lockd: Use xdrgen XDR functions for the NLMv3 LOCK_MSG procedure

Continue the xdrgen migration by converting NLMv3 LOCK_MSG, the
async counterpart to LOCK that clients use to request locks that
may block. The procedure now uses nlm_svc_decode_nlm_lockargs and
nlm_svc_encode_void, generated from the NLM version 3 protocol
specification. The procedure handler reaches the xdrgen types
through the nlm_lockargs_wrapper structure, which 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 NLM async callback mechanism uses client-side functions which
continue to take legacy results like struct lockd_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>

1 files changed, 63 insertions, 14 deletions

diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index cd32cfc62338..17625d43dc37 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -836,19 +836,68 @@ static __be32 nlmsvc_proc_test_msg(struct svc_rqst *rqstp)
 			       __nlmsvc_proc_test_msg);
 }
 
+static __be32
+__nlmsvc_proc_lock_msg(struct svc_rqst *rqstp, struct lockd_res *resp)
+{
+	struct nlm_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 (nlm_netobj_to_cookie(&resp->cookie, &argp->xdrgen.cookie))
+		goto out;
+
+	host = nlm3svc_lookup_host(rqstp, argp->xdrgen.alock.caller_name, true);
+	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 = cast_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;
+}
+
+/**
+ * nlmsvc_proc_lock_msg - LOCK_MSG: Establish a monitored lock
+ * @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_LOCK_MSG(nlm_lockargs) = 7;
+ *
+ * The response to this request is delivered via the LOCK_RES procedure.
+ */
 static __be32 nlmsvc_proc_lock_msg(struct svc_rqst *rqstp)
 {
-	struct lockd_args *argp = rqstp->rq_argp;
-	struct nlm_host	*host;
+	struct nlm_lockargs_wrapper *argp = rqstp->rq_argp;
+	struct nlm_host *host;
 
-	dprintk("lockd: LOCK_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_LOCK_RES,
-			       __nlmsvc_proc_lock);
+			       __nlmsvc_proc_lock_msg);
 }
 
 static __be32 nlmsvc_proc_cancel_msg(struct svc_rqst *rqstp)
@@ -1129,15 +1178,15 @@ static const struct svc_procedure nlmsvc_procedures[24] = {
 		.pc_xdrressize	= XDR_void,
 		.pc_name	= "TEST_MSG",
 	},
-	[NLMPROC_LOCK_MSG] = {
-		.pc_func = nlmsvc_proc_lock_msg,
-		.pc_decode = nlmsvc_decode_lockargs,
-		.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 = "LOCK_MSG",
+	[NLM_LOCK_MSG] = {
+		.pc_func	= nlmsvc_proc_lock_msg,
+		.pc_decode	= nlm_svc_decode_nlm_lockargs,
+		.pc_encode	= nlm_svc_encode_void,
+		.pc_argsize	= sizeof(struct nlm_lockargs_wrapper),
+		.pc_argzero	= 0,
+		.pc_ressize	= 0,
+		.pc_xdrressize	= XDR_void,
+		.pc_name	= "LOCK_MSG",
 	},
 	[NLMPROC_CANCEL_MSG] = {
 		.pc_func = nlmsvc_proc_cancel_msg,