Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3382 insertions, 0 deletions

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
new file mode 100644
index 000000000..a0a82d9a5
--- /dev/null
+++ b/net/sunrpc/xprtsock.c
@@ -0,0 +1,3382 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/addr.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 <trace/events/sunrpc.h>
+
+#include "sunrpc.h"
+
+#define RPC_TCP_READ_CHUNK_SZ	(3*512*1024)
+
+static void xs_close(struct rpc_xprt *xprt);
+static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
+		struct socket *sock);
+
+/*
+ * 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;
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+
+#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!
+ */
+
+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 struct 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 struct 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)
+
+/*
+ * 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)
+
+#if IS_ENABLED(CONFIG_SUNRPC_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
+
+static inline struct rpc_xprt *xprt_from_sock(struct sock *sk)
+{
+	return (struct rpc_xprt *) sk->sk_user_data;
+}
+
+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, bool zerocopy, int *sent_p)
+{
+	ssize_t (*do_sendpage)(struct socket *sock, struct page *page,
+			int offset, size_t size, int flags);
+	struct page **ppage;
+	unsigned int remainder;
+	int err;
+
+	remainder = xdr->page_len - base;
+	base += xdr->page_base;
+	ppage = xdr->pages + (base >> PAGE_SHIFT);
+	base &= ~PAGE_MASK;
+	do_sendpage = sock->ops->sendpage;
+	if (!zerocopy)
+		do_sendpage = sock_no_sendpage;
+	for(;;) {
+		unsigned int len = min_t(unsigned int, PAGE_SIZE - base, remainder);
+		int flags = XS_SENDMSG_FLAGS;
+
+		remainder -= len;
+		if (more)
+			flags |= MSG_MORE;
+		if (remainder != 0)
+			flags |= MSG_SENDPAGE_NOTLAST | MSG_MORE;
+		err = do_sendpage(sock, *ppage, base, len, flags);
+		if (remainder == 0 || err != len)
+			break;
+		*sent_p += err;
+		ppage++;
+		base = 0;
+	}
+	if (err > 0) {
+		*sent_p += err;
+		err = 0;
+	}
+	return err;
+}
+
+/**
+ * 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
+ * @zerocopy: true if it is safe to use sendpage()
+ * @sent_p: return the total number of bytes successfully queued for sending
+ *
+ */
+static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base, bool zerocopy, int *sent_p)
+{
+	unsigned int remainder = xdr->len - base;
+	int err = 0;
+	int sent = 0;
+
+	if (unlikely(!sock))
+		return -ENOTSOCK;
+
+	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_p += 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, zerocopy, &sent);
+		*sent_p += sent;
+		if (remainder == 0 || sent != len)
+			goto out;
+		base = 0;
+	} else
+		base -= xdr->page_len;
+
+	if (base >= xdr->tail[0].iov_len)
+		return 0;
+	err = xs_send_kvec(sock, NULL, 0, &xdr->tail[0], base, 0);
+out:
+	if (err > 0) {
+		*sent_p += err;
+		err = 0;
+	}
+	return err;
+}
+
+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--;
+}
+
+/**
+ * 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);
+	struct sock *sk = transport->inet;
+	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)) {
+		/* wait for more buffer space */
+		sk->sk_write_pending++;
+		xprt_wait_for_buffer_space(task, xs_nospace_callback);
+	} else
+		ret = -ENOTCONN;
+
+	spin_unlock_bh(&xprt->transport_lock);
+
+	/* Race breaker in case memory is freed before above code is called */
+	if (ret == -EAGAIN) {
+		struct socket_wq *wq;
+
+		rcu_read_lock();
+		wq = rcu_dereference(sk->sk_wq);
+		set_bit(SOCKWQ_ASYNC_NOSPACE, &wq->flags);
+		rcu_read_unlock();
+
+		sk->sk_write_space(sk);
+	}
+	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;
+	int sent = 0;
+
+	xs_encode_stream_record_marker(&req->rq_snd_buf);
+
+	xs_pktdump("packet data:",
+			req->rq_svec->iov_base, req->rq_svec->iov_len);
+
+	req->rq_xtime = ktime_get();
+	status = xs_sendpages(transport->sock, NULL, 0, xdr, req->rq_bytes_sent,
+			      true, &sent);
+	dprintk("RPC:       %s(%u) = %d\n",
+			__func__, xdr->len - req->rq_bytes_sent, status);
+
+	if (status == -EAGAIN && sock_writeable(transport->inet))
+		status = -ENOBUFS;
+
+	if (likely(sent > 0) || status == 0) {
+		req->rq_bytes_sent += sent;
+		req->rq_xmit_bytes_sent += sent;
+		if (likely(req->rq_bytes_sent >= req->rq_slen)) {
+			req->rq_bytes_sent = 0;
+			return 0;
+		}
+		status = -EAGAIN;
+	}
+
+	switch (status) {
+	case -ENOBUFS:
+		break;
+	case -EAGAIN:
+		status = xs_nospace(task);
+		break;
+	default:
+		dprintk("RPC:       sendmsg returned unrecognized error %d\n",
+			-status);
+		/* fall through */
+	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 sent = 0;
+	int status;
+
+	xs_pktdump("packet data:",
+				req->rq_svec->iov_base,
+				req->rq_svec->iov_len);
+
+	if (!xprt_bound(xprt))
+		return -ENOTCONN;
+	req->rq_xtime = ktime_get();
+	status = xs_sendpages(transport->sock, xs_addr(xprt), xprt->addrlen,
+			      xdr, req->rq_bytes_sent, true, &sent);
+
+	dprintk("RPC:       xs_udp_send_request(%u) = %d\n",
+			xdr->len - req->rq_bytes_sent, status);
+
+	/* firewall is blocking us, don't return -EAGAIN or we end up looping */
+	if (status == -EPERM)
+		goto process_status;
+
+	if (status == -EAGAIN && sock_writeable(transport->inet))
+		status = -ENOBUFS;
+
+	if (sent > 0 || status == 0) {
+		req->rq_xmit_bytes_sent += sent;
+		if (sent >= req->rq_slen)
+			return 0;
+		/* Still some bytes left; set up for a retry later. */
+		status = -EAGAIN;
+	}
+
+process_status:
+	switch (status) {
+	case -ENOTSOCK:
+		status = -ENOTCONN;
+		/* Should we call xs_close() here? */
+		break;
+	case -EAGAIN:
+		status = xs_nospace(task);
+		break;
+	case -ENETUNREACH:
+	case -ENOBUFS:
+	case -EPIPE:
+	case -ECONNREFUSED:
+	case -EPERM:
+		/* When the server has died, an ICMP port unreachable message
+		 * prompts ECONNREFUSED. */
+		break;
+	default:
+		dprintk("RPC:       sendmsg returned unrecognized error %d\n",
+			-status);
+	}
+
+	return status;
+}
+
+/**
+ * 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;
+	bool zerocopy = true;
+	bool vm_wait = false;
+	int status;
+	int sent;
+
+	xs_encode_stream_record_marker(&req->rq_snd_buf);
+
+	xs_pktdump("packet data:",
+				req->rq_svec->iov_base,
+				req->rq_svec->iov_len);
+	/* Don't use zero copy if this is a resend. If the RPC call
+	 * completes while the socket holds a reference to the pages,
+	 * then we may end up resending corrupted data.
+	 */
+	if (task->tk_flags & RPC_TASK_SENT)
+		zerocopy = false;
+
+	if (test_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state))
+		xs_tcp_set_socket_timeouts(xprt, transport->sock);
+
+	/* Continue transmitting the packet/record. We must be careful
+	 * to cope with writespace callbacks arriving _after_ we have
+	 * called sendmsg(). */
+	req->rq_xtime = ktime_get();
+	while (1) {
+		sent = 0;
+		status = xs_sendpages(transport->sock, NULL, 0, xdr,
+				      req->rq_bytes_sent, zerocopy, &sent);
+
+		dprintk("RPC:       xs_tcp_send_request(%u) = %d\n",
+				xdr->len - req->rq_bytes_sent, status);
+
+		/* If we've sent the entire packet, immediately
+		 * reset the count of bytes sent. */
+		req->rq_bytes_sent += sent;
+		req->rq_xmit_bytes_sent += sent;
+		if (likely(req->rq_bytes_sent >= req->rq_slen)) {
+			req->rq_bytes_sent = 0;
+			return 0;
+		}
+
+		WARN_ON_ONCE(sent == 0 && status == 0);
+
+		if (status == -EAGAIN ) {
+			/*
+			 * Return EAGAIN if we're sure we're hitting the
+			 * socket send buffer limits.
+			 */
+			if (test_bit(SOCK_NOSPACE, &transport->sock->flags))
+				break;
+			/*
+			 * Did we hit a memory allocation failure?
+			 */
+			if (sent == 0) {
+				status = -ENOBUFS;
+				if (vm_wait)
+					break;
+				/* Retry, knowing now that we're below the
+				 * socket send buffer limit
+				 */
+				vm_wait = true;
+			}
+			continue;
+		}
+		if (status < 0)
+			break;
+		vm_wait = false;
+	}
+
+	switch (status) {
+	case -ENOTSOCK:
+		status = -ENOTCONN;
+		/* Should we call xs_close() here? */
+		break;
+	case -EAGAIN:
+		status = xs_nospace(task);
+		break;
+	case -ECONNRESET:
+	case -ECONNREFUSED:
+	case -ENOTCONN:
+	case -EADDRINUSE:
+	case -ENOBUFS:
+	case -EPIPE:
+		break;
+	default:
+		dprintk("RPC:       sendmsg returned unrecognized error %d\n",
+			-status);
+	}
+
+	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, &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_sock_reset_state_flags(struct rpc_xprt *xprt)
+{
+	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
+
+	clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state);
+}
+
+static void xs_sock_reset_connection_flags(struct rpc_xprt *xprt)
+{
+	smp_mb__before_atomic();
+	clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
+	clear_bit(XPRT_CLOSING, &xprt->state);
+	xs_sock_reset_state_flags(xprt);
+	smp_mb__after_atomic();
+}
+
+/**
+ * xs_error_report - callback to handle TCP socket state errors
+ * @sk: socket
+ *
+ * Note: we don't call sock_error() since there may be a rpc_task
+ * using the socket, and so we don't want to clear sk->sk_err.
+ */
+static void xs_error_report(struct sock *sk)
+{
+	struct rpc_xprt *xprt;
+	int err;
+
+	read_lock_bh(&sk->sk_callback_lock);
+	if (!(xprt = xprt_from_sock(sk)))
+		goto out;
+
+	err = -sk->sk_err;
+	if (err == 0)
+		goto out;
+	dprintk("RPC:       xs_error_report client %p, error=%d...\n",
+			xprt, -err);
+	trace_rpc_socket_error(xprt, sk->sk_socket, err);
+	xprt_wake_pending_tasks(xprt, err);
+ out:
+	read_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void xs_reset_transport(struct sock_xprt *transport)
+{
+	struct socket *sock = transport->sock;
+	struct sock *sk = transport->inet;
+	struct rpc_xprt *xprt = &transport->xprt;
+
+	if (sk == NULL)
+		return;
+
+	if (atomic_read(&transport->xprt.swapper))
+		sk_clear_memalloc(sk);
+
+	kernel_sock_shutdown(sock, SHUT_RDWR);
+
+	mutex_lock(&transport->recv_mutex);
+	write_lock_bh(&sk->sk_callback_lock);
+	transport->inet = NULL;
+	transport->sock = NULL;
+
+	sk->sk_user_data = NULL;
+
+	xs_restore_old_callbacks(transport, sk);
+	xprt_clear_connected(xprt);
+	write_unlock_bh(&sk->sk_callback_lock);
+	xs_sock_reset_connection_flags(xprt);
+	mutex_unlock(&transport->recv_mutex);
+
+	trace_rpc_socket_close(xprt, sock);
+	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;
+
+	xprt_disconnect_done(xprt);
+}
+
+static void xs_inject_disconnect(struct rpc_xprt *xprt)
+{
+	dprintk("RPC:       injecting transport disconnect on xprt=%p\n",
+		xprt);
+	xprt_disconnect_done(xprt);
+}
+
+static void xs_xprt_free(struct rpc_xprt *xprt)
+{
+	xs_free_peer_addresses(xprt);
+	xprt_free(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);
+	cancel_work_sync(&transport->recv_worker);
+	xs_xprt_free(xprt);
+	module_put(THIS_MODULE);
+}
+
+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_read_skb
+ * @xprt: transport
+ * @sk: socket
+ * @skb: skbuff
+ *
+ * Currently this assumes we can read the whole reply in a single gulp.
+ */
+static void xs_local_data_read_skb(struct rpc_xprt *xprt,
+		struct sock *sk,
+		struct sk_buff *skb)
+{
+	struct rpc_task *task;
+	struct rpc_rqst *rovr;
+	int repsize, copied;
+	u32 _xid;
+	__be32 *xp;
+
+	repsize = skb->len - sizeof(rpc_fraghdr);
+	if (repsize < 4) {
+		dprintk("RPC:       impossible RPC reply size %d\n", repsize);
+		return;
+	}
+
+	/* Copy the XID from the skb... */
+	xp = skb_header_pointer(skb, sizeof(rpc_fraghdr), sizeof(_xid), &_xid);
+	if (xp == NULL)
+		return;
+
+	/* Look up and lock the request corresponding to the given XID */
+	spin_lock(&xprt->recv_lock);
+	rovr = xprt_lookup_rqst(xprt, *xp);
+	if (!rovr)
+		goto out_unlock;
+	xprt_pin_rqst(rovr);
+	spin_unlock(&xprt->recv_lock);
+	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");
+		spin_lock(&xprt->recv_lock);
+		goto out_unpin;
+	}
+
+	spin_lock(&xprt->recv_lock);
+	xprt_complete_rqst(task, copied);
+out_unpin:
+	xprt_unpin_rqst(rovr);
+ out_unlock:
+	spin_unlock(&xprt->recv_lock);
+}
+
+static void xs_local_data_receive(struct sock_xprt *transport)
+{
+	struct sk_buff *skb;
+	struct sock *sk;
+	int err;
+
+restart:
+	mutex_lock(&transport->recv_mutex);
+	sk = transport->inet;
+	if (sk == NULL)
+		goto out;
+	for (;;) {
+		skb = skb_recv_datagram(sk, 0, 1, &err);
+		if (skb != NULL) {
+			xs_local_data_read_skb(&transport->xprt, sk, skb);
+			skb_free_datagram(sk, skb);
+			continue;
+		}
+		if (!test_and_clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
+			break;
+		if (need_resched()) {
+			mutex_unlock(&transport->recv_mutex);
+			cond_resched();
+			goto restart;
+		}
+	}
+out:
+	mutex_unlock(&transport->recv_mutex);
+}
+
+static void xs_local_data_receive_workfn(struct work_struct *work)
+{
+	struct sock_xprt *transport =
+		container_of(work, struct sock_xprt, recv_worker);
+	xs_local_data_receive(transport);
+}
+
+/**
+ * xs_udp_data_read_skb - receive callback for UDP sockets
+ * @xprt: transport
+ * @sk: socket
+ * @skb: skbuff
+ *
+ */
+static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
+		struct sock *sk,
+		struct sk_buff *skb)
+{
+	struct rpc_task *task;
+	struct rpc_rqst *rovr;
+	int repsize, copied;
+	u32 _xid;
+	__be32 *xp;
+
+	repsize = skb->len;
+	if (repsize < 4) {
+		dprintk("RPC:       impossible RPC reply size %d!\n", repsize);
+		return;
+	}
+
+	/* Copy the XID from the skb... */
+	xp = skb_header_pointer(skb, 0, sizeof(_xid), &_xid);
+	if (xp == NULL)
+		return;
+
+	/* Look up and lock the request corresponding to the given XID */
+	spin_lock(&xprt->recv_lock);
+	rovr = xprt_lookup_rqst(xprt, *xp);
+	if (!rovr)
+		goto out_unlock;
+	xprt_pin_rqst(rovr);
+	xprt_update_rtt(rovr->rq_task);
+	spin_unlock(&xprt->recv_lock);
+	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)) {
+		spin_lock(&xprt->recv_lock);
+		__UDPX_INC_STATS(sk, UDP_MIB_INERRORS);
+		goto out_unpin;
+	}
+
+
+	spin_lock_bh(&xprt->transport_lock);
+	xprt_adjust_cwnd(xprt, task, copied);
+	spin_unlock_bh(&xprt->transport_lock);
+	spin_lock(&xprt->recv_lock);
+	xprt_complete_rqst(task, copied);
+	__UDPX_INC_STATS(sk, UDP_MIB_INDATAGRAMS);
+out_unpin:
+	xprt_unpin_rqst(rovr);
+ out_unlock:
+	spin_unlock(&xprt->recv_lock);
+}
+
+static void xs_udp_data_receive(struct sock_xprt *transport)
+{
+	struct sk_buff *skb;
+	struct sock *sk;
+	int err;
+
+restart:
+	mutex_lock(&transport->recv_mutex);
+	sk = transport->inet;
+	if (sk == NULL)
+		goto out;
+	for (;;) {
+		skb = skb_recv_udp(sk, 0, 1, &err);
+		if (skb != NULL) {
+			xs_udp_data_read_skb(&transport->xprt, sk, skb);
+			consume_skb(skb);
+			continue;
+		}
+		if (!test_and_clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
+			break;
+		if (need_resched()) {
+			mutex_unlock(&transport->recv_mutex);
+			cond_resched();
+			goto restart;
+		}
+	}
+out:
+	mutex_unlock(&transport->recv_mutex);
+}
+
+static void xs_udp_data_receive_workfn(struct work_struct *work)
+{
+	struct sock_xprt *transport =
+		container_of(work, struct sock_xprt, recv_worker);
+	xs_udp_data_receive(transport);
+}
+
+/**
+ * xs_data_ready - "data ready" callback for UDP sockets
+ * @sk: socket with data to read
+ *
+ */
+static void xs_data_ready(struct sock *sk)
+{
+	struct rpc_xprt *xprt;
+
+	read_lock_bh(&sk->sk_callback_lock);
+	dprintk("RPC:       xs_data_ready...\n");
+	xprt = xprt_from_sock(sk);
+	if (xprt != NULL) {
+		struct sock_xprt *transport = container_of(xprt,
+				struct sock_xprt, xprt);
+		transport->old_data_ready(sk);
+		/* Any data means we had a useful conversation, so
+		 * then we don't need to delay the next reconnect
+		 */
+		if (xprt->reestablish_timeout)
+			xprt->reestablish_timeout = 0;
+		if (!test_and_set_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
+			queue_work(xprtiod_workqueue, &transport->recv_worker);
+	}
+	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)
+{
+	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)
+		desc->count = transport->tcp_reclen - transport->tcp_offset;
+	r = xdr_partial_copy_from_skb(rcvbuf, transport->tcp_copied,
+					  desc, xdr_skb_read_bits);
+
+	if (desc->count) {
+		/* 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;
+	}
+
+	transport->tcp_copied += r;
+	transport->tcp_offset += r;
+	desc->count = len - r;
+
+	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->recv_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->recv_lock);
+		return -1;
+	}
+	xprt_pin_rqst(req);
+	spin_unlock(&xprt->recv_lock);
+
+	xs_tcp_read_common(xprt, desc, req);
+
+	spin_lock(&xprt->recv_lock);
+	if (!(transport->tcp_flags & TCP_RCV_COPY_DATA))
+		xprt_complete_rqst(req->rq_task, transport->tcp_copied);
+	xprt_unpin_rqst(req);
+	spin_unlock(&xprt->recv_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 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;
+
+	/* Look up the request corresponding to the given XID */
+	req = xprt_lookup_bc_request(xprt, transport->tcp_xid);
+	if (req == NULL) {
+		printk(KERN_WARNING "Callback slot table overflowed\n");
+		xprt_force_disconnect(xprt);
+		return -1;
+	}
+
+	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))
+		xprt_complete_bc_request(req, 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);
+}
+
+static int xs_tcp_bc_up(struct svc_serv *serv, struct net *net)
+{
+	int ret;
+
+	ret = svc_create_xprt(serv, "tcp-bc", net, PF_INET, 0,
+			      SVC_SOCK_ANONYMOUS);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static size_t xs_tcp_bc_maxpayload(struct rpc_xprt *xprt)
+{
+	return PAGE_SIZE;
+}
+#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,
+	};
+	size_t ret;
+
+	dprintk("RPC:       xs_tcp_data_recv started\n");
+	do {
+		trace_xs_tcp_data_recv(transport);
+		/* 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);
+	ret = len - desc.count;
+	if (ret < rd_desc->count)
+		rd_desc->count -= ret;
+	else
+		rd_desc->count = 0;
+	trace_xs_tcp_data_recv(transport);
+	dprintk("RPC:       xs_tcp_data_recv done\n");
+	return ret;
+}
+
+static void xs_tcp_data_receive(struct sock_xprt *transport)
+{
+	struct rpc_xprt *xprt = &transport->xprt;
+	struct sock *sk;
+	read_descriptor_t rd_desc = {
+		.arg.data = xprt,
+	};
+	unsigned long total = 0;
+	int read = 0;
+
+restart:
+	mutex_lock(&transport->recv_mutex);
+	sk = transport->inet;
+	if (sk == NULL)
+		goto out;
+
+	/* We use rd_desc to pass struct xprt to xs_tcp_data_recv */
+	for (;;) {
+		rd_desc.count = RPC_TCP_READ_CHUNK_SZ;
+		lock_sock(sk);
+		read = tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
+		if (rd_desc.count != 0 || read < 0) {
+			clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state);
+			release_sock(sk);
+			break;
+		}
+		release_sock(sk);
+		total += read;
+		if (need_resched()) {
+			mutex_unlock(&transport->recv_mutex);
+			cond_resched();
+			goto restart;
+		}
+	}
+	if (test_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
+		queue_work(xprtiod_workqueue, &transport->recv_worker);
+out:
+	mutex_unlock(&transport->recv_mutex);
+	trace_xs_tcp_data_ready(xprt, read, total);
+}
+
+static void xs_tcp_data_receive_workfn(struct work_struct *work)
+{
+	struct sock_xprt *transport =
+		container_of(work, struct sock_xprt, recv_worker);
+	xs_tcp_data_receive(transport);
+}
+
+/**
+ * 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;
+	struct sock_xprt *transport;
+
+	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);
+
+	transport = container_of(xprt, struct sock_xprt, xprt);
+	trace_rpc_socket_state_change(xprt, sk->sk_socket);
+	switch (sk->sk_state) {
+	case TCP_ESTABLISHED:
+		spin_lock(&xprt->transport_lock);
+		if (!xprt_test_and_set_connected(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->connect_cookie++;
+			clear_bit(XPRT_SOCK_CONNECTING, &transport->sock_state);
+			xprt_clear_connecting(xprt);
+
+			xprt->stat.connect_count++;
+			xprt->stat.connect_time += (long)jiffies -
+						   xprt->stat.connect_start;
+			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_atomic();
+		clear_bit(XPRT_CONNECTED, &xprt->state);
+		clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
+		smp_mb__after_atomic();
+		break;
+	case TCP_CLOSE_WAIT:
+		/* The server initiated a shutdown of the socket */
+		xprt->connect_cookie++;
+		clear_bit(XPRT_CONNECTED, &xprt->state);
+		xs_tcp_force_close(xprt);
+		/* fall through */
+	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);
+		smp_mb__before_atomic();
+		clear_bit(XPRT_CONNECTED, &xprt->state);
+		smp_mb__after_atomic();
+		break;
+	case TCP_CLOSE:
+		if (test_and_clear_bit(XPRT_SOCK_CONNECTING,
+					&transport->sock_state))
+			xprt_clear_connecting(xprt);
+		clear_bit(XPRT_CLOSING, &xprt->state);
+		if (sk->sk_err)
+			xprt_wake_pending_tasks(xprt, -sk->sk_err);
+		/* Trigger the socket release */
+		xs_tcp_force_close(xprt);
+	}
+ out:
+	read_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void xs_write_space(struct sock *sk)
+{
+	struct socket_wq *wq;
+	struct rpc_xprt *xprt;
+
+	if (!sk->sk_socket)
+		return;
+	clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+
+	if (unlikely(!(xprt = xprt_from_sock(sk))))
+		return;
+	rcu_read_lock();
+	wq = rcu_dereference(sk->sk_wq);
+	if (!wq || test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &wq->flags) == 0)
+		goto out;
+
+	xprt_write_space(xprt);
+out:
+	rcu_read_unlock();
+}
+
+/**
+ * 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_is_writeable(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_xprt *xprt, struct rpc_task *task)
+{
+	spin_lock_bh(&xprt->transport_lock);
+	xprt_adjust_cwnd(xprt, task, -ETIMEDOUT);
+	spin_unlock_bh(&xprt->transport_lock);
+}
+
+static int xs_get_random_port(void)
+{
+	unsigned short min = xprt_min_resvport, max = xprt_max_resvport;
+	unsigned short range;
+	unsigned short rand;
+
+	if (max < min)
+		return -EADDRINUSE;
+	range = max - min + 1;
+	rand = (unsigned short) prandom_u32() % range;
+	return rand + min;
+}
+
+/**
+ * xs_set_reuseaddr_port - set the socket's port and address reuse options
+ * @sock: socket
+ *
+ * Note that this function has to be called on all sockets that share the
+ * same port, and it must be called before binding.
+ */
+static void xs_sock_set_reuseport(struct socket *sock)
+{
+	int opt = 1;
+
+	kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEPORT,
+			(char *)&opt, sizeof(opt));
+}
+
+static unsigned short xs_sock_getport(struct socket *sock)
+{
+	struct sockaddr_storage buf;
+	unsigned short port = 0;
+
+	if (kernel_getsockname(sock, (struct sockaddr *)&buf) < 0)
+		goto out;
+	switch (buf.ss_family) {
+	case AF_INET6:
+		port = ntohs(((struct sockaddr_in6 *)&buf)->sin6_port);
+		break;
+	case AF_INET:
+		port = ntohs(((struct sockaddr_in *)&buf)->sin_port);
+	}
+out:
+	return port;
+}
+
+/**
+ * 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 void xs_set_srcport(struct sock_xprt *transport, struct socket *sock)
+{
+	if (transport->srcport == 0)
+		transport->srcport = xs_sock_getport(sock);
+}
+
+static int xs_get_srcport(struct sock_xprt *transport)
+{
+	int 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;
+	int port = xs_get_srcport(transport);
+	unsigned short last;
+
+	/*
+	 * If we are asking for any ephemeral port (i.e. port == 0 &&
+	 * transport->xprt.resvport == 0), don't bind.  Let the local
+	 * port selection happen implicitly when the socket is used
+	 * (for example at connect time).
+	 *
+	 * This ensures that we can continue to establish TCP
+	 * connections even when all local ephemeral ports are already
+	 * a part of some TCP connection.  This makes no difference
+	 * for UDP sockets, but also doens't harm them.
+	 *
+	 * If we're asking for any reserved port (i.e. port == 0 &&
+	 * transport->xprt.resvport == 1) xs_get_srcport above will
+	 * ensure that port is non-zero and we will bind as needed.
+	 */
+	if (port <= 0)
+		return port;
+
+	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 (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;
+
+	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;
+
+	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;
+
+	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)
+{
+	if (WARN_ON_ONCE(!sock_allow_reclassification(sock->sk)))
+		return;
+
+	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_socket(int family, struct socket *sock)
+{
+}
+#endif
+
+static void xs_dummy_setup_socket(struct work_struct *work)
+{
+}
+
+static struct socket *xs_create_sock(struct rpc_xprt *xprt,
+		struct sock_xprt *transport, int family, int type,
+		int protocol, bool reuseport)
+{
+	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);
+
+	if (reuseport)
+		xs_sock_set_reuseport(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_data_ready;
+		sk->sk_write_space = xs_udp_write_space;
+		sock_set_flag(sk, SOCK_FASYNC);
+		sk->sk_error_report = xs_error_report;
+		sk->sk_allocation = GFP_NOIO;
+
+		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... */
+	return kernel_connect(sock, xs_addr(xprt), xprt->addrlen, 0);
+}
+
+/**
+ * xs_local_setup_socket - create AF_LOCAL socket, connect to a local endpoint
+ * @transport: socket transport to connect
+ */
+static int xs_local_setup_socket(struct sock_xprt *transport)
+{
+	struct rpc_xprt *xprt = &transport->xprt;
+	struct socket *sock;
+	int status = -EIO;
+
+	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_socket(AF_LOCAL, 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);
+	trace_rpc_socket_connect(xprt, sock, status);
+	switch (status) {
+	case 0:
+		dprintk("RPC:       xprt %p connected to %s\n",
+				xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
+		xprt->stat.connect_count++;
+		xprt->stat.connect_time += (long)jiffies -
+					   xprt->stat.connect_start;
+		xprt_set_connected(xprt);
+	case -ENOBUFS:
+		break;
+	case -ENOENT:
+		dprintk("RPC:       xprt %p: socket %s does not exist\n",
+				xprt, xprt->address_strings[RPC_DISPLAY_ADDR]);
+		break;
+	case -ECONNREFUSED:
+		dprintk("RPC:       xprt %p: connection refused for %s\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);
+	return status;
+}
+
+static void xs_local_connect(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
+	int ret;
+
+	 if (RPC_IS_ASYNC(task)) {
+		/*
+		 * We want the AF_LOCAL connect to be resolved in the
+		 * filesystem namespace of the process making the rpc
+		 * call.  Thus we connect synchronously.
+		 *
+		 * If we want to support asynchronous AF_LOCAL calls,
+		 * we'll need to figure out how to pass a namespace to
+		 * connect.
+		 */
+		rpc_exit(task, -ENOTCONN);
+		return;
+	}
+	ret = xs_local_setup_socket(transport);
+	if (ret && !RPC_IS_SOFTCONN(task))
+		msleep_interruptible(15000);
+}
+
+#if IS_ENABLED(CONFIG_SUNRPC_SWAP)
+/*
+ * Note that this should be called with XPRT_LOCKED held (or when we otherwise
+ * know that we have exclusive access to the socket), to guard against
+ * races with xs_reset_transport.
+ */
+static void xs_set_memalloc(struct rpc_xprt *xprt)
+{
+	struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
+			xprt);
+
+	/*
+	 * If there's no sock, then we have nothing to set. The
+	 * reconnecting process will get it for us.
+	 */
+	if (!transport->inet)
+		return;
+	if (atomic_read(&xprt->swapper))
+		sk_set_memalloc(transport->inet);
+}
+
+/**
+ * xs_enable_swap - Tag this transport as being used for swap.
+ * @xprt: transport to tag
+ *
+ * Take a reference to this transport on behalf of the rpc_clnt, and
+ * optionally mark it for swapping if it wasn't already.
+ */
+static int
+xs_enable_swap(struct rpc_xprt *xprt)
+{
+	struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
+
+	if (atomic_inc_return(&xprt->swapper) != 1)
+		return 0;
+	if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE))
+		return -ERESTARTSYS;
+	if (xs->inet)
+		sk_set_memalloc(xs->inet);
+	xprt_release_xprt(xprt, NULL);
+	return 0;
+}
+
+/**
+ * xs_disable_swap - Untag this transport as being used for swap.
+ * @xprt: transport to tag
+ *
+ * Drop a "swapper" reference to this xprt on behalf of the rpc_clnt. If the
+ * swapper refcount goes to 0, untag the socket as a memalloc socket.
+ */
+static void
+xs_disable_swap(struct rpc_xprt *xprt)
+{
+	struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
+
+	if (!atomic_dec_and_test(&xprt->swapper))
+		return;
+	if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE))
+		return;
+	if (xs->inet)
+		sk_clear_memalloc(xs->inet);
+	xprt_release_xprt(xprt, NULL);
+}
+#else
+static void xs_set_memalloc(struct rpc_xprt *xprt)
+{
+}
+
+static int
+xs_enable_swap(struct rpc_xprt *xprt)
+{
+	return -EINVAL;
+}
+
+static void
+xs_disable_swap(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_data_ready;
+		sk->sk_write_space = xs_udp_write_space;
+		sock_set_flag(sk, SOCK_FASYNC);
+		sk->sk_allocation = GFP_NOIO;
+
+		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);
+
+	xprt->stat.connect_start = jiffies;
+}
+
+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;
+	int status = -EIO;
+
+	sock = xs_create_sock(xprt, transport,
+			xs_addr(xprt)->sa_family, SOCK_DGRAM,
+			IPPROTO_UDP, false);
+	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);
+	trace_rpc_socket_connect(xprt, sock, 0);
+	status = 0;
+out:
+	xprt_clear_connecting(xprt);
+	xprt_unlock_connect(xprt, transport);
+	xprt_wake_pending_tasks(xprt, 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_RDWR);
+ */
+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;
+	int skst = transport->inet ? transport->inet->sk_state : TCP_CLOSE;
+
+	if (sock == NULL)
+		return;
+	switch (skst) {
+	default:
+		kernel_sock_shutdown(sock, SHUT_RDWR);
+		trace_rpc_socket_shutdown(xprt, sock);
+		break;
+	case TCP_CLOSE:
+	case TCP_TIME_WAIT:
+		xs_reset_transport(transport);
+	}
+}
+
+static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
+		struct socket *sock)
+{
+	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
+	unsigned int keepidle;
+	unsigned int keepcnt;
+	unsigned int opt_on = 1;
+	unsigned int timeo;
+
+	spin_lock_bh(&xprt->transport_lock);
+	keepidle = DIV_ROUND_UP(xprt->timeout->to_initval, HZ);
+	keepcnt = xprt->timeout->to_retries + 1;
+	timeo = jiffies_to_msecs(xprt->timeout->to_initval) *
+		(xprt->timeout->to_retries + 1);
+	clear_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state);
+	spin_unlock_bh(&xprt->transport_lock);
+
+	/* TCP Keepalive options */
+	kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
+			(char *)&opt_on, sizeof(opt_on));
+	kernel_setsockopt(sock, SOL_TCP, TCP_KEEPIDLE,
+			(char *)&keepidle, sizeof(keepidle));
+	kernel_setsockopt(sock, SOL_TCP, TCP_KEEPINTVL,
+			(char *)&keepidle, sizeof(keepidle));
+	kernel_setsockopt(sock, SOL_TCP, TCP_KEEPCNT,
+			(char *)&keepcnt, sizeof(keepcnt));
+
+	/* TCP user timeout (see RFC5482) */
+	kernel_setsockopt(sock, SOL_TCP, TCP_USER_TIMEOUT,
+			(char *)&timeo, sizeof(timeo));
+}
+
+static void xs_tcp_set_connect_timeout(struct rpc_xprt *xprt,
+		unsigned long connect_timeout,
+		unsigned long reconnect_timeout)
+{
+	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
+	struct rpc_timeout to;
+	unsigned long initval;
+
+	spin_lock_bh(&xprt->transport_lock);
+	if (reconnect_timeout < xprt->max_reconnect_timeout)
+		xprt->max_reconnect_timeout = reconnect_timeout;
+	if (connect_timeout < xprt->connect_timeout) {
+		memcpy(&to, xprt->timeout, sizeof(to));
+		initval = DIV_ROUND_UP(connect_timeout, to.to_retries + 1);
+		/* Arbitrary lower limit */
+		if (initval <  XS_TCP_INIT_REEST_TO << 1)
+			initval = XS_TCP_INIT_REEST_TO << 1;
+		to.to_initval = initval;
+		to.to_maxval = initval;
+		memcpy(&transport->tcp_timeout, &to,
+				sizeof(transport->tcp_timeout));
+		xprt->timeout = &transport->tcp_timeout;
+		xprt->connect_timeout = connect_timeout;
+	}
+	set_bit(XPRT_SOCK_UPD_TIMEOUT, &transport->sock_state);
+	spin_unlock_bh(&xprt->transport_lock);
+}
+
+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;
+		unsigned int addr_pref = IPV6_PREFER_SRC_PUBLIC;
+
+		/* Avoid temporary address, they are bad for long-lived
+		 * connections such as NFS mounts.
+		 * RFC4941, section 3.6 suggests that:
+		 *    Individual applications, which have specific
+		 *    knowledge about the normal duration of connections,
+		 *    MAY override this as appropriate.
+		 */
+		kernel_setsockopt(sock, SOL_IPV6, IPV6_ADDR_PREFERENCES,
+				(char *)&addr_pref, sizeof(addr_pref));
+
+		xs_tcp_set_socket_timeouts(xprt, sock);
+
+		write_lock_bh(&sk->sk_callback_lock);
+
+		xs_save_old_callbacks(transport, sk);
+
+		sk->sk_user_data = xprt;
+		sk->sk_data_ready = xs_data_ready;
+		sk->sk_state_change = xs_tcp_state_change;
+		sk->sk_write_space = xs_tcp_write_space;
+		sock_set_flag(sk, SOCK_FASYNC);
+		sk->sk_error_report = xs_error_report;
+		sk->sk_allocation = GFP_NOIO;
+
+		/* socket options */
+		sock_reset_flag(sk, SOCK_LINGER);
+		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... */
+	set_bit(XPRT_SOCK_CONNECTING, &transport->sock_state);
+	ret = kernel_connect(sock, xs_addr(xprt), xprt->addrlen, O_NONBLOCK);
+	switch (ret) {
+	case 0:
+		xs_set_srcport(transport, sock);
+		/* fall through */
+	case -EINPROGRESS:
+		/* SYN_SENT! */
+		if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
+			xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
+		break;
+	case -EADDRNOTAVAIL:
+		/* Source port number is unavailable. Try a new one! */
+		transport->srcport = 0;
+	}
+out:
+	return ret;
+}
+
+/**
+ * xs_tcp_setup_socket - create a TCP socket and connect to a remote endpoint
+ *
+ * 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 (!sock) {
+		sock = xs_create_sock(xprt, transport,
+				xs_addr(xprt)->sa_family, SOCK_STREAM,
+				IPPROTO_TCP, true);
+		if (IS_ERR(sock)) {
+			status = PTR_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]);
+
+	status = xs_tcp_finish_connecting(xprt, sock);
+	trace_rpc_socket_connect(xprt, sock, status);
+	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);
+		/* fall through */
+	case -EADDRNOTAVAIL:
+		/* We're probably in TIME_WAIT. Get rid of existing socket,
+		 * and retry
+		 */
+		xs_tcp_force_close(xprt);
+		break;
+	case 0:
+	case -EINPROGRESS:
+	case -EALREADY:
+		xprt_unlock_connect(xprt, transport);
+		return;
+	case -EINVAL:
+		/* Happens, for instance, if the user specified a link
+		 * local IPv6 address without a scope-id.
+		 */
+	case -ECONNREFUSED:
+	case -ECONNRESET:
+	case -ENETDOWN:
+	case -ENETUNREACH:
+	case -EHOSTUNREACH:
+	case -EADDRINUSE:
+	case -ENOBUFS:
+		/*
+		 * xs_tcp_force_close() wakes tasks with -EIO.
+		 * We need to wake them first to ensure the
+		 * correct error code.
+		 */
+		xprt_wake_pending_tasks(xprt, status);
+		xs_tcp_force_close(xprt);
+		goto out;
+	}
+	status = -EAGAIN;
+out:
+	xprt_clear_connecting(xprt);
+	xprt_unlock_connect(xprt, transport);
+	xprt_wake_pending_tasks(xprt, status);
+}
+
+static unsigned long xs_reconnect_delay(const struct rpc_xprt *xprt)
+{
+	unsigned long start, now = jiffies;
+
+	start = xprt->stat.connect_start + xprt->reestablish_timeout;
+	if (time_after(start, now))
+		return start - now;
+	return 0;
+}
+
+static void xs_reconnect_backoff(struct rpc_xprt *xprt)
+{
+	xprt->reestablish_timeout <<= 1;
+	if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
+		xprt->reestablish_timeout = xprt->max_reconnect_timeout;
+	if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
+		xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
+}
+
+/**
+ * xs_connect - connect a socket to a remote endpoint
+ * @xprt: pointer to transport structure
+ * @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_xprt *xprt, struct rpc_task *task)
+{
+	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
+	unsigned long delay = 0;
+
+	WARN_ON_ONCE(!xprt_lock_connect(xprt, task, transport));
+
+	if (transport->sock != NULL) {
+		dprintk("RPC:       xs_connect delayed xprt %p for %lu "
+				"seconds\n",
+				xprt, xprt->reestablish_timeout / HZ);
+
+		/* Start by resetting any existing state */
+		xs_reset_transport(transport);
+
+		delay = xs_reconnect_delay(xprt);
+		xs_reconnect_backoff(xprt);
+
+	} else
+		dprintk("RPC:       xs_connect scheduled xprt %p\n", xprt);
+
+	queue_delayed_work(xprtiod_workqueue,
+			&transport->connect_worker,
+			delay);
+}
+
+/**
+ * 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 int bc_malloc(struct rpc_task *task)
+{
+	struct rpc_rqst *rqst = task->tk_rqstp;
+	size_t size = rqst->rq_callsize;
+	struct page *page;
+	struct rpc_buffer *buf;
+
+	if (size > PAGE_SIZE - sizeof(struct rpc_buffer)) {
+		WARN_ONCE(1, "xprtsock: large bc buffer request (size %zu)\n",
+			  size);
+		return -EINVAL;
+	}
+
+	page = alloc_page(GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+
+	buf = page_address(page);
+	buf->len = PAGE_SIZE;
+
+	rqst->rq_buffer = buf->data;
+	rqst->rq_rbuffer = (char *)rqst->rq_buffer + rqst->rq_callsize;
+	return 0;
+}
+
+/*
+ * Free the space allocated in the bc_alloc routine
+ */
+static void bc_free(struct rpc_task *task)
+{
+	void *buffer = task->tk_rqstp->rq_buffer;
+	struct rpc_buffer *buf;
+
+	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;
+	int 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;
+
+	/*
+	 * 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)
+{
+	dprintk("RPC:       bc_destroy xprt %p\n", xprt);
+
+	xs_xprt_free(xprt);
+	module_put(THIS_MODULE);
+}
+
+static const struct rpc_xprt_ops xs_local_ops = {
+	.reserve_xprt		= xprt_reserve_xprt,
+	.release_xprt		= xs_tcp_release_xprt,
+	.alloc_slot		= xprt_alloc_slot,
+	.free_slot		= xprt_free_slot,
+	.rpcbind		= xs_local_rpcbind,
+	.set_port		= xs_local_set_port,
+	.connect		= xs_local_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,
+	.enable_swap		= xs_enable_swap,
+	.disable_swap		= xs_disable_swap,
+};
+
+static const 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,
+	.free_slot		= xprt_free_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,
+	.enable_swap		= xs_enable_swap,
+	.disable_swap		= xs_disable_swap,
+	.inject_disconnect	= xs_inject_disconnect,
+};
+
+static const 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,
+	.free_slot		= xprt_free_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_shutdown,
+	.destroy		= xs_destroy,
+	.set_connect_timeout	= xs_tcp_set_connect_timeout,
+	.print_stats		= xs_tcp_print_stats,
+	.enable_swap		= xs_enable_swap,
+	.disable_swap		= xs_disable_swap,
+	.inject_disconnect	= xs_inject_disconnect,
+#ifdef CONFIG_SUNRPC_BACKCHANNEL
+	.bc_setup		= xprt_setup_bc,
+	.bc_up			= xs_tcp_bc_up,
+	.bc_maxpayload		= xs_tcp_bc_maxpayload,
+	.bc_free_rqst		= xprt_free_bc_rqst,
+	.bc_destroy		= xprt_destroy_bc,
+#endif
+};
+
+/*
+ * The rpc_xprt_ops for the server backchannel
+ */
+
+static const struct rpc_xprt_ops bc_tcp_ops = {
+	.reserve_xprt		= xprt_reserve_xprt,
+	.release_xprt		= xprt_release_xprt,
+	.alloc_slot		= xprt_alloc_slot,
+	.free_slot		= xprt_free_slot,
+	.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,
+	.enable_swap		= xs_enable_swap,
+	.disable_swap		= xs_disable_swap,
+	.inject_disconnect	= xs_inject_disconnect,
+};
+
+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);
+	mutex_init(&new->recv_mutex);
+	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;
+
+	INIT_WORK(&transport->recv_worker, xs_local_data_receive_workfn);
+	INIT_DELAYED_WORK(&transport->connect_worker,
+			xs_dummy_setup_socket);
+
+	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);
+		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:
+	xs_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;
+
+	INIT_WORK(&transport->recv_worker, xs_udp_data_receive_workfn);
+	INIT_DELAYED_WORK(&transport->connect_worker, xs_udp_setup_socket);
+
+	switch (addr->sa_family) {
+	case AF_INET:
+		if (((struct sockaddr_in *)addr)->sin_port != htons(0))
+			xprt_set_bound(xprt);
+
+		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);
+
+		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:
+	xs_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;
+	unsigned int max_slot_table_size = xprt_max_tcp_slot_table_entries;
+
+	if (args->flags & XPRT_CREATE_INFINITE_SLOTS)
+		max_slot_table_size = RPC_MAX_SLOT_TABLE_LIMIT;
+
+	xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries,
+			max_slot_table_size);
+	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;
+
+	xprt->max_reconnect_timeout = xprt->timeout->to_maxval;
+	xprt->connect_timeout = xprt->timeout->to_initval *
+		(xprt->timeout->to_retries + 1);
+
+	INIT_WORK(&transport->recv_worker, xs_tcp_data_receive_workfn);
+	INIT_DELAYED_WORK(&transport->connect_worker, xs_tcp_setup_socket);
+
+	switch (addr->sa_family) {
+	case AF_INET:
+		if (((struct sockaddr_in *)addr)->sin_port != htons(0))
+			xprt_set_bound(xprt);
+
+		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);
+
+		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:
+	xs_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;
+
+	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 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;
+
+	args->bc_xprt->xpt_bc_xprt = NULL;
+	args->bc_xprt->xpt_bc_xps = NULL;
+	xprt_put(xprt);
+	ret = ERR_PTR(-EINVAL);
+out_err:
+	xs_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,
+	.netid		= { "" },
+};
+
+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,
+	.netid		= { "udp", "udp6", "" },
+};
+
+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,
+	.netid		= { "tcp", "tcp6", "" },
+};
+
+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,
+	.netid		= { "" },
+};
+
+/**
+ * init_socket_xprt - set up xprtsock's sysctls, register with RPC client
+ *
+ */
+int init_socket_xprt(void)
+{
+#if IS_ENABLED(CONFIG_SUNRPC_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)
+{
+#if IS_ENABLED(CONFIG_SUNRPC_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 int num;
+	int ret;
+
+	if (!val)
+		return -EINVAL;
+	ret = kstrtouint(val, 0, &num);
+	if (ret)
+		return ret;
+	if (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 const 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 const 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 const 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);