On Wed, Mar 06, 2019 at 03:31:08PM -0500, Jeff Layton wrote: > On Wed, 2019-03-06 at 10:11 -0500, J. Bruce Fields wrote: > > On Tue, Mar 05, 2019 at 04:47:48PM -0500, J. Bruce Fields wrote: > > > On Thu, Feb 14, 2019 at 04:06:52PM -0500, J. Bruce Fields wrote: > > > > After this: > > > > > > > > https://marc.info/?l=linux-nfs&m=154966239918297&w=2 > > > > > > > > delegations would no longer conflict with opens from the same tgid. So > > > > if your threads all run in the same process and you're willing to manage > > > > conflicts among your own clients, that should still allow you to do > > > > multiple opens of the same file without giving up your lease/delegation. > > > > > > > > I'd be curious to know whether that works with Samba's design. > > > > > > Any idea whether that would work? > > > > > > (Easy? Impossible? Possible, but realistically the changes required to > > > Samba would be painful enough that it'd be unlikely to get done?) > > > > Volker reminds me off-list that he'd like to see Ganesha and Samba work > > out an API in userspace first before commiting to a user<->kernel API. > > > > Jeff, wasn't there some work (on Ceph maybe?) on a userspace delegation > > API? Is that close to what's needed? > > > > Here's the C headers for that stuff: > > https://github.com/ceph/ceph/blob/7ba6bece4187eda5d05a9b84211fe6ba8dd287bd/src/include/cephfs/libcephfs.h#L1734 > > It's simple enough and works for us in ganesha, and I think we can > probably adapt it to samba without too much difficulty. The callback > doesn't seem like it'll do for a kernel API though -- you'd almost > certainly need to do something different there (signals? inotify?). SMB3 leases have R/RW and Handle-based leases. Handle leases allow multiple opens of the same pathname that get different handles to share the lease, allowing a client redirector to delay opens or closes locally so long as it has a handle lease. Here are the semantics: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/d8df943d-6ad7-4b30-9f58-96ae90fc6204 I'm not sure a simple file-descriptor based API is enough for us. Can he have a uuid or token based API instead where the server can chose what fd's to cover with a token ?
