Re: atimes not updated over NFS

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, Jan 21, 2008 at 04:09:25PM -0500, bfields wrote:
> On Mon, Jan 21, 2008 at 10:02:30PM +0100, Frank van Maarseveen wrote:
> > "rm -f testfile" and at least one "touch ." in advance to get deterministic behavior.
> > 
> > > 
> > >                 ssh server 'dd </dev/zero >testfile count=1; ls -l --time=atime --full-time testfile'
> > 
> > put a sleep 2 here.
> > 
> > >                 
> > >                 cat testfile >/dev/null
> > 
> > put a sleep 2 here just in case we would race with something in flight
> > 
> > >                 
> > >                 ssh server 'ls -l --time=atime --full-time testfile'
> > >                 ls -l --time=atime --full-time testfile
> > > 
> > 
> > I tried some kernels (same on client and server). There are three atimes
> > after each experiment.
> > 
> > 2.6.21.7:
> > 	t
> > 	t + 2
> > 	t + 2
> > 
> > This seems to work but it doesn't: only the first "cat testfile" will
> > update the atime. Subsequent cat commands will not update atime unless
> > "cat" is executed on the server.
> 
> I think that's just the expected result of client caching, so all you
> can do in that case is add "set check_mbox_size=yes" to your .muttrc or
> something.....
> 
> > 
> > 2.6.22.10:
> > 	t
> > 	t + 2
> > 	t + 2
> > 
> > (same behavior)
> > 
> > 2.6.23.12:
> > 	t
> > 	t
> > 	t
> > 
> > definately not good. "cat" on the server updates atime again.
> 
> Yes, that looks like a server bug, and this:...
> 
> > 
> > 
> > Trying a different combination of kernels:
> > 
> > server 2.6.23.12, client 2.6.22.10:
> > 	t
> > 	t
> > 	t
> > 
> > server 2.6.22.10, client 2.6.23.12:
> > 	t
> > 	t + 2
> > 	t + 2
> 
> ...confirms that since the results appear to depend only on the server
> version, not on the client version.

And I can confirm this here on 2.6.24-rc8 (+ a few patches).
Unfortunately, I don't have any suggestion better right now than
bisecting....

--b.