Re: [PATCH] vfs: automount should ignore LOOKUP_FOLLOW

[Linus Torvalds <torvalds@linux-foundation.org>]

On Thu, Sep 8, 2011 at 6:38 AM, Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> Yes, 2.6.38 and later kernels do trigger on stat(2) but not on lstat(2).
>
> My question is this:  does this behavior improve anything compared to
> kernels before 2.6.38?  Because I don't see that it does, in fact it's
> just causing regressions.
>
> You say it's a step in the right direction but I don't see why.  Either
> we want stat *and* lstat to both be correct and trigger the automount or
> we are satisfied with the incorrect but well established practice of not
> triggering on (l)stat.
>
> The middle ground makes no sense IMO, there's nothing gained by the
> differentiated behavior based on LOOKUP_FOLLOW.
>
> Can you explain why it's better if stat() tiggers automounts and gives a
> correct result but lstat() doesn't?

I have to say that this is a very cogent question.

The one thing I've not seen in the thread yet is a description of the
failure. What does the regression look like? Just "very slow 'ls' with
some versions of 'ls'" or what?

I'm inclined to apply the patch as a regression fix, but I'll let this
thread try to convince me for another day..

                         Linus