generic/465: don't run it on NFS

generic/465: don't run it on NFS

This test kicks off a thread that issues a read against a file, while
writing to the file in 1M chunks. It expects that the reader will see
either the written data or a short read.

NFS allows DIO reads and writes to run in parallel. That means that it's
possible for them to race and the reader to see NULLs in the file if
things get reordered.

Just skip this test on NFS, since we can't guarantee that it will
reliably pass.

Cc: Anna Schumaker <anna@kernel.org>
Cc: Trond Myklebust <trondmy@hammerspace.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/linux-nfs/2f7f6d4490ac08013ef78481ff5c7840f41b1bb4.camel@kernel.org/
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>