On Wed, 2019-03-06 at 13:07 -0800, Jeremy Allison wrote: > 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 ? The libcephfs API takes an opaque void * that could hold such a token. It gets passed back to the callback function when it's called to handle a delegation break. I could envision a delegation storing something similar (maybe an unsigned long or uint64_t) and pass it back in a delegation break. With that you could set multiple delegations on a fd, and use that to store a key for each one. Would something like that work for samba, or am I misunderstanding what it needs? -- Jeff Layton <jlayton@xxxxxxxxxx>
