On Fri, Mar 19, 2021 at 02:36:24PM +1100, NeilBrown wrote: > On Mon, Mar 01 2021, J. Bruce Fields wrote: > > > On Tue, Mar 02, 2021 at 02:01:36PM +1100, NeilBrown wrote: > >> On Mon, Mar 01 2021, J. Bruce Fields wrote: > >> > >> > I've gotten requests for similar functionality, and intended to > >> > implement it using directory notifications on /proc/fs/nfsd/clients. > >> > >> I've been exploring this a bit. > >> When I mount a filesystem, 2 clients get created. > >> With NFSv4.0, the second client is immediately deleted, and the first > >> client is deleted one grace period after the filesystem is unmounted. > >> With NFSv4.1 and 4.2, the first client is immediately deleted, and the > >> second client is deleted immediately after the unmount. > > > > Yeah, internally it's creating an "unconfirmed client" on SETCLIENTID > > (or EXCHANGE_ID) and then a new "confirmed client" on > > SETCLIENTID_CONFIRM (or CREATE_SESSION). > > > > I'm not sure why the ordering's a little different between the 4.0/4.1+ > > cases. > > The multiple clients are not really nfsd's "fault". The Linux NFS > client sends multiple EXCHANGE_ID or SET_CLIENT_ID requests, so NFSD > really does need to create multiple clients. > > For NFSv4.0, when nfsd gets a repeat SET_CLIENT_ID, it keeps the old one > and discards the new. > For NFSv4.1, the spec requires that it keep the new one and discard the > old. > This explains the different ordering. Hm, is this the client's trunking-detection logic? In which case, it's not just unconfirmed clients. > So the clean up the logging, mountd needs to be able to see the > confirmation status. That sounds fine. (The other possibility might be to just not expose clients till they're confirmed. I don't know if unconfirmed clients are really that interesting. But I guess I'd rather err on the side of exposing more information here.) > Following this reply will be a patch to nfsd to provide this status, and > a patch to mountd/exportd to use this status.
