On Tue, Jun 29, 2021 at 8:58 AM Chuck Lever III <chuck.lever@xxxxxxxxxx> wrote: > > > > > On Jun 28, 2021, at 6:06 PM, Trond Myklebust <trondmy@xxxxxxxxxxxxxxx> wrote: > > > > On Mon, 2021-06-28 at 16:23 -0400, Olga Kornievskaia wrote: > >> Hi folks, > >> > >> I have a general question of why the client doesn't throw away the > >> cached server's capabilities on server reboot. Say a client mounted a > >> server when the server didn't support security_labels, then the > >> server > >> was rebooted and support was enabled. Client re-establishes its > >> clientid/session, recovers state, but assumes all the old > >> capabilities > >> apply. A remount is required to clear old/find new capabilities. The > >> opposite is true that a capability could be removed (but I'm assuming > >> that's a less practical example). > >> > >> I'm curious what are the problems of clearing server capabilities and > >> rediscovering them on reboot? Is it because a local filesystem could > >> never have its attributes changed and thus a network file system > >> can't > >> either? > >> > >> Thank you. > > > > In my opinion, the client should aim for the absolute minimum overhead > > on a server reboot. The goal should be to recover state and get I/O > > started again as quickly as possible. > > I 100% agree with the above. However... > > > > Detection of new features, etc > > can wait until the client needs to restart. > > A server reboot can be part of a failover to a different server. I > think capability discovery needs to happen as part of server reboot > recovery, it can't be optimized away. Can you clarify what you mean by a "failover to a different server"? To do reboot recovery it has to be the "same" server (by the definitions of the RFC). My use case I was thinking of was a reboot of the "same" server (major, minor, scope same) but with new features but of course one could argue if it has new features it's no longer the "same" server. I think you are probably thinking about migration or are you thinking of telling a difference between session trunkable servers which are considered to be the same but since it's a different IP it might have different capabilities? Thank you for the feedback! > > > -- > Chuck Lever > > >
