On Thu, Sep 22, 2011 at 9:04 AM, Ian Kent <raven@xxxxxxxxxx> wrote:
>
> I haven't checked what the side effects would be but using the
> LOOKUP_DIRECTORY flag in walks that get caught by the removal of the
> LOOKUP_FOLLOW test in follow_automount() and retaining Miklos's original
> patch is probably a more natural solution IMO.
Ok, I do have to agree with that.
So instead of adding a new flag, let's just document a few *logical*
rules for what causes auto-mounting:
- opening the mount-point itself with LOOKUP_DIRECTORY does so
Logic: when you use LOOKUP_DIRECTORY, you expect to see the
*contents* of the mount-point.
- looking something up *under* the mount-point does so.
This may be obvious, but it actually has a non-obvious special
case: what about the pathname "mountpoint" vs "mountpoint/"
And I think the "LOOKUP_DIRECTORY" rule ends up automatically also
resolving that special case: when we have a slash at the end of the
last component, it not only implies that we care about the contents,
it will also automatically set LOOKUP_DIRECTORY.
So I'm getting more and more convinced that LOOKUP_DIRECTORY is
actually the right thing to trigger on. It automatically means that
"opendir()" on the mountpoint will do the right thing (because
O_DIRECTORY results in LOOKUP_DIRECTORY), and it automatically - and
very naturally - gives user processes the ability to choose whether
they want to see auto-monting or not ("path" doesn't get auto-mounted,
but "path/" does).
Yet at the same time it keeps the "stupid default behavior for
processes that only look at each directory entry and don't even think
about automounting" be the "don't auto-mount when not necessary"
behavior.
So: no new flag. Just make nfs4 use LOOKUP_DIRECTORY, and let's add
big documentation notes about this.
Ok?
Linus
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