/*
   * linux/net/sunrpc/svcsock.c
   *
   * These are the RPC server socket internals.
   *
   * The server scheduling algorithm does not always distribute the load
   * evenly when servicing a single client. May need to modify the

   * svc_xprt_enqueue procedure...

   *
   * TCP support is largely untested and may be a little slow. The problem
   * is that we currently do two separate recvfrom's, one for the 4-byte
   * record length, and the second for the actual record. This could possibly
   * be improved by always reading a minimum size of around 100 bytes and
   * tucking any superfluous bytes away in a temporary store. Still, that
   * leaves write requests out in the rain. An alternative may be to peek at
   * the first skb in the queue, and if it matches the next TCP sequence
   * number, to extract the record marker. Yuck.
   *
   * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   */

  #include <linux/kernel.h>

  #include <linux/sched.h>

  #include <linux/module.h>

  #include <linux/errno.h>
  #include <linux/fcntl.h>
  #include <linux/net.h>
  #include <linux/in.h>
  #include <linux/inet.h>
  #include <linux/udp.h>

  #include <linux/tcp.h>

  #include <linux/unistd.h>
  #include <linux/slab.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>

  #include <linux/file.h>

  #include <linux/freezer.h>

  #include <net/sock.h>
  #include <net/checksum.h>
  #include <net/ip.h>

  #include <net/ipv6.h>

  #include <net/tcp.h>

  #include <net/tcp_states.h>

  #include <asm/uaccess.h>
  #include <asm/ioctls.h>
  
  #include <linux/sunrpc/types.h>

  #include <linux/sunrpc/clnt.h>

  #include <linux/sunrpc/xdr.h>

  #include <linux/sunrpc/msg_prot.h>

  #include <linux/sunrpc/svcsock.h>
  #include <linux/sunrpc/stats.h>

  #include <linux/sunrpc/xprt.h>

  #include "sunrpc.h"

  #define RPCDBG_FACILITY	RPCDBG_SVCXPRT

  
  
  static struct svc_sock *svc_setup_socket(struct svc_serv *, struct socket *,

  					 int *errp, int flags);

  static void		svc_udp_data_ready(struct sock *, int);
  static int		svc_udp_recvfrom(struct svc_rqst *);
  static int		svc_udp_sendto(struct svc_rqst *);

  static void		svc_sock_detach(struct svc_xprt *);

  static void		svc_tcp_sock_detach(struct svc_xprt *);

  static void		svc_sock_free(struct svc_xprt *);

  static struct svc_xprt *svc_create_socket(struct svc_serv *, int,

  					  struct net *, struct sockaddr *,
  					  int, int);

  #if defined(CONFIG_SUNRPC_BACKCHANNEL)

  static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int,
  					     struct net *, struct sockaddr *,
  					     int, int);
  static void svc_bc_sock_free(struct svc_xprt *xprt);

  #endif /* CONFIG_SUNRPC_BACKCHANNEL */

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  static struct lock_class_key svc_key[2];
  static struct lock_class_key svc_slock_key[2];

  static void svc_reclassify_socket(struct socket *sock)

  {
  	struct sock *sk = sock->sk;

  	BUG_ON(sock_owned_by_user(sk));

  	switch (sk->sk_family) {
  	case AF_INET:
  		sock_lock_init_class_and_name(sk, "slock-AF_INET-NFSD",

  					      &svc_slock_key[0],
  					      "sk_xprt.xpt_lock-AF_INET-NFSD",
  					      &svc_key[0]);

  		break;
  
  	case AF_INET6:
  		sock_lock_init_class_and_name(sk, "slock-AF_INET6-NFSD",

  					      &svc_slock_key[1],
  					      "sk_xprt.xpt_lock-AF_INET6-NFSD",
  					      &svc_key[1]);

  		break;
  
  	default:
  		BUG();
  	}
  }
  #else

  static void svc_reclassify_socket(struct socket *sock)

  {
  }
  #endif

  /*
   * Release an skbuff after use
   */

  static void svc_release_skb(struct svc_rqst *rqstp)

  {

  	struct sk_buff *skb = rqstp->rq_xprt_ctxt;

  
  	if (skb) {

  		struct svc_sock *svsk =
  			container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);

  		rqstp->rq_xprt_ctxt = NULL;

  
  		dprintk("svc: service %p, releasing skb %p
  ", rqstp, skb);

  		skb_free_datagram_locked(svsk->sk_sk, skb);

  	}

  }

  union svc_pktinfo_u {
  	struct in_pktinfo pkti;

  	struct in6_pktinfo pkti6;

  };

  #define SVC_PKTINFO_SPACE \
  	CMSG_SPACE(sizeof(union svc_pktinfo_u))

  
  static void svc_set_cmsg_data(struct svc_rqst *rqstp, struct cmsghdr *cmh)
  {

  	struct svc_sock *svsk =
  		container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
  	switch (svsk->sk_sk->sk_family) {

  	case AF_INET: {
  			struct in_pktinfo *pki = CMSG_DATA(cmh);
  
  			cmh->cmsg_level = SOL_IP;
  			cmh->cmsg_type = IP_PKTINFO;
  			pki->ipi_ifindex = 0;

  			pki->ipi_spec_dst.s_addr =
  				 svc_daddr_in(rqstp)->sin_addr.s_addr;

  			cmh->cmsg_len = CMSG_LEN(sizeof(*pki));
  		}
  		break;

  	case AF_INET6: {
  			struct in6_pktinfo *pki = CMSG_DATA(cmh);

  			struct sockaddr_in6 *daddr = svc_daddr_in6(rqstp);

  
  			cmh->cmsg_level = SOL_IPV6;
  			cmh->cmsg_type = IPV6_PKTINFO;

  			pki->ipi6_ifindex = daddr->sin6_scope_id;
  			ipv6_addr_copy(&pki->ipi6_addr,	&daddr->sin6_addr);

  			cmh->cmsg_len = CMSG_LEN(sizeof(*pki));
  		}
  		break;

  	}

  }

  /*

   * send routine intended to be shared by the fore- and back-channel

   */

  int svc_send_common(struct socket *sock, struct xdr_buf *xdr,
  		    struct page *headpage, unsigned long headoffset,
  		    struct page *tailpage, unsigned long tailoffset)

  {

  	int		result;
  	int		size;
  	struct page	**ppage = xdr->pages;
  	size_t		base = xdr->page_base;
  	unsigned int	pglen = xdr->page_len;
  	unsigned int	flags = MSG_MORE;

  	int		slen;
  	int		len = 0;

  
  	slen = xdr->len;

  	/* send head */
  	if (slen == xdr->head[0].iov_len)
  		flags = 0;

  	len = kernel_sendpage(sock, headpage, headoffset,

  				  xdr->head[0].iov_len, flags);

  	if (len != xdr->head[0].iov_len)
  		goto out;
  	slen -= xdr->head[0].iov_len;
  	if (slen == 0)
  		goto out;
  
  	/* send page data */
  	size = PAGE_SIZE - base < pglen ? PAGE_SIZE - base : pglen;
  	while (pglen > 0) {
  		if (slen == size)
  			flags = 0;

  		result = kernel_sendpage(sock, *ppage, base, size, flags);

  		if (result > 0)
  			len += result;
  		if (result != size)
  			goto out;
  		slen -= size;
  		pglen -= size;
  		size = PAGE_SIZE < pglen ? PAGE_SIZE : pglen;
  		base = 0;
  		ppage++;
  	}

  	/* send tail */
  	if (xdr->tail[0].iov_len) {

  		result = kernel_sendpage(sock, tailpage, tailoffset,
  				   xdr->tail[0].iov_len, 0);

  		if (result > 0)
  			len += result;
  	}

  
  out:
  	return len;
  }
  
  
  /*
   * Generic sendto routine
   */
  static int svc_sendto(struct svc_rqst *rqstp, struct xdr_buf *xdr)
  {
  	struct svc_sock	*svsk =
  		container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
  	struct socket	*sock = svsk->sk_sock;
  	union {
  		struct cmsghdr	hdr;
  		long		all[SVC_PKTINFO_SPACE / sizeof(long)];
  	} buffer;
  	struct cmsghdr *cmh = &buffer.hdr;
  	int		len = 0;
  	unsigned long tailoff;
  	unsigned long headoff;
  	RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
  
  	if (rqstp->rq_prot == IPPROTO_UDP) {
  		struct msghdr msg = {
  			.msg_name	= &rqstp->rq_addr,
  			.msg_namelen	= rqstp->rq_addrlen,
  			.msg_control	= cmh,
  			.msg_controllen	= sizeof(buffer),
  			.msg_flags	= MSG_MORE,
  		};
  
  		svc_set_cmsg_data(rqstp, cmh);
  
  		if (sock_sendmsg(sock, &msg, 0) < 0)
  			goto out;
  	}
  
  	tailoff = ((unsigned long)xdr->tail[0].iov_base) & (PAGE_SIZE-1);
  	headoff = 0;
  	len = svc_send_common(sock, xdr, rqstp->rq_respages[0], headoff,
  			       rqstp->rq_respages[0], tailoff);

  out:

  	dprintk("svc: socket %p sendto([%p %Zu... ], %d) = %d (addr %s)
  ",

  		svsk, xdr->head[0].iov_base, xdr->head[0].iov_len,

  		xdr->len, len, svc_print_addr(rqstp, buf, sizeof(buf)));

  
  	return len;
  }
  
  /*

   * Report socket names for nfsdfs
   */

  static int svc_one_sock_name(struct svc_sock *svsk, char *buf, int remaining)

  {

  	const struct sock *sk = svsk->sk_sk;
  	const char *proto_name = sk->sk_protocol == IPPROTO_UDP ?
  							"udp" : "tcp";

  	int len;

  	switch (sk->sk_family) {

  	case PF_INET:
  		len = snprintf(buf, remaining, "ipv4 %s %pI4 %d
  ",

  				proto_name,

  				&inet_sk(sk)->inet_rcv_saddr,
  				inet_sk(sk)->inet_num);

  		break;

  	case PF_INET6:
  		len = snprintf(buf, remaining, "ipv6 %s %pI6 %d
  ",

  				proto_name,
  				&inet6_sk(sk)->rcv_saddr,

  				inet_sk(sk)->inet_num);

  		break;
  	default:

  		len = snprintf(buf, remaining, "*unknown-%d*
  ",

  				sk->sk_family);

  	}

  
  	if (len >= remaining) {
  		*buf = '\0';
  		return -ENAMETOOLONG;

  	}
  	return len;
  }

  /**
   * svc_sock_names - construct a list of listener names in a string
   * @serv: pointer to RPC service
   * @buf: pointer to a buffer to fill in with socket names
   * @buflen: size of the buffer to be filled
   * @toclose: pointer to '\0'-terminated C string containing the name
   *		of a listener to be closed
   *
   * Fills in @buf with a '
  '-separated list of names of listener
   * sockets.  If @toclose is not NULL, the socket named by @toclose
   * is closed, and is not included in the output list.
   *
   * Returns positive length of the socket name string, or a negative
   * errno value on error.
   */
  int svc_sock_names(struct svc_serv *serv, char *buf, const size_t buflen,
  		   const char *toclose)

  {

  	struct svc_sock *svsk, *closesk = NULL;

  	int len = 0;
  
  	if (!serv)
  		return 0;

  	spin_lock_bh(&serv->sv_lock);

  	list_for_each_entry(svsk, &serv->sv_permsocks, sk_xprt.xpt_list) {

  		int onelen = svc_one_sock_name(svsk, buf + len, buflen - len);
  		if (onelen < 0) {
  			len = onelen;
  			break;
  		}

  		if (toclose && strcmp(toclose, buf + len) == 0) {

  			closesk = svsk;

  			svc_xprt_get(&closesk->sk_xprt);
  		} else

  			len += onelen;

  	}

  	spin_unlock_bh(&serv->sv_lock);

  	if (closesk) {

  		/* Should unregister with portmap, but you cannot
  		 * unregister just one protocol...
  		 */

  		svc_close_xprt(&closesk->sk_xprt);

  		svc_xprt_put(&closesk->sk_xprt);
  	} else if (toclose)

  		return -ENOENT;

  	return len;
  }

  EXPORT_SYMBOL_GPL(svc_sock_names);

  
  /*

   * Check input queue length
   */

  static int svc_recv_available(struct svc_sock *svsk)

  {

  	struct socket	*sock = svsk->sk_sock;
  	int		avail, err;

  	err = kernel_sock_ioctl(sock, TIOCINQ, (unsigned long) &avail);

  
  	return (err >= 0)? avail : err;
  }
  
  /*
   * Generic recvfrom routine.
   */

  static int svc_recvfrom(struct svc_rqst *rqstp, struct kvec *iov, int nr,
  			int buflen)

  {

  	struct svc_sock *svsk =
  		container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);

  	struct msghdr msg = {
  		.msg_flags	= MSG_DONTWAIT,
  	};
  	int len;

  	rqstp->rq_xprt_hlen = 0;

  	len = kernel_recvmsg(svsk->sk_sock, &msg, iov, nr, buflen,
  				msg.msg_flags);

  	dprintk("svc: socket %p recvfrom(%p, %Zu) = %d
  ",

  		svsk, iov[0].iov_base, iov[0].iov_len, len);

  	return len;
  }

  static int svc_partial_recvfrom(struct svc_rqst *rqstp,
  				struct kvec *iov, int nr,
  				int buflen, unsigned int base)
  {
  	size_t save_iovlen;
  	void __user *save_iovbase;
  	unsigned int i;
  	int ret;
  
  	if (base == 0)
  		return svc_recvfrom(rqstp, iov, nr, buflen);
  
  	for (i = 0; i < nr; i++) {
  		if (iov[i].iov_len > base)
  			break;
  		base -= iov[i].iov_len;
  	}
  	save_iovlen = iov[i].iov_len;
  	save_iovbase = iov[i].iov_base;
  	iov[i].iov_len -= base;
  	iov[i].iov_base += base;
  	ret = svc_recvfrom(rqstp, &iov[i], nr - i, buflen);
  	iov[i].iov_len = save_iovlen;
  	iov[i].iov_base = save_iovbase;
  	return ret;
  }

  /*
   * Set socket snd and rcv buffer lengths
   */

  static void svc_sock_setbufsize(struct socket *sock, unsigned int snd,
  				unsigned int rcv)

  {
  #if 0
  	mm_segment_t	oldfs;
  	oldfs = get_fs(); set_fs(KERNEL_DS);
  	sock_setsockopt(sock, SOL_SOCKET, SO_SNDBUF,
  			(char*)&snd, sizeof(snd));
  	sock_setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
  			(char*)&rcv, sizeof(rcv));
  #else
  	/* sock_setsockopt limits use to sysctl_?mem_max,
  	 * which isn't acceptable.  Until that is made conditional
  	 * on not having CAP_SYS_RESOURCE or similar, we go direct...
  	 * DaveM said I could!
  	 */
  	lock_sock(sock->sk);
  	sock->sk->sk_sndbuf = snd * 2;
  	sock->sk->sk_rcvbuf = rcv * 2;

  	sock->sk->sk_write_space(sock->sk);

  	release_sock(sock->sk);
  #endif
  }
  /*
   * INET callback when data has been received on the socket.
   */

  static void svc_udp_data_ready(struct sock *sk, int count)

  {

  	struct svc_sock	*svsk = (struct svc_sock *)sk->sk_user_data;

  	wait_queue_head_t *wq = sk_sleep(sk);

  	if (svsk) {
  		dprintk("svc: socket %p(inet %p), count=%d, busy=%d
  ",

  			svsk, sk, count,
  			test_bit(XPT_BUSY, &svsk->sk_xprt.xpt_flags));
  		set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

  		svc_xprt_enqueue(&svsk->sk_xprt);

  	}

  	if (wq && waitqueue_active(wq))
  		wake_up_interruptible(wq);

  }
  
  /*
   * INET callback when space is newly available on the socket.
   */

  static void svc_write_space(struct sock *sk)

  {
  	struct svc_sock	*svsk = (struct svc_sock *)(sk->sk_user_data);

  	wait_queue_head_t *wq = sk_sleep(sk);

  
  	if (svsk) {
  		dprintk("svc: socket %p(inet %p), write_space busy=%d
  ",

  			svsk, sk, test_bit(XPT_BUSY, &svsk->sk_xprt.xpt_flags));

  		svc_xprt_enqueue(&svsk->sk_xprt);

  	}

  	if (wq && waitqueue_active(wq)) {

  		dprintk("RPC svc_write_space: someone sleeping on %p
  ",

  		       svsk);

  		wake_up_interruptible(wq);

  	}
  }

  static void svc_tcp_write_space(struct sock *sk)
  {
  	struct socket *sock = sk->sk_socket;
  
  	if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock)
  		clear_bit(SOCK_NOSPACE, &sock->flags);
  	svc_write_space(sk);
  }

  /*

   * See net/ipv6/ip_sockglue.c : ip_cmsg_recv_pktinfo
   */
  static int svc_udp_get_dest_address4(struct svc_rqst *rqstp,
  				     struct cmsghdr *cmh)
  {
  	struct in_pktinfo *pki = CMSG_DATA(cmh);

  	struct sockaddr_in *daddr = svc_daddr_in(rqstp);

  	if (cmh->cmsg_type != IP_PKTINFO)
  		return 0;

  
  	daddr->sin_family = AF_INET;
  	daddr->sin_addr.s_addr = pki->ipi_spec_dst.s_addr;

  	return 1;
  }
  
  /*
   * See net/ipv6/datagram.c : datagram_recv_ctl
   */
  static int svc_udp_get_dest_address6(struct svc_rqst *rqstp,
  				     struct cmsghdr *cmh)
  {
  	struct in6_pktinfo *pki = CMSG_DATA(cmh);

  	struct sockaddr_in6 *daddr = svc_daddr_in6(rqstp);

  	if (cmh->cmsg_type != IPV6_PKTINFO)
  		return 0;

  
  	daddr->sin6_family = AF_INET6;
  	ipv6_addr_copy(&daddr->sin6_addr, &pki->ipi6_addr);
  	daddr->sin6_scope_id = pki->ipi6_ifindex;

  	return 1;
  }
  
  /*

   * Copy the UDP datagram's destination address to the rqstp structure.
   * The 'destination' address in this case is the address to which the
   * peer sent the datagram, i.e. our local address. For multihomed
   * hosts, this can change from msg to msg. Note that only the IP
   * address changes, the port number should remain the same.
   */

  static int svc_udp_get_dest_address(struct svc_rqst *rqstp,
  				    struct cmsghdr *cmh)

  {

  	switch (cmh->cmsg_level) {
  	case SOL_IP:
  		return svc_udp_get_dest_address4(rqstp, cmh);
  	case SOL_IPV6:
  		return svc_udp_get_dest_address6(rqstp, cmh);

  	}

  
  	return 0;

  }

  /*
   * Receive a datagram from a UDP socket.
   */

  static int svc_udp_recvfrom(struct svc_rqst *rqstp)

  {

  	struct svc_sock	*svsk =
  		container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);

  	struct svc_serv	*serv = svsk->sk_xprt.xpt_server;

  	struct sk_buff	*skb;

  	union {
  		struct cmsghdr	hdr;
  		long		all[SVC_PKTINFO_SPACE / sizeof(long)];
  	} buffer;
  	struct cmsghdr *cmh = &buffer.hdr;

  	struct msghdr msg = {
  		.msg_name = svc_addr(rqstp),
  		.msg_control = cmh,
  		.msg_controllen = sizeof(buffer),
  		.msg_flags = MSG_DONTWAIT,
  	};

  	size_t len;
  	int err;

  	if (test_and_clear_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags))

  	    /* udp sockets need large rcvbuf as all pending
  	     * requests are still in that buffer.  sndbuf must
  	     * also be large enough that there is enough space

  	     * for one reply per thread.  We count all threads
  	     * rather than threads in a particular pool, which
  	     * provides an upper bound on the number of threads
  	     * which will access the socket.

  	     */
  	    svc_sock_setbufsize(svsk->sk_sock,

  				(serv->sv_nrthreads+3) * serv->sv_max_mesg,
  				(serv->sv_nrthreads+3) * serv->sv_max_mesg);

  	clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

  	skb = NULL;
  	err = kernel_recvmsg(svsk->sk_sock, &msg, NULL,
  			     0, 0, MSG_PEEK | MSG_DONTWAIT);
  	if (err >= 0)
  		skb = skb_recv_datagram(svsk->sk_sk, 0, 1, &err);
  
  	if (skb == NULL) {
  		if (err != -EAGAIN) {
  			/* possibly an icmp error */
  			dprintk("svc: recvfrom returned error %d
  ", -err);

  			set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

  		}

  		return -EAGAIN;

  	}

  	len = svc_addr_len(svc_addr(rqstp));

  	if (len == 0)
  		return -EAFNOSUPPORT;

  	rqstp->rq_addrlen = len;

  	if (skb->tstamp.tv64 == 0) {
  		skb->tstamp = ktime_get_real();

  		/* Don't enable netstamp, sunrpc doesn't

  		   need that much accuracy */
  	}

  	svsk->sk_sk->sk_stamp = skb->tstamp;

  	set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags); /* there may be more data... */

  	len  = skb->len - sizeof(struct udphdr);
  	rqstp->rq_arg.len = len;

  	rqstp->rq_prot = IPPROTO_UDP;

  	if (!svc_udp_get_dest_address(rqstp, cmh)) {

  		if (net_ratelimit())

  			printk(KERN_WARNING
  				"svc: received unknown control message %d/%d; "
  				"dropping RPC reply datagram
  ",
  					cmh->cmsg_level, cmh->cmsg_type);

  		skb_free_datagram_locked(svsk->sk_sk, skb);

  		return 0;
  	}

  	rqstp->rq_daddrlen = svc_addr_len(svc_daddr(rqstp));

  
  	if (skb_is_nonlinear(skb)) {
  		/* we have to copy */
  		local_bh_disable();
  		if (csum_partial_copy_to_xdr(&rqstp->rq_arg, skb)) {
  			local_bh_enable();
  			/* checksum error */

  			skb_free_datagram_locked(svsk->sk_sk, skb);

  			return 0;
  		}
  		local_bh_enable();

  		skb_free_datagram_locked(svsk->sk_sk, skb);

  	} else {
  		/* we can use it in-place */

  		rqstp->rq_arg.head[0].iov_base = skb->data +
  			sizeof(struct udphdr);

  		rqstp->rq_arg.head[0].iov_len = len;

  		if (skb_checksum_complete(skb)) {

  			skb_free_datagram_locked(svsk->sk_sk, skb);

  			return 0;

  		}

  		rqstp->rq_xprt_ctxt = skb;

  	}
  
  	rqstp->rq_arg.page_base = 0;
  	if (len <= rqstp->rq_arg.head[0].iov_len) {
  		rqstp->rq_arg.head[0].iov_len = len;
  		rqstp->rq_arg.page_len = 0;

  		rqstp->rq_respages = rqstp->rq_pages+1;

  	} else {
  		rqstp->rq_arg.page_len = len - rqstp->rq_arg.head[0].iov_len;

  		rqstp->rq_respages = rqstp->rq_pages + 1 +

  			DIV_ROUND_UP(rqstp->rq_arg.page_len, PAGE_SIZE);

  	}
  
  	if (serv->sv_stats)
  		serv->sv_stats->netudpcnt++;
  
  	return len;
  }
  
  static int
  svc_udp_sendto(struct svc_rqst *rqstp)
  {
  	int		error;
  
  	error = svc_sendto(rqstp, &rqstp->rq_res);
  	if (error == -ECONNREFUSED)
  		/* ICMP error on earlier request. */
  		error = svc_sendto(rqstp, &rqstp->rq_res);
  
  	return error;
  }

  static void svc_udp_prep_reply_hdr(struct svc_rqst *rqstp)
  {
  }

  static int svc_udp_has_wspace(struct svc_xprt *xprt)
  {
  	struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);

  	struct svc_serv	*serv = xprt->xpt_server;

  	unsigned long required;
  
  	/*
  	 * Set the SOCK_NOSPACE flag before checking the available
  	 * sock space.
  	 */
  	set_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);

  	required = atomic_read(&svsk->sk_xprt.xpt_reserved) + serv->sv_max_mesg;

  	if (required*2 > sock_wspace(svsk->sk_sk))
  		return 0;
  	clear_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);
  	return 1;
  }

  static struct svc_xprt *svc_udp_accept(struct svc_xprt *xprt)
  {
  	BUG();
  	return NULL;
  }

  static struct svc_xprt *svc_udp_create(struct svc_serv *serv,

  				       struct net *net,

  				       struct sockaddr *sa, int salen,
  				       int flags)
  {

  	return svc_create_socket(serv, IPPROTO_UDP, net, sa, salen, flags);

  }

  static struct svc_xprt_ops svc_udp_ops = {

  	.xpo_create = svc_udp_create,

  	.xpo_recvfrom = svc_udp_recvfrom,
  	.xpo_sendto = svc_udp_sendto,

  	.xpo_release_rqst = svc_release_skb,

  	.xpo_detach = svc_sock_detach,
  	.xpo_free = svc_sock_free,

  	.xpo_prep_reply_hdr = svc_udp_prep_reply_hdr,

  	.xpo_has_wspace = svc_udp_has_wspace,

  	.xpo_accept = svc_udp_accept,

  };
  
  static struct svc_xprt_class svc_udp_class = {
  	.xcl_name = "udp",

  	.xcl_owner = THIS_MODULE,

  	.xcl_ops = &svc_udp_ops,

  	.xcl_max_payload = RPCSVC_MAXPAYLOAD_UDP,

  };

  static void svc_udp_init(struct svc_sock *svsk, struct svc_serv *serv)

  {

  	int err, level, optname, one = 1;

  	svc_xprt_init(&svc_udp_class, &svsk->sk_xprt, serv);

  	clear_bit(XPT_CACHE_AUTH, &svsk->sk_xprt.xpt_flags);

  	svsk->sk_sk->sk_data_ready = svc_udp_data_ready;
  	svsk->sk_sk->sk_write_space = svc_write_space;

  
  	/* initialise setting must have enough space to

  	 * receive and respond to one request.

  	 * svc_udp_recvfrom will re-adjust if necessary
  	 */
  	svc_sock_setbufsize(svsk->sk_sock,

  			    3 * svsk->sk_xprt.xpt_server->sv_max_mesg,
  			    3 * svsk->sk_xprt.xpt_server->sv_max_mesg);

  	/* data might have come in before data_ready set up */
  	set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

  	set_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags);

  	/* make sure we get destination address info */

  	switch (svsk->sk_sk->sk_family) {
  	case AF_INET:
  		level = SOL_IP;
  		optname = IP_PKTINFO;
  		break;
  	case AF_INET6:
  		level = SOL_IPV6;
  		optname = IPV6_RECVPKTINFO;
  		break;
  	default:
  		BUG();
  	}
  	err = kernel_setsockopt(svsk->sk_sock, level, optname,
  					(char *)&one, sizeof(one));
  	dprintk("svc: kernel_setsockopt returned %d
  ", err);

  }
  
  /*
   * A data_ready event on a listening socket means there's a connection
   * pending. Do not use state_change as a substitute for it.
   */

  static void svc_tcp_listen_data_ready(struct sock *sk, int count_unused)

  {

  	struct svc_sock	*svsk = (struct svc_sock *)sk->sk_user_data;

  	wait_queue_head_t *wq;

  
  	dprintk("svc: socket %p TCP (listen) state change %d
  ",

  		sk, sk->sk_state);

  	/*
  	 * This callback may called twice when a new connection
  	 * is established as a child socket inherits everything
  	 * from a parent LISTEN socket.
  	 * 1) data_ready method of the parent socket will be called
  	 *    when one of child sockets become ESTABLISHED.
  	 * 2) data_ready method of the child socket may be called
  	 *    when it receives data before the socket is accepted.
  	 * In case of 2, we should ignore it silently.
  	 */
  	if (sk->sk_state == TCP_LISTEN) {
  		if (svsk) {

  			set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);

  			svc_xprt_enqueue(&svsk->sk_xprt);

  		} else
  			printk("svc: socket %p: no user data
  ", sk);

  	}

  	wq = sk_sleep(sk);
  	if (wq && waitqueue_active(wq))
  		wake_up_interruptible_all(wq);

  }
  
  /*
   * A state change on a connected socket means it's dying or dead.
   */

  static void svc_tcp_state_change(struct sock *sk)

  {

  	struct svc_sock	*svsk = (struct svc_sock *)sk->sk_user_data;

  	wait_queue_head_t *wq = sk_sleep(sk);

  
  	dprintk("svc: socket %p TCP (connected) state change %d (svsk %p)
  ",

  		sk, sk->sk_state, sk->sk_user_data);

  	if (!svsk)

  		printk("svc: socket %p: no user data
  ", sk);

  	else {

  		set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);

  		svc_xprt_enqueue(&svsk->sk_xprt);

  	}

  	if (wq && waitqueue_active(wq))
  		wake_up_interruptible_all(wq);

  }

  static void svc_tcp_data_ready(struct sock *sk, int count)

  {

  	struct svc_sock *svsk = (struct svc_sock *)sk->sk_user_data;

  	wait_queue_head_t *wq = sk_sleep(sk);

  
  	dprintk("svc: socket %p TCP data ready (svsk %p)
  ",

  		sk, sk->sk_user_data);
  	if (svsk) {

  		set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

  		svc_xprt_enqueue(&svsk->sk_xprt);

  	}

  	if (wq && waitqueue_active(wq))
  		wake_up_interruptible(wq);

  }
  
  /*
   * Accept a TCP connection
   */

  static struct svc_xprt *svc_tcp_accept(struct svc_xprt *xprt)

  {

  	struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);

  	struct sockaddr_storage addr;
  	struct sockaddr	*sin = (struct sockaddr *) &addr;

  	struct svc_serv	*serv = svsk->sk_xprt.xpt_server;

  	struct socket	*sock = svsk->sk_sock;
  	struct socket	*newsock;

  	struct svc_sock	*newsvsk;
  	int		err, slen;

  	RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);

  
  	dprintk("svc: tcp_accept %p sock %p
  ", svsk, sock);
  	if (!sock)

  		return NULL;

  	clear_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);

  	err = kernel_accept(sock, &newsock, O_NONBLOCK);
  	if (err < 0) {

  		if (err == -ENOMEM)
  			printk(KERN_WARNING "%s: no more sockets!
  ",
  			       serv->sv_name);

  		else if (err != -EAGAIN && net_ratelimit())

  			printk(KERN_WARNING "%s: accept failed (err %d)!
  ",
  				   serv->sv_name, -err);

  		return NULL;

  	}

  	set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);

  	err = kernel_getpeername(newsock, sin, &slen);

  	if (err < 0) {
  		if (net_ratelimit())
  			printk(KERN_WARNING "%s: peername failed (err %d)!
  ",
  				   serv->sv_name, -err);
  		goto failed;		/* aborted connection or whatever */
  	}
  
  	/* Ideally, we would want to reject connections from unauthorized

  	 * hosts here, but when we get encryption, the IP of the host won't
  	 * tell us anything.  For now just warn about unpriv connections.

  	 */

  	if (!svc_port_is_privileged(sin)) {

  		dprintk(KERN_WARNING

  			"%s: connect from unprivileged port: %s
  ",

  			serv->sv_name,

  			__svc_print_addr(sin, buf, sizeof(buf)));

  	}

  	dprintk("%s: connect from %s
  ", serv->sv_name,

  		__svc_print_addr(sin, buf, sizeof(buf)));

  
  	/* make sure that a write doesn't block forever when
  	 * low on memory
  	 */
  	newsock->sk->sk_sndtimeo = HZ*30;

  	if (!(newsvsk = svc_setup_socket(serv, newsock, &err,
  				 (SVC_SOCK_ANONYMOUS | SVC_SOCK_TEMPORARY))))

  		goto failed;

  	svc_xprt_set_remote(&newsvsk->sk_xprt, sin, slen);

  	err = kernel_getsockname(newsock, sin, &slen);
  	if (unlikely(err < 0)) {
  		dprintk("svc_tcp_accept: kernel_getsockname error %d
  ", -err);
  		slen = offsetof(struct sockaddr, sa_data);
  	}

  	svc_xprt_set_local(&newsvsk->sk_xprt, sin, slen);

  	if (serv->sv_stats)
  		serv->sv_stats->nettcpconn++;
  
  	return &newsvsk->sk_xprt;
  
  failed:
  	sock_release(newsock);
  	return NULL;
  }

  static unsigned int svc_tcp_restore_pages(struct svc_sock *svsk, struct svc_rqst *rqstp)
  {
  	unsigned int i, len, npages;
  
  	if (svsk->sk_tcplen <= sizeof(rpc_fraghdr))
  		return 0;
  	len = svsk->sk_tcplen - sizeof(rpc_fraghdr);
  	npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
  	for (i = 0; i < npages; i++) {
  		if (rqstp->rq_pages[i] != NULL)
  			put_page(rqstp->rq_pages[i]);
  		BUG_ON(svsk->sk_pages[i] == NULL);
  		rqstp->rq_pages[i] = svsk->sk_pages[i];
  		svsk->sk_pages[i] = NULL;
  	}
  	rqstp->rq_arg.head[0].iov_base = page_address(rqstp->rq_pages[0]);
  	return len;
  }
  
  static void svc_tcp_save_pages(struct svc_sock *svsk, struct svc_rqst *rqstp)
  {
  	unsigned int i, len, npages;
  
  	if (svsk->sk_tcplen <= sizeof(rpc_fraghdr))
  		return;
  	len = svsk->sk_tcplen - sizeof(rpc_fraghdr);
  	npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
  	for (i = 0; i < npages; i++) {
  		svsk->sk_pages[i] = rqstp->rq_pages[i];
  		rqstp->rq_pages[i] = NULL;
  	}
  }
  
  static void svc_tcp_clear_pages(struct svc_sock *svsk)
  {
  	unsigned int i, len, npages;
  
  	if (svsk->sk_tcplen <= sizeof(rpc_fraghdr))
  		goto out;
  	len = svsk->sk_tcplen - sizeof(rpc_fraghdr);
  	npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
  	for (i = 0; i < npages; i++) {
  		BUG_ON(svsk->sk_pages[i] == NULL);
  		put_page(svsk->sk_pages[i]);
  		svsk->sk_pages[i] = NULL;
  	}
  out:
  	svsk->sk_tcplen = 0;
  }

  /*

   * Receive data.
   * If we haven't gotten the record length yet, get the next four bytes.
   * Otherwise try to gobble up as much as possible up to the complete
   * record length.

   */

  static int svc_tcp_recv_record(struct svc_sock *svsk, struct svc_rqst *rqstp)

  {

  	struct svc_serv	*serv = svsk->sk_xprt.xpt_server;

  	unsigned int want;

  	int len;

  	clear_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

  	if (svsk->sk_tcplen < sizeof(rpc_fraghdr)) {

  		struct kvec	iov;

  		want = sizeof(rpc_fraghdr) - svsk->sk_tcplen;

  		iov.iov_base = ((char *) &svsk->sk_reclen) + svsk->sk_tcplen;
  		iov.iov_len  = want;
  		if ((len = svc_recvfrom(rqstp, &iov, 1, want)) < 0)
  			goto error;
  		svsk->sk_tcplen += len;
  
  		if (len < want) {

  			dprintk("svc: short recvfrom while reading record "
  				"length (%d of %d)
  ", len, want);

  			return -EAGAIN;

  		}
  
  		svsk->sk_reclen = ntohl(svsk->sk_reclen);

  		if (!(svsk->sk_reclen & RPC_LAST_STREAM_FRAGMENT)) {

  			/* FIXME: technically, a record can be fragmented,
  			 *  and non-terminal fragments will not have the top
  			 *  bit set in the fragment length header.
  			 *  But apparently no known nfs clients send fragmented
  			 *  records. */

  			if (net_ratelimit())

  				printk(KERN_NOTICE "RPC: multiple fragments "
  					"per record not supported
  ");

  			goto err_delete;
  		}

  		svsk->sk_reclen &= RPC_FRAGMENT_SIZE_MASK;

  		dprintk("svc: TCP record, %d bytes
  ", svsk->sk_reclen);

  		if (svsk->sk_reclen > serv->sv_max_mesg) {

  			if (net_ratelimit())

  				printk(KERN_NOTICE "RPC: "
  					"fragment too large: 0x%08lx
  ",
  					(unsigned long)svsk->sk_reclen);

  			goto err_delete;
  		}
  	}

  	if (svsk->sk_reclen < 8)
  		goto err_delete; /* client is nuts. */

  	len = svsk->sk_reclen;

  	return len;

  error:
  	dprintk("RPC: TCP recv_record got %d
  ", len);

  	return len;

  err_delete:

  	set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);

  	return -EAGAIN;
  }

  static int receive_cb_reply(struct svc_sock *svsk, struct svc_rqst *rqstp)

  {

  	struct rpc_xprt *bc_xprt = svsk->sk_xprt.xpt_bc_xprt;

  	struct rpc_rqst *req = NULL;

  	struct kvec *src, *dst;
  	__be32 *p = (__be32 *)rqstp->rq_arg.head[0].iov_base;

  	__be32 xid;
  	__be32 calldir;

  	xid = *p++;
  	calldir = *p;

  	if (bc_xprt)
  		req = xprt_lookup_rqst(bc_xprt, xid);

  	if (!req) {
  		printk(KERN_NOTICE
  			"%s: Got unrecognized reply: "
  			"calldir 0x%x xpt_bc_xprt %p xid %08x
  ",
  			__func__, ntohl(calldir),
  			bc_xprt, xid);
  		return -EAGAIN;

  	}

  
  	memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
  	/*
  	 * XXX!: cheating for now!  Only copying HEAD.
  	 * But we know this is good enough for now (in fact, for any
  	 * callback reply in the forseeable future).
  	 */
  	dst = &req->rq_private_buf.head[0];
  	src = &rqstp->rq_arg.head[0];
  	if (dst->iov_len < src->iov_len)
  		return -EAGAIN; /* whatever; just giving up. */
  	memcpy(dst->iov_base, src->iov_base, src->iov_len);
  	xprt_complete_rqst(req->rq_task, svsk->sk_reclen);
  	rqstp->rq_arg.len = 0;
  	return 0;
  }
  
  static int copy_pages_to_kvecs(struct kvec *vec, struct page **pages, int len)
  {
  	int i = 0;
  	int t = 0;
  
  	while (t < len) {
  		vec[i].iov_base = page_address(pages[i]);
  		vec[i].iov_len = PAGE_SIZE;
  		i++;
  		t += PAGE_SIZE;
  	}
  	return i;

  }

  /*
   * Receive data from a TCP socket.
   */
  static int svc_tcp_recvfrom(struct svc_rqst *rqstp)
  {
  	struct svc_sock	*svsk =
  		container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
  	struct svc_serv	*serv = svsk->sk_xprt.xpt_server;
  	int		len;
  	struct kvec *vec;

  	unsigned int want, base;

  	__be32 *p;
  	__be32 calldir;

  	int pnum;

  
  	dprintk("svc: tcp_recv %p data %d conn %d close %d
  ",
  		svsk, test_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags),
  		test_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags),
  		test_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags));
  
  	len = svc_tcp_recv_record(svsk, rqstp);
  	if (len < 0)
  		goto error;

  	base = svc_tcp_restore_pages(svsk, rqstp);
  	want = svsk->sk_reclen - base;

  	vec = rqstp->rq_vec;

  	pnum = copy_pages_to_kvecs(&vec[0], &rqstp->rq_pages[0],
  						svsk->sk_reclen);

  	rqstp->rq_respages = &rqstp->rq_pages[pnum];

  
  	/* Now receive data */

  	len = svc_partial_recvfrom(rqstp, vec, pnum, want, base);
  	if (len >= 0)
  		svsk->sk_tcplen += len;
  	if (len != want) {
  		if (len < 0 && len != -EAGAIN)
  			goto err_other;
  		svc_tcp_save_pages(svsk, rqstp);
  		dprintk("svc: incomplete TCP record (%d of %d)
  ",
  			svsk->sk_tcplen, svsk->sk_reclen);
  		goto err_noclose;
  	}

  	rqstp->rq_arg.len = svsk->sk_reclen;

  	rqstp->rq_arg.page_base = 0;

  	if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len) {
  		rqstp->rq_arg.head[0].iov_len = rqstp->rq_arg.len;

  		rqstp->rq_arg.page_len = 0;

  	} else
  		rqstp->rq_arg.page_len = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len;

  	rqstp->rq_xprt_ctxt   = NULL;

  	rqstp->rq_prot	      = IPPROTO_TCP;

  	p = (__be32 *)rqstp->rq_arg.head[0].iov_base;
  	calldir = p[1];

  	if (calldir)

  		len = receive_cb_reply(svsk, rqstp);

  	/* Reset TCP read info */
  	svsk->sk_reclen = 0;
  	svsk->sk_tcplen = 0;

  	/* If we have more data, signal svc_xprt_enqueue() to try again */
  	if (svc_recv_available(svsk) > sizeof(rpc_fraghdr))
  		set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

  	if (len < 0)
  		goto error;

  	svc_xprt_copy_addrs(rqstp, &svsk->sk_xprt);

  	if (serv->sv_stats)
  		serv->sv_stats->nettcpcnt++;

  	dprintk("svc: TCP complete record (%d bytes)
  ", rqstp->rq_arg.len);

  	return rqstp->rq_arg.len;

  error:

  	if (len != -EAGAIN)
  		goto err_other;
  	dprintk("RPC: TCP recvfrom got EAGAIN
  ");

  	return -EAGAIN;

  err_other:
  	printk(KERN_NOTICE "%s: recvfrom returned errno %d
  ",
  	       svsk->sk_xprt.xpt_server->sv_name, -len);
  	set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);
  err_noclose:
  	return -EAGAIN;	/* record not complete */

  }
  
  /*
   * Send out data on TCP socket.
   */

  static int svc_tcp_sendto(struct svc_rqst *rqstp)

  {
  	struct xdr_buf	*xbufp = &rqstp->rq_res;
  	int sent;

  	__be32 reclen;

  
  	/* Set up the first element of the reply kvec.
  	 * Any other kvecs that may be in use have been taken
  	 * care of by the server implementation itself.
  	 */
  	reclen = htonl(0x80000000|((xbufp->len ) - 4));
  	memcpy(xbufp->head[0].iov_base, &reclen, 4);

  	sent = svc_sendto(rqstp, &rqstp->rq_res);
  	if (sent != xbufp->len) {

  		printk(KERN_NOTICE
  		       "rpc-srv/tcp: %s: %s %d when sending %d bytes "
  		       "- shutting down socket
  ",

  		       rqstp->rq_xprt->xpt_server->sv_name,

  		       (sent<0)?"got error":"sent only",
  		       sent, xbufp->len);

  		set_bit(XPT_CLOSE, &rqstp->rq_xprt->xpt_flags);

  		svc_xprt_enqueue(rqstp->rq_xprt);

  		sent = -EAGAIN;
  	}
  	return sent;
  }

  /*
   * Setup response header. TCP has a 4B record length field.
   */
  static void svc_tcp_prep_reply_hdr(struct svc_rqst *rqstp)
  {
  	struct kvec *resv = &rqstp->rq_res.head[0];
  
  	/* tcp needs a space for the record length... */
  	svc_putnl(resv, 0);
  }

  static int svc_tcp_has_wspace(struct svc_xprt *xprt)
  {

  	struct svc_sock *svsk =	container_of(xprt, struct svc_sock, sk_xprt);

  	struct svc_serv *serv = svsk->sk_xprt.xpt_server;

  	int required;

  	if (test_bit(XPT_LISTENER, &xprt->xpt_flags))
  		return 1;
  	required = atomic_read(&xprt->xpt_reserved) + serv->sv_max_mesg;
  	if (sk_stream_wspace(svsk->sk_sk) >= required)
  		return 1;

  	set_bit(SOCK_NOSPACE, &svsk->sk_sock->flags);

  	return 0;

  }

  static struct svc_xprt *svc_tcp_create(struct svc_serv *serv,

  				       struct net *net,

  				       struct sockaddr *sa, int salen,
  				       int flags)
  {

  	return svc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags);

  }

  #if defined(CONFIG_SUNRPC_BACKCHANNEL)

  static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int,
  					     struct net *, struct sockaddr *,
  					     int, int);
  static void svc_bc_sock_free(struct svc_xprt *xprt);
  
  static struct svc_xprt *svc_bc_tcp_create(struct svc_serv *serv,
  				       struct net *net,
  				       struct sockaddr *sa, int salen,
  				       int flags)
  {
  	return svc_bc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags);
  }
  
  static void svc_bc_tcp_sock_detach(struct svc_xprt *xprt)
  {
  }
  
  static struct svc_xprt_ops svc_tcp_bc_ops = {
  	.xpo_create = svc_bc_tcp_create,
  	.xpo_detach = svc_bc_tcp_sock_detach,
  	.xpo_free = svc_bc_sock_free,
  	.xpo_prep_reply_hdr = svc_tcp_prep_reply_hdr,
  };
  
  static struct svc_xprt_class svc_tcp_bc_class = {
  	.xcl_name = "tcp-bc",
  	.xcl_owner = THIS_MODULE,
  	.xcl_ops = &svc_tcp_bc_ops,
  	.xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP,
  };

  
  static void svc_init_bc_xprt_sock(void)
  {
  	svc_reg_xprt_class(&svc_tcp_bc_class);
  }
  
  static void svc_cleanup_bc_xprt_sock(void)
  {
  	svc_unreg_xprt_class(&svc_tcp_bc_class);
  }

  #else /* CONFIG_SUNRPC_BACKCHANNEL */

  static void svc_init_bc_xprt_sock(void)
  {
  }
  
  static void svc_cleanup_bc_xprt_sock(void)
  {
  }

  #endif /* CONFIG_SUNRPC_BACKCHANNEL */

  static struct svc_xprt_ops svc_tcp_ops = {

  	.xpo_create = svc_tcp_create,

  	.xpo_recvfrom = svc_tcp_recvfrom,
  	.xpo_sendto = svc_tcp_sendto,

  	.xpo_release_rqst = svc_release_skb,

  	.xpo_detach = svc_tcp_sock_detach,

  	.xpo_free = svc_sock_free,

  	.xpo_prep_reply_hdr = svc_tcp_prep_reply_hdr,

  	.xpo_has_wspace = svc_tcp_has_wspace,

  	.xpo_accept = svc_tcp_accept,

  };
  
  static struct svc_xprt_class svc_tcp_class = {
  	.xcl_name = "tcp",

  	.xcl_owner = THIS_MODULE,

  	.xcl_ops = &svc_tcp_ops,

  	.xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP,

  };
  
  void svc_init_xprt_sock(void)
  {
  	svc_reg_xprt_class(&svc_tcp_class);
  	svc_reg_xprt_class(&svc_udp_class);

  	svc_init_bc_xprt_sock();

  }
  
  void svc_cleanup_xprt_sock(void)
  {
  	svc_unreg_xprt_class(&svc_tcp_class);
  	svc_unreg_xprt_class(&svc_udp_class);

  	svc_cleanup_bc_xprt_sock();

  }

  static void svc_tcp_init(struct svc_sock *svsk, struct svc_serv *serv)

  {
  	struct sock	*sk = svsk->sk_sk;

  	svc_xprt_init(&svc_tcp_class, &svsk->sk_xprt, serv);

  	set_bit(XPT_CACHE_AUTH, &svsk->sk_xprt.xpt_flags);

  	if (sk->sk_state == TCP_LISTEN) {
  		dprintk("setting up TCP socket for listening
  ");

  		set_bit(XPT_LISTENER, &svsk->sk_xprt.xpt_flags);

  		sk->sk_data_ready = svc_tcp_listen_data_ready;

  		set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);

  	} else {
  		dprintk("setting up TCP socket for reading
  ");
  		sk->sk_state_change = svc_tcp_state_change;
  		sk->sk_data_ready = svc_tcp_data_ready;

  		sk->sk_write_space = svc_tcp_write_space;

  
  		svsk->sk_reclen = 0;
  		svsk->sk_tcplen = 0;

  		memset(&svsk->sk_pages[0], 0, sizeof(svsk->sk_pages));

  		tcp_sk(sk)->nonagle |= TCP_NAGLE_OFF;

  		set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

  		if (sk->sk_state != TCP_ESTABLISHED)

  			set_bit(XPT_CLOSE, &svsk->sk_xprt.xpt_flags);

  	}
  }

  void svc_sock_update_bufs(struct svc_serv *serv)

  {
  	/*
  	 * The number of server threads has changed. Update
  	 * rcvbuf and sndbuf accordingly on all sockets
  	 */

  	struct svc_sock *svsk;

  
  	spin_lock_bh(&serv->sv_lock);

  	list_for_each_entry(svsk, &serv->sv_permsocks, sk_xprt.xpt_list)

  		set_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags);

  	list_for_each_entry(svsk, &serv->sv_tempsocks, sk_xprt.xpt_list)

  		set_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags);

  	spin_unlock_bh(&serv->sv_lock);
  }

  EXPORT_SYMBOL_GPL(svc_sock_update_bufs);

  
  /*

   * Initialize socket for RPC use and create svc_sock struct
   * XXX: May want to setsockopt SO_SNDBUF and SO_RCVBUF.
   */

  static struct svc_sock *svc_setup_socket(struct svc_serv *serv,
  						struct socket *sock,
  						int *errp, int flags)

  {
  	struct svc_sock	*svsk;
  	struct sock	*inet;

  	int		pmap_register = !(flags & SVC_SOCK_ANONYMOUS);

  
  	dprintk("svc: svc_setup_socket %p
  ", sock);

  	if (!(svsk = kzalloc(sizeof(*svsk), GFP_KERNEL))) {

  		*errp = -ENOMEM;
  		return NULL;
  	}

  
  	inet = sock->sk;
  
  	/* Register socket with portmapper */
  	if (*errp >= 0 && pmap_register)

  		*errp = svc_register(serv, inet->sk_family, inet->sk_protocol,

  				     ntohs(inet_sk(inet)->inet_sport));

  
  	if (*errp < 0) {
  		kfree(svsk);
  		return NULL;
  	}

  	inet->sk_user_data = svsk;
  	svsk->sk_sock = sock;
  	svsk->sk_sk = inet;
  	svsk->sk_ostate = inet->sk_state_change;
  	svsk->sk_odata = inet->sk_data_ready;
  	svsk->sk_owspace = inet->sk_write_space;

  
  	/* Initialize the socket */
  	if (sock->type == SOCK_DGRAM)

  		svc_udp_init(svsk, serv);

  	else {
  		/* initialise setting must have enough space to
  		 * receive and respond to one request.
  		 */
  		svc_sock_setbufsize(svsk->sk_sock, 4 * serv->sv_max_mesg,
  					4 * serv->sv_max_mesg);

  		svc_tcp_init(svsk, serv);

  	}

  	dprintk("svc: svc_setup_socket created %p (inet %p)
  ",
  				svsk, svsk->sk_sk);

  	return svsk;
  }

  /**
   * svc_addsock - add a listener socket to an RPC service
   * @serv: pointer to RPC service to which to add a new listener
   * @fd: file descriptor of the new listener
   * @name_return: pointer to buffer to fill in with name of listener
   * @len: size of the buffer
   *
   * Fills in socket name and returns positive length of name if successful.
   * Name is terminated with '
  '.  On error, returns a negative errno
   * value.
   */
  int svc_addsock(struct svc_serv *serv, const int fd, char *name_return,
  		const size_t len)

  {
  	int err = 0;
  	struct socket *so = sockfd_lookup(fd, &err);
  	struct svc_sock *svsk = NULL;
  
  	if (!so)
  		return err;

  	if ((so->sk->sk_family != PF_INET) && (so->sk->sk_family != PF_INET6))

  		err =  -EAFNOSUPPORT;
  	else if (so->sk->sk_protocol != IPPROTO_TCP &&
  	    so->sk->sk_protocol != IPPROTO_UDP)
  		err =  -EPROTONOSUPPORT;
  	else if (so->state > SS_UNCONNECTED)
  		err = -EISCONN;
  	else {

  		if (!try_module_get(THIS_MODULE))
  			err = -ENOENT;
  		else
  			svsk = svc_setup_socket(serv, so, &err,
  						SVC_SOCK_DEFAULTS);

  		if (svsk) {

  			struct sockaddr_storage addr;
  			struct sockaddr *sin = (struct sockaddr *)&addr;
  			int salen;
  			if (kernel_getsockname(svsk->sk_sock, sin, &salen) == 0)
  				svc_xprt_set_local(&svsk->sk_xprt, sin, salen);

  			clear_bit(XPT_TEMP, &svsk->sk_xprt.xpt_flags);
  			spin_lock_bh(&serv->sv_lock);
  			list_add(&svsk->sk_xprt.xpt_list, &serv->sv_permsocks);
  			spin_unlock_bh(&serv->sv_lock);

  			svc_xprt_received(&svsk->sk_xprt);

  			err = 0;

  		} else
  			module_put(THIS_MODULE);

  	}
  	if (err) {
  		sockfd_put(so);
  		return err;
  	}

  	return svc_one_sock_name(svsk, name_return, len);

  }
  EXPORT_SYMBOL_GPL(svc_addsock);

  /*
   * Create socket for RPC service.
   */

  static struct svc_xprt *svc_create_socket(struct svc_serv *serv,
  					  int protocol,

  					  struct net *net,

  					  struct sockaddr *sin, int len,
  					  int flags)

  {
  	struct svc_sock	*svsk;
  	struct socket	*sock;
  	int		error;
  	int		type;

  	struct sockaddr_storage addr;
  	struct sockaddr *newsin = (struct sockaddr *)&addr;
  	int		newlen;

  	int		family;
  	int		val;

  	RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);

  	dprintk("svc: svc_create_socket(%s, %d, %s)
  ",
  			serv->sv_program->pg_name, protocol,

  			__svc_print_addr(sin, buf, sizeof(buf)));

  
  	if (protocol != IPPROTO_UDP && protocol != IPPROTO_TCP) {
  		printk(KERN_WARNING "svc: only UDP and TCP "
  				"sockets supported
  ");

  		return ERR_PTR(-EINVAL);

  	}

  	type = (protocol == IPPROTO_UDP)? SOCK_DGRAM : SOCK_STREAM;

  	switch (sin->sa_family) {
  	case AF_INET6:
  		family = PF_INET6;
  		break;
  	case AF_INET:
  		family = PF_INET;
  		break;
  	default:
  		return ERR_PTR(-EINVAL);
  	}

  	error = __sock_create(net, family, type, protocol, &sock, 1);

  	if (error < 0)

  		return ERR_PTR(error);

  	svc_reclassify_socket(sock);

  	/*
  	 * If this is an PF_INET6 listener, we want to avoid
  	 * getting requests from IPv4 remotes.  Those should
  	 * be shunted to a PF_INET listener via rpcbind.
  	 */
  	val = 1;
  	if (family == PF_INET6)
  		kernel_setsockopt(sock, SOL_IPV6, IPV6_V6ONLY,
  					(char *)&val, sizeof(val));

  	if (type == SOCK_STREAM)

  		sock->sk->sk_reuse = 1;		/* allow address reuse */
  	error = kernel_bind(sock, sin, len);

  	if (error < 0)
  		goto bummer;

  	newlen = len;
  	error = kernel_getsockname(sock, newsin, &newlen);
  	if (error < 0)
  		goto bummer;

  	if (protocol == IPPROTO_TCP) {

  		if ((error = kernel_listen(sock, 64)) < 0)

  			goto bummer;
  	}

  	if ((svsk = svc_setup_socket(serv, sock, &error, flags)) != NULL) {

  		svc_xprt_set_local(&svsk->sk_xprt, newsin, newlen);

  		return (struct svc_xprt *)svsk;

  	}

  
  bummer:
  	dprintk("svc: svc_create_socket error = %d
  ", -error);
  	sock_release(sock);

  	return ERR_PTR(error);

  }
  
  /*

   * Detach the svc_sock from the socket so that no
   * more callbacks occur.
   */
  static void svc_sock_detach(struct svc_xprt *xprt)
  {
  	struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
  	struct sock *sk = svsk->sk_sk;

  	wait_queue_head_t *wq;

  
  	dprintk("svc: svc_sock_detach(%p)
  ", svsk);
  
  	/* put back the old socket callbacks */
  	sk->sk_state_change = svsk->sk_ostate;
  	sk->sk_data_ready = svsk->sk_odata;
  	sk->sk_write_space = svsk->sk_owspace;

  	wq = sk_sleep(sk);
  	if (wq && waitqueue_active(wq))
  		wake_up_interruptible(wq);

  }
  
  /*
   * Disconnect the socket, and reset the callbacks
   */
  static void svc_tcp_sock_detach(struct svc_xprt *xprt)
  {
  	struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
  
  	dprintk("svc: svc_tcp_sock_detach(%p)
  ", svsk);
  
  	svc_sock_detach(xprt);

  	if (!test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
  		svc_tcp_clear_pages(svsk);

  		kernel_sock_shutdown(svsk->sk_sock, SHUT_RDWR);

  	}

  }
  
  /*
   * Free the svc_sock's socket resources and the svc_sock itself.
   */
  static void svc_sock_free(struct svc_xprt *xprt)
  {
  	struct svc_sock *svsk = container_of(xprt, struct svc_sock, sk_xprt);
  	dprintk("svc: svc_sock_free(%p)
  ", svsk);

  	if (svsk->sk_sock->file)
  		sockfd_put(svsk->sk_sock);
  	else
  		sock_release(svsk->sk_sock);
  	kfree(svsk);
  }

  #if defined(CONFIG_SUNRPC_BACKCHANNEL)

  /*

   * Create a back channel svc_xprt which shares the fore channel socket.

   */

  static struct svc_xprt *svc_bc_create_socket(struct svc_serv *serv,
  					     int protocol,
  					     struct net *net,
  					     struct sockaddr *sin, int len,
  					     int flags)

  {
  	struct svc_sock *svsk;

  	struct svc_xprt *xprt;
  
  	if (protocol != IPPROTO_TCP) {
  		printk(KERN_WARNING "svc: only TCP sockets"
  			" supported on shared back channel
  ");
  		return ERR_PTR(-EINVAL);
  	}

  	svsk = kzalloc(sizeof(*svsk), GFP_KERNEL);
  	if (!svsk)

  		return ERR_PTR(-ENOMEM);

  
  	xprt = &svsk->sk_xprt;

  	svc_xprt_init(&svc_tcp_bc_class, xprt, serv);

  	serv->sv_bc_xprt = xprt;