lockd: Use xdrgen XDR functions for the NLMv3 CANCEL_MSG procedure

The CANCEL_MSG procedure is part of NLM's asynchronous lock
request flow, where clients send CANCEL_MSG to cancel pending
lock requests. This patch continues the xdrgen migration by
converting CANCEL_MSG to use generated XDR functions.

This patch converts the CANCEL_MSG procedure to use xdrgen
functions nlm_svc_decode_nlm_cancargs and nlm_svc_encode_void
generated from the NLM version 3 protocol specification. The
procedure handler uses xdrgen types through the
nlm_cancargs_wrapper structure that bridges between generated
code and the legacy lockd_lock representation.

Setting pc_argzero to zero is safe because the generated decoder
fills the argp->xdrgen subfields before the procedure runs, so the
zeroing memset performed by the dispatch layer is not needed. The
lock member of the wrapper is populated explicitly in
nlm3svc_lookup_file() rather than relying on zero-initialization.

The previous hand-written decoder in svcxdr_decode_cookie()
rewrote a zero-length NLM cookie into a four-byte zero cookie,
with a comment attributing the substitution to HP-UX clients.
The xdrgen-generated netobj decoder performs no such rewrite, so
a zero-length request cookie now round-trips unchanged into the
CANCEL_RES reply. HP-UX has reached end of support, and CANCEL_MSG
is fire-and-forget with no client-side reply matching on the NLM
cookie, so the workaround is dropped intentionally here.

The NLM async callback mechanism uses client-side functions
which continue to take legacy results like struct lockd_res,
preventing CANCEL and CANCEL_MSG from sharing code for now.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

0 files changed, 0 insertions, 0 deletions