[PATCH v1 05/13] NFSD: Use xdrgen XDR functions for the NFS-ACL v3 NULL procedure

[Chuck Lever <cel@kernel.org>]

Hand-written XDR encoders and decoders are difficult to maintain and
can diverge from protocol specifications. Migrating to xdrgen-generated
code improves type safety and ensures the implementation matches the
NFS_ACL version 3 protocol description exactly.

Convert the NULL procedure to xdrgen_svc_decode_void and
xdrgen_svc_encode_void. NULL has no arguments or results, so it is the
first procedure converted and needs only the generic void codecs, not
the generated NFS_ACLv3 header. GETACL and SETACL remain hand-rolled
until subsequent patches.

NULL returns no XDR-encoded data, so pc_xdrressize is set to XDR_void.
The argzero field is also set to zero since xdrgen decoders initialize
all decoded values.

Signed-off-by: Chuck Lever <cel@kernel.org>
---
 fs/nfsd/nfs3acl.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/fs/nfsd/nfs3acl.c b/fs/nfsd/nfs3acl.c
index 536593ba59bc..048046af15c0 100644
--- a/fs/nfsd/nfs3acl.c
+++ b/fs/nfsd/nfs3acl.c
@@ -110,11 +110,17 @@ static __be32 nfsd3_map_status(__be32 status)
 	return status;
 }
 
-/*
- * NULL call.
+/**
+ * nfsd3_proc_null - NULL: Do nothing
+ * @rqstp: RPC transaction context
+ *
+ * Return:
+ *   %rpc_success:		RPC executed successfully
+ *
+ * RPC synopsis:
+ *   void ACLPROC3_NULL(void) = 0;
  */
-static __be32
-nfsd3_proc_null(struct svc_rqst *rqstp)
+static __be32 nfsd3_proc_null(struct svc_rqst *rqstp)
 {
 	return rpc_success;
 }
@@ -342,13 +348,13 @@ static void nfs3svc_release_setacl(struct svc_rqst *rqstp)
 static const struct svc_procedure nfsd_acl_procedures3[3] = {
 	[ACLPROC3_NULL] = {
 		.pc_func = nfsd3_proc_null,
-		.pc_decode = nfssvc_decode_voidarg,
-		.pc_encode = nfssvc_encode_voidres,
-		.pc_argsize = sizeof(struct nfsd_voidargs),
-		.pc_argzero = sizeof(struct nfsd_voidargs),
-		.pc_ressize = sizeof(struct nfsd_voidres),
+		.pc_decode = xdrgen_svc_decode_void,
+		.pc_encode = xdrgen_svc_encode_void,
+		.pc_argsize = XDR_void,
+		.pc_argzero = 0,
+		.pc_ressize = 0,
 		.pc_cachetype = RC_NOCACHE,
-		.pc_xdrressize = ST,
+		.pc_xdrressize = XDR_void,
 		.pc_name = "NULL",
 	},
 	[ACLPROC3_GETACL] = {
-- 
2.56.0