[LTP] [PATCH v2 1/1] nfsstat01: Update client RPC calls for kernel 6.9

[Petr Vorel]

Hi all,

> On 23. 08. 24 23:59, NeilBrown wrote:
> > On Fri, 23 Aug 2024, Petr Vorel wrote:
> > > We discussed in v1 how to fix tests.  Neil suggested to fix the test the way so
> > > that it works on all kernels. As I note [1]

> > > 1) either we give up on checking the new functionality still works (if we
> > > fallback to old behavior)

> > I don't understand.  What exactly do you mean by "the new
> > functionality".
> > As I understand it there is no new functionality.  All there was was and
> > information leak between network namespaces, and we stopped the leak.
> > Do you consider that to be new functionality?

Thanks Martin for jumping in. I hoped I was clear, but obviously not.

Following are the questions for kernel maintainers and developers. I put my
opinion, but it's really up to you what you want to have tested.

> The new functionality is that the patches add a new file to network
> namespaces: /proc/net/rpc/nfs. This file did not exist outside the root
> network namespace at least on some of the kernels where we still need to run
> this test. So the question is: How aggressively do we want to enforce
> backporting of these NFS patches into distros with older kernels?

> We have 3 options how to fix the test depending on the answer:
> 1) Don't enforce at all. We'll check whether /proc/net/rpc/nfs exists in the
> client namespace and read it only if it does. Otherwise we'll fall back on
> the global file.

1) is IMHO the worst case because it's not testing patch gets reverted.

> 2) Enforce aggressively. We'll hardcode a minimal kernel version into the
> test (e.g. v5.4) and if the procfile doesn't exist on any newer kernel, it's
> a bug.

I would prefer 2), which is the usual LTP approach (do not hide bugs, we even
fail on upstream kernel WONTFIX [1], why we should refuse the policy here?).

Whichever older LTS upstream kernel gets fixed would drive the line where new
functionality is requested (currently v5.14, I suppose at least 5.10 will also
be fixed). LTP also has a way to specify enterprise distro kernel version if
older enterprise kernel also gets fixed (this should not be needed, but it'd be
possible).

> 3) Enforce on new kernels only. We'll set a hard requirement for kernel
> v6.9+ as in option 2) and check for existence of the procfile on any older
> kernels as in option 1).

Due way to specify enterprise distro kernel version and upstream kernel testing
expecting people update to the latest stable/LTS we should not worry much about
people with older kernels.

Kind regards,
Petr

[1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/ustat/ustat01.c#L48-L49