[PATCH 4/9] NFSD: Encoder and decoder functions are always present

[Chuck Lever <chuck.lever@xxxxxxxxxx>]

nfsd_dispatch() is a hot path. Let's optimize the XDR method calls
for the by-far common case, which is that the methods are indeed
present.

Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 fs/nfsd/nfs2acl.c  |    6 ++++++
 fs/nfsd/nfs3acl.c  |    1 +
 fs/nfsd/nfs3proc.c |    1 +
 fs/nfsd/nfs3xdr.c  |    6 ++++++
 fs/nfsd/nfs4proc.c |    1 +
 fs/nfsd/nfs4xdr.c  |    6 ++++++
 fs/nfsd/nfssvc.c   |    5 ++---
 fs/nfsd/xdr3.h     |    1 +
 fs/nfsd/xdr4.h     |    1 +
 9 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfs2acl.c b/fs/nfsd/nfs2acl.c
index 8d20e0d74417..3c8b9250dc4a 100644
--- a/fs/nfsd/nfs2acl.c
+++ b/fs/nfsd/nfs2acl.c
@@ -183,6 +183,11 @@ static __be32 nfsacld_proc_access(struct svc_rqst *rqstp)
 /*
  * XDR decode functions
  */
+static int nfsaclsvc_decode_voidarg(struct svc_rqst *rqstp, __be32 *p)
+{
+	return 1;
+}
+
 static int nfsaclsvc_decode_getaclargs(struct svc_rqst *rqstp, __be32 *p)
 {
 	struct nfsd3_getaclargs *argp = rqstp->rq_argp;
@@ -357,6 +362,7 @@ struct nfsd3_voidargs { int dummy; };
 static const struct svc_procedure nfsd_acl_procedures2[5] = {
 	[ACLPROC2_NULL] = {
 		.pc_func = nfsacld_proc_null,
+		.pc_decode = nfsaclsvc_decode_voidarg,
 		.pc_encode = nfsaclsvc_encode_voidres,
 		.pc_argsize = sizeof(struct nfsd3_voidargs),
 		.pc_ressize = sizeof(struct nfsd3_voidargs),
diff --git a/fs/nfsd/nfs3acl.c b/fs/nfsd/nfs3acl.c
index 292acb2e529c..614168675c17 100644
--- a/fs/nfsd/nfs3acl.c
+++ b/fs/nfsd/nfs3acl.c
@@ -245,6 +245,7 @@ struct nfsd3_voidargs { int dummy; };
 static const struct svc_procedure nfsd_acl_procedures3[3] = {
 	[ACLPROC3_NULL] = {
 		.pc_func = nfsd3_proc_null,
+		.pc_decode = nfs3svc_decode_voidarg,
 		.pc_encode = nfs3svc_encode_voidres,
 		.pc_argsize = sizeof(struct nfsd3_voidargs),
 		.pc_ressize = sizeof(struct nfsd3_voidargs),
diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 288bc76b4574..3d09959c7042 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -716,6 +716,7 @@ struct nfsd3_voidargs { int dummy; };
 static const struct svc_procedure nfsd_procedures3[22] = {
 	[NFS3PROC_NULL] = {
 		.pc_func = nfsd3_proc_null,
+		.pc_decode = nfs3svc_decode_voidarg,
 		.pc_encode = nfs3svc_encode_voidres,
 		.pc_argsize = sizeof(struct nfsd3_voidargs),
 		.pc_ressize = sizeof(struct nfsd3_voidres),
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index aae514d40b64..e540fd1a29d8 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -304,6 +304,12 @@ void fill_post_wcc(struct svc_fh *fhp)
 /*
  * XDR decode functions
  */
+int
+nfs3svc_decode_voidarg(struct svc_rqst *rqstp, __be32 *p)
+{
+	return 1;
+}
+
 int
 nfs3svc_decode_fhandle(struct svc_rqst *rqstp, __be32 *p)
 {
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index eaf50eafa935..b99c050797db 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -3279,6 +3279,7 @@ struct nfsd4_voidargs { int dummy; };
 static const struct svc_procedure nfsd_procedures4[2] = {
 	[NFSPROC4_NULL] = {
 		.pc_func = nfsd4_proc_null,
+		.pc_decode = nfs4svc_decode_voidarg,
 		.pc_encode = nfs4svc_encode_voidres,
 		.pc_argsize = sizeof(struct nfsd4_voidargs),
 		.pc_ressize = sizeof(struct nfsd4_voidres),
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 259d5ad0e3f4..4449d9858bdc 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -5156,6 +5156,12 @@ void nfsd4_release_compoundargs(struct svc_rqst *rqstp)
 	}
 }
 
+int
+nfs4svc_decode_voidarg(struct svc_rqst *rqstp, __be32 *p)
+{
+	return 1;
+}
+
 int
 nfs4svc_decode_compoundargs(struct svc_rqst *rqstp, __be32 *p)
 {
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index f6bc94cab9da..b2d20920a998 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -1022,8 +1022,7 @@ nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
 	 */
 	rqstp->rq_cachetype = proc->pc_cachetype;
 	/* Decode arguments */
-	if (proc->pc_decode &&
-	    !proc->pc_decode(rqstp, (__be32*)rqstp->rq_arg.head[0].iov_base)) {
+	if (!proc->pc_decode(rqstp, (__be32 *)rqstp->rq_arg.head[0].iov_base)) {
 		dprintk("nfsd: failed to decode arguments!\n");
 		*statp = rpc_garbage_args;
 		return 1;
@@ -1062,7 +1061,7 @@ nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
 	 * For NFSv2, additional info is never returned in case of an error.
 	 */
 	if (!(nfserr && rqstp->rq_vers == 2)) {
-		if (proc->pc_encode && !proc->pc_encode(rqstp, nfserrp)) {
+		if (!proc->pc_encode(rqstp, nfserrp)) {
 			/* Failed to encode result. Release cache entry */
 			dprintk("nfsd: failed to encode result!\n");
 			nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
diff --git a/fs/nfsd/xdr3.h b/fs/nfsd/xdr3.h
index 4155fd71714c..ae6fa6c9cb46 100644
--- a/fs/nfsd/xdr3.h
+++ b/fs/nfsd/xdr3.h
@@ -273,6 +273,7 @@ union nfsd3_xdrstore {
 
 #define NFS3_SVC_XDRSIZE		sizeof(union nfsd3_xdrstore)
 
+int nfs3svc_decode_voidarg(struct svc_rqst *, __be32 *);
 int nfs3svc_decode_fhandle(struct svc_rqst *, __be32 *);
 int nfs3svc_decode_sattrargs(struct svc_rqst *, __be32 *);
 int nfs3svc_decode_diropargs(struct svc_rqst *, __be32 *);
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 66499fb6b567..679d40af1bbb 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -781,6 +781,7 @@ set_change_info(struct nfsd4_change_info *cinfo, struct svc_fh *fhp)
 
 
 bool nfsd4_mach_creds_match(struct nfs4_client *cl, struct svc_rqst *rqstp);
+int nfs4svc_decode_voidarg(struct svc_rqst *, __be32 *);
 int nfs4svc_encode_voidres(struct svc_rqst *, __be32 *);
 int nfs4svc_decode_compoundargs(struct svc_rqst *, __be32 *);
 int nfs4svc_encode_compoundres(struct svc_rqst *, __be32 *);