[PATCH v2] Samba RADOS service registration

[David Disseldorp]

On Thu, 15 Feb 2018 14:05:55 -0500, Jeff Layton wrote:

> Got it, thanks. I guess the fact that it changes it not a problem here?

I think at this stage it's a trade off between having duplicate
registrations for a short period of time, and potentially clobbering
the registration of another server with a non-unique hostname (see
Jason's mail).

> I'm not that well versed in what ceph-mgr does, tbqh...
> 
> One thing you may want to be careful about: I found some thread safety
> problems a few months ago in how CephContext objects are handled in the
> ceph code. While I patched them up as best I could, a lot of older
> shipping versions still have those bugs. Even with those fixes, I think
> there may still be lurking problems when we have multiple ceph/rados
> clients within the same process image.

Hmm okay, I haven't come across this yet, but will take a look.

> The upshot here is that if you have the rados client here and (e.g.) a
> vfs_ceph client for exporting cephfs, you can hit some races
> particularly on setup and teardown of those clients that can cause
> crashes.
> 
> libcephfs has a ceph_create_with_context image and librados has
> something similar. You might consider having a truly global cct object,
> and then have the vfs_ceph create a client handle with the same object.

That would share instance id and credentials across all smbd consumers,
right? One thing I'd hoped to gain in future was SMB<->Ceph user mapping
for end-to-end privilege separation. This would be a step in the
opposite direction, IIUC.

Cheers, David