On Tue, 2014-08-19 at 21:16 +1000, NeilBrown wrote:
> On Tue, 19 Aug 2014 18:02:27 +0800 Ian Kent <raven@xxxxxxxxxx> wrote:
>
> > On Mon, 2014-08-18 at 16:25 +0800, Ian Kent wrote:
> > > On Mon, 2014-08-18 at 16:33 +1000, NeilBrown wrote:
> > > > Hi Ian,
> > > > Have you had a chance to run your tests in these patches yet?
> > > > I've done what testing I can think of and cannot fault them.
> > >
> > > I haven't, I've been plagued with illness so I'm not getting nearly
> > > enough done. I'll try to put a kernel together and run the test in the
> > > next week or so.
> >
> > Just to let you know that I managed to spend some time on this. I built
> > a kernel (3.17.0-rc1) with the series and ran a couple of tests.
> >
> > I'm not certain that the patches I used are identical to your posting, I
> > saw one difference, after the fact, that shouldn't matter, I'll have to
> > check that.
> >
> > It isn't possible to test expire to mount races because the mounts in
> > the tree never expire.
> >
> > At first I thought it was because so many processes were accessing the
> > tree all the time but manually constructing the maps and mounting the
> > mounts shows that nothing ever expires, at least for this tree.
> >
> > However, issuing a shut down does expire all the mounts and shuts down
> > autofs cleanly.
> >
> > So there is something not quite right with the expire check or my
> > patches have mistakes.
>
> Ahh.. I bet I know what it is.
> autofs4_can_expire() isn't idempotent.
> Because we call should_expire twice, autofs4_can_expire() is called twice and
> the second time it failed because the first time it resets ->last_used.
LOL, indeed that looks like it.
I'll carefully check the patches anyway, rebuild and re-test.
>
> diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
> index eb4b770a4bf6..80133a9d9427 100644
> --- a/fs/autofs4/expire.c
> +++ b/fs/autofs4/expire.c
> @@ -26,6 +26,9 @@ static inline int autofs4_can_expire(struct dentry *dentry,
> if (ino == NULL)
> return 0;
>
> + if (ino->flags & AUTOFS_INF_NO_RCU)
> + /* Already performed this test */
> + return 1;
> if (!do_now) {
> /* Too young to die */
> if (!timeout || time_after(ino->last_used + timeout, now))
>
>
>
> might fix it, but might be a hack.
> (tests.... yep, that seems to fix it).
>
> I'll think some more tomorrow.
>
> Thanks,
> NeilBrown
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