Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 2192 insertions, 0 deletions

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
new file mode 100644
index 0000000000..ab453ede54
--- /dev/null
+++ b/net/sunrpc/xprt.c
@@ -0,0 +1,2192 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/net/sunrpc/xprt.c
+ *
+ *  This is a generic RPC call interface supporting congestion avoidance,
+ *  and asynchronous calls.
+ *
+ *  The interface works like this:
+ *
+ *  -	When a process places a call, it allocates a request slot if
+ *	one is available. Otherwise, it sleeps on the backlog queue
+ *	(xprt_reserve).
+ *  -	Next, the caller puts together the RPC message, stuffs it into
+ *	the request struct, and calls xprt_transmit().
+ *  -	xprt_transmit sends the message and installs the caller on the
+ *	transport's wait list. At the same time, if a reply is expected,
+ *	it installs a timer that is run after the packet's timeout has
+ *	expired.
+ *  -	When a packet arrives, the data_ready handler walks the list of
+ *	pending requests for that transport. If a matching XID is found, the
+ *	caller is woken up, and the timer removed.
+ *  -	When no reply arrives within the timeout interval, the timer is
+ *	fired by the kernel and runs xprt_timer(). It either adjusts the
+ *	timeout values (minor timeout) or wakes up the caller with a status
+ *	of -ETIMEDOUT.
+ *  -	When the caller receives a notification from RPC that a reply arrived,
+ *	it should release the RPC slot, and process the reply.
+ *	If the call timed out, it may choose to retry the operation by
+ *	adjusting the initial timeout value, and simply calling rpc_call
+ *	again.
+ *
+ *  Support for async RPC is done through a set of RPC-specific scheduling
+ *  primitives that `transparently' work for processes as well as async
+ *  tasks that rely on callbacks.
+ *
+ *  Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
+ *
+ *  Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
+ */
+
+#include <linux/module.h>
+
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/net.h>
+#include <linux/ktime.h>
+
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/metrics.h>
+#include <linux/sunrpc/bc_xprt.h>
+#include <linux/rcupdate.h>
+#include <linux/sched/mm.h>
+
+#include <trace/events/sunrpc.h>
+
+#include "sunrpc.h"
+#include "sysfs.h"
+#include "fail.h"
+
+/*
+ * Local variables
+ */
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+# define RPCDBG_FACILITY	RPCDBG_XPRT
+#endif
+
+/*
+ * Local functions
+ */
+static void	xprt_init(struct rpc_xprt *xprt, struct net *net);
+static __be32	xprt_alloc_xid(struct rpc_xprt *xprt);
+static void	xprt_destroy(struct rpc_xprt *xprt);
+static void	xprt_request_init(struct rpc_task *task);
+static int	xprt_request_prepare(struct rpc_rqst *req, struct xdr_buf *buf);
+
+static DEFINE_SPINLOCK(xprt_list_lock);
+static LIST_HEAD(xprt_list);
+
+static unsigned long xprt_request_timeout(const struct rpc_rqst *req)
+{
+	unsigned long timeout = jiffies + req->rq_timeout;
+
+	if (time_before(timeout, req->rq_majortimeo))
+		return timeout;
+	return req->rq_majortimeo;
+}
+
+/**
+ * xprt_register_transport - register a transport implementation
+ * @transport: transport to register
+ *
+ * If a transport implementation is loaded as a kernel module, it can
+ * call this interface to make itself known to the RPC client.
+ *
+ * Returns:
+ * 0:		transport successfully registered
+ * -EEXIST:	transport already registered
+ * -EINVAL:	transport module being unloaded
+ */
+int xprt_register_transport(struct xprt_class *transport)
+{
+	struct xprt_class *t;
+	int result;
+
+	result = -EEXIST;
+	spin_lock(&xprt_list_lock);
+	list_for_each_entry(t, &xprt_list, list) {
+		/* don't register the same transport class twice */
+		if (t->ident == transport->ident)
+			goto out;
+	}
+
+	list_add_tail(&transport->list, &xprt_list);
+	printk(KERN_INFO "RPC: Registered %s transport module.\n",
+	       transport->name);
+	result = 0;
+
+out:
+	spin_unlock(&xprt_list_lock);
+	return result;
+}
+EXPORT_SYMBOL_GPL(xprt_register_transport);
+
+/**
+ * xprt_unregister_transport - unregister a transport implementation
+ * @transport: transport to unregister
+ *
+ * Returns:
+ * 0:		transport successfully unregistered
+ * -ENOENT:	transport never registered
+ */
+int xprt_unregister_transport(struct xprt_class *transport)
+{
+	struct xprt_class *t;
+	int result;
+
+	result = 0;
+	spin_lock(&xprt_list_lock);
+	list_for_each_entry(t, &xprt_list, list) {
+		if (t == transport) {
+			printk(KERN_INFO
+				"RPC: Unregistered %s transport module.\n",
+				transport->name);
+			list_del_init(&transport->list);
+			goto out;
+		}
+	}
+	result = -ENOENT;
+
+out:
+	spin_unlock(&xprt_list_lock);
+	return result;
+}
+EXPORT_SYMBOL_GPL(xprt_unregister_transport);
+
+static void
+xprt_class_release(const struct xprt_class *t)
+{
+	module_put(t->owner);
+}
+
+static const struct xprt_class *
+xprt_class_find_by_ident_locked(int ident)
+{
+	const struct xprt_class *t;
+
+	list_for_each_entry(t, &xprt_list, list) {
+		if (t->ident != ident)
+			continue;
+		if (!try_module_get(t->owner))
+			continue;
+		return t;
+	}
+	return NULL;
+}
+
+static const struct xprt_class *
+xprt_class_find_by_ident(int ident)
+{
+	const struct xprt_class *t;
+
+	spin_lock(&xprt_list_lock);
+	t = xprt_class_find_by_ident_locked(ident);
+	spin_unlock(&xprt_list_lock);
+	return t;
+}
+
+static const struct xprt_class *
+xprt_class_find_by_netid_locked(const char *netid)
+{
+	const struct xprt_class *t;
+	unsigned int i;
+
+	list_for_each_entry(t, &xprt_list, list) {
+		for (i = 0; t->netid[i][0] != '\0'; i++) {
+			if (strcmp(t->netid[i], netid) != 0)
+				continue;
+			if (!try_module_get(t->owner))
+				continue;
+			return t;
+		}
+	}
+	return NULL;
+}
+
+static const struct xprt_class *
+xprt_class_find_by_netid(const char *netid)
+{
+	const struct xprt_class *t;
+
+	spin_lock(&xprt_list_lock);
+	t = xprt_class_find_by_netid_locked(netid);
+	if (!t) {
+		spin_unlock(&xprt_list_lock);
+		request_module("rpc%s", netid);
+		spin_lock(&xprt_list_lock);
+		t = xprt_class_find_by_netid_locked(netid);
+	}
+	spin_unlock(&xprt_list_lock);
+	return t;
+}
+
+/**
+ * xprt_find_transport_ident - convert a netid into a transport identifier
+ * @netid: transport to load
+ *
+ * Returns:
+ * > 0:		transport identifier
+ * -ENOENT:	transport module not available
+ */
+int xprt_find_transport_ident(const char *netid)
+{
+	const struct xprt_class *t;
+	int ret;
+
+	t = xprt_class_find_by_netid(netid);
+	if (!t)
+		return -ENOENT;
+	ret = t->ident;
+	xprt_class_release(t);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_find_transport_ident);
+
+static void xprt_clear_locked(struct rpc_xprt *xprt)
+{
+	xprt->snd_task = NULL;
+	if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state))
+		clear_bit_unlock(XPRT_LOCKED, &xprt->state);
+	else
+		queue_work(xprtiod_workqueue, &xprt->task_cleanup);
+}
+
+/**
+ * xprt_reserve_xprt - serialize write access to transports
+ * @task: task that is requesting access to the transport
+ * @xprt: pointer to the target transport
+ *
+ * This prevents mixing the payload of separate requests, and prevents
+ * transport connects from colliding with writes.  No congestion control
+ * is provided.
+ */
+int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+
+	if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
+		if (task == xprt->snd_task)
+			goto out_locked;
+		goto out_sleep;
+	}
+	if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
+		goto out_unlock;
+	xprt->snd_task = task;
+
+out_locked:
+	trace_xprt_reserve_xprt(xprt, task);
+	return 1;
+
+out_unlock:
+	xprt_clear_locked(xprt);
+out_sleep:
+	task->tk_status = -EAGAIN;
+	if  (RPC_IS_SOFT(task))
+		rpc_sleep_on_timeout(&xprt->sending, task, NULL,
+				xprt_request_timeout(req));
+	else
+		rpc_sleep_on(&xprt->sending, task, NULL);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
+
+static bool
+xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
+{
+	return test_bit(XPRT_CWND_WAIT, &xprt->state);
+}
+
+static void
+xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
+{
+	if (!list_empty(&xprt->xmit_queue)) {
+		/* Peek at head of queue to see if it can make progress */
+		if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
+					rq_xmit)->rq_cong)
+			return;
+	}
+	set_bit(XPRT_CWND_WAIT, &xprt->state);
+}
+
+static void
+xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
+{
+	if (!RPCXPRT_CONGESTED(xprt))
+		clear_bit(XPRT_CWND_WAIT, &xprt->state);
+}
+
+/*
+ * xprt_reserve_xprt_cong - serialize write access to transports
+ * @task: task that is requesting access to the transport
+ *
+ * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
+ * integrated into the decision of whether a request is allowed to be
+ * woken up and given access to the transport.
+ * Note that the lock is only granted if we know there are free slots.
+ */
+int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+
+	if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
+		if (task == xprt->snd_task)
+			goto out_locked;
+		goto out_sleep;
+	}
+	if (req == NULL) {
+		xprt->snd_task = task;
+		goto out_locked;
+	}
+	if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
+		goto out_unlock;
+	if (!xprt_need_congestion_window_wait(xprt)) {
+		xprt->snd_task = task;
+		goto out_locked;
+	}
+out_unlock:
+	xprt_clear_locked(xprt);
+out_sleep:
+	task->tk_status = -EAGAIN;
+	if (RPC_IS_SOFT(task))
+		rpc_sleep_on_timeout(&xprt->sending, task, NULL,
+				xprt_request_timeout(req));
+	else
+		rpc_sleep_on(&xprt->sending, task, NULL);
+	return 0;
+out_locked:
+	trace_xprt_reserve_cong(xprt, task);
+	return 1;
+}
+EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
+
+static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	int retval;
+
+	if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
+		return 1;
+	spin_lock(&xprt->transport_lock);
+	retval = xprt->ops->reserve_xprt(xprt, task);
+	spin_unlock(&xprt->transport_lock);
+	return retval;
+}
+
+static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
+{
+	struct rpc_xprt *xprt = data;
+
+	xprt->snd_task = task;
+	return true;
+}
+
+static void __xprt_lock_write_next(struct rpc_xprt *xprt)
+{
+	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
+		return;
+	if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
+		goto out_unlock;
+	if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
+				__xprt_lock_write_func, xprt))
+		return;
+out_unlock:
+	xprt_clear_locked(xprt);
+}
+
+static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
+{
+	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
+		return;
+	if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
+		goto out_unlock;
+	if (xprt_need_congestion_window_wait(xprt))
+		goto out_unlock;
+	if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
+				__xprt_lock_write_func, xprt))
+		return;
+out_unlock:
+	xprt_clear_locked(xprt);
+}
+
+/**
+ * xprt_release_xprt - allow other requests to use a transport
+ * @xprt: transport with other tasks potentially waiting
+ * @task: task that is releasing access to the transport
+ *
+ * Note that "task" can be NULL.  No congestion control is provided.
+ */
+void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	if (xprt->snd_task == task) {
+		xprt_clear_locked(xprt);
+		__xprt_lock_write_next(xprt);
+	}
+	trace_xprt_release_xprt(xprt, task);
+}
+EXPORT_SYMBOL_GPL(xprt_release_xprt);
+
+/**
+ * xprt_release_xprt_cong - allow other requests to use a transport
+ * @xprt: transport with other tasks potentially waiting
+ * @task: task that is releasing access to the transport
+ *
+ * Note that "task" can be NULL.  Another task is awoken to use the
+ * transport if the transport's congestion window allows it.
+ */
+void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	if (xprt->snd_task == task) {
+		xprt_clear_locked(xprt);
+		__xprt_lock_write_next_cong(xprt);
+	}
+	trace_xprt_release_cong(xprt, task);
+}
+EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
+
+void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	if (xprt->snd_task != task)
+		return;
+	spin_lock(&xprt->transport_lock);
+	xprt->ops->release_xprt(xprt, task);
+	spin_unlock(&xprt->transport_lock);
+}
+
+/*
+ * Van Jacobson congestion avoidance. Check if the congestion window
+ * overflowed. Put the task to sleep if this is the case.
+ */
+static int
+__xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+	if (req->rq_cong)
+		return 1;
+	trace_xprt_get_cong(xprt, req->rq_task);
+	if (RPCXPRT_CONGESTED(xprt)) {
+		xprt_set_congestion_window_wait(xprt);
+		return 0;
+	}
+	req->rq_cong = 1;
+	xprt->cong += RPC_CWNDSCALE;
+	return 1;
+}
+
+/*
+ * Adjust the congestion window, and wake up the next task
+ * that has been sleeping due to congestion
+ */
+static void
+__xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+	if (!req->rq_cong)
+		return;
+	req->rq_cong = 0;
+	xprt->cong -= RPC_CWNDSCALE;
+	xprt_test_and_clear_congestion_window_wait(xprt);
+	trace_xprt_put_cong(xprt, req->rq_task);
+	__xprt_lock_write_next_cong(xprt);
+}
+
+/**
+ * xprt_request_get_cong - Request congestion control credits
+ * @xprt: pointer to transport
+ * @req: pointer to RPC request
+ *
+ * Useful for transports that require congestion control.
+ */
+bool
+xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+	bool ret = false;
+
+	if (req->rq_cong)
+		return true;
+	spin_lock(&xprt->transport_lock);
+	ret = __xprt_get_cong(xprt, req) != 0;
+	spin_unlock(&xprt->transport_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_request_get_cong);
+
+/**
+ * xprt_release_rqst_cong - housekeeping when request is complete
+ * @task: RPC request that recently completed
+ *
+ * Useful for transports that require congestion control.
+ */
+void xprt_release_rqst_cong(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+
+	__xprt_put_cong(req->rq_xprt, req);
+}
+EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
+
+static void xprt_clear_congestion_window_wait_locked(struct rpc_xprt *xprt)
+{
+	if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state))
+		__xprt_lock_write_next_cong(xprt);
+}
+
+/*
+ * Clear the congestion window wait flag and wake up the next
+ * entry on xprt->sending
+ */
+static void
+xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
+{
+	if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
+		spin_lock(&xprt->transport_lock);
+		__xprt_lock_write_next_cong(xprt);
+		spin_unlock(&xprt->transport_lock);
+	}
+}
+
+/**
+ * xprt_adjust_cwnd - adjust transport congestion window
+ * @xprt: pointer to xprt
+ * @task: recently completed RPC request used to adjust window
+ * @result: result code of completed RPC request
+ *
+ * The transport code maintains an estimate on the maximum number of out-
+ * standing RPC requests, using a smoothed version of the congestion
+ * avoidance implemented in 44BSD. This is basically the Van Jacobson
+ * congestion algorithm: If a retransmit occurs, the congestion window is
+ * halved; otherwise, it is incremented by 1/cwnd when
+ *
+ *	-	a reply is received and
+ *	-	a full number of requests are outstanding and
+ *	-	the congestion window hasn't been updated recently.
+ */
+void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	unsigned long cwnd = xprt->cwnd;
+
+	if (result >= 0 && cwnd <= xprt->cong) {
+		/* The (cwnd >> 1) term makes sure
+		 * the result gets rounded properly. */
+		cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
+		if (cwnd > RPC_MAXCWND(xprt))
+			cwnd = RPC_MAXCWND(xprt);
+		__xprt_lock_write_next_cong(xprt);
+	} else if (result == -ETIMEDOUT) {
+		cwnd >>= 1;
+		if (cwnd < RPC_CWNDSCALE)
+			cwnd = RPC_CWNDSCALE;
+	}
+	dprintk("RPC:       cong %ld, cwnd was %ld, now %ld\n",
+			xprt->cong, xprt->cwnd, cwnd);
+	xprt->cwnd = cwnd;
+	__xprt_put_cong(xprt, req);
+}
+EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
+
+/**
+ * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
+ * @xprt: transport with waiting tasks
+ * @status: result code to plant in each task before waking it
+ *
+ */
+void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
+{
+	if (status < 0)
+		rpc_wake_up_status(&xprt->pending, status);
+	else
+		rpc_wake_up(&xprt->pending);
+}
+EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
+
+/**
+ * xprt_wait_for_buffer_space - wait for transport output buffer to clear
+ * @xprt: transport
+ *
+ * Note that we only set the timer for the case of RPC_IS_SOFT(), since
+ * we don't in general want to force a socket disconnection due to
+ * an incomplete RPC call transmission.
+ */
+void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
+{
+	set_bit(XPRT_WRITE_SPACE, &xprt->state);
+}
+EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
+
+static bool
+xprt_clear_write_space_locked(struct rpc_xprt *xprt)
+{
+	if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
+		__xprt_lock_write_next(xprt);
+		dprintk("RPC:       write space: waking waiting task on "
+				"xprt %p\n", xprt);
+		return true;
+	}
+	return false;
+}
+
+/**
+ * xprt_write_space - wake the task waiting for transport output buffer space
+ * @xprt: transport with waiting tasks
+ *
+ * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
+ */
+bool xprt_write_space(struct rpc_xprt *xprt)
+{
+	bool ret;
+
+	if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
+		return false;
+	spin_lock(&xprt->transport_lock);
+	ret = xprt_clear_write_space_locked(xprt);
+	spin_unlock(&xprt->transport_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_write_space);
+
+static unsigned long xprt_abs_ktime_to_jiffies(ktime_t abstime)
+{
+	s64 delta = ktime_to_ns(ktime_get() - abstime);
+	return likely(delta >= 0) ?
+		jiffies - nsecs_to_jiffies(delta) :
+		jiffies + nsecs_to_jiffies(-delta);
+}
+
+static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
+{
+	const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
+	unsigned long majortimeo = req->rq_timeout;
+
+	if (to->to_exponential)
+		majortimeo <<= to->to_retries;
+	else
+		majortimeo += to->to_increment * to->to_retries;
+	if (majortimeo > to->to_maxval || majortimeo == 0)
+		majortimeo = to->to_maxval;
+	return majortimeo;
+}
+
+static void xprt_reset_majortimeo(struct rpc_rqst *req)
+{
+	req->rq_majortimeo += xprt_calc_majortimeo(req);
+}
+
+static void xprt_reset_minortimeo(struct rpc_rqst *req)
+{
+	req->rq_minortimeo += req->rq_timeout;
+}
+
+static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
+{
+	unsigned long time_init;
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	if (likely(xprt && xprt_connected(xprt)))
+		time_init = jiffies;
+	else
+		time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
+	req->rq_timeout = task->tk_client->cl_timeout->to_initval;
+	req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
+	req->rq_minortimeo = time_init + req->rq_timeout;
+}
+
+/**
+ * xprt_adjust_timeout - adjust timeout values for next retransmit
+ * @req: RPC request containing parameters to use for the adjustment
+ *
+ */
+int xprt_adjust_timeout(struct rpc_rqst *req)
+{
+	struct rpc_xprt *xprt = req->rq_xprt;
+	const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
+	int status = 0;
+
+	if (time_before(jiffies, req->rq_majortimeo)) {
+		if (time_before(jiffies, req->rq_minortimeo))
+			return status;
+		if (to->to_exponential)
+			req->rq_timeout <<= 1;
+		else
+			req->rq_timeout += to->to_increment;
+		if (to->to_maxval && req->rq_timeout >= to->to_maxval)
+			req->rq_timeout = to->to_maxval;
+		req->rq_retries++;
+	} else {
+		req->rq_timeout = to->to_initval;
+		req->rq_retries = 0;
+		xprt_reset_majortimeo(req);
+		/* Reset the RTT counters == "slow start" */
+		spin_lock(&xprt->transport_lock);
+		rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
+		spin_unlock(&xprt->transport_lock);
+		status = -ETIMEDOUT;
+	}
+	xprt_reset_minortimeo(req);
+
+	if (req->rq_timeout == 0) {
+		printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
+		req->rq_timeout = 5 * HZ;
+	}
+	return status;
+}
+
+static void xprt_autoclose(struct work_struct *work)
+{
+	struct rpc_xprt *xprt =
+		container_of(work, struct rpc_xprt, task_cleanup);
+	unsigned int pflags = memalloc_nofs_save();
+
+	trace_xprt_disconnect_auto(xprt);
+	xprt->connect_cookie++;
+	smp_mb__before_atomic();
+	clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
+	xprt->ops->close(xprt);
+	xprt_release_write(xprt, NULL);
+	wake_up_bit(&xprt->state, XPRT_LOCKED);
+	memalloc_nofs_restore(pflags);
+}
+
+/**
+ * xprt_disconnect_done - mark a transport as disconnected
+ * @xprt: transport to flag for disconnect
+ *
+ */
+void xprt_disconnect_done(struct rpc_xprt *xprt)
+{
+	trace_xprt_disconnect_done(xprt);
+	spin_lock(&xprt->transport_lock);
+	xprt_clear_connected(xprt);
+	xprt_clear_write_space_locked(xprt);
+	xprt_clear_congestion_window_wait_locked(xprt);
+	xprt_wake_pending_tasks(xprt, -ENOTCONN);
+	spin_unlock(&xprt->transport_lock);
+}
+EXPORT_SYMBOL_GPL(xprt_disconnect_done);
+
+/**
+ * xprt_schedule_autoclose_locked - Try to schedule an autoclose RPC call
+ * @xprt: transport to disconnect
+ */
+static void xprt_schedule_autoclose_locked(struct rpc_xprt *xprt)
+{
+	if (test_and_set_bit(XPRT_CLOSE_WAIT, &xprt->state))
+		return;
+	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
+		queue_work(xprtiod_workqueue, &xprt->task_cleanup);
+	else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
+		rpc_wake_up_queued_task_set_status(&xprt->pending,
+						   xprt->snd_task, -ENOTCONN);
+}
+
+/**
+ * xprt_force_disconnect - force a transport to disconnect
+ * @xprt: transport to disconnect
+ *
+ */
+void xprt_force_disconnect(struct rpc_xprt *xprt)
+{
+	trace_xprt_disconnect_force(xprt);
+
+	/* Don't race with the test_bit() in xprt_clear_locked() */
+	spin_lock(&xprt->transport_lock);
+	xprt_schedule_autoclose_locked(xprt);
+	spin_unlock(&xprt->transport_lock);
+}
+EXPORT_SYMBOL_GPL(xprt_force_disconnect);
+
+static unsigned int
+xprt_connect_cookie(struct rpc_xprt *xprt)
+{
+	return READ_ONCE(xprt->connect_cookie);
+}
+
+static bool
+xprt_request_retransmit_after_disconnect(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
+		!xprt_connected(xprt);
+}
+
+/**
+ * xprt_conditional_disconnect - force a transport to disconnect
+ * @xprt: transport to disconnect
+ * @cookie: 'connection cookie'
+ *
+ * This attempts to break the connection if and only if 'cookie' matches
+ * the current transport 'connection cookie'. It ensures that we don't
+ * try to break the connection more than once when we need to retransmit
+ * a batch of RPC requests.
+ *
+ */
+void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
+{
+	/* Don't race with the test_bit() in xprt_clear_locked() */
+	spin_lock(&xprt->transport_lock);
+	if (cookie != xprt->connect_cookie)
+		goto out;
+	if (test_bit(XPRT_CLOSING, &xprt->state))
+		goto out;
+	xprt_schedule_autoclose_locked(xprt);
+out:
+	spin_unlock(&xprt->transport_lock);
+}
+
+static bool
+xprt_has_timer(const struct rpc_xprt *xprt)
+{
+	return xprt->idle_timeout != 0;
+}
+
+static void
+xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
+	__must_hold(&xprt->transport_lock)
+{
+	xprt->last_used = jiffies;
+	if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
+		mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
+}
+
+static void
+xprt_init_autodisconnect(struct timer_list *t)
+{
+	struct rpc_xprt *xprt = from_timer(xprt, t, timer);
+
+	if (!RB_EMPTY_ROOT(&xprt->recv_queue))
+		return;
+	/* Reset xprt->last_used to avoid connect/autodisconnect cycling */
+	xprt->last_used = jiffies;
+	if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
+		return;
+	queue_work(xprtiod_workqueue, &xprt->task_cleanup);
+}
+
+#if IS_ENABLED(CONFIG_FAIL_SUNRPC)
+static void xprt_inject_disconnect(struct rpc_xprt *xprt)
+{
+	if (!fail_sunrpc.ignore_client_disconnect &&
+	    should_fail(&fail_sunrpc.attr, 1))
+		xprt->ops->inject_disconnect(xprt);
+}
+#else
+static inline void xprt_inject_disconnect(struct rpc_xprt *xprt)
+{
+}
+#endif
+
+bool xprt_lock_connect(struct rpc_xprt *xprt,
+		struct rpc_task *task,
+		void *cookie)
+{
+	bool ret = false;
+
+	spin_lock(&xprt->transport_lock);
+	if (!test_bit(XPRT_LOCKED, &xprt->state))
+		goto out;
+	if (xprt->snd_task != task)
+		goto out;
+	set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
+	xprt->snd_task = cookie;
+	ret = true;
+out:
+	spin_unlock(&xprt->transport_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_lock_connect);
+
+void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
+{
+	spin_lock(&xprt->transport_lock);
+	if (xprt->snd_task != cookie)
+		goto out;
+	if (!test_bit(XPRT_LOCKED, &xprt->state))
+		goto out;
+	xprt->snd_task =NULL;
+	clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
+	xprt->ops->release_xprt(xprt, NULL);
+	xprt_schedule_autodisconnect(xprt);
+out:
+	spin_unlock(&xprt->transport_lock);
+	wake_up_bit(&xprt->state, XPRT_LOCKED);
+}
+EXPORT_SYMBOL_GPL(xprt_unlock_connect);
+
+/**
+ * xprt_connect - schedule a transport connect operation
+ * @task: RPC task that is requesting the connect
+ *
+ */
+void xprt_connect(struct rpc_task *task)
+{
+	struct rpc_xprt	*xprt = task->tk_rqstp->rq_xprt;
+
+	trace_xprt_connect(xprt);
+
+	if (!xprt_bound(xprt)) {
+		task->tk_status = -EAGAIN;
+		return;
+	}
+	if (!xprt_lock_write(xprt, task))
+		return;
+
+	if (!xprt_connected(xprt) && !test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
+		task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
+		rpc_sleep_on_timeout(&xprt->pending, task, NULL,
+				xprt_request_timeout(task->tk_rqstp));
+
+		if (test_bit(XPRT_CLOSING, &xprt->state))
+			return;
+		if (xprt_test_and_set_connecting(xprt))
+			return;
+		/* Race breaker */
+		if (!xprt_connected(xprt)) {
+			xprt->stat.connect_start = jiffies;
+			xprt->ops->connect(xprt, task);
+		} else {
+			xprt_clear_connecting(xprt);
+			task->tk_status = 0;
+			rpc_wake_up_queued_task(&xprt->pending, task);
+		}
+	}
+	xprt_release_write(xprt, task);
+}
+
+/**
+ * xprt_reconnect_delay - compute the wait before scheduling a connect
+ * @xprt: transport instance
+ *
+ */
+unsigned long xprt_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;
+}
+EXPORT_SYMBOL_GPL(xprt_reconnect_delay);
+
+/**
+ * xprt_reconnect_backoff - compute the new re-establish timeout
+ * @xprt: transport instance
+ * @init_to: initial reestablish timeout
+ *
+ */
+void xprt_reconnect_backoff(struct rpc_xprt *xprt, unsigned long init_to)
+{
+	xprt->reestablish_timeout <<= 1;
+	if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
+		xprt->reestablish_timeout = xprt->max_reconnect_timeout;
+	if (xprt->reestablish_timeout < init_to)
+		xprt->reestablish_timeout = init_to;
+}
+EXPORT_SYMBOL_GPL(xprt_reconnect_backoff);
+
+enum xprt_xid_rb_cmp {
+	XID_RB_EQUAL,
+	XID_RB_LEFT,
+	XID_RB_RIGHT,
+};
+static enum xprt_xid_rb_cmp
+xprt_xid_cmp(__be32 xid1, __be32 xid2)
+{
+	if (xid1 == xid2)
+		return XID_RB_EQUAL;
+	if ((__force u32)xid1 < (__force u32)xid2)
+		return XID_RB_LEFT;
+	return XID_RB_RIGHT;
+}
+
+static struct rpc_rqst *
+xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
+{
+	struct rb_node *n = xprt->recv_queue.rb_node;
+	struct rpc_rqst *req;
+
+	while (n != NULL) {
+		req = rb_entry(n, struct rpc_rqst, rq_recv);
+		switch (xprt_xid_cmp(xid, req->rq_xid)) {
+		case XID_RB_LEFT:
+			n = n->rb_left;
+			break;
+		case XID_RB_RIGHT:
+			n = n->rb_right;
+			break;
+		case XID_RB_EQUAL:
+			return req;
+		}
+	}
+	return NULL;
+}
+
+static void
+xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
+{
+	struct rb_node **p = &xprt->recv_queue.rb_node;
+	struct rb_node *n = NULL;
+	struct rpc_rqst *req;
+
+	while (*p != NULL) {
+		n = *p;
+		req = rb_entry(n, struct rpc_rqst, rq_recv);
+		switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
+		case XID_RB_LEFT:
+			p = &n->rb_left;
+			break;
+		case XID_RB_RIGHT:
+			p = &n->rb_right;
+			break;
+		case XID_RB_EQUAL:
+			WARN_ON_ONCE(new != req);
+			return;
+		}
+	}
+	rb_link_node(&new->rq_recv, n, p);
+	rb_insert_color(&new->rq_recv, &xprt->recv_queue);
+}
+
+static void
+xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+	rb_erase(&req->rq_recv, &xprt->recv_queue);
+}
+
+/**
+ * xprt_lookup_rqst - find an RPC request corresponding to an XID
+ * @xprt: transport on which the original request was transmitted
+ * @xid: RPC XID of incoming reply
+ *
+ * Caller holds xprt->queue_lock.
+ */
+struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
+{
+	struct rpc_rqst *entry;
+
+	entry = xprt_request_rb_find(xprt, xid);
+	if (entry != NULL) {
+		trace_xprt_lookup_rqst(xprt, xid, 0);
+		entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
+		return entry;
+	}
+
+	dprintk("RPC:       xprt_lookup_rqst did not find xid %08x\n",
+			ntohl(xid));
+	trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
+	xprt->stat.bad_xids++;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
+
+static bool
+xprt_is_pinned_rqst(struct rpc_rqst *req)
+{
+	return atomic_read(&req->rq_pin) != 0;
+}
+
+/**
+ * xprt_pin_rqst - Pin a request on the transport receive list
+ * @req: Request to pin
+ *
+ * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
+ * so should be holding xprt->queue_lock.
+ */
+void xprt_pin_rqst(struct rpc_rqst *req)
+{
+	atomic_inc(&req->rq_pin);
+}
+EXPORT_SYMBOL_GPL(xprt_pin_rqst);
+
+/**
+ * xprt_unpin_rqst - Unpin a request on the transport receive list
+ * @req: Request to pin
+ *
+ * Caller should be holding xprt->queue_lock.
+ */
+void xprt_unpin_rqst(struct rpc_rqst *req)
+{
+	if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
+		atomic_dec(&req->rq_pin);
+		return;
+	}
+	if (atomic_dec_and_test(&req->rq_pin))
+		wake_up_var(&req->rq_pin);
+}
+EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
+
+static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
+{
+	wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
+}
+
+static bool
+xprt_request_data_received(struct rpc_task *task)
+{
+	return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
+		READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
+}
+
+static bool
+xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
+{
+	return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
+		READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
+}
+
+/**
+ * xprt_request_enqueue_receive - Add an request to the receive queue
+ * @task: RPC task
+ *
+ */
+int
+xprt_request_enqueue_receive(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+	int ret;
+
+	if (!xprt_request_need_enqueue_receive(task, req))
+		return 0;
+
+	ret = xprt_request_prepare(task->tk_rqstp, &req->rq_rcv_buf);
+	if (ret)
+		return ret;
+	spin_lock(&xprt->queue_lock);
+
+	/* Update the softirq receive buffer */
+	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
+			sizeof(req->rq_private_buf));
+
+	/* Add request to the receive list */
+	xprt_request_rb_insert(xprt, req);
+	set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
+	spin_unlock(&xprt->queue_lock);
+
+	/* Turn off autodisconnect */
+	del_timer_sync(&xprt->timer);
+	return 0;
+}
+
+/**
+ * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
+ * @task: RPC task
+ *
+ * Caller must hold xprt->queue_lock.
+ */
+static void
+xprt_request_dequeue_receive_locked(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+
+	if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
+		xprt_request_rb_remove(req->rq_xprt, req);
+}
+
+/**
+ * xprt_update_rtt - Update RPC RTT statistics
+ * @task: RPC request that recently completed
+ *
+ * Caller holds xprt->queue_lock.
+ */
+void xprt_update_rtt(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_rtt *rtt = task->tk_client->cl_rtt;
+	unsigned int timer = task->tk_msg.rpc_proc->p_timer;
+	long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
+
+	if (timer) {
+		if (req->rq_ntrans == 1)
+			rpc_update_rtt(rtt, timer, m);
+		rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
+	}
+}
+EXPORT_SYMBOL_GPL(xprt_update_rtt);
+
+/**
+ * xprt_complete_rqst - called when reply processing is complete
+ * @task: RPC request that recently completed
+ * @copied: actual number of bytes received from the transport
+ *
+ * Caller holds xprt->queue_lock.
+ */
+void xprt_complete_rqst(struct rpc_task *task, int copied)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	xprt->stat.recvs++;
+
+	xdr_free_bvec(&req->rq_rcv_buf);
+	req->rq_private_buf.bvec = NULL;
+	req->rq_private_buf.len = copied;
+	/* Ensure all writes are done before we update */
+	/* req->rq_reply_bytes_recvd */
+	smp_wmb();
+	req->rq_reply_bytes_recvd = copied;
+	xprt_request_dequeue_receive_locked(task);
+	rpc_wake_up_queued_task(&xprt->pending, task);
+}
+EXPORT_SYMBOL_GPL(xprt_complete_rqst);
+
+static void xprt_timer(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	if (task->tk_status != -ETIMEDOUT)
+		return;
+
+	trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
+	if (!req->rq_reply_bytes_recvd) {
+		if (xprt->ops->timer)
+			xprt->ops->timer(xprt, task);
+	} else
+		task->tk_status = 0;
+}
+
+/**
+ * xprt_wait_for_reply_request_def - wait for reply
+ * @task: pointer to rpc_task
+ *
+ * Set a request's retransmit timeout based on the transport's
+ * default timeout parameters.  Used by transports that don't adjust
+ * the retransmit timeout based on round-trip time estimation,
+ * and put the task to sleep on the pending queue.
+ */
+void xprt_wait_for_reply_request_def(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+
+	rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
+			xprt_request_timeout(req));
+}
+EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_def);
+
+/**
+ * xprt_wait_for_reply_request_rtt - wait for reply using RTT estimator
+ * @task: pointer to rpc_task
+ *
+ * Set a request's retransmit timeout using the RTT estimator,
+ * and put the task to sleep on the pending queue.
+ */
+void xprt_wait_for_reply_request_rtt(struct rpc_task *task)
+{
+	int timer = task->tk_msg.rpc_proc->p_timer;
+	struct rpc_clnt *clnt = task->tk_client;
+	struct rpc_rtt *rtt = clnt->cl_rtt;
+	struct rpc_rqst *req = task->tk_rqstp;
+	unsigned long max_timeout = clnt->cl_timeout->to_maxval;
+	unsigned long timeout;
+
+	timeout = rpc_calc_rto(rtt, timer);
+	timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
+	if (timeout > max_timeout || timeout == 0)
+		timeout = max_timeout;
+	rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
+			jiffies + timeout);
+}
+EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_rtt);
+
+/**
+ * xprt_request_wait_receive - wait for the reply to an RPC request
+ * @task: RPC task about to send a request
+ *
+ */
+void xprt_request_wait_receive(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
+		return;
+	/*
+	 * Sleep on the pending queue if we're expecting a reply.
+	 * The spinlock ensures atomicity between the test of
+	 * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
+	 */
+	spin_lock(&xprt->queue_lock);
+	if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
+		xprt->ops->wait_for_reply_request(task);
+		/*
+		 * Send an extra queue wakeup call if the
+		 * connection was dropped in case the call to
+		 * rpc_sleep_on() raced.
+		 */
+		if (xprt_request_retransmit_after_disconnect(task))
+			rpc_wake_up_queued_task_set_status(&xprt->pending,
+					task, -ENOTCONN);
+	}
+	spin_unlock(&xprt->queue_lock);
+}
+
+static bool
+xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
+{
+	return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
+}
+
+/**
+ * xprt_request_enqueue_transmit - queue a task for transmission
+ * @task: pointer to rpc_task
+ *
+ * Add a task to the transmission queue.
+ */
+void
+xprt_request_enqueue_transmit(struct rpc_task *task)
+{
+	struct rpc_rqst *pos, *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+	int ret;
+
+	if (xprt_request_need_enqueue_transmit(task, req)) {
+		ret = xprt_request_prepare(task->tk_rqstp, &req->rq_snd_buf);
+		if (ret) {
+			task->tk_status = ret;
+			return;
+		}
+		req->rq_bytes_sent = 0;
+		spin_lock(&xprt->queue_lock);
+		/*
+		 * Requests that carry congestion control credits are added
+		 * to the head of the list to avoid starvation issues.
+		 */
+		if (req->rq_cong) {
+			xprt_clear_congestion_window_wait(xprt);
+			list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
+				if (pos->rq_cong)
+					continue;
+				/* Note: req is added _before_ pos */
+				list_add_tail(&req->rq_xmit, &pos->rq_xmit);
+				INIT_LIST_HEAD(&req->rq_xmit2);
+				goto out;
+			}
+		} else if (!req->rq_seqno) {
+			list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
+				if (pos->rq_task->tk_owner != task->tk_owner)
+					continue;
+				list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
+				INIT_LIST_HEAD(&req->rq_xmit);
+				goto out;
+			}
+		}
+		list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
+		INIT_LIST_HEAD(&req->rq_xmit2);
+out:
+		atomic_long_inc(&xprt->xmit_queuelen);
+		set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
+		spin_unlock(&xprt->queue_lock);
+	}
+}
+
+/**
+ * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
+ * @task: pointer to rpc_task
+ *
+ * Remove a task from the transmission queue
+ * Caller must hold xprt->queue_lock
+ */
+static void
+xprt_request_dequeue_transmit_locked(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+
+	if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+		return;
+	if (!list_empty(&req->rq_xmit)) {
+		list_del(&req->rq_xmit);
+		if (!list_empty(&req->rq_xmit2)) {
+			struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
+					struct rpc_rqst, rq_xmit2);
+			list_del(&req->rq_xmit2);
+			list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
+		}
+	} else
+		list_del(&req->rq_xmit2);
+	atomic_long_dec(&req->rq_xprt->xmit_queuelen);
+	xdr_free_bvec(&req->rq_snd_buf);
+}
+
+/**
+ * xprt_request_dequeue_transmit - remove a task from the transmission queue
+ * @task: pointer to rpc_task
+ *
+ * Remove a task from the transmission queue
+ */
+static void
+xprt_request_dequeue_transmit(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	spin_lock(&xprt->queue_lock);
+	xprt_request_dequeue_transmit_locked(task);
+	spin_unlock(&xprt->queue_lock);
+}
+
+/**
+ * xprt_request_dequeue_xprt - remove a task from the transmit+receive queue
+ * @task: pointer to rpc_task
+ *
+ * Remove a task from the transmit and receive queues, and ensure that
+ * it is not pinned by the receive work item.
+ */
+void
+xprt_request_dequeue_xprt(struct rpc_task *task)
+{
+	struct rpc_rqst	*req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
+	    test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
+	    xprt_is_pinned_rqst(req)) {
+		spin_lock(&xprt->queue_lock);
+		while (xprt_is_pinned_rqst(req)) {
+			set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
+			spin_unlock(&xprt->queue_lock);
+			xprt_wait_on_pinned_rqst(req);
+			spin_lock(&xprt->queue_lock);
+			clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
+		}
+		xprt_request_dequeue_transmit_locked(task);
+		xprt_request_dequeue_receive_locked(task);
+		spin_unlock(&xprt->queue_lock);
+		xdr_free_bvec(&req->rq_rcv_buf);
+	}
+}
+
+/**
+ * xprt_request_prepare - prepare an encoded request for transport
+ * @req: pointer to rpc_rqst
+ * @buf: pointer to send/rcv xdr_buf
+ *
+ * Calls into the transport layer to do whatever is needed to prepare
+ * the request for transmission or receive.
+ * Returns error, or zero.
+ */
+static int
+xprt_request_prepare(struct rpc_rqst *req, struct xdr_buf *buf)
+{
+	struct rpc_xprt *xprt = req->rq_xprt;
+
+	if (xprt->ops->prepare_request)
+		return xprt->ops->prepare_request(req, buf);
+	return 0;
+}
+
+/**
+ * xprt_request_need_retransmit - Test if a task needs retransmission
+ * @task: pointer to rpc_task
+ *
+ * Test for whether a connection breakage requires the task to retransmit
+ */
+bool
+xprt_request_need_retransmit(struct rpc_task *task)
+{
+	return xprt_request_retransmit_after_disconnect(task);
+}
+
+/**
+ * xprt_prepare_transmit - reserve the transport before sending a request
+ * @task: RPC task about to send a request
+ *
+ */
+bool xprt_prepare_transmit(struct rpc_task *task)
+{
+	struct rpc_rqst	*req = task->tk_rqstp;
+	struct rpc_xprt	*xprt = req->rq_xprt;
+
+	if (!xprt_lock_write(xprt, task)) {
+		/* Race breaker: someone may have transmitted us */
+		if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+			rpc_wake_up_queued_task_set_status(&xprt->sending,
+					task, 0);
+		return false;
+
+	}
+	if (atomic_read(&xprt->swapper))
+		/* This will be clear in __rpc_execute */
+		current->flags |= PF_MEMALLOC;
+	return true;
+}
+
+void xprt_end_transmit(struct rpc_task *task)
+{
+	struct rpc_xprt	*xprt = task->tk_rqstp->rq_xprt;
+
+	xprt_inject_disconnect(xprt);
+	xprt_release_write(xprt, task);
+}
+
+/**
+ * xprt_request_transmit - send an RPC request on a transport
+ * @req: pointer to request to transmit
+ * @snd_task: RPC task that owns the transport lock
+ *
+ * This performs the transmission of a single request.
+ * Note that if the request is not the same as snd_task, then it
+ * does need to be pinned.
+ * Returns '0' on success.
+ */
+static int
+xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
+{
+	struct rpc_xprt *xprt = req->rq_xprt;
+	struct rpc_task *task = req->rq_task;
+	unsigned int connect_cookie;
+	int is_retrans = RPC_WAS_SENT(task);
+	int status;
+
+	if (!req->rq_bytes_sent) {
+		if (xprt_request_data_received(task)) {
+			status = 0;
+			goto out_dequeue;
+		}
+		/* Verify that our message lies in the RPCSEC_GSS window */
+		if (rpcauth_xmit_need_reencode(task)) {
+			status = -EBADMSG;
+			goto out_dequeue;
+		}
+		if (RPC_SIGNALLED(task)) {
+			status = -ERESTARTSYS;
+			goto out_dequeue;
+		}
+	}
+
+	/*
+	 * Update req->rq_ntrans before transmitting to avoid races with
+	 * xprt_update_rtt(), which needs to know that it is recording a
+	 * reply to the first transmission.
+	 */
+	req->rq_ntrans++;
+
+	trace_rpc_xdr_sendto(task, &req->rq_snd_buf);
+	connect_cookie = xprt->connect_cookie;
+	status = xprt->ops->send_request(req);
+	if (status != 0) {
+		req->rq_ntrans--;
+		trace_xprt_transmit(req, status);
+		return status;
+	}
+
+	if (is_retrans) {
+		task->tk_client->cl_stats->rpcretrans++;
+		trace_xprt_retransmit(req);
+	}
+
+	xprt_inject_disconnect(xprt);
+
+	task->tk_flags |= RPC_TASK_SENT;
+	spin_lock(&xprt->transport_lock);
+
+	xprt->stat.sends++;
+	xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
+	xprt->stat.bklog_u += xprt->backlog.qlen;
+	xprt->stat.sending_u += xprt->sending.qlen;
+	xprt->stat.pending_u += xprt->pending.qlen;
+	spin_unlock(&xprt->transport_lock);
+
+	req->rq_connect_cookie = connect_cookie;
+out_dequeue:
+	trace_xprt_transmit(req, status);
+	xprt_request_dequeue_transmit(task);
+	rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
+	return status;
+}
+
+/**
+ * xprt_transmit - send an RPC request on a transport
+ * @task: controlling RPC task
+ *
+ * Attempts to drain the transmit queue. On exit, either the transport
+ * signalled an error that needs to be handled before transmission can
+ * resume, or @task finished transmitting, and detected that it already
+ * received a reply.
+ */
+void
+xprt_transmit(struct rpc_task *task)
+{
+	struct rpc_rqst *next, *req = task->tk_rqstp;
+	struct rpc_xprt	*xprt = req->rq_xprt;
+	int status;
+
+	spin_lock(&xprt->queue_lock);
+	for (;;) {
+		next = list_first_entry_or_null(&xprt->xmit_queue,
+						struct rpc_rqst, rq_xmit);
+		if (!next)
+			break;
+		xprt_pin_rqst(next);
+		spin_unlock(&xprt->queue_lock);
+		status = xprt_request_transmit(next, task);
+		if (status == -EBADMSG && next != req)
+			status = 0;
+		spin_lock(&xprt->queue_lock);
+		xprt_unpin_rqst(next);
+		if (status < 0) {
+			if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+				task->tk_status = status;
+			break;
+		}
+		/* Was @task transmitted, and has it received a reply? */
+		if (xprt_request_data_received(task) &&
+		    !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+			break;
+		cond_resched_lock(&xprt->queue_lock);
+	}
+	spin_unlock(&xprt->queue_lock);
+}
+
+static void xprt_complete_request_init(struct rpc_task *task)
+{
+	if (task->tk_rqstp)
+		xprt_request_init(task);
+}
+
+void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	set_bit(XPRT_CONGESTED, &xprt->state);
+	rpc_sleep_on(&xprt->backlog, task, xprt_complete_request_init);
+}
+EXPORT_SYMBOL_GPL(xprt_add_backlog);
+
+static bool __xprt_set_rq(struct rpc_task *task, void *data)
+{
+	struct rpc_rqst *req = data;
+
+	if (task->tk_rqstp == NULL) {
+		memset(req, 0, sizeof(*req));	/* mark unused */
+		task->tk_rqstp = req;
+		return true;
+	}
+	return false;
+}
+
+bool xprt_wake_up_backlog(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+	if (rpc_wake_up_first(&xprt->backlog, __xprt_set_rq, req) == NULL) {
+		clear_bit(XPRT_CONGESTED, &xprt->state);
+		return false;
+	}
+	return true;
+}
+EXPORT_SYMBOL_GPL(xprt_wake_up_backlog);
+
+static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	bool ret = false;
+
+	if (!test_bit(XPRT_CONGESTED, &xprt->state))
+		goto out;
+	spin_lock(&xprt->reserve_lock);
+	if (test_bit(XPRT_CONGESTED, &xprt->state)) {
+		xprt_add_backlog(xprt, task);
+		ret = true;
+	}
+	spin_unlock(&xprt->reserve_lock);
+out:
+	return ret;
+}
+
+static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
+{
+	struct rpc_rqst *req = ERR_PTR(-EAGAIN);
+
+	if (xprt->num_reqs >= xprt->max_reqs)
+		goto out;
+	++xprt->num_reqs;
+	spin_unlock(&xprt->reserve_lock);
+	req = kzalloc(sizeof(*req), rpc_task_gfp_mask());
+	spin_lock(&xprt->reserve_lock);
+	if (req != NULL)
+		goto out;
+	--xprt->num_reqs;
+	req = ERR_PTR(-ENOMEM);
+out:
+	return req;
+}
+
+static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+	if (xprt->num_reqs > xprt->min_reqs) {
+		--xprt->num_reqs;
+		kfree(req);
+		return true;
+	}
+	return false;
+}
+
+void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	struct rpc_rqst *req;
+
+	spin_lock(&xprt->reserve_lock);
+	if (!list_empty(&xprt->free)) {
+		req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
+		list_del(&req->rq_list);
+		goto out_init_req;
+	}
+	req = xprt_dynamic_alloc_slot(xprt);
+	if (!IS_ERR(req))
+		goto out_init_req;
+	switch (PTR_ERR(req)) {
+	case -ENOMEM:
+		dprintk("RPC:       dynamic allocation of request slot "
+				"failed! Retrying\n");
+		task->tk_status = -ENOMEM;
+		break;
+	case -EAGAIN:
+		xprt_add_backlog(xprt, task);
+		dprintk("RPC:       waiting for request slot\n");
+		fallthrough;
+	default:
+		task->tk_status = -EAGAIN;
+	}
+	spin_unlock(&xprt->reserve_lock);
+	return;
+out_init_req:
+	xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
+				     xprt->num_reqs);
+	spin_unlock(&xprt->reserve_lock);
+
+	task->tk_status = 0;
+	task->tk_rqstp = req;
+}
+EXPORT_SYMBOL_GPL(xprt_alloc_slot);
+
+void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+	spin_lock(&xprt->reserve_lock);
+	if (!xprt_wake_up_backlog(xprt, req) &&
+	    !xprt_dynamic_free_slot(xprt, req)) {
+		memset(req, 0, sizeof(*req));	/* mark unused */
+		list_add(&req->rq_list, &xprt->free);
+	}
+	spin_unlock(&xprt->reserve_lock);
+}
+EXPORT_SYMBOL_GPL(xprt_free_slot);
+
+static void xprt_free_all_slots(struct rpc_xprt *xprt)
+{
+	struct rpc_rqst *req;
+	while (!list_empty(&xprt->free)) {
+		req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
+		list_del(&req->rq_list);
+		kfree(req);
+	}
+}
+
+static DEFINE_IDA(rpc_xprt_ids);
+
+void xprt_cleanup_ids(void)
+{
+	ida_destroy(&rpc_xprt_ids);
+}
+
+static int xprt_alloc_id(struct rpc_xprt *xprt)
+{
+	int id;
+
+	id = ida_alloc(&rpc_xprt_ids, GFP_KERNEL);
+	if (id < 0)
+		return id;
+
+	xprt->id = id;
+	return 0;
+}
+
+static void xprt_free_id(struct rpc_xprt *xprt)
+{
+	ida_free(&rpc_xprt_ids, xprt->id);
+}
+
+struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
+		unsigned int num_prealloc,
+		unsigned int max_alloc)
+{
+	struct rpc_xprt *xprt;
+	struct rpc_rqst *req;
+	int i;
+
+	xprt = kzalloc(size, GFP_KERNEL);
+	if (xprt == NULL)
+		goto out;
+
+	xprt_alloc_id(xprt);
+	xprt_init(xprt, net);
+
+	for (i = 0; i < num_prealloc; i++) {
+		req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
+		if (!req)
+			goto out_free;
+		list_add(&req->rq_list, &xprt->free);
+	}
+	xprt->max_reqs = max_t(unsigned int, max_alloc, num_prealloc);
+	xprt->min_reqs = num_prealloc;
+	xprt->num_reqs = num_prealloc;
+
+	return xprt;
+
+out_free:
+	xprt_free(xprt);
+out:
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(xprt_alloc);
+
+void xprt_free(struct rpc_xprt *xprt)
+{
+	put_net_track(xprt->xprt_net, &xprt->ns_tracker);
+	xprt_free_all_slots(xprt);
+	xprt_free_id(xprt);
+	rpc_sysfs_xprt_destroy(xprt);
+	kfree_rcu(xprt, rcu);
+}
+EXPORT_SYMBOL_GPL(xprt_free);
+
+static void
+xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
+{
+	req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
+}
+
+static __be32
+xprt_alloc_xid(struct rpc_xprt *xprt)
+{
+	__be32 xid;
+
+	spin_lock(&xprt->reserve_lock);
+	xid = (__force __be32)xprt->xid++;
+	spin_unlock(&xprt->reserve_lock);
+	return xid;
+}
+
+static void
+xprt_init_xid(struct rpc_xprt *xprt)
+{
+	xprt->xid = get_random_u32();
+}
+
+static void
+xprt_request_init(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = task->tk_xprt;
+	struct rpc_rqst	*req = task->tk_rqstp;
+
+	req->rq_task	= task;
+	req->rq_xprt    = xprt;
+	req->rq_buffer  = NULL;
+	req->rq_xid	= xprt_alloc_xid(xprt);
+	xprt_init_connect_cookie(req, xprt);
+	req->rq_snd_buf.len = 0;
+	req->rq_snd_buf.buflen = 0;
+	req->rq_rcv_buf.len = 0;
+	req->rq_rcv_buf.buflen = 0;
+	req->rq_snd_buf.bvec = NULL;
+	req->rq_rcv_buf.bvec = NULL;
+	req->rq_release_snd_buf = NULL;
+	xprt_init_majortimeo(task, req);
+
+	trace_xprt_reserve(req);
+}
+
+static void
+xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	xprt->ops->alloc_slot(xprt, task);
+	if (task->tk_rqstp != NULL)
+		xprt_request_init(task);
+}
+
+/**
+ * xprt_reserve - allocate an RPC request slot
+ * @task: RPC task requesting a slot allocation
+ *
+ * If the transport is marked as being congested, or if no more
+ * slots are available, place the task on the transport's
+ * backlog queue.
+ */
+void xprt_reserve(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = task->tk_xprt;
+
+	task->tk_status = 0;
+	if (task->tk_rqstp != NULL)
+		return;
+
+	task->tk_status = -EAGAIN;
+	if (!xprt_throttle_congested(xprt, task))
+		xprt_do_reserve(xprt, task);
+}
+
+/**
+ * xprt_retry_reserve - allocate an RPC request slot
+ * @task: RPC task requesting a slot allocation
+ *
+ * If no more slots are available, place the task on the transport's
+ * backlog queue.
+ * Note that the only difference with xprt_reserve is that we now
+ * ignore the value of the XPRT_CONGESTED flag.
+ */
+void xprt_retry_reserve(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = task->tk_xprt;
+
+	task->tk_status = 0;
+	if (task->tk_rqstp != NULL)
+		return;
+
+	task->tk_status = -EAGAIN;
+	xprt_do_reserve(xprt, task);
+}
+
+/**
+ * xprt_release - release an RPC request slot
+ * @task: task which is finished with the slot
+ *
+ */
+void xprt_release(struct rpc_task *task)
+{
+	struct rpc_xprt	*xprt;
+	struct rpc_rqst	*req = task->tk_rqstp;
+
+	if (req == NULL) {
+		if (task->tk_client) {
+			xprt = task->tk_xprt;
+			xprt_release_write(xprt, task);
+		}
+		return;
+	}
+
+	xprt = req->rq_xprt;
+	xprt_request_dequeue_xprt(task);
+	spin_lock(&xprt->transport_lock);
+	xprt->ops->release_xprt(xprt, task);
+	if (xprt->ops->release_request)
+		xprt->ops->release_request(task);
+	xprt_schedule_autodisconnect(xprt);
+	spin_unlock(&xprt->transport_lock);
+	if (req->rq_buffer)
+		xprt->ops->buf_free(task);
+	if (req->rq_cred != NULL)
+		put_rpccred(req->rq_cred);
+	if (req->rq_release_snd_buf)
+		req->rq_release_snd_buf(req);
+
+	task->tk_rqstp = NULL;
+	if (likely(!bc_prealloc(req)))
+		xprt->ops->free_slot(xprt, req);
+	else
+		xprt_free_bc_request(req);
+}
+
+#ifdef CONFIG_SUNRPC_BACKCHANNEL
+void
+xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
+{
+	struct xdr_buf *xbufp = &req->rq_snd_buf;
+
+	task->tk_rqstp = req;
+	req->rq_task = task;
+	xprt_init_connect_cookie(req, req->rq_xprt);
+	/*
+	 * Set up the xdr_buf length.
+	 * This also indicates that the buffer is XDR encoded already.
+	 */
+	xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
+		xbufp->tail[0].iov_len;
+}
+#endif
+
+static void xprt_init(struct rpc_xprt *xprt, struct net *net)
+{
+	kref_init(&xprt->kref);
+
+	spin_lock_init(&xprt->transport_lock);
+	spin_lock_init(&xprt->reserve_lock);
+	spin_lock_init(&xprt->queue_lock);
+
+	INIT_LIST_HEAD(&xprt->free);
+	xprt->recv_queue = RB_ROOT;
+	INIT_LIST_HEAD(&xprt->xmit_queue);
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+	spin_lock_init(&xprt->bc_pa_lock);
+	INIT_LIST_HEAD(&xprt->bc_pa_list);
+#endif /* CONFIG_SUNRPC_BACKCHANNEL */
+	INIT_LIST_HEAD(&xprt->xprt_switch);
+
+	xprt->last_used = jiffies;
+	xprt->cwnd = RPC_INITCWND;
+	xprt->bind_index = 0;
+
+	rpc_init_wait_queue(&xprt->binding, "xprt_binding");
+	rpc_init_wait_queue(&xprt->pending, "xprt_pending");
+	rpc_init_wait_queue(&xprt->sending, "xprt_sending");
+	rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
+
+	xprt_init_xid(xprt);
+
+	xprt->xprt_net = get_net_track(net, &xprt->ns_tracker, GFP_KERNEL);
+}
+
+/**
+ * xprt_create_transport - create an RPC transport
+ * @args: rpc transport creation arguments
+ *
+ */
+struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
+{
+	struct rpc_xprt	*xprt;
+	const struct xprt_class *t;
+
+	t = xprt_class_find_by_ident(args->ident);
+	if (!t) {
+		dprintk("RPC: transport (%d) not supported\n", args->ident);
+		return ERR_PTR(-EIO);
+	}
+
+	xprt = t->setup(args);
+	xprt_class_release(t);
+
+	if (IS_ERR(xprt))
+		goto out;
+	if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
+		xprt->idle_timeout = 0;
+	INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
+	if (xprt_has_timer(xprt))
+		timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
+	else
+		timer_setup(&xprt->timer, NULL, 0);
+
+	if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
+		xprt_destroy(xprt);
+		return ERR_PTR(-EINVAL);
+	}
+	xprt->servername = kstrdup(args->servername, GFP_KERNEL);
+	if (xprt->servername == NULL) {
+		xprt_destroy(xprt);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	rpc_xprt_debugfs_register(xprt);
+
+	trace_xprt_create(xprt);
+out:
+	return xprt;
+}
+
+static void xprt_destroy_cb(struct work_struct *work)
+{
+	struct rpc_xprt *xprt =
+		container_of(work, struct rpc_xprt, task_cleanup);
+
+	trace_xprt_destroy(xprt);
+
+	rpc_xprt_debugfs_unregister(xprt);
+	rpc_destroy_wait_queue(&xprt->binding);
+	rpc_destroy_wait_queue(&xprt->pending);
+	rpc_destroy_wait_queue(&xprt->sending);
+	rpc_destroy_wait_queue(&xprt->backlog);
+	kfree(xprt->servername);
+	/*
+	 * Destroy any existing back channel
+	 */
+	xprt_destroy_backchannel(xprt, UINT_MAX);
+
+	/*
+	 * Tear down transport state and free the rpc_xprt
+	 */
+	xprt->ops->destroy(xprt);
+}
+
+/**
+ * xprt_destroy - destroy an RPC transport, killing off all requests.
+ * @xprt: transport to destroy
+ *
+ */
+static void xprt_destroy(struct rpc_xprt *xprt)
+{
+	/*
+	 * Exclude transport connect/disconnect handlers and autoclose
+	 */
+	wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
+
+	/*
+	 * xprt_schedule_autodisconnect() can run after XPRT_LOCKED
+	 * is cleared.  We use ->transport_lock to ensure the mod_timer()
+	 * can only run *before* del_time_sync(), never after.
+	 */
+	spin_lock(&xprt->transport_lock);
+	del_timer_sync(&xprt->timer);
+	spin_unlock(&xprt->transport_lock);
+
+	/*
+	 * Destroy sockets etc from the system workqueue so they can
+	 * safely flush receive work running on rpciod.
+	 */
+	INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
+	schedule_work(&xprt->task_cleanup);
+}
+
+static void xprt_destroy_kref(struct kref *kref)
+{
+	xprt_destroy(container_of(kref, struct rpc_xprt, kref));
+}
+
+/**
+ * xprt_get - return a reference to an RPC transport.
+ * @xprt: pointer to the transport
+ *
+ */
+struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
+{
+	if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
+		return xprt;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(xprt_get);
+
+/**
+ * xprt_put - release a reference to an RPC transport.
+ * @xprt: pointer to the transport
+ *
+ */
+void xprt_put(struct rpc_xprt *xprt)
+{
+	if (xprt != NULL)
+		kref_put(&xprt->kref, xprt_destroy_kref);
+}
+EXPORT_SYMBOL_GPL(xprt_put);
+
+void xprt_set_offline_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
+{
+	if (!test_and_set_bit(XPRT_OFFLINE, &xprt->state)) {
+		spin_lock(&xps->xps_lock);
+		xps->xps_nactive--;
+		spin_unlock(&xps->xps_lock);
+	}
+}
+
+void xprt_set_online_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
+{
+	if (test_and_clear_bit(XPRT_OFFLINE, &xprt->state)) {
+		spin_lock(&xps->xps_lock);
+		xps->xps_nactive++;
+		spin_unlock(&xps->xps_lock);
+	}
+}
+
+void xprt_delete_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
+{
+	if (test_and_set_bit(XPRT_REMOVE, &xprt->state))
+		return;
+
+	xprt_force_disconnect(xprt);
+	if (!test_bit(XPRT_CONNECTED, &xprt->state))
+		return;
+
+	if (!xprt->sending.qlen && !xprt->pending.qlen &&
+	    !xprt->backlog.qlen && !atomic_long_read(&xprt->queuelen))
+		rpc_xprt_switch_remove_xprt(xps, xprt, true);
+}