-----Original Message----- From: Daniel Gryniewicz [mailto:dang@redhat.com] Sent: Wednesday, July 1, 2020 7:21 AM To: devel(a)lists.nfs-ganesha.org Subject: [NFS-Ganesha-Devel] Re: Callbacks supported with 4.1 It appears the implemented callbacks are layout recall, device notify, delegation recall, and getattr. You can check the callpoints of nfs_rpc_cb_single() to see which callbacks are sent. Daniel On 7/1/20 9:13 AM, Trishali Nayar wrote: > Hi all, > > Recently while doing some testing we observed that CB_NOTIFY_LOCK > callback does not seem to supported by Ganesha. Is that understanding correct? > > Also, any insights on the 4.1 callbacks that we do support, would be > good to know. The RFC mentions quite a few of them. > > Thanks and regards, > Trishali. > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Trishali Nayar > IBM Systems > ETZ, Pune. > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > _______________________________________________ > Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe send > an email to devel-leave(a)lists.nfs-ganesha.org > _______________________________________________ Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe send an email to devel-leave(a)lists.nfs-ganesha.org

Since we don't implement callbacks or fairness, we could just drop locks of type STATE_NFSV4_BLOCKING? The current code might be there to implement callback in future though, just trying to understand the code. Regards, Malahal. On Thu, Jul 2, 2020 at 12:10 AM Frank Filz <ffilzlnx(a)mindspring.com&gt; wrote: > Yea, the notify lock callback is not supported, that would take some > effort to implement non-blocking locks for NFS v4.1 which is complicated in > that I'm not sure if the callback is a guaranteed deal, that the client > will send some kind of cancellation if it gives up waiting for a blocked > lock, If not, then we need to time out 4.x blocked locks. We also have to > make them provisional until the client actually comes back with a new lock > request, which means they COULD be handed out to another client in the > meantime. This provisional (or courtesy) behavior may be hard to assure in > a cluster or even a single node where there are other processes using > locking on the same file system (since the courtesy lock would be a normal > held lock on the backend - Ganesha can only give a conflicting lock out and > cancel the courtesy lock for locks that come through that Ganesha instance). > > Frank > > > -----Original Message----- > > From: Daniel Gryniewicz [mailto:dang@redhat.com] > > Sent: Wednesday, July 1, 2020 7:21 AM > > To: devel(a)lists.nfs-ganesha.org > > Subject: [NFS-Ganesha-Devel] Re: Callbacks supported with 4.1 > > > > It appears the implemented callbacks are layout recall, device notify, > delegation > > recall, and getattr. You can check the callpoints of > > nfs_rpc_cb_single() to see which callbacks are sent. > > > > Daniel > > > > On 7/1/20 9:13 AM, Trishali Nayar wrote: > > > Hi all, > > > > > > Recently while doing some testing we observed that CB_NOTIFY_LOCK > > > callback does not seem to supported by Ganesha. Is that understanding > > correct? > > > > > > Also, any insights on the 4.1 callbacks that we do support, would be > > > good to know. The RFC mentions quite a few of them. > > > > > > Thanks and regards, > > > Trishali. > > > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > Trishali Nayar > > > IBM Systems > > > ETZ, Pune. > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > > > > > > _______________________________________________ > > > Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe send > > > an email to devel-leave(a)lists.nfs-ganesha.org > > > > > _______________________________________________ > > Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe send > an email to > > devel-leave(a)lists.nfs-ganesha.org > _______________________________________________ > Devel mailing list -- devel(a)lists.nfs-ganesha.org > To unsubscribe send an email to devel-leave(a)lists.nfs-ganesha.org >

Yea, the notify lock callback is not supported, that would take some effort to implement non-blocking locks for NFS v4.1 which is complicated in that I'm not sure if the callback is a guaranteed deal , that the client will send some kind of cancellation if it gives up waiting for a blocked lock

, If not, then we need to time out 4.x blocked locks. We also have to make them provisional until the client actually comes back with a new lock request, which means they COULD be handed out to another client in the meantime.

This provisional (or courtesy) behavior may be hard to assure in a cluster or even a single node where there are other processes using locking on the same file system (since the courtesy lock would be a normal held lock on the backend - Ganesha can only give a conflicting lock out and cancel the courtesy lock for locks that come through that Ganesha instance).

> On Wed, 2020-07-01 at 11:39 -0700, Frank Filz wrote: > > Yea, the notify lock callback is not supported, that would take some > > effort to implement non-blocking locks for NFS v4.1 which is > > complicated in that I'm not sure if the callback is a guaranteed deal > > , that the client will send some kind of cancellation if it gives up > > waiting for a blocked lock > > There's nothing guaranteed. The client can always just drop off the net. > In knfsd, we just assume that the lock will be revisited at least once each lease > period, and just drop the blocked request if they aren't. The Linux kernel client > will still re-poll for the lock every 30s if it doesn't get a notification. > > > , If not, then we need to time out 4.x blocked locks. We also have to make > them provisional until the client actually comes back with a new lock request, > which means they COULD be handed out to another client in the meantime. > > A v4.1 CB_NOTIFY_LOCK is _completely_ advisory. It just says "this is a good > time to retry that lock you wanted". There's never a guarantee that you'll get it > and the server is under no obligation to hold it for the client being notified. This > is fundamentally different from (and simpler > than) NLM. Ok, so the 4.1 blocks would have to be maintained on a list in order of most recently polled. Then the reaper thread would look at the LRU of the list and release any wait for notification entries that have expired until it hits one that hasn't expired.

> > This provisional (or courtesy) behavior may be hard to assure in a cluster or > even a single node where there are other processes using locking on the same > file system (since the courtesy lock would be a normal held lock on the backend - > Ganesha can only give a conflicting lock out and cancel the courtesy lock for > locks that come through that Ganesha instance). > > I think it's probably possible to do it with some FSALs. For example, it'd probably > be doable in libcephfs and then we could wire that into nfs-ganesha. FSAL_VFS > (and similar) might actually be the toughest place to make it work, since the > kernel would need new interfaces for it. Yea, I assume it would be straightforward to implement in Ceph, tying somehow into the caps logic. And yea, FSAL_VFS would either have to modify the kernel, or it could just wait on a blocked lock, and then when the blocked lock is granted, immediately drop it and send a notification.