On Tue, 2020-04-21 at 15:47 -0400, Olga Kornievskaia wrote: > On Mon, Apr 20, 2020 at 5:20 PM Trond Myklebust < > trondmy@xxxxxxxxxxxxxxx> wrote: > > On Mon, 2020-04-20 at 15:35 -0400, Olga Kornievskaia wrote: > > > On Mon, Apr 20, 2020 at 3:02 PM Trond Myklebust < > > > trondmy@xxxxxxxxxxxxxxx> wrote: > > > > On Mon, 2020-04-20 at 10:59 -0400, Olga Kornievskaia wrote: > > > > > On Mon, Apr 20, 2020 at 10:53 AM Olga Kornievskaia < > > > > > olga.kornievskaia@xxxxxxxxx> wrote: > > > > > > Yes we are consistent in requesting to same connection to > > > > > > with > > > > > > the > > > > > > same channel binding, but we don't send > > > > > > BIND_CONN_TO_SESSION as > > > > > > the > > > > > > first thing on the "main" connection (ie connection that > > > > > > cared > > > > > > the > > > > > > CREATE_SESSION and was bound to fore and back channel by > > > > > > default). > > > > > > When that connection is reset, the first thing that happens > > > > > > is > > > > > > the > > > > > > client re-sends the operation that was not replied to. That > > > > > > has > > > > > > a > > > > > > SEQUENCE and by the rule the server binds that connection > > > > > > to > > > > > > the > > > > > > fore channel only (and sets the callback being down). We > > > > > > then > > > > > > send > > > > > > BIND_CONN_TO_SESSION and request FORE_OR_BOTH where this > > > > > > has > > > > > > already been bound to FORE only. > > > > > > > > > > > > > > > > How about this: before we send BIND_CONN_TO_SESSION with > > > > > fore_or_both, we somehow always reset the connection (maybe > > > > > you > > > > > were > > > > > suggestion that already and i wasn't following). > > > > > > > > No. I didn't realise that we were being automatically set to > > > > just > > > > the > > > > fore channel. However as I said earlier, the spec says that the > > > > server > > > > MUST reply with NFS4ERR_INVAL in this case. It is not allowed > > > > to > > > > just > > > > return NFS4_OK and silently set the wrong channel binding. > > > > > > How's this: > > > client sends BIND_CONN_TO_SESSION with FORE_OR_BOTH, server > > > select > > > FORE channel. connection breaks before the reply gets to the > > > client. > > > Client resends. Is the server suppose to now fail with ERR_INVAL? > > > > > > There actually is such a thing between demand and request. FORE > > > and > > > BACK are demands and FORE_OR_BOTH and BACK_OR_BOTH are requests. > > > The > > > spec writes only about demands and not the requests. I believe > > > that's > > > intentional because BIND_CONN_TO_SESSIOn doesn't have a sequence > > > and > > > not protected by reply session semantics. > > > > OK. However if we take that interpretation, then the question is > > why > > would the server downgrade our FORE_OR_BOTH to FORE and what is the > > point of the client even retrying at all in that case? > > As far as I can tell, the client behaves improperly. It shouldn't > have > sent an operation on a new connection before sending > BIND_CONN_TO_SESSION. > > > The server can always reject the client's back channel creation > > attempt, but doing so has consequences: it means there is no way to > > hand out delegations or layouts. So I'm confused by the concept of > > a > > server that sets SEQ4_STATUS_CB_PATH_DOWN or > > SEQ4_STATUS_CB_PATH_DOWN_SESSION, but then doesn't allow the client > > to > > set a back channel. > > Because we can't guarantee that BIND_CONN_TO_SESSION happens as the > first operation, I think the solution is for the transport that will > do FORE_OR_BOTH request, the client must reset the connection first? > Would that be acceptable? > It sounds like we have no choice. However in that case, we should not try to recover in the case where the attempt to bind the backchannel fails. -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
