Re: Stale file not being refreshed automatically?

[Trond Myklebust <Trond.Myklebust@netapp.com>]

On Tue, 2011-01-25 at 14:38 -0800, Nathan March wrote: 
> Ah ha, yes, it's using a stat call.
> 
> What would be the proper C call to check the file exists without 
> incurring the stat()?

access("file", F_OK) should do it.

Cheers
  Trond

> On 1/25/2011 2:28 PM, Trond Myklebust wrote:
> > On Tue, 2011-01-25 at 14:11 -0800, Nathan March wrote:
> >> Hi All,
> >>
> >> Having a strange issue, I've reproduced this both on nfs 3 and 4.
> >> Currently using v4 with:
> >>
> >> exports:
> >> /var/home/voyage
> >> 10.2.1.0/24(rw,fsid=0,async,wdelay,secure,no_subtree_check,anonuid=1000,anongid=1006)
> >>
> >> fstab:
> >> 10.2.1.1:/ /mnt/voyage nfs4
> >> rsize=32768,wsize=32768,noatime,nosuid,rw,bg,hard,intr 0 0
> >>
> >> Can be produced using these two commands on 2 machines:
> >>
> >> perl -le '$| = 1 ; while (1) { sleep 1; $res = -e "/home/voyage/test";
> >> if ($res) { print "-e : $res"; } else { print "-e : $res ($!)"; } }'
> >> -e : 1
> >>
> >> perl -le '$| = 1 ; while (1) { sleep 5; open(F, ">",
> >> "/home/voyage/test.foo"); close F; my $res =
> >> rename("/home/voyage/test.foo", "/home/voyage/test"); print "rename
> >> ($res)"; }'
> >>
> >> The first command will occasionally print out: -e :  (Stale NFS file handle)
> >>
> >> Now according to http://nfs.sourceforge.net/#faq_a10 as of 2.6.12 the
> >> vfs should automatically retry when it gets a estale during path
> >> resolution. This doesn't appear to be happening though based on the
> >> errors I'm seeing.
> >>
> >> Anyone have any thoughts on what might be happening here? Or am I
> >> misinterpreting that faq entry? (This is on ext3 if it matters)
> > Does '-e' in perl only do a lookup, or does it result in a 'stat()'
> > call? If the latter, then your test is flawed: a stat() is a lookup+a
> > getattr, and the latter can definitely return ESTALE when you are
> > constantly replacing the file.
> >
> > Cheers
> >    Trond

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@netapp.com
www.netapp.com