On Thu, 2016-11-17 at 16:26 -0500, bfields@xxxxxxxxxxxx wrote:
> On Thu, Nov 17, 2016 at 04:05:32PM -0500, Olga Kornievskaia wrote:
> >
> > On Thu, Nov 17, 2016 at 3:46 PM, bfields@xxxxxxxxxxxx
> > <bfields@xxxxxxxxxxxx> wrote:
> > >
> > > On Thu, Nov 17, 2016 at 03:29:11PM -0500, Olga Kornievskaia
> > > wrote:
> > > >
> > > > On Thu, Nov 17, 2016 at 3:17 PM, bfields@xxxxxxxxxxxx
> > > > <bfields@xxxxxxxxxxxx> wrote:
> > > > >
> > > > > On Thu, Nov 17, 2016 at 02:58:12PM -0500, Olga Kornievskaia
> > > > > wrote:
> > > > > >
> > > > > > On Thu, Nov 17, 2016 at 2:32 PM, bfields@xxxxxxxxxxxx
> > > > > > <bfields@xxxxxxxxxxxx> wrote:
> > > > > > >
> > > > > > > On Thu, Nov 17, 2016 at 05:45:52PM +0000, Trond Myklebust
> > > > > > > wrote:
> > > > > > > >
> > > > > > > > On Thu, 2016-11-17 at 11:31 -0500, J. Bruce Fields
> > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > > On Wed, Nov 16, 2016 at 02:55:05PM -0600, Jason L
> > > > > > > > > Tibbitts III wrote:
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > I'm replying to a rather old message, but the issue
> > > > > > > > > > has just now
> > > > > > > > > > popped
> > > > > > > > > > back up again.
> > > > > > > > > >
> > > > > > > > > > To recap, a client stops being able to access _any_
> > > > > > > > > > mount on a
> > > > > > > > > > particular server, and "NFS:
> > > > > > > > > > nfs4_reclaim_open_state: Lock reclaim
> > > > > > > > > > failed!" appears several hundred times per second
> > > > > > > > > > in the kernel
> > > > > > > > > > log.
> > > > > > > > > > The load goes up by one for ever process attempting
> > > > > > > > > > to access any
> > > > > > > > > > mount
> > > > > > > > > > from that particular server. Mounts to other
> > > > > > > > > > servers are fine, and
> > > > > > > > > > other clients can mount things from that one server
> > > > > > > > > > without
> > > > > > > > > > problems.
> > > > > > > > > >
> > > > > > > > > > When I kill every process keeping that particular
> > > > > > > > > > mount active and
> > > > > > > > > > then
> > > > > > > > > > umount it, I see:
> > > > > > > > > >
> > > > > > > > > > NFS: nfs4_reclaim_open_state: unhandled error
> > > > > > > > > > -10068
> > > > > > > > >
> > > > > > > > > NFS4ERR_RETRY_UNCACHED_REP.
> > > > > > > > >
> > > > > > > > > So, you're using NFSv4.1 or 4.2, and the server
> > > > > > > > > thinks that the
> > > > > > > > > client
> > > > > > > > > has reused a (slot, sequence number) pair, but the
> > > > > > > > > server doesn't
> > > > > > > > > have a
> > > > > > > > > cached response to return.
> > > > > > > > >
> > > > > > > > > Hard to know how that happened, and it's not shown in
> > > > > > > > > the below.
> > > > > > > > > Sounds like a bug, though.
> > > > > > > >
> > > > > > > > ...or a Ctrl-C....
> > > > > > >
> > > > > > > How does that happen?
> > > > > > >
> > > > > >
> > > > > > If I may chime in...
> > > > > >
> > > > > > Bruce, when an application sends a Ctrl-C and clients's
> > > > > > session slot
> > > > > > has sent out an RPC but didn't process the reply, the
> > > > > > client doesn't
> > > > > > know if the server processed that sequence id or not. In
> > > > > > that case,
> > > > > > the client doesn't increment the sequence number. Normally
> > > > > > the client
> > > > > > would handle getting such an error by retrying again (and
> > > > > > resetting
> > > > > > the slots) but I think during recovery operation the client
> > > > > > handles
> > > > > > errors differently (by just erroring). I believe the
> > > > > > reasoning that we
> > > > > > don't want to be stuck trying to recover from the recovery
> > > > > > from the
> > > > > > recovery etc...
> > > > >
> > > > > So in that case the client can end up sending a different rpc
> > > > > reusing
> > > > > the old slot and sequence number?
> > > >
> > > > Correct.
> > >
> > > So that could get UNCACHED_REP as the response. But if you're
> > > very
> > > unlucky, couldn't this also happen?:
> > >
> > > 1) the compound previously sent on that slot was
> > > processed by
> > > the server and cached
> > > 2) the compound you're sending now happens to have the
> > > same set
> > > of operations
> > >
> > > with the result that the client doesn't detect that the reply was
> > > actually to some other rpc, and instead it returns bad data to
> > > the
> > > application?
> >
> > If you are sending exactly the same operations and arguments, then
> > why
> > is a reply from the cache would lead to bad data?
>
> That would probably be fine, I was wondering what would happen if you
> sent the same operation but different arguments.
> So the original cancelled operation is something like
> PUTFH(fh1)+OPEN("foo")+GETFH, and the new one is
> PUTFH(fh2)+OPEN("bar")+GETFH. In theory couldn't the second one
> succeed
> and leave the client thinking it had opened (fh2, bar) when the
> filehandle it got back was really for (fh1, foo)?
>
The client would receive a filehandle for fh1/"foo", so it would apply
any state it thought it had received to that file. However, normally,
I'd expect to see a NFS4ERR_FALSE_RETRY in this case.��.n��������+%������w��{.n�����{��w��� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
