On Wed, 2024-01-24 at 18:18 -0500, Josef Bacik wrote:
> On Wed, Jan 24, 2024 at 05:57:06PM -0500, Jeff Layton wrote:
> > On Wed, 2024-01-24 at 17:12 -0500, Josef Bacik wrote:
> > > On Wed, Jan 24, 2024 at 03:32:06PM -0500, Chuck Lever wrote:
> > > > On Wed, Jan 24, 2024 at 02:37:00PM -0500, Josef Bacik wrote:
> > > > > We are running nfsd servers inside of containers with their own network
> > > > > namespace, and we want to monitor these services using the stats found
> > > > > in /proc. However these are not exposed in the proc inside of the
> > > > > container, so we have to bind mount the host /proc into our containers
> > > > > to get at this information.
> > > > >
> > > > > Separate out the stat counters init and the proc registration, and move
> > > > > the proc registration into the pernet operations entry and exit points
> > > > > so that these stats can be exposed inside of network namespaces.
> > > >
> > > > Maybe I missed something, but this looks like it exposes the global
> > > > stat counters to all net namespaces...? Is that an information leak?
> > > > As an administrator I might be surprised by that behavior.
> > > >
> > > > Seems like this patch needs to make nfsdstats and nfsd_svcstats into
> > > > per-namespace objects as well.
> > > >
> > > >
> > >
> > > I've got the patches written for this, but I've got a question. There's a
> > >
> > > svc_seq_show(seq, &nfsd_svcstats);
> > >
> > > in nfsd/stats.c. This appears to be an empty struct, there's nothing that
> > > utilizes it, so this is always going to print 0 right? There's a svc_info in
> > > the nfsd_net, and that stats block appears to get updated properly. Should I
> > > print this out here? I don't see anywhere we get the rpc stats out of nfsd, am
> > > I missing something? I don't want to rip out stuff that I don't quite
> > > understand. Thanks,
> > >
> > >
> >
> > nfsd_svcstats ends up being the sv_stats for the nfsd service. The RPC
> > code has some counters in there for counting different sorts of net and
> > rpc events (see svc_process_common, and some of the recv and accept
> > handlers). I think nfsstat(8) may fetch that info via the above
> > seqfile, so it's definitely not unused (and it should be printing more
> > than just a '0').
>
> Ahhh, I missed this bit
>
> struct svc_program nfsd_program = {
> #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
> .pg_next = &nfsd_acl_program,
> #endif
> .pg_prog = NFS_PROGRAM, /* program number */
> .pg_nvers = NFSD_NRVERS, /* nr of entries in
> nfsd_version */
> .pg_vers = nfsd_version, /* version table */
> .pg_name = "nfsd", /* program name */
> .pg_class = "nfsd", /* authentication class
> */
> .pg_stats = &nfsd_svcstats, /* version table */
> .pg_authenticate = &svc_set_client, /* export authentication
> */
> .pg_init_request = nfsd_init_request,
> .pg_rpcbind_set = nfsd_rpcbind_set,
> };
>
> and so nfsd_svcstats definitely is getting used.
>
> >
> > svc_info is a completely different thing: it's a container for the
> > svc_serv...so I'm not sure I understand your question?
>
> I was just confused, and still am a little bit.
>
> The counters are easy, I put those into the nfsd_net struct and make everything
> mess with those counters and report those from proc.
>
> However the nfsd_svcstats are in this svc_program thing, which appears to need
> to be global? Or do I need to make it per net as well? Or do I need to do
> something completely different to track the rpc stats per network namespace?
Making the svc_program per-net is unnecessary for this (and probably not
desirable). That structure sort of describes the nfsd rpc "program" and
that is pretty much the same between containers.
I think making having a different sv_stats per-namespace makes sense.
It'll be a departure from the way it works today though. Looking at
nfsstat in the init_ns will no longer show global counters. I don't
think it's a bad change, but it will be a change that we'll need to take
into account (and maybe document).
This is all really old, crusty code, and some of it like the sv_stats
code originates from the 90s. Right now, sv_stats is only assigned in
svc_create and it comes from the svc_program. You'll need to do
something different there.
Now that I look too, it looks like we're just doing bare increments to
the counters without any locking, which seems a bit racy. I wonder
whether we ought to be doing something percpu there instead?
--
Jeff Layton <jlayton@xxxxxxxxxx>
