net: nfs: Use the tx buffer to construct rpc msgs

Instead of always allocating a huge temporary buffer on the stack and
then memcpy()ing the result into the transmit buffer, simply figure out
where in the transmit buffer the bytes will belong and write them there
directly as each message is built.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

net/nfs.c

@@ -183,41 +183,41 @@ static uint32_t *rpc_add_credentials(uint32_t *p)
 /**************************************************************************
 RPC_LOOKUP - Lookup RPC Port numbers
 **************************************************************************/
-static void rpc_req(int rpc_prog, int rpc_proc, uint32_t *data, int datalen)
+static struct rpc_t *rpc_req_prep(void)
+{
+	return (struct rpc_t *)(net_tx_packet + net_eth_hdr_size() +
+				IP_UDP_HDR_SIZE);
+}
+
+static void rpc_req(int rpc_prog, int rpc_proc, struct rpc_t *rpc_pkt,
+		    int datalen)
 {
-	struct rpc_t rpc_pkt;
 	unsigned long id;
-	uint32_t *p;
 	int pktlen;
 	int sport;
 
 	id = ++rpc_id;
-	rpc_pkt.u.call.id = htonl(id);
-	rpc_pkt.u.call.type = htonl(MSG_CALL);
-	rpc_pkt.u.call.rpcvers = htonl(2);	/* use RPC version 2 */
-	rpc_pkt.u.call.prog = htonl(rpc_prog);
+	rpc_pkt->u.call.id = htonl(id);
+	rpc_pkt->u.call.type = htonl(MSG_CALL);
+	rpc_pkt->u.call.rpcvers = htonl(2);	/* use RPC version 2 */
+	rpc_pkt->u.call.prog = htonl(rpc_prog);
 	switch (rpc_prog) {
 	case PROG_NFS:
 		if (supported_nfs_versions & NFSV2_FLAG)
-			rpc_pkt.u.call.vers = htonl(2);	/* NFS v2 */
+			rpc_pkt->u.call.vers = htonl(2);	/* NFS v2 */
 		else /* NFSV3_FLAG */
-			rpc_pkt.u.call.vers = htonl(3);	/* NFS v3 */
+			rpc_pkt->u.call.vers = htonl(3);	/* NFS v3 */
 		break;
 	case PROG_PORTMAP:
 	case PROG_MOUNT:
 	default:
-		rpc_pkt.u.call.vers = htonl(2);	/* portmapper is version 2 */
+		/* portmapper is version 2 */
+		rpc_pkt->u.call.vers = htonl(2);
 	}
-	rpc_pkt.u.call.proc = htonl(rpc_proc);
-	p = (uint32_t *)&(rpc_pkt.u.call.data);
-
-	if (datalen)
-		memcpy((char *)p, (char *)data, datalen*sizeof(uint32_t));
-
-	pktlen = (char *)p + datalen * sizeof(uint32_t) - (char *)&rpc_pkt;
+	rpc_pkt->u.call.proc = htonl(rpc_proc);
 
-	memcpy((char *)net_tx_packet + net_eth_hdr_size() + IP_UDP_HDR_SIZE,
-	       &rpc_pkt.u.data[0], pktlen);
+	pktlen = ((char *)&rpc_pkt->u.call.data - (char *)&rpc_pkt) +
+		datalen * sizeof(uint32_t);
 
 	if (rpc_prog == PROG_PORTMAP)
 		sport = SUNRPC_PORT;
@@ -235,15 +235,17 @@ RPC_LOOKUP - Lookup RPC Port numbers
 **************************************************************************/
 static void rpc_lookup_req(int prog, int ver)
 {
-	uint32_t data[16];
+	uint32_t *data;
+	struct rpc_t *rpc_pkt = rpc_req_prep();
 
+	data = rpc_pkt->u.call.data;
 	data[0] = 0; data[1] = 0;	/* auth credential */
 	data[2] = 0; data[3] = 0;	/* auth verifier */
 	data[4] = htonl(prog);
 	data[5] = htonl(ver);
 	data[6] = htonl(17);	/* IP_UDP */
 	data[7] = 0;
-	rpc_req(PROG_PORTMAP, PORTMAP_GETPORT, data, 8);
+	rpc_req(PROG_PORTMAP, PORTMAP_GETPORT, rpc_pkt, 8);
 }
 
 /**************************************************************************
@@ -251,14 +253,14 @@ NFS_MOUNT - Mount an NFS Filesystem
 **************************************************************************/
 static void nfs_mount_req(char *path)
 {
-	uint32_t data[1024];
 	uint32_t *p;
 	int len;
 	int pathlen;
+	struct rpc_t *rpc_pkt = rpc_req_prep();
 
 	pathlen = strlen(path);
 
-	p = &(data[0]);
+	p = rpc_pkt->u.call.data;
 	p = rpc_add_credentials(p);
 
 	*p++ = htonl(pathlen);
@@ -267,9 +269,9 @@ static void nfs_mount_req(char *path)
 	memcpy(p, path, pathlen);
 	p += (pathlen + 3) / 4;
 
-	len = (uint32_t *)p - (uint32_t *)&(data[0]);
+	len = (uint32_t *)p - (uint32_t *)&(rpc_pkt->u.call.data);
 
-	rpc_req(PROG_MOUNT, MOUNT_ADDENTRY, data, len);
+	rpc_req(PROG_MOUNT, MOUNT_ADDENTRY, rpc_pkt, len);
 }
 
 /**************************************************************************
@@ -277,20 +279,20 @@ NFS_UMOUNTALL - Unmount all our NFS Filesystems on the Server
 **************************************************************************/
 static void nfs_umountall_req(void)
 {
-	uint32_t data[1024];
 	uint32_t *p;
 	int len;
+	struct rpc_t *rpc_pkt = rpc_req_prep();
 
 	if ((nfs_server_mount_port == -1) || (!fs_mounted))
 		/* Nothing mounted, nothing to umount */
 		return;
 
-	p = &(data[0]);
+	p = rpc_pkt->u.call.data;
 	p = rpc_add_credentials(p);
 
-	len = (uint32_t *)p - (uint32_t *)&(data[0]);
+	len = (uint32_t *)p - (uint32_t *)&(rpc_pkt->u.call.data);
 
-	rpc_req(PROG_MOUNT, MOUNT_UMOUNTALL, data, len);
+	rpc_req(PROG_MOUNT, MOUNT_UMOUNTALL, rpc_pkt, len);
 }
 
 /***************************************************************************
@@ -302,11 +304,11 @@ static void nfs_umountall_req(void)
  **************************************************************************/
 static void nfs_readlink_req(void)
 {
-	uint32_t data[1024];
 	uint32_t *p;
 	int len;
+	struct rpc_t *rpc_pkt = rpc_req_prep();
 
-	p = &(data[0]);
+	p = rpc_pkt->u.call.data;
 	p = rpc_add_credentials(p);
 
 	if (supported_nfs_versions & NFSV2_FLAG) {
@@ -318,9 +320,9 @@ static void nfs_readlink_req(void)
 		p += (filefh3_length / 4);
 	}
 
-	len = (uint32_t *)p - (uint32_t *)&(data[0]);
+	len = (uint32_t *)p - (uint32_t *)&(rpc_pkt->u.call.data);
 
-	rpc_req(PROG_NFS, NFS_READLINK, data, len);
+	rpc_req(PROG_NFS, NFS_READLINK, rpc_pkt, len);
 }
 
 /**************************************************************************
@@ -328,14 +330,14 @@ NFS_LOOKUP - Lookup Pathname
 **************************************************************************/
 static void nfs_lookup_req(char *fname)
 {
-	uint32_t data[1024];
 	uint32_t *p;
 	int len;
 	int fnamelen;
+	struct rpc_t *rpc_pkt = rpc_req_prep();
 
 	fnamelen = strlen(fname);
 
-	p = &(data[0]);
+	p = rpc_pkt->u.call.data;
 	p = rpc_add_credentials(p);
 
 	if (supported_nfs_versions & NFSV2_FLAG) {
@@ -347,9 +349,9 @@ static void nfs_lookup_req(char *fname)
 		memcpy(p, fname, fnamelen);
 		p += (fnamelen + 3) / 4;
 
-		len = (uint32_t *)p - (uint32_t *)&(data[0]);
+		len = (uint32_t *)p - (uint32_t *)&(rpc_pkt->u.call.data);
 
-		rpc_req(PROG_NFS, NFS_LOOKUP, data, len);
+		rpc_req(PROG_NFS, NFS_LOOKUP, rpc_pkt, len);
 	} else {  /* NFSV3_FLAG */
 		*p++ = htonl(NFS_FHSIZE);	/* Dir handle length */
 		memcpy(p, dirfh, NFS_FHSIZE);
@@ -360,9 +362,9 @@ static void nfs_lookup_req(char *fname)
 		memcpy(p, fname, fnamelen);
 		p += (fnamelen + 3) / 4;
 
-		len = (uint32_t *)p - (uint32_t *)&(data[0]);
+		len = (uint32_t *)p - (uint32_t *)&(rpc_pkt->u.call.data);
 
-		rpc_req(PROG_NFS, NFS3PROC_LOOKUP, data, len);
+		rpc_req(PROG_NFS, NFS3PROC_LOOKUP, rpc_pkt, len);
 	}
 }
 
@@ -371,11 +373,11 @@ NFS_READ - Read File on NFS Server
 **************************************************************************/
 static void nfs_read_req(int offset, int readlen)
 {
-	uint32_t data[1024];
 	uint32_t *p;
 	int len;
+	struct rpc_t *rpc_pkt = rpc_req_prep();
 
-	p = &(data[0]);
+	p = rpc_pkt->u.call.data;
 	p = rpc_add_credentials(p);
 
 	if (supported_nfs_versions & NFSV2_FLAG) {
@@ -394,9 +396,9 @@ static void nfs_read_req(int offset, int readlen)
 		*p++ = 0;
 	}
 
-	len = (uint32_t *)p - (uint32_t *)&(data[0]);
+	len = (uint32_t *)p - (uint32_t *)&(rpc_pkt->u.call.data);
 
-	rpc_req(PROG_NFS, NFS_READ, data, len);
+	rpc_req(PROG_NFS, NFS_READ, rpc_pkt, len);
 }
 
 /**************************************************************************