[PATCH v2 38/42] lockd: Use xdrgen XDR functions for the NLMv4 NM_LOCK procedure

[Chuck Lever <cel@kernel.org>]

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

Now that nlm4svc_do_lock() has been introduced to handle both
monitored and non-monitored lock requests, the NLMv4 NM_LOCK
procedure can be converted to use xdrgen-generated XDR
functions. This conversion allows the removal of
__nlm4svc_proc_lock(), a helper function that was previously
shared between the LOCK and NM_LOCK procedures.

Replace the NLMPROC4_NM_LOCK entry in the nlm_procedures4
array with an entry that uses xdrgen-built XDR decoders and
encoders. The procedure handler is updated to call
nlm4svc_do_lock() directly and access arguments through the
argp->xdrgen hierarchy.

The .pc_argzero field is set to zero because xdrgen decoders
fully initialize all fields in argp->xdrgen, making the early
defensive memset unnecessary. The remaining argp fields that
fall outside the xdrgen structures are cleared explicitly as
needed.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/lockd/svc4proc.c | 100 +++++++++++++++++++-------------------------
 1 file changed, 44 insertions(+), 56 deletions(-)

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index 316b4d623130..76d259658604 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -353,43 +353,6 @@ static __be32 nlm4svc_proc_test(struct svc_rqst *rqstp)
 		rpc_drop_reply : rpc_success;
 }
 
-static __be32
-__nlm4svc_proc_lock(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: LOCK          called\n");
-
-	resp->cookie = argp->cookie;
-
-	/* Obtain client and file */
-	if ((resp->status = nlm4svc_retrieve_args(rqstp, argp, &host, &file)))
-		return resp->status == nlm_drop_reply ? rpc_drop_reply :rpc_success;
-
-	/* Now try to lock the file */
-	resp->status = nlmsvc_lock(rqstp, file, host, &argp->lock,
-					argp->block, &argp->cookie,
-					argp->reclaim);
-	switch (resp->status) {
-	case nlm_drop_reply:
-		rc = rpc_drop_reply;
-		break;
-	case nlm__int__deadlock:
-		resp->status = nlm4_deadlock;
-		fallthrough;
-	default:
-		dprintk("lockd: LOCK         status %d\n", ntohl(resp->status));
-	}
-
-	nlmsvc_release_lockowner(&argp->lock);
-	nlmsvc_release_host(host);
-	nlm_release_file(file);
-	return rc;
-}
-
 static __be32
 nlm4svc_do_lock(struct svc_rqst *rqstp, bool monitored)
 {
@@ -1181,18 +1144,43 @@ static __be32 nlm4svc_proc_unshare(struct svc_rqst *rqstp)
 		rpc_drop_reply : rpc_success;
 }
 
-/*
- * NM_LOCK: Create an unmonitored lock
+/**
+ * nlm4svc_proc_nm_lock - NM_LOCK: Establish a non-monitored lock
+ * @rqstp: RPC transaction context
+ *
+ * Returns:
+ *   %rpc_success:		RPC executed successfully.
+ *   %rpc_drop_reply:		Do not send an RPC reply.
+ *
+ * RPC synopsis:
+ *   nlm4_res NLMPROC4_NM_LOCK(nlm4_lockargs) = 22;
+ *
+ * Permissible procedure status codes:
+ *   %NLM4_GRANTED:		The requested lock was granted.
+ *   %NLM4_DENIED:		The requested lock conflicted with existing
+ *				lock reservations for the file.
+ *   %NLM4_DENIED_NOLOCKS:	The server could not allocate the resources
+ *				needed to process the request.
+ *   %NLM4_BLOCKED:		The blocking request cannot be granted
+ *				immediately. The server will send an
+ *				NLMPROC4_GRANTED callback to the client when
+ *				the lock can be granted.
+ *   %NLM4_DENIED_GRACE_PERIOD:	The server has recently restarted and is
+ *				re-establishing existing locks, and is not
+ *				yet ready to accept normal service requests.
+ *
+ * The Linux NLM server implementation also returns:
+ *   %NLM4_DEADLCK:		The request could not be granted and
+ *				blocking would cause a deadlock.
+ *   %NLM4_STALE_FH:		The request specified an invalid file handle.
+ *   %NLM4_FBIG:		The request specified a length or offset
+ *				that exceeds the range supported by the
+ *				server.
+ *   %NLM4_FAILED:		The request failed for an unspecified reason.
  */
-static __be32
-nlm4svc_proc_nm_lock(struct svc_rqst *rqstp)
+static __be32 nlm4svc_proc_nm_lock(struct svc_rqst *rqstp)
 {
-	struct nlm_args *argp = rqstp->rq_argp;
-
-	dprintk("lockd: NM_LOCK       called\n");
-
-	argp->monitor = 0;		/* just clean the monitor flag */
-	return __nlm4svc_proc_lock(rqstp, rqstp->rq_resp);
+	return nlm4svc_do_lock(rqstp, false);
 }
 
 /*
@@ -1446,15 +1434,15 @@ static const struct svc_procedure nlm4svc_procedures[24] = {
 		.pc_xdrressize	= NLM4_nlm4_shareres_sz,
 		.pc_name	= "UNSHARE",
 	},
-	[NLMPROC_NM_LOCK] = {
-		.pc_func = nlm4svc_proc_nm_lock,
-		.pc_decode = nlm4svc_decode_lockargs,
-		.pc_encode = nlm4svc_encode_res,
-		.pc_argsize = sizeof(struct nlm_args),
-		.pc_argzero = sizeof(struct nlm_args),
-		.pc_ressize = sizeof(struct nlm_res),
-		.pc_xdrressize = Ck+St,
-		.pc_name = "NM_LOCK",
+	[NLMPROC4_NM_LOCK] = {
+		.pc_func	= nlm4svc_proc_nm_lock,
+		.pc_decode	= nlm4_svc_decode_nlm4_lockargs,
+		.pc_encode	= nlm4_svc_encode_nlm4_res,
+		.pc_argsize	= sizeof(struct nlm4_lockargs_wrapper),
+		.pc_argzero	= 0,
+		.pc_ressize	= sizeof(struct nlm4_res_wrapper),
+		.pc_xdrressize	= NLM4_nlm4_res_sz,
+		.pc_name	= "NM_LOCK",
 	},
 	[NLMPROC_FREE_ALL] = {
 		.pc_func = nlm4svc_proc_free_all,
-- 
2.52.0