text: /*
   * linux/net/sunrpc/xprtsock.c
   *
   * Client-side transport implementation for sockets.
   *
   * TCP callback races fixes (C) 1998 Red Hat
   * TCP send fixes (C) 1998 Red Hat
   * TCP NFS related read + write fixes
   *  (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
   *
   * Rewrite of larges part of the code in order to stabilize TCP stuff.
   * Fix behaviour when socket buffer is full.
   *  (C) 1999 Trond Myklebust <trond.myklebust@fys.uio.no>
   *
   * IP socket transport implementation, (C) 2005 Chuck Lever <cel@netapp.com>
   *
   * IPv6 support contributed by Gilles Quillard, Bull Open Source, 2005.
   *   <gilles.quillard@bull.net>
   */
  
  #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/capability.h>
  #include <linux/pagemap.h>
  #include <linux/errno.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/net.h>
  #include <linux/mm.h>
  #include <linux/un.h>
  #include <linux/udp.h>
  #include <linux/tcp.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/sunrpc/sched.h>
  #include <linux/sunrpc/svcsock.h>
  #include <linux/sunrpc/xprtsock.h>
  #include <linux/file.h>
  #ifdef CONFIG_SUNRPC_BACKCHANNEL
  #include <linux/sunrpc/bc_xprt.h>
  #endif
  
  #include <net/sock.h>
  #include <net/checksum.h>
  #include <net/udp.h>
  #include <net/tcp.h>
  
  #include "sunrpc.h"
  
  static void xs_close(struct rpc_xprt *xprt);
  
  /*
   * xprtsock tunables
   */
  static unsigned int xprt_udp_slot_table_entries = RPC_DEF_SLOT_TABLE;
  static unsigned int xprt_tcp_slot_table_entries = RPC_MIN_SLOT_TABLE;
  static unsigned int xprt_max_tcp_slot_table_entries = RPC_MAX_SLOT_TABLE;
  
  static unsigned int xprt_min_resvport = RPC_DEF_MIN_RESVPORT;
  static unsigned int xprt_max_resvport = RPC_DEF_MAX_RESVPORT;
  
  #define XS_TCP_LINGER_TO	(15U * HZ)
  static unsigned int xs_tcp_fin_timeout __read_mostly = XS_TCP_LINGER_TO;
  
  /*
   * We can register our own files under /proc/sys/sunrpc by
   * calling register_sysctl_table() again.  The files in that
   * directory become the union of all files registered there.
   *
   * We simply need to make sure that we don't collide with
   * someone else's file names!
   */
  
  #ifdef RPC_DEBUG
  
  static unsigned int min_slot_table_size = RPC_MIN_SLOT_TABLE;
  static unsigned int max_slot_table_size = RPC_MAX_SLOT_TABLE;
  static unsigned int max_tcp_slot_table_limit = RPC_MAX_SLOT_TABLE_LIMIT;
  static unsigned int xprt_min_resvport_limit = RPC_MIN_RESVPORT;
  static unsigned int xprt_max_resvport_limit = RPC_MAX_RESVPORT;
  
  static struct ctl_table_header *sunrpc_table_header;
  
  /*
   * FIXME: changing the UDP slot table size should also resize the UDP
   *        socket buffers for existing UDP transports
   */
  static ctl_table xs_tunables_table[] = {
  	{
  		.procname	= "udp_slot_table_entries",
  		.data		= &xprt_udp_slot_table_entries,
  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_minmax,
  		.extra1		= &min_slot_table_size,
  		.extra2		= &max_slot_table_size
  	},
  	{
  		.procname	= "tcp_slot_table_entries",
  		.data		= &xprt_tcp_slot_table_entries,
  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_minmax,
  		.extra1		= &min_slot_table_size,
  		.extra2		= &max_slot_table_size
  	},
  	{
  		.procname	= "tcp_max_slot_table_entries",
  		.data		= &xprt_max_tcp_slot_table_entries,
  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_minmax,
  		.extra1		= &min_slot_table_size,
  		.extra2		= &max_tcp_slot_table_limit
  	},
  	{
  		.procname	= "min_resvport",
  		.data		= &xprt_min_resvport,
  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_minmax,
  		.extra1		= &xprt_min_resvport_limit,
  		.extra2		= &xprt_max_resvport_limit
  	},
  	{
  		.procname	= "max_resvport",
  		.data		= &xprt_max_resvport,
  		.maxlen		= sizeof(unsigned int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_minmax,
  		.extra1		= &xprt_min_resvport_limit,
  		.extra2		= &xprt_max_resvport_limit
  	},
  	{
  		.procname	= "tcp_fin_timeout",
  		.data		= &xs_tcp_fin_timeout,
  		.maxlen		= sizeof(xs_tcp_fin_timeout),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec_jiffies,
  	},
  	{ },
  };
  
  static ctl_table sunrpc_table[] = {
  	{
  		.procname	= "sunrpc",
  		.mode		= 0555,
  		.child		= xs_tunables_table
  	},
  	{ },
  };
  
  #endif
  
  /*
   * Wait duration for a reply from the RPC portmapper.
   */
  #define XS_BIND_TO		(60U * HZ)
  
  /*
   * Delay if a UDP socket connect error occurs.  This is most likely some
   * kind of resource problem on the local host.
   */
  #define XS_UDP_REEST_TO		(2U * HZ)
  
  /*
   * The reestablish timeout allows clients to delay for a bit before attempting
   * to reconnect to a server that just dropped our connection.
   *
   * We implement an exponential backoff when trying to reestablish a TCP
   * transport connection with the server.  Some servers like to drop a TCP
   * connection when they are overworked, so we start with a short timeout and
   * increase over time if the server is down or not responding.
   */
  #define XS_TCP_INIT_REEST_TO	(3U * HZ)
  #define XS_TCP_MAX_REEST_TO	(5U * 60 * HZ)
  
  /*
   * TCP idle timeout; client drops the transport socket if it is idle
   * for this long.  Note that we also timeout UDP sockets to prevent
   * holding port numbers when there is no RPC traffic.
   */
  #define XS_IDLE_DISC_TO		(5U * 60 * HZ)
  
  #ifdef RPC_DEBUG
  # undef  RPC_DEBUG_DATA
  # define RPCDBG_FACILITY	RPCDBG_TRANS
  #endif
  
  #ifdef RPC_DEBUG_DATA
  static void xs_pktdump(char *msg, u32 *packet, unsigned int count)
  {
  	u8 *buf = (u8 *) packet;
  	int j;
  
  	dprintk("RPC:       %s\n", msg);
  	for (j = 0; j < count && j < 128; j += 4) {
  		if (!(j & 31)) {
  			if (j)
  				dprintk("\n");
  			dprintk("0x%04x ", j);
  		}
  		dprintk("%02x%02x%02x%02x ",
  			buf[j], buf[j+1], buf[j+2], buf[j+3]);
  	}
  	dprintk("\n");
  }
  #else
  static inline void xs_pktdump(char *msg, u32 *packet, unsigned int count)
  {
  	/* NOP */
  }
  #endif
  
  struct sock_xprt {
  	struct rpc_xprt		xprt;
  
  	/*
  	 * Network layer
  	 */
  	struct socket *		sock;
  	struct sock *		inet;
  
  	/*
  	 * State of TCP reply receive
  	 */
  	__be32			tcp_fraghdr,
  				tcp_xid,
  				tcp_calldir;
  
  	u32			tcp_offset,
  				tcp_reclen;
  
  	unsigned long		tcp_copied,
  				tcp_flags;
  
  	/*
  	 * Connection of transports
  	 */
  	struct delayed_work	connect_worker;
  	struct sockaddr_storage	srcaddr;
  	unsigned short		srcport;
  
  	/*
  	 * UDP socket buffer size parameters
  	 */
  	size_t			rcvsize,
  				sndsize;
  
  	/*
  	 * Saved socket callback addresses
  	 */
  	void			(*old_data_ready)(struct sock *, int);
  	void			(*old_state_change)(struct sock *);
  	void			(*old_write_space)(struct sock *);
  	void			(*old_error_report)(struct sock *);
  };
  
  /*
   * TCP receive state flags
   */
  #define TCP_RCV_LAST_FRAG	(1UL << 0)
  #define TCP_RCV_COPY_FRAGHDR	(1UL << 1)
  #define TCP_RCV_COPY_XID	(1UL << 2)
  #define TCP_RCV_COPY_DATA	(1UL << 3)
  #define TCP_RCV_READ_CALLDIR	(1UL << 4)
  #define TCP_RCV_COPY_CALLDIR	(1UL << 5)
  
  /*
   * TCP RPC flags
   */
  #define TCP_RPC_REPLY		(1UL << 6)
  
  static inline struct sockaddr *xs_addr(struct rpc_xprt *xprt)
  {
  	return (struct sockaddr *) &xprt->addr;
  }
  
  static inline struct sockaddr_un *xs_addr_un(struct rpc_xprt *xprt)
  {
  	return (struct sockaddr_un *) &xprt->addr;
  }
  
  static inline struct sockaddr_in *xs_addr_in(struct rpc_xprt *xprt)
  {
  	return (struct sockaddr_in *) &xprt->addr;
  }
  
  static inline struct sockaddr_in6 *xs_addr_in6(struct rpc_xprt *xprt)
  {
  	return (struct sockaddr_in6 *) &xprt->addr;
  }
  
  static void xs_format_common_peer_addresses(struct rpc_xprt *xprt)
  {
  	struct sockaddr *sap = xs_addr(xprt);
  	struct sockaddr_in6 *sin6;
  	struct sockaddr_in *sin;
  	struct sockaddr_un *sun;
  	char buf[128];
  
  	switch (sap->sa_family) {
  	case AF_LOCAL:
  		sun = xs_addr_un(xprt);
  		strlcpy(buf, sun->sun_path, sizeof(buf));
  		xprt->address_strings[RPC_DISPLAY_ADDR] =
  						kstrdup(buf, GFP_KERNEL);
  		break;
  	case AF_INET:
  		(void)rpc_ntop(sap, buf, sizeof(buf));
  		xprt->address_strings[RPC_DISPLAY_ADDR] =
  						kstrdup(buf, GFP_KERNEL);
  		sin = xs_addr_in(xprt);
  		snprintf(buf, sizeof(buf), "%08x", ntohl(sin->sin_addr.s_addr));
  		break;
  	case AF_INET6:
  		(void)rpc_ntop(sap, buf, sizeof(buf));
  		xprt->address_strings[RPC_DISPLAY_ADDR] =
  						kstrdup(buf, GFP_KERNEL);
  		sin6 = xs_addr_in6(xprt);
  		snprintf(buf, sizeof(buf), "%pi6", &sin6->sin6_addr);
  		break;
  	default:
  		BUG();
  	}
  
  	xprt->address_strings[RPC_DISPLAY_HEX_ADDR] = kstrdup(buf, GFP_KERNEL);
  }
  
  static void xs_format_common_peer_ports(struct rpc_xprt *xprt)
  {
  	struct sockaddr *sap = xs_addr(xprt);
  	char buf[128];
  
  	snprintf(buf, sizeof(buf), "%u", rpc_get_port(sap));
  	xprt->address_strings[RPC_DISPLAY_PORT] = kstrdup(buf, GFP_KERNEL);
  
  	snprintf(buf, sizeof(buf), "%4hx", rpc_get_port(sap));
  	xprt->address_strings[RPC_DISPLAY_HEX_PORT] = kstrdup(buf, GFP_KERNEL);
  }
  
  static void xs_format_peer_addresses(struct rpc_xprt *xprt,
  				     const char *protocol,
  				     const char *netid)
  {
  	xprt->address_strings[RPC_DISPLAY_PROTO] = protocol;
  	xprt->address_strings[RPC_DISPLAY_NETID] = netid;
  	xs_format_common_peer_addresses(xprt);
  	xs_format_common_peer_ports(xprt);
  }
  
  static void xs_update_peer_port(struct rpc_xprt *xprt)
  {
  	kfree(xprt->address_strings[RPC_DISPLAY_HEX_PORT]);
  	kfree(xprt->address_strings[RPC_DISPLAY_PORT]);
  
  	xs_format_common_peer_ports(xprt);
  }
  
  static void xs_free_peer_addresses(struct rpc_xprt *xprt)
  {
  	unsigned int i;
  
  	for (i = 0; i < RPC_DISPLAY_MAX; i++)
  		switch (i) {
  		case RPC_DISPLAY_PROTO:
  		case RPC_DISPLAY_NETID:
  			continue;
  		default:
  			kfree(xprt->address_strings[i]);
  		}
  }
  
  #define XS_SENDMSG_FLAGS	(MSG_DONTWAIT | MSG_NOSIGNAL)
  
  static int xs_send_kvec(struct socket *sock, struct sockaddr *addr, int addrlen, struct kvec *vec, unsigned int base, int more)
  {
  	struct msghdr msg = {
  		.msg_name	= addr,
  		.msg_namelen	= addrlen,
  		.msg_flags	= XS_SENDMSG_FLAGS | (more ? MSG_MORE : 0),
  	};
  	struct kvec iov = {
  		.iov_base	= vec->iov_base + base,
  		.iov_len	= vec->iov_len - base,
  	};
  
  	if (iov.iov_len != 0)
  		return kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
  	return kernel_sendmsg(sock, &msg, NULL, 0, 0);
  }
  
  static int xs_send_pagedata(struct socket *sock, struct xdr_buf *xdr, unsigned int base, int more)
  {
  	struct page **ppage;
  	unsigned int remainder;
  	int err, sent = 0;
  
  	remainder = xdr->page_len - base;
  	base += xdr->page_base;
  	ppage = xdr->pages + (base >> PAGE_SHIFT);
  	base &= ~PAGE_MASK;
  	for(;;) {
  		unsigned int len = min_t(unsigned int, PAGE_SIZE - base, remainder);
  		int flags = XS_SENDMSG_FLAGS;
  
  		remainder -= len;
  		if (remainder != 0 || more)
  			flags |= MSG_MORE;
  		err = sock->ops->sendpage(sock, *ppage, base, len, flags);
  		if (remainder == 0 || err != len)
  			break;
  		sent += err;
  		ppage++;
  		base = 0;
  	}
  	if (sent == 0)
  		return err;
  	if (err > 0)
  		sent += err;
  	return sent;
  }
  
  /**
   * xs_sendpages - write pages directly to a socket
   * @sock: socket to send on
   * @addr: UDP only -- address of destination
   * @addrlen: UDP only -- length of destination address
   * @xdr: buffer containing this request
   * @base: starting position in the buffer
   *
   */
  static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base)
  {
  	unsigned int remainder = xdr->len - base;
  	int err, sent = 0;
  
  	if (unlikely(!sock))
  		return -ENOTSOCK;
  
  	clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
  	if (base != 0) {
  		addr = NULL;
  		addrlen = 0;
  	}
  
  	if (base < xdr->head[0].iov_len || addr != NULL) {
  		unsigned int len = xdr->head[0].iov_len - base;
  		remainder -= len;
  		err = xs_send_kvec(sock, addr, addrlen, &xdr->head[0], base, remainder != 0);
  		if (remainder == 0 || err != len)
  			goto out;
  		sent += err;
  		base = 0;
  	} else
  		base -= xdr->head[0].iov_len;
  
  	if (base < xdr->page_len) {
  		unsigned int len = xdr->page_len - base;
  		remainder -= len;
  		err = xs_send_pagedata(sock, xdr, base, remainder != 0);
  		if (remainder == 0 || err != len)
  			goto out;
  		sent += err;
  		base = 0;
  	} else
  		base -= xdr->page_len;
  
  	if (base >= xdr->tail[0].iov_len)
  		return sent;
  	err = xs_send_kvec(sock, NULL, 0, &xdr->tail[0], base, 0);
  out:
  	if (sent == 0)
  		return err;
  	if (err > 0)
  		sent += err;
  	return sent;
  }
  
  static void xs_nospace_callback(struct rpc_task *task)
  {
  	struct sock_xprt *transport = container_of(task->tk_rqstp->rq_xprt, struct sock_xprt, xprt);
  
  	transport->inet->sk_write_pending--;
  	clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
  }
  
  /**
   * xs_nospace - place task on wait queue if transmit was incomplete
   * @task: task to put to sleep
   *
   */
  static int xs_nospace(struct rpc_task *task)
  {
  	struct rpc_rqst *req = task->tk_rqstp;
  	struct rpc_xprt *xprt = req->rq_xprt;
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	int ret = -EAGAIN;
  
  	dprintk("RPC: %5u xmit incomplete (%u left of %u)\n",
  			task->tk_pid, req->rq_slen - req->rq_bytes_sent,
  			req->rq_slen);
  
  	/* Protect against races with write_space */
  	spin_lock_bh(&xprt->transport_lock);
  
  	/* Don't race with disconnect */
  	if (xprt_connected(xprt)) {
  		if (test_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags)) {
  			/*
  			 * Notify TCP that we're limited by the application
  			 * window size
  			 */
  			set_bit(SOCK_NOSPACE, &transport->sock->flags);
  			transport->inet->sk_write_pending++;
  			/* ...and wait for more buffer space */
  			xprt_wait_for_buffer_space(task, xs_nospace_callback);
  		}
  	} else {
  		clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
  		ret = -ENOTCONN;
  	}
  
  	spin_unlock_bh(&xprt->transport_lock);
  	return ret;
  }
  
  /*
   * Construct a stream transport record marker in @buf.
   */
  static inline void xs_encode_stream_record_marker(struct xdr_buf *buf)
  {
  	u32 reclen = buf->len - sizeof(rpc_fraghdr);
  	rpc_fraghdr *base = buf->head[0].iov_base;
  	*base = cpu_to_be32(RPC_LAST_STREAM_FRAGMENT | reclen);
  }
  
  /**
   * xs_local_send_request - write an RPC request to an AF_LOCAL socket
   * @task: RPC task that manages the state of an RPC request
   *
   * Return values:
   *        0:	The request has been sent
   *   EAGAIN:	The socket was blocked, please call again later to
   *		complete the request
   * ENOTCONN:	Caller needs to invoke connect logic then call again
   *    other:	Some other error occured, the request was not sent
   */
  static int xs_local_send_request(struct rpc_task *task)
  {
  	struct rpc_rqst *req = task->tk_rqstp;
  	struct rpc_xprt *xprt = req->rq_xprt;
  	struct sock_xprt *transport =
  				container_of(xprt, struct sock_xprt, xprt);
  	struct xdr_buf *xdr = &req->rq_snd_buf;
  	int status;
  
  	xs_encode_stream_record_marker(&req->rq_snd_buf);
  
  	xs_pktdump("packet data:",
  			req->rq_svec->iov_base, req->rq_svec->iov_len);
  
  	status = xs_sendpages(transport->sock, NULL, 0,
  						xdr, req->rq_bytes_sent);
  	dprintk("RPC:       %s(%u) = %d\n",
  			__func__, xdr->len - req->rq_bytes_sent, status);
  	if (likely(status >= 0)) {
  		req->rq_bytes_sent += status;
  		req->rq_xmit_bytes_sent += status;
  		if (likely(req->rq_bytes_sent >= req->rq_slen)) {
  			req->rq_bytes_sent = 0;
  			return 0;
  		}
  		status = -EAGAIN;
  	}
  
  	switch (status) {
  	case -EAGAIN:
  		status = xs_nospace(task);
  		break;
  	default:
  		dprintk("RPC:       sendmsg returned unrecognized error %d\n",
  			-status);
  	case -EPIPE:
  		xs_close(xprt);
  		status = -ENOTCONN;
  	}
  
  	return status;
  }
  
  /**
   * xs_udp_send_request - write an RPC request to a UDP socket
   * @task: address of RPC task that manages the state of an RPC request
   *
   * Return values:
   *        0:	The request has been sent
   *   EAGAIN:	The socket was blocked, please call again later to
   *		complete the request
   * ENOTCONN:	Caller needs to invoke connect logic then call again
   *    other:	Some other error occurred, the request was not sent
   */
  static int xs_udp_send_request(struct rpc_task *task)
  {
  	struct rpc_rqst *req = task->tk_rqstp;
  	struct rpc_xprt *xprt = req->rq_xprt;
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	struct xdr_buf *xdr = &req->rq_snd_buf;
  	int status;
  
  	xs_pktdump("packet data:",
  				req->rq_svec->iov_base,
  				req->rq_svec->iov_len);
  
  	if (!xprt_bound(xprt))
  		return -ENOTCONN;
  	status = xs_sendpages(transport->sock,
  			      xs_addr(xprt),
  			      xprt->addrlen, xdr,
  			      req->rq_bytes_sent);
  
  	dprintk("RPC:       xs_udp_send_request(%u) = %d\n",
  			xdr->len - req->rq_bytes_sent, status);
  
  	if (status >= 0) {
  		req->rq_xmit_bytes_sent += status;
  		if (status >= req->rq_slen)
  			return 0;
  		/* Still some bytes left; set up for a retry later. */
  		status = -EAGAIN;
  	}
  
  	switch (status) {
  	case -ENOTSOCK:
  		status = -ENOTCONN;
  		/* Should we call xs_close() here? */
  		break;
  	case -EAGAIN:
  		status = xs_nospace(task);
  		break;
  	default:
  		dprintk("RPC:       sendmsg returned unrecognized error %d\n",
  			-status);
  	case -ENETUNREACH:
  	case -EPIPE:
  	case -ECONNREFUSED:
  		/* When the server has died, an ICMP port unreachable message
  		 * prompts ECONNREFUSED. */
  		clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
  	}
  
  	return status;
  }
  
  /**
   * xs_tcp_shutdown - gracefully shut down a TCP socket
   * @xprt: transport
   *
   * Initiates a graceful shutdown of the TCP socket by calling the
   * equivalent of shutdown(SHUT_WR);
   */
  static void xs_tcp_shutdown(struct rpc_xprt *xprt)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	struct socket *sock = transport->sock;
  
  	if (sock != NULL)
  		kernel_sock_shutdown(sock, SHUT_WR);
  }
  
  /**
   * xs_tcp_send_request - write an RPC request to a TCP socket
   * @task: address of RPC task that manages the state of an RPC request
   *
   * Return values:
   *        0:	The request has been sent
   *   EAGAIN:	The socket was blocked, please call again later to
   *		complete the request
   * ENOTCONN:	Caller needs to invoke connect logic then call again
   *    other:	Some other error occurred, the request was not sent
   *
   * XXX: In the case of soft timeouts, should we eventually give up
   *	if sendmsg is not able to make progress?
   */
  static int xs_tcp_send_request(struct rpc_task *task)
  {
  	struct rpc_rqst *req = task->tk_rqstp;
  	struct rpc_xprt *xprt = req->rq_xprt;
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	struct xdr_buf *xdr = &req->rq_snd_buf;
  	int status;
  
  	xs_encode_stream_record_marker(&req->rq_snd_buf);
  
  	xs_pktdump("packet data:",
  				req->rq_svec->iov_base,
  				req->rq_svec->iov_len);
  
  	/* Continue transmitting the packet/record. We must be careful
  	 * to cope with writespace callbacks arriving _after_ we have
  	 * called sendmsg(). */
  	while (1) {
  		status = xs_sendpages(transport->sock,
  					NULL, 0, xdr, req->rq_bytes_sent);
  
  		dprintk("RPC:       xs_tcp_send_request(%u) = %d\n",
  				xdr->len - req->rq_bytes_sent, status);
  
  		if (unlikely(status < 0))
  			break;
  
  		/* If we've sent the entire packet, immediately
  		 * reset the count of bytes sent. */
  		req->rq_bytes_sent += status;
  		req->rq_xmit_bytes_sent += status;
  		if (likely(req->rq_bytes_sent >= req->rq_slen)) {
  			req->rq_bytes_sent = 0;
  			return 0;
  		}
  
  		if (status != 0)
  			continue;
  		status = -EAGAIN;
  		break;
  	}
  
  	switch (status) {
  	case -ENOTSOCK:
  		status = -ENOTCONN;
  		/* Should we call xs_close() here? */
  		break;
  	case -EAGAIN:
  		status = xs_nospace(task);
  		break;
  	default:
  		dprintk("RPC:       sendmsg returned unrecognized error %d\n",
  			-status);
  	case -ECONNRESET:
  	case -EPIPE:
  		xs_tcp_shutdown(xprt);
  	case -ECONNREFUSED:
  	case -ENOTCONN:
  		clear_bit(SOCK_ASYNC_NOSPACE, &transport->sock->flags);
  	}
  
  	return status;
  }
  
  /**
   * xs_tcp_release_xprt - clean up after a tcp transmission
   * @xprt: transport
   * @task: rpc task
   *
   * This cleans up if an error causes us to abort the transmission of a request.
   * In this case, the socket may need to be reset in order to avoid confusing
   * the server.
   */
  static void xs_tcp_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
  {
  	struct rpc_rqst *req;
  
  	if (task != xprt->snd_task)
  		return;
  	if (task == NULL)
  		goto out_release;
  	req = task->tk_rqstp;
  	if (req == NULL)
  		goto out_release;
  	if (req->rq_bytes_sent == 0)
  		goto out_release;
  	if (req->rq_bytes_sent == req->rq_snd_buf.len)
  		goto out_release;
  	set_bit(XPRT_CLOSE_WAIT, &task->tk_xprt->state);
  out_release:
  	xprt_release_xprt(xprt, task);
  }
  
  static void xs_save_old_callbacks(struct sock_xprt *transport, struct sock *sk)
  {
  	transport->old_data_ready = sk->sk_data_ready;
  	transport->old_state_change = sk->sk_state_change;
  	transport->old_write_space = sk->sk_write_space;
  	transport->old_error_report = sk->sk_error_report;
  }
  
  static void xs_restore_old_callbacks(struct sock_xprt *transport, struct sock *sk)
  {
  	sk->sk_data_ready = transport->old_data_ready;
  	sk->sk_state_change = transport->old_state_change;
  	sk->sk_write_space = transport->old_write_space;
  	sk->sk_error_report = transport->old_error_report;
  }
  
  static void xs_reset_transport(struct sock_xprt *transport)
  {
  	struct socket *sock = transport->sock;
  	struct sock *sk = transport->inet;
  
  	if (sk == NULL)
  		return;
  
  	transport->srcport = 0;
  
  	write_lock_bh(&sk->sk_callback_lock);
  	transport->inet = NULL;
  	transport->sock = NULL;
  
  	sk->sk_user_data = NULL;
  
  	xs_restore_old_callbacks(transport, sk);
  	write_unlock_bh(&sk->sk_callback_lock);
  
  	sk->sk_no_check = 0;
  
  	sock_release(sock);
  }
  
  /**
   * xs_close - close a socket
   * @xprt: transport
   *
   * This is used when all requests are complete; ie, no DRC state remains
   * on the server we want to save.
   *
   * The caller _must_ be holding XPRT_LOCKED in order to avoid issues with
   * xs_reset_transport() zeroing the socket from underneath a writer.
   */
  static void xs_close(struct rpc_xprt *xprt)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  
  	dprintk("RPC:       xs_close xprt %p\n", xprt);
  
  	xs_reset_transport(transport);
  	xprt->reestablish_timeout = 0;
  
  	smp_mb__before_clear_bit();
  	clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
  	clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
  	clear_bit(XPRT_CLOSING, &xprt->state);
  	smp_mb__after_clear_bit();
  	xprt_disconnect_done(xprt);
  }
  
  static void xs_tcp_close(struct rpc_xprt *xprt)
  {
  	if (test_and_clear_bit(XPRT_CONNECTION_CLOSE, &xprt->state))
  		xs_close(xprt);
  	else
  		xs_tcp_shutdown(xprt);
  }
  
  /**
   * xs_destroy - prepare to shutdown a transport
   * @xprt: doomed transport
   *
   */
  static void xs_destroy(struct rpc_xprt *xprt)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  
  	dprintk("RPC:       xs_destroy xprt %p\n", xprt);
  
  	cancel_delayed_work_sync(&transport->connect_worker);
  
  	xs_close(xprt);
  	xs_free_peer_addresses(xprt);
  	xprt_free(xprt);
  	module_put(THIS_MODULE);
  }
  
  static inline struct rpc_xprt *xprt_from_sock(struct sock *sk)
  {
  	return (struct rpc_xprt *) sk->sk_user_data;
  }
  
  static int xs_local_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
  {
  	struct xdr_skb_reader desc = {
  		.skb		= skb,
  		.offset		= sizeof(rpc_fraghdr),
  		.count		= skb->len - sizeof(rpc_fraghdr),
  	};
  
  	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
  		return -1;
  	if (desc.count)
  		return -1;
  	return 0;
  }
  
  /**
   * xs_local_data_ready - "data ready" callback for AF_LOCAL sockets
   * @sk: socket with data to read
   * @len: how much data to read
   *
   * Currently this assumes we can read the whole reply in a single gulp.
   */
  static void xs_local_data_ready(struct sock *sk, int len)
  {
  	struct rpc_task *task;
  	struct rpc_xprt *xprt;
  	struct rpc_rqst *rovr;
  	struct sk_buff *skb;
  	int err, repsize, copied;
  	u32 _xid;
  	__be32 *xp;
  
  	read_lock_bh(&sk->sk_callback_lock);
  	dprintk("RPC:       %s...\n", __func__);
  	xprt = xprt_from_sock(sk);
  	if (xprt == NULL)
  		goto out;
  
  	skb = skb_recv_datagram(sk, 0, 1, &err);
  	if (skb == NULL)
  		goto out;
  
  	if (xprt->shutdown)
  		goto dropit;
  
  	repsize = skb->len - sizeof(rpc_fraghdr);
  	if (repsize < 4) {
  		dprintk("RPC:       impossible RPC reply size %d\n", repsize);
  		goto dropit;
  	}
  
  	/* Copy the XID from the skb... */
  	xp = skb_header_pointer(skb, sizeof(rpc_fraghdr), sizeof(_xid), &_xid);
  	if (xp == NULL)
  		goto dropit;
  
  	/* Look up and lock the request corresponding to the given XID */
  	spin_lock(&xprt->transport_lock);
  	rovr = xprt_lookup_rqst(xprt, *xp);
  	if (!rovr)
  		goto out_unlock;
  	task = rovr->rq_task;
  
  	copied = rovr->rq_private_buf.buflen;
  	if (copied > repsize)
  		copied = repsize;
  
  	if (xs_local_copy_to_xdr(&rovr->rq_private_buf, skb)) {
  		dprintk("RPC:       sk_buff copy failed\n");
  		goto out_unlock;
  	}
  
  	xprt_complete_rqst(task, copied);
  
   out_unlock:
  	spin_unlock(&xprt->transport_lock);
   dropit:
  	skb_free_datagram(sk, skb);
   out:
  	read_unlock_bh(&sk->sk_callback_lock);
  }
  
  /**
   * xs_udp_data_ready - "data ready" callback for UDP sockets
   * @sk: socket with data to read
   * @len: how much data to read
   *
   */
  static void xs_udp_data_ready(struct sock *sk, int len)
  {
  	struct rpc_task *task;
  	struct rpc_xprt *xprt;
  	struct rpc_rqst *rovr;
  	struct sk_buff *skb;
  	int err, repsize, copied;
  	u32 _xid;
  	__be32 *xp;
  
  	read_lock_bh(&sk->sk_callback_lock);
  	dprintk("RPC:       xs_udp_data_ready...\n");
  	if (!(xprt = xprt_from_sock(sk)))
  		goto out;
  
  	if ((skb = skb_recv_datagram(sk, 0, 1, &err)) == NULL)
  		goto out;
  
  	if (xprt->shutdown)
  		goto dropit;
  
  	repsize = skb->len - sizeof(struct udphdr);
  	if (repsize < 4) {
  		dprintk("RPC:       impossible RPC reply size %d!\n", repsize);
  		goto dropit;
  	}
  
  	/* Copy the XID from the skb... */
  	xp = skb_header_pointer(skb, sizeof(struct udphdr),
  				sizeof(_xid), &_xid);
  	if (xp == NULL)
  		goto dropit;
  
  	/* Look up and lock the request corresponding to the given XID */
  	spin_lock(&xprt->transport_lock);
  	rovr = xprt_lookup_rqst(xprt, *xp);
  	if (!rovr)
  		goto out_unlock;
  	task = rovr->rq_task;
  
  	if ((copied = rovr->rq_private_buf.buflen) > repsize)
  		copied = repsize;
  
  	/* Suck it into the iovec, verify checksum if not done by hw. */
  	if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb)) {
  		UDPX_INC_STATS_BH(sk, UDP_MIB_INERRORS);
  		goto out_unlock;
  	}
  
  	UDPX_INC_STATS_BH(sk, UDP_MIB_INDATAGRAMS);
  
  	xprt_adjust_cwnd(task, copied);
  	xprt_complete_rqst(task, copied);
  
   out_unlock:
  	spin_unlock(&xprt->transport_lock);
   dropit:
  	skb_free_datagram(sk, skb);
   out:
  	read_unlock_bh(&sk->sk_callback_lock);
  }
  
  /*
   * Helper function to force a TCP close if the server is sending
   * junk and/or it has put us in CLOSE_WAIT
   */
  static void xs_tcp_force_close(struct rpc_xprt *xprt)
  {
  	set_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
  	xprt_force_disconnect(xprt);
  }
  
  static inline void xs_tcp_read_fraghdr(struct rpc_xprt *xprt, struct xdr_skb_reader *desc)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	size_t len, used;
  	char *p;
  
  	p = ((char *) &transport->tcp_fraghdr) + transport->tcp_offset;
  	len = sizeof(transport->tcp_fraghdr) - transport->tcp_offset;
  	used = xdr_skb_read_bits(desc, p, len);
  	transport->tcp_offset += used;
  	if (used != len)
  		return;
  
  	transport->tcp_reclen = ntohl(transport->tcp_fraghdr);
  	if (transport->tcp_reclen & RPC_LAST_STREAM_FRAGMENT)
  		transport->tcp_flags |= TCP_RCV_LAST_FRAG;
  	else
  		transport->tcp_flags &= ~TCP_RCV_LAST_FRAG;
  	transport->tcp_reclen &= RPC_FRAGMENT_SIZE_MASK;
  
  	transport->tcp_flags &= ~TCP_RCV_COPY_FRAGHDR;
  	transport->tcp_offset = 0;
  
  	/* Sanity check of the record length */
  	if (unlikely(transport->tcp_reclen < 8)) {
  		dprintk("RPC:       invalid TCP record fragment length\n");
  		xs_tcp_force_close(xprt);
  		return;
  	}
  	dprintk("RPC:       reading TCP record fragment of length %d\n",
  			transport->tcp_reclen);
  }
  
  static void xs_tcp_check_fraghdr(struct sock_xprt *transport)
  {
  	if (transport->tcp_offset == transport->tcp_reclen) {
  		transport->tcp_flags |= TCP_RCV_COPY_FRAGHDR;
  		transport->tcp_offset = 0;
  		if (transport->tcp_flags & TCP_RCV_LAST_FRAG) {
  			transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
  			transport->tcp_flags |= TCP_RCV_COPY_XID;
  			transport->tcp_copied = 0;
  		}
  	}
  }
  
  static inline void xs_tcp_read_xid(struct sock_xprt *transport, struct xdr_skb_reader *desc)
  {
  	size_t len, used;
  	char *p;
  
  	len = sizeof(transport->tcp_xid) - transport->tcp_offset;
  	dprintk("RPC:       reading XID (%Zu bytes)\n", len);
  	p = ((char *) &transport->tcp_xid) + transport->tcp_offset;
  	used = xdr_skb_read_bits(desc, p, len);
  	transport->tcp_offset += used;
  	if (used != len)
  		return;
  	transport->tcp_flags &= ~TCP_RCV_COPY_XID;
  	transport->tcp_flags |= TCP_RCV_READ_CALLDIR;
  	transport->tcp_copied = 4;
  	dprintk("RPC:       reading %s XID %08x\n",
  			(transport->tcp_flags & TCP_RPC_REPLY) ? "reply for"
  							      : "request with",
  			ntohl(transport->tcp_xid));
  	xs_tcp_check_fraghdr(transport);
  }
  
  static inline void xs_tcp_read_calldir(struct sock_xprt *transport,
  				       struct xdr_skb_reader *desc)
  {
  	size_t len, used;
  	u32 offset;
  	char *p;
  
  	/*
  	 * We want transport->tcp_offset to be 8 at the end of this routine
  	 * (4 bytes for the xid and 4 bytes for the call/reply flag).
  	 * When this function is called for the first time,
  	 * transport->tcp_offset is 4 (after having already read the xid).
  	 */
  	offset = transport->tcp_offset - sizeof(transport->tcp_xid);
  	len = sizeof(transport->tcp_calldir) - offset;
  	dprintk("RPC:       reading CALL/REPLY flag (%Zu bytes)\n", len);
  	p = ((char *) &transport->tcp_calldir) + offset;
  	used = xdr_skb_read_bits(desc, p, len);
  	transport->tcp_offset += used;
  	if (used != len)
  		return;
  	transport->tcp_flags &= ~TCP_RCV_READ_CALLDIR;
  	/*
  	 * We don't yet have the XDR buffer, so we will write the calldir
  	 * out after we get the buffer from the 'struct rpc_rqst'
  	 */
  	switch (ntohl(transport->tcp_calldir)) {
  	case RPC_REPLY:
  		transport->tcp_flags |= TCP_RCV_COPY_CALLDIR;
  		transport->tcp_flags |= TCP_RCV_COPY_DATA;
  		transport->tcp_flags |= TCP_RPC_REPLY;
  		break;
  	case RPC_CALL:
  		transport->tcp_flags |= TCP_RCV_COPY_CALLDIR;
  		transport->tcp_flags |= TCP_RCV_COPY_DATA;
  		transport->tcp_flags &= ~TCP_RPC_REPLY;
  		break;
  	default:
  		dprintk("RPC:       invalid request message type\n");
  		xs_tcp_force_close(&transport->xprt);
  	}
  	xs_tcp_check_fraghdr(transport);
  }
  
  static inline void xs_tcp_read_common(struct rpc_xprt *xprt,
  				     struct xdr_skb_reader *desc,
  				     struct rpc_rqst *req)
  {
  	struct sock_xprt *transport =
  				container_of(xprt, struct sock_xprt, xprt);
  	struct xdr_buf *rcvbuf;
  	size_t len;
  	ssize_t r;
  
  	rcvbuf = &req->rq_private_buf;
  
  	if (transport->tcp_flags & TCP_RCV_COPY_CALLDIR) {
  		/*
  		 * Save the RPC direction in the XDR buffer
  		 */
  		memcpy(rcvbuf->head[0].iov_base + transport->tcp_copied,
  			&transport->tcp_calldir,
  			sizeof(transport->tcp_calldir));
  		transport->tcp_copied += sizeof(transport->tcp_calldir);
  		transport->tcp_flags &= ~TCP_RCV_COPY_CALLDIR;
  	}
  
  	len = desc->count;
  	if (len > transport->tcp_reclen - transport->tcp_offset) {
  		struct xdr_skb_reader my_desc;
  
  		len = transport->tcp_reclen - transport->tcp_offset;
  		memcpy(&my_desc, desc, sizeof(my_desc));
  		my_desc.count = len;
  		r = xdr_partial_copy_from_skb(rcvbuf, transport->tcp_copied,
  					  &my_desc, xdr_skb_read_bits);
  		desc->count -= r;
  		desc->offset += r;
  	} else
  		r = xdr_partial_copy_from_skb(rcvbuf, transport->tcp_copied,
  					  desc, xdr_skb_read_bits);
  
  	if (r > 0) {
  		transport->tcp_copied += r;
  		transport->tcp_offset += r;
  	}
  	if (r != len) {
  		/* Error when copying to the receive buffer,
  		 * usually because we weren't able to allocate
  		 * additional buffer pages. All we can do now
  		 * is turn off TCP_RCV_COPY_DATA, so the request
  		 * will not receive any additional updates,
  		 * and time out.
  		 * Any remaining data from this record will
  		 * be discarded.
  		 */
  		transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
  		dprintk("RPC:       XID %08x truncated request\n",
  				ntohl(transport->tcp_xid));
  		dprintk("RPC:       xprt = %p, tcp_copied = %lu, "
  				"tcp_offset = %u, tcp_reclen = %u\n",
  				xprt, transport->tcp_copied,
  				transport->tcp_offset, transport->tcp_reclen);
  		return;
  	}
  
  	dprintk("RPC:       XID %08x read %Zd bytes\n",
  			ntohl(transport->tcp_xid), r);
  	dprintk("RPC:       xprt = %p, tcp_copied = %lu, tcp_offset = %u, "
  			"tcp_reclen = %u\n", xprt, transport->tcp_copied,
  			transport->tcp_offset, transport->tcp_reclen);
  
  	if (transport->tcp_copied == req->rq_private_buf.buflen)
  		transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
  	else if (transport->tcp_offset == transport->tcp_reclen) {
  		if (transport->tcp_flags & TCP_RCV_LAST_FRAG)
  			transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
  	}
  }
  
  /*
   * Finds the request corresponding to the RPC xid and invokes the common
   * tcp read code to read the data.
   */
  static inline int xs_tcp_read_reply(struct rpc_xprt *xprt,
  				    struct xdr_skb_reader *desc)
  {
  	struct sock_xprt *transport =
  				container_of(xprt, struct sock_xprt, xprt);
  	struct rpc_rqst *req;
  
  	dprintk("RPC:       read reply XID %08x\n", ntohl(transport->tcp_xid));
  
  	/* Find and lock the request corresponding to this xid */
  	spin_lock(&xprt->transport_lock);
  	req = xprt_lookup_rqst(xprt, transport->tcp_xid);
  	if (!req) {
  		dprintk("RPC:       XID %08x request not found!\n",
  				ntohl(transport->tcp_xid));
  		spin_unlock(&xprt->transport_lock);
  		return -1;
  	}
  
  	xs_tcp_read_common(xprt, desc, req);
  
  	if (!(transport->tcp_flags & TCP_RCV_COPY_DATA))
  		xprt_complete_rqst(req->rq_task, transport->tcp_copied);
  
  	spin_unlock(&xprt->transport_lock);
  	return 0;
  }
  
  #if defined(CONFIG_SUNRPC_BACKCHANNEL)
  /*
   * Obtains an rpc_rqst previously allocated and invokes the common
   * tcp read code to read the data.  The result is placed in the callback
   * queue.
   * If we're unable to obtain the rpc_rqst we schedule the closing of the
   * connection and return -1.
   */
  static inline int xs_tcp_read_callback(struct rpc_xprt *xprt,
  				       struct xdr_skb_reader *desc)
  {
  	struct sock_xprt *transport =
  				container_of(xprt, struct sock_xprt, xprt);
  	struct rpc_rqst *req;
  
  	req = xprt_alloc_bc_request(xprt);
  	if (req == NULL) {
  		printk(KERN_WARNING "Callback slot table overflowed\n");
  		xprt_force_disconnect(xprt);
  		return -1;
  	}
  
  	req->rq_xid = transport->tcp_xid;
  	dprintk("RPC:       read callback  XID %08x\n", ntohl(req->rq_xid));
  	xs_tcp_read_common(xprt, desc, req);
  
  	if (!(transport->tcp_flags & TCP_RCV_COPY_DATA)) {
  		struct svc_serv *bc_serv = xprt->bc_serv;
  
  		/*
  		 * Add callback request to callback list.  The callback
  		 * service sleeps on the sv_cb_waitq waiting for new
  		 * requests.  Wake it up after adding enqueing the
  		 * request.
  		 */
  		dprintk("RPC:       add callback request to list\n");
  		spin_lock(&bc_serv->sv_cb_lock);
  		list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
  		spin_unlock(&bc_serv->sv_cb_lock);
  		wake_up(&bc_serv->sv_cb_waitq);
  	}
  
  	req->rq_private_buf.len = transport->tcp_copied;
  
  	return 0;
  }
  
  static inline int _xs_tcp_read_data(struct rpc_xprt *xprt,
  					struct xdr_skb_reader *desc)
  {
  	struct sock_xprt *transport =
  				container_of(xprt, struct sock_xprt, xprt);
  
  	return (transport->tcp_flags & TCP_RPC_REPLY) ?
  		xs_tcp_read_reply(xprt, desc) :
  		xs_tcp_read_callback(xprt, desc);
  }
  #else
  static inline int _xs_tcp_read_data(struct rpc_xprt *xprt,
  					struct xdr_skb_reader *desc)
  {
  	return xs_tcp_read_reply(xprt, desc);
  }
  #endif /* CONFIG_SUNRPC_BACKCHANNEL */
  
  /*
   * Read data off the transport.  This can be either an RPC_CALL or an
   * RPC_REPLY.  Relay the processing to helper functions.
   */
  static void xs_tcp_read_data(struct rpc_xprt *xprt,
  				    struct xdr_skb_reader *desc)
  {
  	struct sock_xprt *transport =
  				container_of(xprt, struct sock_xprt, xprt);
  
  	if (_xs_tcp_read_data(xprt, desc) == 0)
  		xs_tcp_check_fraghdr(transport);
  	else {
  		/*
  		 * The transport_lock protects the request handling.
  		 * There's no need to hold it to update the tcp_flags.
  		 */
  		transport->tcp_flags &= ~TCP_RCV_COPY_DATA;
  	}
  }
  
  static inline void xs_tcp_read_discard(struct sock_xprt *transport, struct xdr_skb_reader *desc)
  {
  	size_t len;
  
  	len = transport->tcp_reclen - transport->tcp_offset;
  	if (len > desc->count)
  		len = desc->count;
  	desc->count -= len;
  	desc->offset += len;
  	transport->tcp_offset += len;
  	dprintk("RPC:       discarded %Zu bytes\n", len);
  	xs_tcp_check_fraghdr(transport);
  }
  
  static int xs_tcp_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb, unsigned int offset, size_t len)
  {
  	struct rpc_xprt *xprt = rd_desc->arg.data;
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	struct xdr_skb_reader desc = {
  		.skb	= skb,
  		.offset	= offset,
  		.count	= len,
  	};
  
  	dprintk("RPC:       xs_tcp_data_recv started\n");
  	do {
  		/* Read in a new fragment marker if necessary */
  		/* Can we ever really expect to get completely empty fragments? */
  		if (transport->tcp_flags & TCP_RCV_COPY_FRAGHDR) {
  			xs_tcp_read_fraghdr(xprt, &desc);
  			continue;
  		}
  		/* Read in the xid if necessary */
  		if (transport->tcp_flags & TCP_RCV_COPY_XID) {
  			xs_tcp_read_xid(transport, &desc);
  			continue;
  		}
  		/* Read in the call/reply flag */
  		if (transport->tcp_flags & TCP_RCV_READ_CALLDIR) {
  			xs_tcp_read_calldir(transport, &desc);
  			continue;
  		}
  		/* Read in the request data */
  		if (transport->tcp_flags & TCP_RCV_COPY_DATA) {
  			xs_tcp_read_data(xprt, &desc);
  			continue;
  		}
  		/* Skip over any trailing bytes on short reads */
  		xs_tcp_read_discard(transport, &desc);
  	} while (desc.count);
  	dprintk("RPC:       xs_tcp_data_recv done\n");
  	return len - desc.count;
  }
  
  /**
   * xs_tcp_data_ready - "data ready" callback for TCP sockets
   * @sk: socket with data to read
   * @bytes: how much data to read
   *
   */
  static void xs_tcp_data_ready(struct sock *sk, int bytes)
  {
  	struct rpc_xprt *xprt;
  	read_descriptor_t rd_desc;
  	int read;
  
  	dprintk("RPC:       xs_tcp_data_ready...\n");
  
  	read_lock_bh(&sk->sk_callback_lock);
  	if (!(xprt = xprt_from_sock(sk)))
  		goto out;
  	if (xprt->shutdown)
  		goto out;
  
  	/* Any data means we had a useful conversation, so
  	 * the we don't need to delay the next reconnect
  	 */
  	if (xprt->reestablish_timeout)
  		xprt->reestablish_timeout = 0;
  
  	/* We use rd_desc to pass struct xprt to xs_tcp_data_recv */
  	rd_desc.arg.data = xprt;
  	do {
  		rd_desc.count = 65536;
  		read = tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
  	} while (read > 0);
  out:
  	read_unlock_bh(&sk->sk_callback_lock);
  }
  
  /*
   * Do the equivalent of linger/linger2 handling for dealing with
   * broken servers that don't close the socket in a timely
   * fashion
   */
  static void xs_tcp_schedule_linger_timeout(struct rpc_xprt *xprt,
  		unsigned long timeout)
  {
  	struct sock_xprt *transport;
  
  	if (xprt_test_and_set_connecting(xprt))
  		return;
  	set_bit(XPRT_CONNECTION_ABORT, &xprt->state);
  	transport = container_of(xprt, struct sock_xprt, xprt);
  	queue_delayed_work(rpciod_workqueue, &transport->connect_worker,
  			   timeout);
  }
  
  static void xs_tcp_cancel_linger_timeout(struct rpc_xprt *xprt)
  {
  	struct sock_xprt *transport;
  
  	transport = container_of(xprt, struct sock_xprt, xprt);
  
  	if (!test_bit(XPRT_CONNECTION_ABORT, &xprt->state) ||
  	    !cancel_delayed_work(&transport->connect_worker))
  		return;
  	clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
  	xprt_clear_connecting(xprt);
  }
  
  static void xs_sock_mark_closed(struct rpc_xprt *xprt)
  {
  	smp_mb__before_clear_bit();
  	clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
  	clear_bit(XPRT_CONNECTION_CLOSE, &xprt->state);
  	clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
  	clear_bit(XPRT_CLOSING, &xprt->state);
  	smp_mb__after_clear_bit();
  	/* Mark transport as closed and wake up all pending tasks */
  	xprt_disconnect_done(xprt);
  }
  
  /**
   * xs_tcp_state_change - callback to handle TCP socket state changes
   * @sk: socket whose state has changed
   *
   */
  static void xs_tcp_state_change(struct sock *sk)
  {
  	struct rpc_xprt *xprt;
  
  	read_lock_bh(&sk->sk_callback_lock);
  	if (!(xprt = xprt_from_sock(sk)))
  		goto out;
  	dprintk("RPC:       xs_tcp_state_change client %p...\n", xprt);
  	dprintk("RPC:       state %x conn %d dead %d zapped %d sk_shutdown %d\n",
  			sk->sk_state, xprt_connected(xprt),
  			sock_flag(sk, SOCK_DEAD),
  			sock_flag(sk, SOCK_ZAPPED),
  			sk->sk_shutdown);
  
  	switch (sk->sk_state) {
  	case TCP_ESTABLISHED:
  		spin_lock(&xprt->transport_lock);
  		if (!xprt_test_and_set_connected(xprt)) {
  			struct sock_xprt *transport = container_of(xprt,
  					struct sock_xprt, xprt);
  
  			/* Reset TCP record info */
  			transport->tcp_offset = 0;
  			transport->tcp_reclen = 0;
  			transport->tcp_copied = 0;
  			transport->tcp_flags =
  				TCP_RCV_COPY_FRAGHDR | TCP_RCV_COPY_XID;
  
  			xprt_wake_pending_tasks(xprt, -EAGAIN);
  		}
  		spin_unlock(&xprt->transport_lock);
  		break;
  	case TCP_FIN_WAIT1:
  		/* The client initiated a shutdown of the socket */
  		xprt->connect_cookie++;
  		xprt->reestablish_timeout = 0;
  		set_bit(XPRT_CLOSING, &xprt->state);
  		smp_mb__before_clear_bit();
  		clear_bit(XPRT_CONNECTED, &xprt->state);
  		clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
  		smp_mb__after_clear_bit();
  		xs_tcp_schedule_linger_timeout(xprt, xs_tcp_fin_timeout);
  		break;
  	case TCP_CLOSE_WAIT:
  		/* The server initiated a shutdown of the socket */
  		xprt->connect_cookie++;
  		xs_tcp_force_close(xprt);
  	case TCP_CLOSING:
  		/*
  		 * If the server closed down the connection, make sure that
  		 * we back off before reconnecting
  		 */
  		if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
  			xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
  		break;
  	case TCP_LAST_ACK:
  		set_bit(XPRT_CLOSING, &xprt->state);
  		xs_tcp_schedule_linger_timeout(xprt, xs_tcp_fin_timeout);
  		smp_mb__before_clear_bit();
  		clear_bit(XPRT_CONNECTED, &xprt->state);
  		smp_mb__after_clear_bit();
  		break;
  	case TCP_CLOSE:
  		xs_tcp_cancel_linger_timeout(xprt);
  		xs_sock_mark_closed(xprt);
  	}
   out:
  	read_unlock_bh(&sk->sk_callback_lock);
  }
  
  /**
   * xs_error_report - callback mainly for catching socket errors
   * @sk: socket
   */
  static void xs_error_report(struct sock *sk)
  {
  	struct rpc_xprt *xprt;
  
  	read_lock_bh(&sk->sk_callback_lock);
  	if (!(xprt = xprt_from_sock(sk)))
  		goto out;
  	dprintk("RPC:       %s client %p...\n"
  			"RPC:       error %d\n",
  			__func__, xprt, sk->sk_err);
  	xprt_wake_pending_tasks(xprt, -EAGAIN);
  out:
  	read_unlock_bh(&sk->sk_callback_lock);
  }
  
  static void xs_write_space(struct sock *sk)
  {
  	struct socket *sock;
  	struct rpc_xprt *xprt;
  
  	if (unlikely(!(sock = sk->sk_socket)))
  		return;
  	clear_bit(SOCK_NOSPACE, &sock->flags);
  
  	if (unlikely(!(xprt = xprt_from_sock(sk))))
  		return;
  	if (test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags) == 0)
  		return;
  
  	xprt_write_space(xprt);
  }
  
  /**
   * xs_udp_write_space - callback invoked when socket buffer space
   *                             becomes available
   * @sk: socket whose state has changed
   *
   * Called when more output buffer space is available for this socket.
   * We try not to wake our writers until they can make "significant"
   * progress, otherwise we'll waste resources thrashing kernel_sendmsg
   * with a bunch of small requests.
   */
  static void xs_udp_write_space(struct sock *sk)
  {
  	read_lock_bh(&sk->sk_callback_lock);
  
  	/* from net/core/sock.c:sock_def_write_space */
  	if (sock_writeable(sk))
  		xs_write_space(sk);
  
  	read_unlock_bh(&sk->sk_callback_lock);
  }
  
  /**
   * xs_tcp_write_space - callback invoked when socket buffer space
   *                             becomes available
   * @sk: socket whose state has changed
   *
   * Called when more output buffer space is available for this socket.
   * We try not to wake our writers until they can make "significant"
   * progress, otherwise we'll waste resources thrashing kernel_sendmsg
   * with a bunch of small requests.
   */
  static void xs_tcp_write_space(struct sock *sk)
  {
  	read_lock_bh(&sk->sk_callback_lock);
  
  	/* from net/core/stream.c:sk_stream_write_space */
  	if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk))
  		xs_write_space(sk);
  
  	read_unlock_bh(&sk->sk_callback_lock);
  }
  
  static void xs_udp_do_set_buffer_size(struct rpc_xprt *xprt)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	struct sock *sk = transport->inet;
  
  	if (transport->rcvsize) {
  		sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
  		sk->sk_rcvbuf = transport->rcvsize * xprt->max_reqs * 2;
  	}
  	if (transport->sndsize) {
  		sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
  		sk->sk_sndbuf = transport->sndsize * xprt->max_reqs * 2;
  		sk->sk_write_space(sk);
  	}
  }
  
  /**
   * xs_udp_set_buffer_size - set send and receive limits
   * @xprt: generic transport
   * @sndsize: requested size of send buffer, in bytes
   * @rcvsize: requested size of receive buffer, in bytes
   *
   * Set socket send and receive buffer size limits.
   */
  static void xs_udp_set_buffer_size(struct rpc_xprt *xprt, size_t sndsize, size_t rcvsize)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  
  	transport->sndsize = 0;
  	if (sndsize)
  		transport->sndsize = sndsize + 1024;
  	transport->rcvsize = 0;
  	if (rcvsize)
  		transport->rcvsize = rcvsize + 1024;
  
  	xs_udp_do_set_buffer_size(xprt);
  }
  
  /**
   * xs_udp_timer - called when a retransmit timeout occurs on a UDP transport
   * @task: task that timed out
   *
   * Adjust the congestion window after a retransmit timeout has occurred.
   */
  static void xs_udp_timer(struct rpc_task *task)
  {
  	xprt_adjust_cwnd(task, -ETIMEDOUT);
  }
  
  static unsigned short xs_get_random_port(void)
  {
  	unsigned short range = xprt_max_resvport - xprt_min_resvport;
  	unsigned short rand = (unsigned short) net_random() % range;
  	return rand + xprt_min_resvport;
  }
  
  /**
   * xs_set_port - reset the port number in the remote endpoint address
   * @xprt: generic transport
   * @port: new port number
   *
   */
  static void xs_set_port(struct rpc_xprt *xprt, unsigned short port)
  {
  	dprintk("RPC:       setting port for xprt %p to %u\n", xprt, port);
  
  	rpc_set_port(xs_addr(xprt), port);
  	xs_update_peer_port(xprt);
  }
  
  static unsigned short xs_get_srcport(struct sock_xprt *transport)
  {
  	unsigned short port = transport->srcport;
  
  	if (port == 0 && transport->xprt.resvport)
  		port = xs_get_random_port();
  	return port;
  }
  
  static unsigned short xs_next_srcport(struct sock_xprt *transport, unsigned short port)
  {
  	if (transport->srcport != 0)
  		transport->srcport = 0;
  	if (!transport->xprt.resvport)
  		return 0;
  	if (port <= xprt_min_resvport || port > xprt_max_resvport)
  		return xprt_max_resvport;
  	return --port;
  }
  static int xs_bind(struct sock_xprt *transport, struct socket *sock)
  {
  	struct sockaddr_storage myaddr;
  	int err, nloop = 0;
  	unsigned short port = xs_get_srcport(transport);
  	unsigned short last;
  
  	memcpy(&myaddr, &transport->srcaddr, transport->xprt.addrlen);
  	do {
  		rpc_set_port((struct sockaddr *)&myaddr, port);
  		err = kernel_bind(sock, (struct sockaddr *)&myaddr,
  				transport->xprt.addrlen);
  		if (port == 0)
  			break;
  		if (err == 0) {
  			transport->srcport = port;
  			break;
  		}
  		last = port;
  		port = xs_next_srcport(transport, port);
  		if (port > last)
  			nloop++;
  	} while (err == -EADDRINUSE && nloop != 2);
  
  	if (myaddr.ss_family == AF_INET)
  		dprintk("RPC:       %s %pI4:%u: %s (%d)\n", __func__,
  				&((struct sockaddr_in *)&myaddr)->sin_addr,
  				port, err ? "failed" : "ok", err);
  	else
  		dprintk("RPC:       %s %pI6:%u: %s (%d)\n", __func__,
  				&((struct sockaddr_in6 *)&myaddr)->sin6_addr,
  				port, err ? "failed" : "ok", err);
  	return err;
  }
  
  /*
   * We don't support autobind on AF_LOCAL sockets
   */
  static void xs_local_rpcbind(struct rpc_task *task)
  {
  	xprt_set_bound(task->tk_xprt);
  }
  
  static void xs_local_set_port(struct rpc_xprt *xprt, unsigned short port)
  {
  }
  
  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  static struct lock_class_key xs_key[2];
  static struct lock_class_key xs_slock_key[2];
  
  static inline void xs_reclassify_socketu(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  
  	BUG_ON(sock_owned_by_user(sk));
  	sock_lock_init_class_and_name(sk, "slock-AF_LOCAL-RPC",
  		&xs_slock_key[1], "sk_lock-AF_LOCAL-RPC", &xs_key[1]);
  }
  
  static inline void xs_reclassify_socket4(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  
  	BUG_ON(sock_owned_by_user(sk));
  	sock_lock_init_class_and_name(sk, "slock-AF_INET-RPC",
  		&xs_slock_key[0], "sk_lock-AF_INET-RPC", &xs_key[0]);
  }
  
  static inline void xs_reclassify_socket6(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  
  	BUG_ON(sock_owned_by_user(sk));
  	sock_lock_init_class_and_name(sk, "slock-AF_INET6-RPC",
  		&xs_slock_key[1], "sk_lock-AF_INET6-RPC", &xs_key[1]);
  }
  
  static inline void xs_reclassify_socket(int family, struct socket *sock)
  {
  	switch (family) {
  	case AF_LOCAL:
  		xs_reclassify_socketu(sock);
  		break;
  	case AF_INET:
  		xs_reclassify_socket4(sock);
  		break;
  	case AF_INET6:
  		xs_reclassify_socket6(sock);
  		break;
  	}
  }
  #else
  static inline void xs_reclassify_socketu(struct socket *sock)
  {
  }
  
  static inline void xs_reclassify_socket4(struct socket *sock)
  {
  }
  
  static inline void xs_reclassify_socket6(struct socket *sock)
  {
  }
  
  static inline void xs_reclassify_socket(int family, struct socket *sock)
  {
  }
  #endif
  
  static struct socket *xs_create_sock(struct rpc_xprt *xprt,
  		struct sock_xprt *transport, int family, int type, int protocol)
  {
  	struct socket *sock;
  	int err;
  
  	err = __sock_create(xprt->xprt_net, family, type, protocol, &sock, 1);
  	if (err < 0) {
  		dprintk("RPC:       can't create %d transport socket (%d).\n",
  				protocol, -err);
  		goto out;
  	}
  	xs_reclassify_socket(family, sock);
  
  	err = xs_bind(transport, sock);
  	if (err) {
  		sock_release(sock);
  		goto out;
  	}
  
  	return sock;
  out:
  	return ERR_PTR(err);
  }
  
  static int xs_local_finish_connecting(struct rpc_xprt *xprt,
  				      struct socket *sock)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
  									xprt);
  
  	if (!transport->inet) {
  		struct sock *sk = sock->sk;
  
  		write_lock_bh(&sk->sk_callback_lock);
  
  		xs_save_old_callbacks(transport, sk);
  
  		sk->sk_user_data = xprt;
  		sk->sk_data_ready = xs_local_data_ready;
  		sk->sk_write_space = xs_udp_write_space;
  		sk->sk_error_report = xs_error_report;
  		sk->sk_allocation = GFP_ATOMIC;
  
  		xprt_clear_connected(xprt);
  
  		/* Reset to new socket */
  		transport->sock = sock;
  		transport->inet = sk;
  
  		write_unlock_bh(&sk->sk_callback_lock);
  	}
  
  	/* Tell the socket layer to start connecting... */
  	xprt->stat.connect_count++;
  	xprt->stat.connect_start = jiffies;
  	return kernel_connect(sock, xs_addr(xprt), xprt->addrlen, 0);
  }
  
  /**
   * xs_local_setup_socket - create AF_LOCAL socket, connect to a local endpoint
   * @xprt: RPC transport to connect
   * @transport: socket transport to connect
   * @create_sock: function to create a socket of the correct type
   *
   * Invoked by a work queue tasklet.
   */
  static void xs_local_setup_socket(struct work_struct *work)
  {
  	struct sock_xprt *transport =
  		container_of(work, struct sock_xprt, connect_worker.work);
  	struct rpc_xprt *xprt = &transport->xprt;
  	struct socket *sock;
  	int status = -EIO;
  
  	if (xprt->shutdown)
  		goto out;
  
  	current->flags |= PF_FSTRANS;
  
  	clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
  	status = __sock_create(xprt->xprt_net, AF_LOCAL,
  					SOCK_STREAM, 0, &sock, 1);
  	if (status < 0) {
  		dprintk("RPC:       can't create AF_LOCAL "
  			"transport socket (%d).\n", -status);
  		goto out;
  	}
  	xs_reclassify_socketu(sock);
  
  	dprintk("RPC:       worker connecting xprt %p via AF_LOCAL to %s\n",
  			xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
  
  	status = xs_local_finish_connecting(xprt, sock);
  	switch (status) {
  	case 0:
  		dprintk("RPC:       xprt %p connected to %s\n",
  				xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
  		xprt_set_connected(xprt);
  		break;
  	case -ENOENT:
  		dprintk("RPC:       xprt %p: socket %s does not exist\n",
  				xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
  		break;
  	default:
  		printk(KERN_ERR "%s: unhandled error (%d) connecting to %s\n",
  				__func__, -status,
  				xprt->address_strings[RPC_DISPLAY_ADDR]);
  	}
  
  out:
  	xprt_clear_connecting(xprt);
  	xprt_wake_pending_tasks(xprt, status);
  	current->flags &= ~PF_FSTRANS;
  }
  
  #ifdef CONFIG_SUNRPC_SWAP
  static void xs_set_memalloc(struct rpc_xprt *xprt)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
  			xprt);
  
  	if (xprt->swapper)
  		sk_set_memalloc(transport->inet);
  }
  
  /**
   * xs_swapper - Tag this transport as being used for swap.
   * @xprt: transport to tag
   * @enable: enable/disable
   *
   */
  int xs_swapper(struct rpc_xprt *xprt, int enable)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
  			xprt);
  	int err = 0;
  
  	if (enable) {
  		xprt->swapper++;
  		xs_set_memalloc(xprt);
  	} else if (xprt->swapper) {
  		xprt->swapper--;
  		sk_clear_memalloc(transport->inet);
  	}
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(xs_swapper);
  #else
  static void xs_set_memalloc(struct rpc_xprt *xprt)
  {
  }
  #endif
  
  static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  
  	if (!transport->inet) {
  		struct sock *sk = sock->sk;
  
  		write_lock_bh(&sk->sk_callback_lock);
  
  		xs_save_old_callbacks(transport, sk);
  
  		sk->sk_user_data = xprt;
  		sk->sk_data_ready = xs_udp_data_ready;
  		sk->sk_write_space = xs_udp_write_space;
  		sk->sk_error_report = xs_error_report;
  		sk->sk_no_check = UDP_CSUM_NORCV;
  		sk->sk_allocation = GFP_ATOMIC;
  
  		xprt_set_connected(xprt);
  
  		/* Reset to new socket */
  		transport->sock = sock;
  		transport->inet = sk;
  
  		xs_set_memalloc(xprt);
  
  		write_unlock_bh(&sk->sk_callback_lock);
  	}
  	xs_udp_do_set_buffer_size(xprt);
  }
  
  static void xs_udp_setup_socket(struct work_struct *work)
  {
  	struct sock_xprt *transport =
  		container_of(work, struct sock_xprt, connect_worker.work);
  	struct rpc_xprt *xprt = &transport->xprt;
  	struct socket *sock = transport->sock;
  	int status = -EIO;
  
  	if (xprt->shutdown)
  		goto out;
  
  	current->flags |= PF_FSTRANS;
  
  	/* Start by resetting any existing state */
  	xs_reset_transport(transport);
  	sock = xs_create_sock(xprt, transport,
  			xs_addr(xprt)->sa_family, SOCK_DGRAM, IPPROTO_UDP);
  	if (IS_ERR(sock))
  		goto out;
  
  	dprintk("RPC:       worker connecting xprt %p via %s to "
  				"%s (port %s)\n", xprt,
  			xprt->address_strings[RPC_DISPLAY_PROTO],
  			xprt->address_strings[RPC_DISPLAY_ADDR],
  			xprt->address_strings[RPC_DISPLAY_PORT]);
  
  	xs_udp_finish_connecting(xprt, sock);
  	status = 0;
  out:
  	xprt_clear_connecting(xprt);
  	xprt_wake_pending_tasks(xprt, status);
  	current->flags &= ~PF_FSTRANS;
  }
  
  /*
   * We need to preserve the port number so the reply cache on the server can
   * find our cached RPC replies when we get around to reconnecting.
   */
  static void xs_abort_connection(struct sock_xprt *transport)
  {
  	int result;
  	struct sockaddr any;
  
  	dprintk("RPC:       disconnecting xprt %p to reuse port\n", transport);
  
  	/*
  	 * Disconnect the transport socket by doing a connect operation
  	 * with AF_UNSPEC.  This should return immediately...
  	 */
  	memset(&any, 0, sizeof(any));
  	any.sa_family = AF_UNSPEC;
  	result = kernel_connect(transport->sock, &any, sizeof(any), 0);
  	if (!result)
  		xs_sock_mark_closed(&transport->xprt);
  	else
  		dprintk("RPC:       AF_UNSPEC connect return code %d\n",
  				result);
  }
  
  static void xs_tcp_reuse_connection(struct sock_xprt *transport)
  {
  	unsigned int state = transport->inet->sk_state;
  
  	if (state == TCP_CLOSE && transport->sock->state == SS_UNCONNECTED) {
  		/* we don't need to abort the connection if the socket
  		 * hasn't undergone a shutdown
  		 */
  		if (transport->inet->sk_shutdown == 0)
  			return;
  		dprintk("RPC:       %s: TCP_CLOSEd and sk_shutdown set to %d\n",
  				__func__, transport->inet->sk_shutdown);
  	}
  	if ((1 << state) & (TCPF_ESTABLISHED|TCPF_SYN_SENT)) {
  		/* we don't need to abort the connection if the socket
  		 * hasn't undergone a shutdown
  		 */
  		if (transport->inet->sk_shutdown == 0)
  			return;
  		dprintk("RPC:       %s: ESTABLISHED/SYN_SENT "
  				"sk_shutdown set to %d\n",
  				__func__, transport->inet->sk_shutdown);
  	}
  	xs_abort_connection(transport);
  }
  
  static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	int ret = -ENOTCONN;
  
  	if (!transport->inet) {
  		struct sock *sk = sock->sk;
  
  		write_lock_bh(&sk->sk_callback_lock);
  
  		xs_save_old_callbacks(transport, sk);
  
  		sk->sk_user_data = xprt;
  		sk->sk_data_ready = xs_tcp_data_ready;
  		sk->sk_state_change = xs_tcp_state_change;
  		sk->sk_write_space = xs_tcp_write_space;
  		sk->sk_error_report = xs_error_report;
  		sk->sk_allocation = GFP_ATOMIC;
  
  		/* socket options */
  		sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
  		sock_reset_flag(sk, SOCK_LINGER);
  		tcp_sk(sk)->linger2 = 0;
  		tcp_sk(sk)->nonagle |= TCP_NAGLE_OFF;
  
  		xprt_clear_connected(xprt);
  
  		/* Reset to new socket */
  		transport->sock = sock;
  		transport->inet = sk;
  
  		write_unlock_bh(&sk->sk_callback_lock);
  	}
  
  	if (!xprt_bound(xprt))
  		goto out;
  
  	xs_set_memalloc(xprt);
  
  	/* Tell the socket layer to start connecting... */
  	xprt->stat.connect_count++;
  	xprt->stat.connect_start = jiffies;
  	ret = kernel_connect(sock, xs_addr(xprt), xprt->addrlen, O_NONBLOCK);
  	switch (ret) {
  	case 0:
  	case -EINPROGRESS:
  		/* SYN_SENT! */
  		xprt->connect_cookie++;
  		if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
  			xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
  	}
  out:
  	return ret;
  }
  
  /**
   * xs_tcp_setup_socket - create a TCP socket and connect to a remote endpoint
   * @xprt: RPC transport to connect
   * @transport: socket transport to connect
   * @create_sock: function to create a socket of the correct type
   *
   * Invoked by a work queue tasklet.
   */
  static void xs_tcp_setup_socket(struct work_struct *work)
  {
  	struct sock_xprt *transport =
  		container_of(work, struct sock_xprt, connect_worker.work);
  	struct socket *sock = transport->sock;
  	struct rpc_xprt *xprt = &transport->xprt;
  	int status = -EIO;
  
  	if (xprt->shutdown)
  		goto out;
  
  	current->flags |= PF_FSTRANS;
  
  	if (!sock) {
  		clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
  		sock = xs_create_sock(xprt, transport,
  				xs_addr(xprt)->sa_family, SOCK_STREAM, IPPROTO_TCP);
  		if (IS_ERR(sock)) {
  			status = PTR_ERR(sock);
  			goto out;
  		}
  	} else {
  		int abort_and_exit;
  
  		abort_and_exit = test_and_clear_bit(XPRT_CONNECTION_ABORT,
  				&xprt->state);
  		/* "close" the socket, preserving the local port */
  		xs_tcp_reuse_connection(transport);
  
  		if (abort_and_exit)
  			goto out_eagain;
  	}
  
  	dprintk("RPC:       worker connecting xprt %p via %s to "
  				"%s (port %s)\n", xprt,
  			xprt->address_strings[RPC_DISPLAY_PROTO],
  			xprt->address_strings[RPC_DISPLAY_ADDR],
  			xprt->address_strings[RPC_DISPLAY_PORT]);
  
  	status = xs_tcp_finish_connecting(xprt, sock);
  	dprintk("RPC:       %p connect status %d connected %d sock state %d\n",
  			xprt, -status, xprt_connected(xprt),
  			sock->sk->sk_state);
  	switch (status) {
  	default:
  		printk("%s: connect returned unhandled error %d\n",
  			__func__, status);
  	case -EADDRNOTAVAIL:
  		/* We're probably in TIME_WAIT. Get rid of existing socket,
  		 * and retry
  		 */
  		xs_tcp_force_close(xprt);
  		break;
  	case -ECONNREFUSED:
  	case -ECONNRESET:
  	case -ENETUNREACH:
  		/* retry with existing socket, after a delay */
  	case 0:
  	case -EINPROGRESS:
  	case -EALREADY:
  		xprt_clear_connecting(xprt);
  		current->flags &= ~PF_FSTRANS;
  		return;
  	case -EINVAL:
  		/* Happens, for instance, if the user specified a link
  		 * local IPv6 address without a scope-id.
  		 */
  		goto out;
  	}
  out_eagain:
  	status = -EAGAIN;
  out:
  	xprt_clear_connecting(xprt);
  	xprt_wake_pending_tasks(xprt, status);
  	current->flags &= ~PF_FSTRANS;
  }
  
  /**
   * xs_connect - connect a socket to a remote endpoint
   * @task: address of RPC task that manages state of connect request
   *
   * TCP: If the remote end dropped the connection, delay reconnecting.
   *
   * UDP socket connects are synchronous, but we use a work queue anyway
   * to guarantee that even unprivileged user processes can set up a
   * socket on a privileged port.
   *
   * If a UDP socket connect fails, the delay behavior here prevents
   * retry floods (hard mounts).
   */
  static void xs_connect(struct rpc_task *task)
  {
  	struct rpc_xprt *xprt = task->tk_xprt;
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  
  	if (transport->sock != NULL && !RPC_IS_SOFTCONN(task)) {
  		dprintk("RPC:       xs_connect delayed xprt %p for %lu "
  				"seconds\n",
  				xprt, xprt->reestablish_timeout / HZ);
  		queue_delayed_work(rpciod_workqueue,
  				   &transport->connect_worker,
  				   xprt->reestablish_timeout);
  		xprt->reestablish_timeout <<= 1;
  		if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
  			xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
  		if (xprt->reestablish_timeout > XS_TCP_MAX_REEST_TO)
  			xprt->reestablish_timeout = XS_TCP_MAX_REEST_TO;
  	} else {
  		dprintk("RPC:       xs_connect scheduled xprt %p\n", xprt);
  		queue_delayed_work(rpciod_workqueue,
  				   &transport->connect_worker, 0);
  	}
  }
  
  /**
   * xs_local_print_stats - display AF_LOCAL socket-specifc stats
   * @xprt: rpc_xprt struct containing statistics
   * @seq: output file
   *
   */
  static void xs_local_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
  {
  	long idle_time = 0;
  
  	if (xprt_connected(xprt))
  		idle_time = (long)(jiffies - xprt->last_used) / HZ;
  
  	seq_printf(seq, "\txprt:\tlocal %lu %lu %lu %ld %lu %lu %lu "
  			"%llu %llu %lu %llu %llu\n",
  			xprt->stat.bind_count,
  			xprt->stat.connect_count,
  			xprt->stat.connect_time,
  			idle_time,
  			xprt->stat.sends,
  			xprt->stat.recvs,
  			xprt->stat.bad_xids,
  			xprt->stat.req_u,
  			xprt->stat.bklog_u,
  			xprt->stat.max_slots,
  			xprt->stat.sending_u,
  			xprt->stat.pending_u);
  }
  
  /**
   * xs_udp_print_stats - display UDP socket-specifc stats
   * @xprt: rpc_xprt struct containing statistics
   * @seq: output file
   *
   */
  static void xs_udp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  
  	seq_printf(seq, "\txprt:\tudp %u %lu %lu %lu %lu %llu %llu "
  			"%lu %llu %llu\n",
  			transport->srcport,
  			xprt->stat.bind_count,
  			xprt->stat.sends,
  			xprt->stat.recvs,
  			xprt->stat.bad_xids,
  			xprt->stat.req_u,
  			xprt->stat.bklog_u,
  			xprt->stat.max_slots,
  			xprt->stat.sending_u,
  			xprt->stat.pending_u);
  }
  
  /**
   * xs_tcp_print_stats - display TCP socket-specifc stats
   * @xprt: rpc_xprt struct containing statistics
   * @seq: output file
   *
   */
  static void xs_tcp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
  {
  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
  	long idle_time = 0;
  
  	if (xprt_connected(xprt))
  		idle_time = (long)(jiffies - xprt->last_used) / HZ;
  
  	seq_printf(seq, "\txprt:\ttcp %u %lu %lu %lu %ld %lu %lu %lu "
  			"%llu %llu %lu %llu %llu\n",
  			transport->srcport,
  			xprt->stat.bind_count,
  			xprt->stat.connect_count,
  			xprt->stat.connect_time,
  			idle_time,
  			xprt->stat.sends,
  			xprt->stat.recvs,
  			xprt->stat.bad_xids,
  			xprt->stat.req_u,
  			xprt->stat.bklog_u,
  			xprt->stat.max_slots,
  			xprt->stat.sending_u,
  			xprt->stat.pending_u);
  }
  
  /*
   * Allocate a bunch of pages for a scratch buffer for the rpc code. The reason
   * we allocate pages instead doing a kmalloc like rpc_malloc is because we want
   * to use the server side send routines.
   */
  static void *bc_malloc(struct rpc_task *task, size_t size)
  {
  	struct page *page;
  	struct rpc_buffer *buf;
  
  	BUG_ON(size > PAGE_SIZE - sizeof(struct rpc_buffer));
  	page = alloc_page(GFP_KERNEL);
  
  	if (!page)
  		return NULL;
  
  	buf = page_address(page);
  	buf->len = PAGE_SIZE;
  
  	return buf->data;
  }
  
  /*
   * Free the space allocated in the bc_alloc routine
   */
  static void bc_free(void *buffer)
  {
  	struct rpc_buffer *buf;
  
  	if (!buffer)
  		return;
  
  	buf = container_of(buffer, struct rpc_buffer, data);
  	free_page((unsigned long)buf);
  }
  
  /*
   * Use the svc_sock to send the callback. Must be called with svsk->sk_mutex
   * held. Borrows heavily from svc_tcp_sendto and xs_tcp_send_request.
   */
  static int bc_sendto(struct rpc_rqst *req)
  {
  	int len;
  	struct xdr_buf *xbufp = &req->rq_snd_buf;
  	struct rpc_xprt *xprt = req->rq_xprt;
  	struct sock_xprt *transport =
  				container_of(xprt, struct sock_xprt, xprt);
  	struct socket *sock = transport->sock;
  	unsigned long headoff;
  	unsigned long tailoff;
  
  	xs_encode_stream_record_marker(xbufp);
  
  	tailoff = (unsigned long)xbufp->tail[0].iov_base & ~PAGE_MASK;
  	headoff = (unsigned long)xbufp->head[0].iov_base & ~PAGE_MASK;
  	len = svc_send_common(sock, xbufp,
  			      virt_to_page(xbufp->head[0].iov_base), headoff,
  			      xbufp->tail[0].iov_base, tailoff);
  
  	if (len != xbufp->len) {
  		printk(KERN_NOTICE "Error sending entire callback!\n");
  		len = -EAGAIN;
  	}
  
  	return len;
  }
  
  /*
   * The send routine. Borrows from svc_send
   */
  static int bc_send_request(struct rpc_task *task)
  {
  	struct rpc_rqst *req = task->tk_rqstp;
  	struct svc_xprt	*xprt;
  	struct svc_sock         *svsk;
  	u32                     len;
  
  	dprintk("sending request with xid: %08x\n", ntohl(req->rq_xid));
  	/*
  	 * Get the server socket associated with this callback xprt
  	 */
  	xprt = req->rq_xprt->bc_xprt;
  	svsk = container_of(xprt, struct svc_sock, sk_xprt);
  
  	/*
  	 * Grab the mutex to serialize data as the connection is shared
  	 * with the fore channel
  	 */
  	if (!mutex_trylock(&xprt->xpt_mutex)) {
  		rpc_sleep_on(&xprt->xpt_bc_pending, task, NULL);
  		if (!mutex_trylock(&xprt->xpt_mutex))
  			return -EAGAIN;
  		rpc_wake_up_queued_task(&xprt->xpt_bc_pending, task);
  	}
  	if (test_bit(XPT_DEAD, &xprt->xpt_flags))
  		len = -ENOTCONN;
  	else
  		len = bc_sendto(req);
  	mutex_unlock(&xprt->xpt_mutex);
  
  	if (len > 0)
  		len = 0;
  
  	return len;
  }
  
  /*
   * The close routine. Since this is client initiated, we do nothing
   */
  
  static void bc_close(struct rpc_xprt *xprt)
  {
  }
  
  /*
   * The xprt destroy routine. Again, because this connection is client
   * initiated, we do nothing
   */
  
  static void bc_destroy(struct rpc_xprt *xprt)
  {
  }
  
  static struct rpc_xprt_ops xs_local_ops = {
  	.reserve_xprt		= xprt_reserve_xprt,
  	.release_xprt		= xs_tcp_release_xprt,
  	.alloc_slot		= xprt_alloc_slot,
  	.rpcbind		= xs_local_rpcbind,
  	.set_port		= xs_local_set_port,
  	.connect		= xs_connect,
  	.buf_alloc		= rpc_malloc,
  	.buf_free		= rpc_free,
  	.send_request		= xs_local_send_request,
  	.set_retrans_timeout	= xprt_set_retrans_timeout_def,
  	.close			= xs_close,
  	.destroy		= xs_destroy,
  	.print_stats		= xs_local_print_stats,
  };
  
  static struct rpc_xprt_ops xs_udp_ops = {
  	.set_buffer_size	= xs_udp_set_buffer_size,
  	.reserve_xprt		= xprt_reserve_xprt_cong,
  	.release_xprt		= xprt_release_xprt_cong,
  	.alloc_slot		= xprt_alloc_slot,
  	.rpcbind		= rpcb_getport_async,
  	.set_port		= xs_set_port,
  	.connect		= xs_connect,
  	.buf_alloc		= rpc_malloc,
  	.buf_free		= rpc_free,
  	.send_request		= xs_udp_send_request,
  	.set_retrans_timeout	= xprt_set_retrans_timeout_rtt,
  	.timer			= xs_udp_timer,
  	.release_request	= xprt_release_rqst_cong,
  	.close			= xs_close,
  	.destroy		= xs_destroy,
  	.print_stats		= xs_udp_print_stats,
  };
  
  static struct rpc_xprt_ops xs_tcp_ops = {
  	.reserve_xprt		= xprt_reserve_xprt,
  	.release_xprt		= xs_tcp_release_xprt,
  	.alloc_slot		= xprt_lock_and_alloc_slot,
  	.rpcbind		= rpcb_getport_async,
  	.set_port		= xs_set_port,
  	.connect		= xs_connect,
  	.buf_alloc		= rpc_malloc,
  	.buf_free		= rpc_free,
  	.send_request		= xs_tcp_send_request,
  	.set_retrans_timeout	= xprt_set_retrans_timeout_def,
  	.close			= xs_tcp_close,
  	.destroy		= xs_destroy,
  	.print_stats		= xs_tcp_print_stats,
  };
  
  /*
   * The rpc_xprt_ops for the server backchannel
   */
  
  static struct rpc_xprt_ops bc_tcp_ops = {
  	.reserve_xprt		= xprt_reserve_xprt,
  	.release_xprt		= xprt_release_xprt,
  	.rpcbind		= xs_local_rpcbind,
  	.buf_alloc		= bc_malloc,
  	.buf_free		= bc_free,
  	.send_request		= bc_send_request,
  	.set_retrans_timeout	= xprt_set_retrans_timeout_def,
  	.close			= bc_close,
  	.destroy		= bc_destroy,
  	.print_stats		= xs_tcp_print_stats,
  };
  
  static int xs_init_anyaddr(const int family, struct sockaddr *sap)
  {
  	static const struct sockaddr_in sin = {
  		.sin_family		= AF_INET,
  		.sin_addr.s_addr	= htonl(INADDR_ANY),
  	};
  	static const struct sockaddr_in6 sin6 = {
  		.sin6_family		= AF_INET6,
  		.sin6_addr		= IN6ADDR_ANY_INIT,
  	};
  
  	switch (family) {
  	case AF_LOCAL:
  		break;
  	case AF_INET:
  		memcpy(sap, &sin, sizeof(sin));
  		break;
  	case AF_INET6:
  		memcpy(sap, &sin6, sizeof(sin6));
  		break;
  	default:
  		dprintk("RPC:       %s: Bad address family\n", __func__);
  		return -EAFNOSUPPORT;
  	}
  	return 0;
  }
  
  static struct rpc_xprt *xs_setup_xprt(struct xprt_create *args,
  				      unsigned int slot_table_size,
  				      unsigned int max_slot_table_size)
  {
  	struct rpc_xprt *xprt;
  	struct sock_xprt *new;
  
  	if (args->addrlen > sizeof(xprt->addr)) {
  		dprintk("RPC:       xs_setup_xprt: address too large\n");
  		return ERR_PTR(-EBADF);
  	}
  
  	xprt = xprt_alloc(args->net, sizeof(*new), slot_table_size,
  			max_slot_table_size);
  	if (xprt == NULL) {
  		dprintk("RPC:       xs_setup_xprt: couldn't allocate "
  				"rpc_xprt\n");
  		return ERR_PTR(-ENOMEM);
  	}
  
  	new = container_of(xprt, struct sock_xprt, xprt);
  	memcpy(&xprt->addr, args->dstaddr, args->addrlen);
  	xprt->addrlen = args->addrlen;
  	if (args->srcaddr)
  		memcpy(&new->srcaddr, args->srcaddr, args->addrlen);
  	else {
  		int err;
  		err = xs_init_anyaddr(args->dstaddr->sa_family,
  					(struct sockaddr *)&new->srcaddr);
  		if (err != 0) {
  			xprt_free(xprt);
  			return ERR_PTR(err);
  		}
  	}
  
  	return xprt;
  }
  
  static const struct rpc_timeout xs_local_default_timeout = {
  	.to_initval = 10 * HZ,
  	.to_maxval = 10 * HZ,
  	.to_retries = 2,
  };
  
  /**
   * xs_setup_local - Set up transport to use an AF_LOCAL socket
   * @args: rpc transport creation arguments
   *
   * AF_LOCAL is a "tpi_cots_ord" transport, just like TCP
   */
  static struct rpc_xprt *xs_setup_local(struct xprt_create *args)
  {
  	struct sockaddr_un *sun = (struct sockaddr_un *)args->dstaddr;
  	struct sock_xprt *transport;
  	struct rpc_xprt *xprt;
  	struct rpc_xprt *ret;
  
  	xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries,
  			xprt_max_tcp_slot_table_entries);
  	if (IS_ERR(xprt))
  		return xprt;
  	transport = container_of(xprt, struct sock_xprt, xprt);
  
  	xprt->prot = 0;
  	xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
  	xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;
  
  	xprt->bind_timeout = XS_BIND_TO;
  	xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
  	xprt->idle_timeout = XS_IDLE_DISC_TO;
  
  	xprt->ops = &xs_local_ops;
  	xprt->timeout = &xs_local_default_timeout;
  
  	switch (sun->sun_family) {
  	case AF_LOCAL:
  		if (sun->sun_path[0] != '/') {
  			dprintk("RPC:       bad AF_LOCAL address: %s\n",
  					sun->sun_path);
  			ret = ERR_PTR(-EINVAL);
  			goto out_err;
  		}
  		xprt_set_bound(xprt);
  		INIT_DELAYED_WORK(&transport->connect_worker,
  					xs_local_setup_socket);
  		xs_format_peer_addresses(xprt, "local", RPCBIND_NETID_LOCAL);
  		break;
  	default:
  		ret = ERR_PTR(-EAFNOSUPPORT);
  		goto out_err;
  	}
  
  	dprintk("RPC:       set up xprt to %s via AF_LOCAL\n",
  			xprt->address_strings[RPC_DISPLAY_ADDR]);
  
  	if (try_module_get(THIS_MODULE))
  		return xprt;
  	ret = ERR_PTR(-EINVAL);
  out_err:
  	xprt_free(xprt);
  	return ret;
  }
  
  static const struct rpc_timeout xs_udp_default_timeout = {
  	.to_initval = 5 * HZ,
  	.to_maxval = 30 * HZ,
  	.to_increment = 5 * HZ,
  	.to_retries = 5,
  };
  
  /**
   * xs_setup_udp - Set up transport to use a UDP socket
   * @args: rpc transport creation arguments
   *
   */
  static struct rpc_xprt *xs_setup_udp(struct xprt_create *args)
  {
  	struct sockaddr *addr = args->dstaddr;
  	struct rpc_xprt *xprt;
  	struct sock_xprt *transport;
  	struct rpc_xprt *ret;
  
  	xprt = xs_setup_xprt(args, xprt_udp_slot_table_entries,
  			xprt_udp_slot_table_entries);
  	if (IS_ERR(xprt))
  		return xprt;
  	transport = container_of(xprt, struct sock_xprt, xprt);
  
  	xprt->prot = IPPROTO_UDP;
  	xprt->tsh_size = 0;
  	/* XXX: header size can vary due to auth type, IPv6, etc. */
  	xprt->max_payload = (1U << 16) - (MAX_HEADER << 3);
  
  	xprt->bind_timeout = XS_BIND_TO;
  	xprt->reestablish_timeout = XS_UDP_REEST_TO;
  	xprt->idle_timeout = XS_IDLE_DISC_TO;
  
  	xprt->ops = &xs_udp_ops;
  
  	xprt->timeout = &xs_udp_default_timeout;
  
  	switch (addr->sa_family) {
  	case AF_INET:
  		if (((struct sockaddr_in *)addr)->sin_port != htons(0))
  			xprt_set_bound(xprt);
  
  		INIT_DELAYED_WORK(&transport->connect_worker,
  					xs_udp_setup_socket);
  		xs_format_peer_addresses(xprt, "udp", RPCBIND_NETID_UDP);
  		break;
  	case AF_INET6:
  		if (((struct sockaddr_in6 *)addr)->sin6_port != htons(0))
  			xprt_set_bound(xprt);
  
  		INIT_DELAYED_WORK(&transport->connect_worker,
  					xs_udp_setup_socket);
  		xs_format_peer_addresses(xprt, "udp", RPCBIND_NETID_UDP6);
  		break;
  	default:
  		ret = ERR_PTR(-EAFNOSUPPORT);
  		goto out_err;
  	}
  
  	if (xprt_bound(xprt))
  		dprintk("RPC:       set up xprt to %s (port %s) via %s\n",
  				xprt->address_strings[RPC_DISPLAY_ADDR],
  				xprt->address_strings[RPC_DISPLAY_PORT],
  				xprt->address_strings[RPC_DISPLAY_PROTO]);
  	else
  		dprintk("RPC:       set up xprt to %s (autobind) via %s\n",
  				xprt->address_strings[RPC_DISPLAY_ADDR],
  				xprt->address_strings[RPC_DISPLAY_PROTO]);
  
  	if (try_module_get(THIS_MODULE))
  		return xprt;
  	ret = ERR_PTR(-EINVAL);
  out_err:
  	xprt_free(xprt);
  	return ret;
  }
  
  static const struct rpc_timeout xs_tcp_default_timeout = {
  	.to_initval = 60 * HZ,
  	.to_maxval = 60 * HZ,
  	.to_retries = 2,
  };
  
  /**
   * xs_setup_tcp - Set up transport to use a TCP socket
   * @args: rpc transport creation arguments
   *
   */
  static struct rpc_xprt *xs_setup_tcp(struct xprt_create *args)
  {
  	struct sockaddr *addr = args->dstaddr;
  	struct rpc_xprt *xprt;
  	struct sock_xprt *transport;
  	struct rpc_xprt *ret;
  
  	xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries,
  			xprt_max_tcp_slot_table_entries);
  	if (IS_ERR(xprt))
  		return xprt;
  	transport = container_of(xprt, struct sock_xprt, xprt);
  
  	xprt->prot = IPPROTO_TCP;
  	xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
  	xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;
  
  	xprt->bind_timeout = XS_BIND_TO;
  	xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
  	xprt->idle_timeout = XS_IDLE_DISC_TO;
  
  	xprt->ops = &xs_tcp_ops;
  	xprt->timeout = &xs_tcp_default_timeout;
  
  	switch (addr->sa_family) {
  	case AF_INET:
  		if (((struct sockaddr_in *)addr)->sin_port != htons(0))
  			xprt_set_bound(xprt);
  
  		INIT_DELAYED_WORK(&transport->connect_worker,
  					xs_tcp_setup_socket);
  		xs_format_peer_addresses(xprt, "tcp", RPCBIND_NETID_TCP);
  		break;
  	case AF_INET6:
  		if (((struct sockaddr_in6 *)addr)->sin6_port != htons(0))
  			xprt_set_bound(xprt);
  
  		INIT_DELAYED_WORK(&transport->connect_worker,
  					xs_tcp_setup_socket);
  		xs_format_peer_addresses(xprt, "tcp", RPCBIND_NETID_TCP6);
  		break;
  	default:
  		ret = ERR_PTR(-EAFNOSUPPORT);
  		goto out_err;
  	}
  
  	if (xprt_bound(xprt))
  		dprintk("RPC:       set up xprt to %s (port %s) via %s\n",
  				xprt->address_strings[RPC_DISPLAY_ADDR],
  				xprt->address_strings[RPC_DISPLAY_PORT],
  				xprt->address_strings[RPC_DISPLAY_PROTO]);
  	else
  		dprintk("RPC:       set up xprt to %s (autobind) via %s\n",
  				xprt->address_strings[RPC_DISPLAY_ADDR],
  				xprt->address_strings[RPC_DISPLAY_PROTO]);
  
  
  	if (try_module_get(THIS_MODULE))
  		return xprt;
  	ret = ERR_PTR(-EINVAL);
  out_err:
  	xprt_free(xprt);
  	return ret;
  }
  
  /**
   * xs_setup_bc_tcp - Set up transport to use a TCP backchannel socket
   * @args: rpc transport creation arguments
   *
   */
  static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
  {
  	struct sockaddr *addr = args->dstaddr;
  	struct rpc_xprt *xprt;
  	struct sock_xprt *transport;
  	struct svc_sock *bc_sock;
  	struct rpc_xprt *ret;
  
  	if (args->bc_xprt->xpt_bc_xprt) {
  		/*
  		 * This server connection already has a backchannel
  		 * export; we can't create a new one, as we wouldn't be
  		 * able to match replies based on xid any more.  So,
  		 * reuse the already-existing one:
  		 */
  		 return args->bc_xprt->xpt_bc_xprt;
  	}
  	xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries,
  			xprt_tcp_slot_table_entries);
  	if (IS_ERR(xprt))
  		return xprt;
  	transport = container_of(xprt, struct sock_xprt, xprt);
  
  	xprt->prot = IPPROTO_TCP;
  	xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
  	xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;
  	xprt->timeout = &xs_tcp_default_timeout;
  
  	/* backchannel */
  	xprt_set_bound(xprt);
  	xprt->bind_timeout = 0;
  	xprt->reestablish_timeout = 0;
  	xprt->idle_timeout = 0;
  
  	xprt->ops = &bc_tcp_ops;
  
  	switch (addr->sa_family) {
  	case AF_INET:
  		xs_format_peer_addresses(xprt, "tcp",
  					 RPCBIND_NETID_TCP);
  		break;
  	case AF_INET6:
  		xs_format_peer_addresses(xprt, "tcp",
  				   RPCBIND_NETID_TCP6);
  		break;
  	default:
  		ret = ERR_PTR(-EAFNOSUPPORT);
  		goto out_err;
  	}
  
  	dprintk("RPC:       set up xprt to %s (port %s) via %s\n",
  			xprt->address_strings[RPC_DISPLAY_ADDR],
  			xprt->address_strings[RPC_DISPLAY_PORT],
  			xprt->address_strings[RPC_DISPLAY_PROTO]);
  
  	/*
  	 * Once we've associated a backchannel xprt with a connection,
  	 * we want to keep it around as long as long as the connection
  	 * lasts, in case we need to start using it for a backchannel
  	 * again; this reference won't be dropped until bc_xprt is
  	 * destroyed.
  	 */
  	xprt_get(xprt);
  	args->bc_xprt->xpt_bc_xprt = xprt;
  	xprt->bc_xprt = args->bc_xprt;
  	bc_sock = container_of(args->bc_xprt, struct svc_sock, sk_xprt);
  	transport->sock = bc_sock->sk_sock;
  	transport->inet = bc_sock->sk_sk;
  
  	/*
  	 * Since we don't want connections for the backchannel, we set
  	 * the xprt status to connected
  	 */
  	xprt_set_connected(xprt);
  
  
  	if (try_module_get(THIS_MODULE))
  		return xprt;
  	xprt_put(xprt);
  	ret = ERR_PTR(-EINVAL);
  out_err:
  	xprt_free(xprt);
  	return ret;
  }
  
  static struct xprt_class	xs_local_transport = {
  	.list		= LIST_HEAD_INIT(xs_local_transport.list),
  	.name		= "named UNIX socket",
  	.owner		= THIS_MODULE,
  	.ident		= XPRT_TRANSPORT_LOCAL,
  	.setup		= xs_setup_local,
  };
  
  static struct xprt_class	xs_udp_transport = {
  	.list		= LIST_HEAD_INIT(xs_udp_transport.list),
  	.name		= "udp",
  	.owner		= THIS_MODULE,
  	.ident		= XPRT_TRANSPORT_UDP,
  	.setup		= xs_setup_udp,
  };
  
  static struct xprt_class	xs_tcp_transport = {
  	.list		= LIST_HEAD_INIT(xs_tcp_transport.list),
  	.name		= "tcp",
  	.owner		= THIS_MODULE,
  	.ident		= XPRT_TRANSPORT_TCP,
  	.setup		= xs_setup_tcp,
  };
  
  static struct xprt_class	xs_bc_tcp_transport = {
  	.list		= LIST_HEAD_INIT(xs_bc_tcp_transport.list),
  	.name		= "tcp NFSv4.1 backchannel",
  	.owner		= THIS_MODULE,
  	.ident		= XPRT_TRANSPORT_BC_TCP,
  	.setup		= xs_setup_bc_tcp,
  };
  
  /**
   * init_socket_xprt - set up xprtsock's sysctls, register with RPC client
   *
   */
  int init_socket_xprt(void)
  {
  #ifdef RPC_DEBUG
  	if (!sunrpc_table_header)
  		sunrpc_table_header = register_sysctl_table(sunrpc_table);
  #endif
  
  	xprt_register_transport(&xs_local_transport);
  	xprt_register_transport(&xs_udp_transport);
  	xprt_register_transport(&xs_tcp_transport);
  	xprt_register_transport(&xs_bc_tcp_transport);
  
  	return 0;
  }
  
  /**
   * cleanup_socket_xprt - remove xprtsock's sysctls, unregister
   *
   */
  void cleanup_socket_xprt(void)
  {
  #ifdef RPC_DEBUG
  	if (sunrpc_table_header) {
  		unregister_sysctl_table(sunrpc_table_header);
  		sunrpc_table_header = NULL;
  	}
  #endif
  
  	xprt_unregister_transport(&xs_local_transport);
  	xprt_unregister_transport(&xs_udp_transport);
  	xprt_unregister_transport(&xs_tcp_transport);
  	xprt_unregister_transport(&xs_bc_tcp_transport);
  }
  
  static int param_set_uint_minmax(const char *val,
  		const struct kernel_param *kp,
  		unsigned int min, unsigned int max)
  {
  	unsigned long num;
  	int ret;
  
  	if (!val)
  		return -EINVAL;
  	ret = strict_strtoul(val, 0, &num);
  	if (ret == -EINVAL || num < min || num > max)
  		return -EINVAL;
  	*((unsigned int *)kp->arg) = num;
  	return 0;
  }
  
  static int param_set_portnr(const char *val, const struct kernel_param *kp)
  {
  	return param_set_uint_minmax(val, kp,
  			RPC_MIN_RESVPORT,
  			RPC_MAX_RESVPORT);
  }
  
  static struct kernel_param_ops param_ops_portnr = {
  	.set = param_set_portnr,
  	.get = param_get_uint,
  };
  
  #define param_check_portnr(name, p) \
  	__param_check(name, p, unsigned int);
  
  module_param_named(min_resvport, xprt_min_resvport, portnr, 0644);
  module_param_named(max_resvport, xprt_max_resvport, portnr, 0644);
  
  static int param_set_slot_table_size(const char *val,
  				     const struct kernel_param *kp)
  {
  	return param_set_uint_minmax(val, kp,
  			RPC_MIN_SLOT_TABLE,
  			RPC_MAX_SLOT_TABLE);
  }
  
  static struct kernel_param_ops param_ops_slot_table_size = {
  	.set = param_set_slot_table_size,
  	.get = param_get_uint,
  };
  
  #define param_check_slot_table_size(name, p) \
  	__param_check(name, p, unsigned int);
  
  static int param_set_max_slot_table_size(const char *val,
  				     const struct kernel_param *kp)
  {
  	return param_set_uint_minmax(val, kp,
  			RPC_MIN_SLOT_TABLE,
  			RPC_MAX_SLOT_TABLE_LIMIT);
  }
  
  static struct kernel_param_ops param_ops_max_slot_table_size = {
  	.set = param_set_max_slot_table_size,
  	.get = param_get_uint,
  };
  
  #define param_check_max_slot_table_size(name, p) \
  	__param_check(name, p, unsigned int);
  
  module_param_named(tcp_slot_table_entries, xprt_tcp_slot_table_entries,
  		   slot_table_size, 0644);
  module_param_named(tcp_max_slot_table_entries, xprt_max_tcp_slot_table_entries,
  		   max_slot_table_size, 0644);
  module_param_named(udp_slot_table_entries, xprt_udp_slot_table_entries,
  		   slot_table_size, 0644);
  
  