v7 iget().

So I suspect that you are right - your variant of iget was pretty much
one-to-one implementation of Bach's description of v7 iget.

Ok, that makes sense. My copy of Bach literally had the system call
list "marked off" when I implemented them back when.

I may still have that paperbook copy somewhere. I don't _think_ I'd
have thrown it out, it has sentimental value.

quoted

I think that in a perfect world, the O_PATH'ness of '42' would be the
deciding factor. Wouldn't those be the best and most consistent
semantics?

And then 'cwd'/'root' always have the O_PATH behavior.

See above - unless I'm misparsing you, you wanted mount traversals in the
starting point if it's ...at() with O_PATH fd.

.. and see above, it was just my confusion about the sense of O_PATH.

For cwd and root the situation is opposite - we do NOT traverse mounts
for those.  And that's really too late to change.

Oh, absolutely.

[ snip some more about your automount digging. Looks about right, but
I'm not going to make a peep after getting O_PATH reversed ;) ]

            Linus