On Thu, Feb 07, 2019 at 10:28:05AM -0500, Tom Talpey wrote: > On 2/7/2019 10:04 AM, Chuck Lever wrote: > > > > > > > On Feb 7, 2019, at 12:23 AM, Jason Gunthorpe <jgg@xxxxxxxx> wrote: > > > > > > On Thu, Feb 07, 2019 at 02:52:58PM +1100, Dave Chinner wrote: > > > > > > > Requiring ODP capable hardware and applications that control RDMA > > > > access to use file leases and be able to cancel/recall client side > > > > delegations (like NFS is already able to do!) seems like a pretty > > > > > > So, what happens on NFS if the revoke takes too long? > > > > NFS distinguishes between "recall" and "revoke". Dave used "recall" > > here, it means that the server recalls the client's delegation. If > > the client doesn't respond, the server revokes the delegation > > unilaterally and other users are allowed to proceed. > > The SMB3 protocol has a similar "lease break" mechanism, btw. > > SMB3 "push mode" has long-expected to allow DAX mapping of files > only when an exclusive lease is held by the requesting client. > The server may recall the lease if the DAX mapping needs to change. > > Once local (MMU) and remote (RDMA) mappings are dropped, the > client may re-request that the server reestablish them. No > connection or process is terminated, and no data is silently lost. How long does one wait for these remote mappings to be dropped? Ira
