[PATCH v3 10/29] lockd: Use xdrgen XDR functions for the NLMv4 LOCK_MSG procedure

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

The LOCK_MSG procedure is part of NLM's asynchronous lock
request flow, where clients send LOCK_MSG to request locks
that may block. This patch continues the xdrgen migration by
converting LOCK_MSG to use generated XDR functions.

This patch converts the LOCK_MSG procedure to use xdrgen
functions nlm4_svc_decode_nlm4_lockargs and
nlm4_svc_encode_void generated from the NLM version 4
protocol specification. The procedure handler uses xdrgen
types through the nlm4_lockargs_wrapper structure that
bridges between generated code and the legacy nlm_lock
representation.

The pc_argzero field is set to zero because xdrgen decoders
reliably initialize all arguments in the argp->xdrgen field,
making the early defensive memset unnecessary. Remaining
argp fields are cleared as needed.

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

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/lockd/svc4proc.c | 77 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 61 insertions(+), 16 deletions(-)

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index afce778b62d3..d9406a4ab176 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -812,19 +812,64 @@ static __be32 nlm4svc_proc_test_msg(struct svc_rqst *rqstp)
 				__nlm4svc_proc_test_msg);
 }
 
+static __be32
+__nlm4svc_proc_lock_msg(struct svc_rqst *rqstp, struct nlm_res *resp)
+{
+	struct nlm4_lockargs_wrapper *argp = rqstp->rq_argp;
+	unsigned char type = argp->xdrgen.exclusive ? F_WRLCK : F_RDLCK;
+	struct nlm_file	*file = NULL;
+	struct nlm_host	*host = NULL;
+
+	resp->status = nlm_lck_denied_nolocks;
+	if (nlm4_netobj_to_cookie(&resp->cookie, &argp->xdrgen.cookie))
+		goto out;
+
+	host = nlm4svc_lookup_host(rqstp, argp->xdrgen.alock.caller_name, true);
+	if (!host)
+		goto out;
+
+	resp->status = nlm4svc_lookup_file(rqstp, host, &argp->lock,
+					   &file, &argp->xdrgen.alock, type);
+	if (resp->status)
+		goto out;
+
+	resp->status = nlmsvc_lock(rqstp, file, host, &argp->lock,
+				   argp->xdrgen.block, &resp->cookie,
+				   argp->xdrgen.reclaim);
+	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;
+}
+
+/**
+ * nlm4svc_proc_lock_msg - LOCK_MSG: Establish a monitored lock
+ * @rqstp: RPC transaction context
+ *
+ * Returns:
+ *   %rpc_success:		RPC executed successfully.
+ *   %rpc_system_err:		RPC execution failed.
+ *
+ * RPC synopsis:
+ *   void NLMPROC4_LOCK_MSG(nlm4_lockargs) = 7;
+ *
+ * The response to this request is delivered via the LOCK_RES procedure.
+ */
 static __be32 nlm4svc_proc_lock_msg(struct svc_rqst *rqstp)
 {
-	struct nlm_args *argp = rqstp->rq_argp;
-	struct nlm_host	*host;
+	struct nlm4_lockargs_wrapper *argp = rqstp->rq_argp;
+	struct nlm_host *host;
 
-	dprintk("lockd: LOCK_MSG      called\n");
-
-	host = nlmsvc_lookup_host(rqstp, argp->lock.caller, argp->lock.len);
+	host = nlm4svc_lookup_host(rqstp, argp->xdrgen.alock.caller_name, true);
 	if (!host)
 		return rpc_system_err;
 
-	return nlm4svc_callback(rqstp, host, NLMPROC_LOCK_RES,
-				__nlm4svc_proc_lock);
+	return nlm4svc_callback(rqstp, host, NLMPROC4_LOCK_RES,
+				__nlm4svc_proc_lock_msg);
 }
 
 static __be32 nlm4svc_proc_cancel_msg(struct svc_rqst *rqstp)
@@ -1103,15 +1148,15 @@ static const struct svc_procedure nlm4svc_procedures[24] = {
 		.pc_xdrressize	= XDR_void,
 		.pc_name	= "TEST_MSG",
 	},
-	[NLMPROC_LOCK_MSG] = {
-		.pc_func = nlm4svc_proc_lock_msg,
-		.pc_decode = nlm4svc_decode_lockargs,
-		.pc_encode = nlm4svc_encode_void,
-		.pc_argsize = sizeof(struct nlm_args),
-		.pc_argzero = sizeof(struct nlm_args),
-		.pc_ressize = sizeof(struct nlm_void),
-		.pc_xdrressize = St,
-		.pc_name = "LOCK_MSG",
+	[NLMPROC4_LOCK_MSG] = {
+		.pc_func	= nlm4svc_proc_lock_msg,
+		.pc_decode	= nlm4_svc_decode_nlm4_lockargs,
+		.pc_encode	= nlm4_svc_encode_void,
+		.pc_argsize	= sizeof(struct nlm4_lockargs_wrapper),
+		.pc_argzero	= 0,
+		.pc_ressize	= 0,
+		.pc_xdrressize	= XDR_void,
+		.pc_name	= "LOCK_MSG",
 	},
 	[NLMPROC_CANCEL_MSG] = {
 		.pc_func = nlm4svc_proc_cancel_msg,
-- 
2.53.0