[PATCH v3 09/29] lockd: Use xdrgen XDR functions for the NLMv4 TEST_MSG procedure

[Chuck Lever <cel@kernel.org>]

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

The TEST_MSG procedure is part of NLM's asynchronous lock request
flow, where clients send TEST_MSG to check lock availability
without blocking. This patch continues the xdrgen migration by
converting TEST_MSG to use generated XDR functions.

This patch converts the TEST_MSG procedure to use xdrgen
functions nlm4_svc_decode_nlm4_testargs and
nlm4_svc_encode_void generated from the NLM version 4 protocol
specification. The procedure handler uses xdrgen types through
the nlm4_testargs_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 TEST and TEST_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 | 114 +++++++++++++++++++++++---------------------
 1 file changed, 60 insertions(+), 54 deletions(-)

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index f1a692f72a39..afce778b62d3 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -260,39 +260,6 @@ nlm4svc_proc_null(struct svc_rqst *rqstp)
 	return rpc_success;
 }
 
-/*
- * TEST: Check for conflicting lock
- */
-static __be32
-__nlm4svc_proc_test(struct svc_rqst *rqstp, struct nlm_res *resp)
-{
-	struct nlm_args *argp = rqstp->rq_argp;
-	struct nlm_host	*host;
-	struct nlm_file	*file;
-	__be32 rc = rpc_success;
-
-	dprintk("lockd: TEST4        called\n");
-	resp->cookie = argp->cookie;
-
-	/* Obtain client and file */
-	if ((resp->status = nlm4svc_retrieve_args(rqstp, argp, &host, &file)))
-		return resp->status == nlm__int__drop_reply ?
-			rpc_drop_reply : rpc_success;
-
-	/* Now check for conflicting locks */
-	resp->status = nlmsvc_testlock(rqstp, file, host, &argp->lock,
-				       &resp->lock);
-	if (resp->status == nlm__int__drop_reply)
-		rc = rpc_drop_reply;
-	else
-		dprintk("lockd: TEST4        status %d\n", ntohl(resp->status));
-
-	nlmsvc_release_lockowner(&argp->lock);
-	nlmsvc_release_host(host);
-	nlm_release_file(file);
-	return rc;
-}
-
 /**
  * nlm4svc_proc_test - TEST: Check for conflicting lock
  * @rqstp: RPC transaction context
@@ -785,25 +752,64 @@ nlm4svc_callback(struct svc_rqst *rqstp, struct nlm_host *host, u32 proc,
 	return rpc_success;
 }
 
-/*
- * 'Async' versions of the above service routines. They aren't really,
- * because we send the callback before the reply proper. I hope this
- * doesn't break any clients.
- */
+static __be32
+__nlm4svc_proc_test_msg(struct svc_rqst *rqstp, struct nlm_res *resp)
+{
+	struct nlm4_testargs_wrapper *argp = rqstp->rq_argp;
+	unsigned char type = argp->xdrgen.exclusive ? F_WRLCK : F_RDLCK;
+	struct nlm_lockowner *owner;
+	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, false);
+	if (!host)
+		goto out;
+
+	resp->status = nlm4svc_lookup_file(rqstp, host, &argp->lock,
+					   &file, &argp->xdrgen.alock, type);
+	if (resp->status)
+		goto out;
+
+	owner = argp->lock.fl.c.flc_owner;
+	resp->status = nlmsvc_testlock(rqstp, file, host, &argp->lock,
+				       &resp->lock);
+	nlmsvc_put_lockowner(owner);
+
+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_test_msg - TEST_MSG: Check for conflicting lock
+ * @rqstp: RPC transaction context
+ *
+ * Returns:
+ *   %rpc_success:		RPC executed successfully.
+ *   %rpc_system_err:		RPC execution failed.
+ *
+ * RPC synopsis:
+ *   void NLMPROC4_TEST_MSG(nlm4_testargs) = 6;
+ *
+ * The response to this request is delivered via the TEST_RES procedure.
+ */
 static __be32 nlm4svc_proc_test_msg(struct svc_rqst *rqstp)
 {
-	struct nlm_args *argp = rqstp->rq_argp;
-	struct nlm_host	*host;
+	struct nlm4_testargs_wrapper *argp = rqstp->rq_argp;
+	struct nlm_host *host;
 
-	dprintk("lockd: TEST_MSG      called\n");
-
-	host = nlmsvc_lookup_host(rqstp, argp->lock.caller, argp->lock.len);
+	host = nlm4svc_lookup_host(rqstp, argp->xdrgen.alock.caller_name, false);
 	if (!host)
 		return rpc_system_err;
 
-	return nlm4svc_callback(rqstp, host, NLMPROC_TEST_RES,
-				__nlm4svc_proc_test);
+	return nlm4svc_callback(rqstp, host, NLMPROC4_TEST_RES,
+				__nlm4svc_proc_test_msg);
 }
 
 static __be32 nlm4svc_proc_lock_msg(struct svc_rqst *rqstp)
@@ -1087,15 +1093,15 @@ static const struct svc_procedure nlm4svc_procedures[24] = {
 		.pc_xdrressize	= NLM4_nlm4_res_sz,
 		.pc_name	= "GRANTED",
 	},
-	[NLMPROC_TEST_MSG] = {
-		.pc_func = nlm4svc_proc_test_msg,
-		.pc_decode = nlm4svc_decode_testargs,
-		.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 = "TEST_MSG",
+	[NLMPROC4_TEST_MSG] = {
+		.pc_func	= nlm4svc_proc_test_msg,
+		.pc_decode	= nlm4_svc_decode_nlm4_testargs,
+		.pc_encode	= nlm4_svc_encode_void,
+		.pc_argsize	= sizeof(struct nlm4_testargs_wrapper),
+		.pc_argzero	= 0,
+		.pc_ressize	= 0,
+		.pc_xdrressize	= XDR_void,
+		.pc_name	= "TEST_MSG",
 	},
 	[NLMPROC_LOCK_MSG] = {
 		.pc_func = nlm4svc_proc_lock_msg,
-- 
2.53.0