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>

1 files changed, 67 insertions, 47 deletions

diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index 17625d43dc37..d055079c9485 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -478,39 +478,6 @@ nlmsvc_proc_lock(struct svc_rqst *rqstp)
 	return nlmsvc_do_lock(rqstp, true);
 }
 
-static __be32
-__nlmsvc_proc_cancel(struct svc_rqst *rqstp, struct lockd_res *resp)
-{
-	struct lockd_args *argp = rqstp->rq_argp;
-	struct nlm_host	*host;
-	struct nlm_file	*file;
-	struct net *net = SVC_NET(rqstp);
-
-	dprintk("lockd: CANCEL        called\n");
-
-	resp->cookie = argp->cookie;
-
-	/* Don't accept requests during grace period */
-	if (locks_in_grace(net)) {
-		resp->status = nlm_lck_denied_grace_period;
-		return rpc_success;
-	}
-
-	/* Obtain client and file */
-	if ((resp->status = nlmsvc_retrieve_args(rqstp, argp, &host, &file)))
-		return resp->status == nlm__int__drop_reply ?
-			rpc_drop_reply : rpc_success;
-
-	/* Try to cancel request. */
-	resp->status = cast_status(nlmsvc_cancel_blocked(net, file, &argp->lock));
-
-	dprintk("lockd: CANCEL        status %d\n", ntohl(resp->status));
-	nlmsvc_release_lockowner(&argp->lock);
-	nlmsvc_release_host(host);
-	nlm_release_file(file);
-	return rpc_success;
-}
-
 /**
  * nlmsvc_proc_cancel - CANCEL: Cancel an outstanding blocked lock request
  * @rqstp: RPC transaction context
@@ -900,19 +867,72 @@ static __be32 nlmsvc_proc_lock_msg(struct svc_rqst *rqstp)
 			       __nlmsvc_proc_lock_msg);
 }
 
+static __be32
+__nlmsvc_proc_cancel_msg(struct svc_rqst *rqstp, struct lockd_res *resp)
+{
+	struct nlm_cancargs_wrapper *argp = rqstp->rq_argp;
+	unsigned char type = argp->xdrgen.exclusive ? F_WRLCK : F_RDLCK;
+	struct net *net = SVC_NET(rqstp);
+	struct nlm_file	*file = NULL;
+	struct nlm_host	*host = NULL;
+
+	resp->status = nlm_lck_denied_nolocks;
+	if (nlm_netobj_to_cookie(&resp->cookie, &argp->xdrgen.cookie))
+		goto out;
+
+	resp->status = nlm_lck_denied_grace_period;
+	if (locks_in_grace(net))
+		goto out;
+
+	resp->status = nlm_lck_denied_nolocks;
+	host = nlm3svc_lookup_host(rqstp, argp->xdrgen.alock.caller_name, false);
+	if (!host)
+		goto out;
+
+	resp->status = nlm3svc_lookup_file(rqstp, host, &argp->lock,
+					   &file, &argp->xdrgen.alock, type);
+	if (resp->status)
+		goto out;
+
+	resp->status = nlmsvc_cancel_blocked(net, file, &argp->lock);
+	nlmsvc_release_lockowner(&argp->lock);
+
+out:
+	if (file)
+		nlm_release_file(file);
+	nlmsvc_release_host(host);
+	return resp->status == nlm__int__drop_reply ? rpc_drop_reply : rpc_success;
+}
+
+/**
+ * nlmsvc_proc_cancel_msg - CANCEL_MSG: Cancel an outstanding lock request
+ * @rqstp: RPC transaction context
+ *
+ * Returns:
+ *   %rpc_success:		RPC executed successfully.
+ *   %rpc_drop_reply:		Do not send an RPC reply.
+ *   %rpc_garbage_args:	The request arguments are malformed.
+ *   %rpc_system_err:		RPC execution failed.
+ *
+ * RPC synopsis:
+ *   void NLMPROC_CANCEL_MSG(nlm_cancargs) = 8;
+ *
+ * The response to this request is delivered via the CANCEL_RES procedure.
+ */
 static __be32 nlmsvc_proc_cancel_msg(struct svc_rqst *rqstp)
 {
-	struct lockd_args *argp = rqstp->rq_argp;
-	struct nlm_host	*host;
+	struct nlm_cancargs_wrapper *argp = rqstp->rq_argp;
+	struct nlm_host *host;
 
-	dprintk("lockd: CANCEL_MSG    called\n");
+	if (argp->xdrgen.cookie.len > NLM_MAXCOOKIELEN)
+		return rpc_garbage_args;
 
-	host = nlmsvc_lookup_host(rqstp, argp->lock.caller, argp->lock.len);
+	host = nlm3svc_lookup_host(rqstp, argp->xdrgen.alock.caller_name, false);
 	if (!host)
 		return rpc_system_err;
 
 	return nlmsvc_callback(rqstp, host, NLMPROC_CANCEL_RES,
-			       __nlmsvc_proc_cancel);
+			       __nlmsvc_proc_cancel_msg);
 }
 
 static __be32 nlmsvc_proc_unlock_msg(struct svc_rqst *rqstp)
@@ -1188,15 +1208,15 @@ static const struct svc_procedure nlmsvc_procedures[24] = {
 		.pc_xdrressize	= XDR_void,
 		.pc_name	= "LOCK_MSG",
 	},
-	[NLMPROC_CANCEL_MSG] = {
-		.pc_func = nlmsvc_proc_cancel_msg,
-		.pc_decode = nlmsvc_decode_cancargs,
-		.pc_encode = nlmsvc_encode_void,
-		.pc_argsize = sizeof(struct lockd_args),
-		.pc_argzero = sizeof(struct lockd_args),
-		.pc_ressize = sizeof(struct nlm_void),
-		.pc_xdrressize = St,
-		.pc_name = "CANCEL_MSG",
+	[NLM_CANCEL_MSG] = {
+		.pc_func	= nlmsvc_proc_cancel_msg,
+		.pc_decode	= nlm_svc_decode_nlm_cancargs,
+		.pc_encode	= nlm_svc_encode_void,
+		.pc_argsize	= sizeof(struct nlm_cancargs_wrapper),
+		.pc_argzero	= 0,
+		.pc_ressize	= 0,
+		.pc_xdrressize	= XDR_void,
+		.pc_name	= "CANCEL_MSG",
 	},
 	[NLMPROC_UNLOCK_MSG] = {
 		.pc_func = nlmsvc_proc_unlock_msg,