Re: compat: autofs v5 packet size ambiguity - update

From: Ian Kent
Date: Tue Feb 21 2012 - 23:20:15 EST


On Tue, 2012-02-21 at 19:47 -0800, Linus Torvalds wrote:
> On Tue, Feb 21, 2012 at 7:33 PM, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > But I'm sure that the autofs daemon does something simple that we can
> > depend on in practice.
>
> I didn't find the most recent source code, but the first thing that
> automount.c does after calling "mount" (which is a for+exec, so we
> cannot take the mounting is_compat_task() into account is to open the
> new root for the ioctlfd, and then it does a stat.
>
> And then it does a AUTOFS_IOC_PROTOVER ioctl to see what the protocol
> version is.
>
> So we could just decide that
>
> (a) we add a mount option for the packet size (or just "v6" - which
> would be "v5 with a fixed packet size")
>
> (b) in the absence of an explicit mount option, we look at
> is_compat_task() for the first AUTOFS_IOC_PROTOVER ioctl we get.
>
> That looks fairly straightforward and safe. Hmm?
>
> Where are the automount sources supposed to be, anyway? kernel.org has
> a v5 directory, but it's empty.

I'm repopulating the autofs directory with content right now.
I had some difficulty with getting appropriate signatures for my PGP
key, consequently my account wasn't activated for quite. The upshot of
that is I wasn't aware of announcements about kup either. Anyway, I've
sorted that out and I'm trying to upload the content right now.

The git repo has been available for a while now though @
/pub/scm/linux/kernel/git/raven/autofs

at least that is the place I thought it should go?
Ian


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