Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y

1 files changed, 1035 insertions, 0 deletions

diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
new file mode 100644
index 0000000..385f427
--- /dev/null
+++ b/net/sunrpc/sched.c
@@ -0,0 +1,1035 @@
+/*
+ * linux/net/sunrpc/sched.c
+ *
+ * Scheduling for synchronous and asynchronous RPC requests.
+ *
+ * Copyright (C) 1996 Olaf Kirch, <okir@monad.swb.de>
+ *
+ * TCP NFS related read + write fixes
+ * (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
+ */
+
+#include <linux/module.h>
+
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/mempool.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+
+#include <linux/sunrpc/clnt.h>
+
+#ifdef RPC_DEBUG
+#define RPCDBG_FACILITY		RPCDBG_SCHED
+#define RPC_TASK_MAGIC_ID	0xf00baa
+#endif
+
+/*
+ * RPC slabs and memory pools
+ */
+#define RPC_BUFFER_MAXSIZE	(2048)
+#define RPC_BUFFER_POOLSIZE	(8)
+#define RPC_TASK_POOLSIZE	(8)
+static struct kmem_cache	*rpc_task_slabp __read_mostly;
+static struct kmem_cache	*rpc_buffer_slabp __read_mostly;
+static mempool_t	*rpc_task_mempool __read_mostly;
+static mempool_t	*rpc_buffer_mempool __read_mostly;
+
+static void			rpc_async_schedule(struct work_struct *);
+static void			 rpc_release_task(struct rpc_task *task);
+static void __rpc_queue_timer_fn(unsigned long ptr);
+
+/*
+ * RPC tasks sit here while waiting for conditions to improve.
+ */
+static struct rpc_wait_queue delay_queue;
+
+/*
+ * rpciod-related stuff
+ */
+struct workqueue_struct *rpciod_workqueue;
+
+/*
+ * Disable the timer for a given RPC task. Should be called with
+ * queue->lock and bh_disabled in order to avoid races within
+ * rpc_run_timer().
+ */
+static void
+__rpc_disable_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	if (task->tk_timeout == 0)
+		return;
+	dprintk("RPC: %5u disabling timer\n", task->tk_pid);
+	task->tk_timeout = 0;
+	list_del(&task->u.tk_wait.timer_list);
+	if (list_empty(&queue->timer_list.list))
+		del_timer(&queue->timer_list.timer);
+}
+
+static void
+rpc_set_queue_timer(struct rpc_wait_queue *queue, unsigned long expires)
+{
+	queue->timer_list.expires = expires;
+	mod_timer(&queue->timer_list.timer, expires);
+}
+
+/*
+ * Set up a timer for the current task.
+ */
+static void
+__rpc_add_timer(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	if (!task->tk_timeout)
+		return;
+
+	dprintk("RPC: %5u setting alarm for %lu ms\n",
+			task->tk_pid, task->tk_timeout * 1000 / HZ);
+
+	task->u.tk_wait.expires = jiffies + task->tk_timeout;
+	if (list_empty(&queue->timer_list.list) || time_before(task->u.tk_wait.expires, queue->timer_list.expires))
+		rpc_set_queue_timer(queue, task->u.tk_wait.expires);
+	list_add(&task->u.tk_wait.timer_list, &queue->timer_list.list);
+}
+
+/*
+ * Add new request to a priority queue.
+ */
+static void __rpc_add_wait_queue_priority(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	struct list_head *q;
+	struct rpc_task *t;
+
+	INIT_LIST_HEAD(&task->u.tk_wait.links);
+	q = &queue->tasks[task->tk_priority];
+	if (unlikely(task->tk_priority > queue->maxpriority))
+		q = &queue->tasks[queue->maxpriority];
+	list_for_each_entry(t, q, u.tk_wait.list) {
+		if (t->tk_owner == task->tk_owner) {
+			list_add_tail(&task->u.tk_wait.list, &t->u.tk_wait.links);
+			return;
+		}
+	}
+	list_add_tail(&task->u.tk_wait.list, q);
+}
+
+/*
+ * Add new request to wait queue.
+ *
+ * Swapper tasks always get inserted at the head of the queue.
+ * This should avoid many nasty memory deadlocks and hopefully
+ * improve overall performance.
+ * Everyone else gets appended to the queue to ensure proper FIFO behavior.
+ */
+static void __rpc_add_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	BUG_ON (RPC_IS_QUEUED(task));
+
+	if (RPC_IS_PRIORITY(queue))
+		__rpc_add_wait_queue_priority(queue, task);
+	else if (RPC_IS_SWAPPER(task))
+		list_add(&task->u.tk_wait.list, &queue->tasks[0]);
+	else
+		list_add_tail(&task->u.tk_wait.list, &queue->tasks[0]);
+	task->tk_waitqueue = queue;
+	queue->qlen++;
+	rpc_set_queued(task);
+
+	dprintk("RPC: %5u added to queue %p \"%s\"\n",
+			task->tk_pid, queue, rpc_qname(queue));
+}
+
+/*
+ * Remove request from a priority queue.
+ */
+static void __rpc_remove_wait_queue_priority(struct rpc_task *task)
+{
+	struct rpc_task *t;
+
+	if (!list_empty(&task->u.tk_wait.links)) {
+		t = list_entry(task->u.tk_wait.links.next, struct rpc_task, u.tk_wait.list);
+		list_move(&t->u.tk_wait.list, &task->u.tk_wait.list);
+		list_splice_init(&task->u.tk_wait.links, &t->u.tk_wait.links);
+	}
+}
+
+/*
+ * Remove request from queue.
+ * Note: must be called with spin lock held.
+ */
+static void __rpc_remove_wait_queue(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	__rpc_disable_timer(queue, task);
+	if (RPC_IS_PRIORITY(queue))
+		__rpc_remove_wait_queue_priority(task);
+	list_del(&task->u.tk_wait.list);
+	queue->qlen--;
+	dprintk("RPC: %5u removed from queue %p \"%s\"\n",
+			task->tk_pid, queue, rpc_qname(queue));
+}
+
+static inline void rpc_set_waitqueue_priority(struct rpc_wait_queue *queue, int priority)
+{
+	queue->priority = priority;
+	queue->count = 1 << (priority * 2);
+}
+
+static inline void rpc_set_waitqueue_owner(struct rpc_wait_queue *queue, pid_t pid)
+{
+	queue->owner = pid;
+	queue->nr = RPC_BATCH_COUNT;
+}
+
+static inline void rpc_reset_waitqueue_priority(struct rpc_wait_queue *queue)
+{
+	rpc_set_waitqueue_priority(queue, queue->maxpriority);
+	rpc_set_waitqueue_owner(queue, 0);
+}
+
+static void __rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname, unsigned char nr_queues)
+{
+	int i;
+
+	spin_lock_init(&queue->lock);
+	for (i = 0; i < ARRAY_SIZE(queue->tasks); i++)
+		INIT_LIST_HEAD(&queue->tasks[i]);
+	queue->maxpriority = nr_queues - 1;
+	rpc_reset_waitqueue_priority(queue);
+	queue->qlen = 0;
+	setup_timer(&queue->timer_list.timer, __rpc_queue_timer_fn, (unsigned long)queue);
+	INIT_LIST_HEAD(&queue->timer_list.list);
+#ifdef RPC_DEBUG
+	queue->name = qname;
+#endif
+}
+
+void rpc_init_priority_wait_queue(struct rpc_wait_queue *queue, const char *qname)
+{
+	__rpc_init_priority_wait_queue(queue, qname, RPC_NR_PRIORITY);
+}
+
+void rpc_init_wait_queue(struct rpc_wait_queue *queue, const char *qname)
+{
+	__rpc_init_priority_wait_queue(queue, qname, 1);
+}
+EXPORT_SYMBOL_GPL(rpc_init_wait_queue);
+
+void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
+{
+	del_timer_sync(&queue->timer_list.timer);
+}
+EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);
+
+static int rpc_wait_bit_killable(void *word)
+{
+	if (fatal_signal_pending(current))
+		return -ERESTARTSYS;
+	schedule();
+	return 0;
+}
+
+#ifdef RPC_DEBUG
+static void rpc_task_set_debuginfo(struct rpc_task *task)
+{
+	static atomic_t rpc_pid;
+
+	task->tk_magic = RPC_TASK_MAGIC_ID;
+	task->tk_pid = atomic_inc_return(&rpc_pid);
+}
+#else
+static inline void rpc_task_set_debuginfo(struct rpc_task *task)
+{
+}
+#endif
+
+static void rpc_set_active(struct rpc_task *task)
+{
+	struct rpc_clnt *clnt;
+	if (test_and_set_bit(RPC_TASK_ACTIVE, &task->tk_runstate) != 0)
+		return;
+	rpc_task_set_debuginfo(task);
+	/* Add to global list of all tasks */
+	clnt = task->tk_client;
+	if (clnt != NULL) {
+		spin_lock(&clnt->cl_lock);
+		list_add_tail(&task->tk_task, &clnt->cl_tasks);
+		spin_unlock(&clnt->cl_lock);
+	}
+}
+
+/*
+ * Mark an RPC call as having completed by clearing the 'active' bit
+ */
+static void rpc_mark_complete_task(struct rpc_task *task)
+{
+	smp_mb__before_clear_bit();
+	clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
+	smp_mb__after_clear_bit();
+	wake_up_bit(&task->tk_runstate, RPC_TASK_ACTIVE);
+}
+
+/*
+ * Allow callers to wait for completion of an RPC call
+ */
+int __rpc_wait_for_completion_task(struct rpc_task *task, int (*action)(void *))
+{
+	if (action == NULL)
+		action = rpc_wait_bit_killable;
+	return wait_on_bit(&task->tk_runstate, RPC_TASK_ACTIVE,
+			action, TASK_KILLABLE);
+}
+EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
+
+/*
+ * Make an RPC task runnable.
+ *
+ * Note: If the task is ASYNC, this must be called with
+ * the spinlock held to protect the wait queue operation.
+ */
+static void rpc_make_runnable(struct rpc_task *task)
+{
+	rpc_clear_queued(task);
+	if (rpc_test_and_set_running(task))
+		return;
+	/* We might have raced */
+	if (RPC_IS_QUEUED(task)) {
+		rpc_clear_running(task);
+		return;
+	}
+	if (RPC_IS_ASYNC(task)) {
+		int status;
+
+		INIT_WORK(&task->u.tk_work, rpc_async_schedule);
+		status = queue_work(rpciod_workqueue, &task->u.tk_work);
+		if (status < 0) {
+			printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
+			task->tk_status = status;
+			return;
+		}
+	} else
+		wake_up_bit(&task->tk_runstate, RPC_TASK_QUEUED);
+}
+
+/*
+ * Prepare for sleeping on a wait queue.
+ * By always appending tasks to the list we ensure FIFO behavior.
+ * NB: An RPC task will only receive interrupt-driven events as long
+ * as it's on a wait queue.
+ */
+static void __rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
+			rpc_action action)
+{
+	dprintk("RPC: %5u sleep_on(queue \"%s\" time %lu)\n",
+			task->tk_pid, rpc_qname(q), jiffies);
+
+	if (!RPC_IS_ASYNC(task) && !RPC_IS_ACTIVATED(task)) {
+		printk(KERN_ERR "RPC: Inactive synchronous task put to sleep!\n");
+		return;
+	}
+
+	__rpc_add_wait_queue(q, task);
+
+	BUG_ON(task->tk_callback != NULL);
+	task->tk_callback = action;
+	__rpc_add_timer(q, task);
+}
+
+void rpc_sleep_on(struct rpc_wait_queue *q, struct rpc_task *task,
+				rpc_action action)
+{
+	/* Mark the task as being activated if so needed */
+	rpc_set_active(task);
+
+	/*
+	 * Protect the queue operations.
+	 */
+	spin_lock_bh(&q->lock);
+	__rpc_sleep_on(q, task, action);
+	spin_unlock_bh(&q->lock);
+}
+EXPORT_SYMBOL_GPL(rpc_sleep_on);
+
+/**
+ * __rpc_do_wake_up_task - wake up a single rpc_task
+ * @queue: wait queue
+ * @task: task to be woken up
+ *
+ * Caller must hold queue->lock, and have cleared the task queued flag.
+ */
+static void __rpc_do_wake_up_task(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	dprintk("RPC: %5u __rpc_wake_up_task (now %lu)\n",
+			task->tk_pid, jiffies);
+
+#ifdef RPC_DEBUG
+	BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
+#endif
+	/* Has the task been executed yet? If not, we cannot wake it up! */
+	if (!RPC_IS_ACTIVATED(task)) {
+		printk(KERN_ERR "RPC: Inactive task (%p) being woken up!\n", task);
+		return;
+	}
+
+	__rpc_remove_wait_queue(queue, task);
+
+	rpc_make_runnable(task);
+
+	dprintk("RPC:       __rpc_wake_up_task done\n");
+}
+
+/*
+ * Wake up a queued task while the queue lock is being held
+ */
+static void rpc_wake_up_task_queue_locked(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	if (RPC_IS_QUEUED(task) && task->tk_waitqueue == queue)
+		__rpc_do_wake_up_task(queue, task);
+}
+
+/*
+ * Wake up a task on a specific queue
+ */
+void rpc_wake_up_queued_task(struct rpc_wait_queue *queue, struct rpc_task *task)
+{
+	spin_lock_bh(&queue->lock);
+	rpc_wake_up_task_queue_locked(queue, task);
+	spin_unlock_bh(&queue->lock);
+}
+EXPORT_SYMBOL_GPL(rpc_wake_up_queued_task);
+
+/*
+ * Wake up the specified task
+ */
+static void rpc_wake_up_task(struct rpc_task *task)
+{
+	rpc_wake_up_queued_task(task->tk_waitqueue, task);
+}
+
+/*
+ * Wake up the next task on a priority queue.
+ */
+static struct rpc_task * __rpc_wake_up_next_priority(struct rpc_wait_queue *queue)
+{
+	struct list_head *q;
+	struct rpc_task *task;
+
+	/*
+	 * Service a batch of tasks from a single owner.
+	 */
+	q = &queue->tasks[queue->priority];
+	if (!list_empty(q)) {
+		task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
+		if (queue->owner == task->tk_owner) {
+			if (--queue->nr)
+				goto out;
+			list_move_tail(&task->u.tk_wait.list, q);
+		}
+		/*
+		 * Check if we need to switch queues.
+		 */
+		if (--queue->count)
+			goto new_owner;
+	}
+
+	/*
+	 * Service the next queue.
+	 */
+	do {
+		if (q == &queue->tasks[0])
+			q = &queue->tasks[queue->maxpriority];
+		else
+			q = q - 1;
+		if (!list_empty(q)) {
+			task = list_entry(q->next, struct rpc_task, u.tk_wait.list);
+			goto new_queue;
+		}
+	} while (q != &queue->tasks[queue->priority]);
+
+	rpc_reset_waitqueue_priority(queue);
+	return NULL;
+
+new_queue:
+	rpc_set_waitqueue_priority(queue, (unsigned int)(q - &queue->tasks[0]));
+new_owner:
+	rpc_set_waitqueue_owner(queue, task->tk_owner);
+out:
+	rpc_wake_up_task_queue_locked(queue, task);
+	return task;
+}
+
+/*
+ * Wake up the next task on the wait queue.
+ */
+struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue)
+{
+	struct rpc_task	*task = NULL;
+
+	dprintk("RPC:       wake_up_next(%p \"%s\")\n",
+			queue, rpc_qname(queue));
+	spin_lock_bh(&queue->lock);
+	if (RPC_IS_PRIORITY(queue))
+		task = __rpc_wake_up_next_priority(queue);
+	else {
+		task_for_first(task, &queue->tasks[0])
+			rpc_wake_up_task_queue_locked(queue, task);
+	}
+	spin_unlock_bh(&queue->lock);
+
+	return task;
+}
+EXPORT_SYMBOL_GPL(rpc_wake_up_next);
+
+/**
+ * rpc_wake_up - wake up all rpc_tasks
+ * @queue: rpc_wait_queue on which the tasks are sleeping
+ *
+ * Grabs queue->lock
+ */
+void rpc_wake_up(struct rpc_wait_queue *queue)
+{
+	struct rpc_task *task, *next;
+	struct list_head *head;
+
+	spin_lock_bh(&queue->lock);
+	head = &queue->tasks[queue->maxpriority];
+	for (;;) {
+		list_for_each_entry_safe(task, next, head, u.tk_wait.list)
+			rpc_wake_up_task_queue_locked(queue, task);
+		if (head == &queue->tasks[0])
+			break;
+		head--;
+	}
+	spin_unlock_bh(&queue->lock);
+}
+EXPORT_SYMBOL_GPL(rpc_wake_up);
+
+/**
+ * rpc_wake_up_status - wake up all rpc_tasks and set their status value.
+ * @queue: rpc_wait_queue on which the tasks are sleeping
+ * @status: status value to set
+ *
+ * Grabs queue->lock
+ */
+void rpc_wake_up_status(struct rpc_wait_queue *queue, int status)
+{
+	struct rpc_task *task, *next;
+	struct list_head *head;
+
+	spin_lock_bh(&queue->lock);
+	head = &queue->tasks[queue->maxpriority];
+	for (;;) {
+		list_for_each_entry_safe(task, next, head, u.tk_wait.list) {
+			task->tk_status = status;
+			rpc_wake_up_task_queue_locked(queue, task);
+		}
+		if (head == &queue->tasks[0])
+			break;
+		head--;
+	}
+	spin_unlock_bh(&queue->lock);
+}
+EXPORT_SYMBOL_GPL(rpc_wake_up_status);
+
+static void __rpc_queue_timer_fn(unsigned long ptr)
+{
+	struct rpc_wait_queue *queue = (struct rpc_wait_queue *)ptr;
+	struct rpc_task *task, *n;
+	unsigned long expires, now, timeo;
+
+	spin_lock(&queue->lock);
+	expires = now = jiffies;
+	list_for_each_entry_safe(task, n, &queue->timer_list.list, u.tk_wait.timer_list) {
+		timeo = task->u.tk_wait.expires;
+		if (time_after_eq(now, timeo)) {
+			dprintk("RPC: %5u timeout\n", task->tk_pid);
+			task->tk_status = -ETIMEDOUT;
+			rpc_wake_up_task_queue_locked(queue, task);
+			continue;
+		}
+		if (expires == now || time_after(expires, timeo))
+			expires = timeo;
+	}
+	if (!list_empty(&queue->timer_list.list))
+		rpc_set_queue_timer(queue, expires);
+	spin_unlock(&queue->lock);
+}
+
+static void __rpc_atrun(struct rpc_task *task)
+{
+	task->tk_status = 0;
+}
+
+/*
+ * Run a task at a later time
+ */
+void rpc_delay(struct rpc_task *task, unsigned long delay)
+{
+	task->tk_timeout = delay;
+	rpc_sleep_on(&delay_queue, task, __rpc_atrun);
+}
+EXPORT_SYMBOL_GPL(rpc_delay);
+
+/*
+ * Helper to call task->tk_ops->rpc_call_prepare
+ */
+static void rpc_prepare_task(struct rpc_task *task)
+{
+	task->tk_ops->rpc_call_prepare(task, task->tk_calldata);
+}
+
+/*
+ * Helper that calls task->tk_ops->rpc_call_done if it exists
+ */
+void rpc_exit_task(struct rpc_task *task)
+{
+	task->tk_action = NULL;
+	if (task->tk_ops->rpc_call_done != NULL) {
+		task->tk_ops->rpc_call_done(task, task->tk_calldata);
+		if (task->tk_action != NULL) {
+			WARN_ON(RPC_ASSASSINATED(task));
+			/* Always release the RPC slot and buffer memory */
+			xprt_release(task);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(rpc_exit_task);
+
+void rpc_release_calldata(const struct rpc_call_ops *ops, void *calldata)
+{
+	if (ops->rpc_release != NULL)
+		ops->rpc_release(calldata);
+}
+
+/*
+ * This is the RPC `scheduler' (or rather, the finite state machine).
+ */
+static void __rpc_execute(struct rpc_task *task)
+{
+	int		status = 0;
+
+	dprintk("RPC: %5u __rpc_execute flags=0x%x\n",
+			task->tk_pid, task->tk_flags);
+
+	BUG_ON(RPC_IS_QUEUED(task));
+
+	for (;;) {
+
+		/*
+		 * Execute any pending callback.
+		 */
+		if (task->tk_callback) {
+			void (*save_callback)(struct rpc_task *);
+
+			/*
+			 * We set tk_callback to NULL before calling it,
+			 * in case it sets the tk_callback field itself:
+			 */
+			save_callback = task->tk_callback;
+			task->tk_callback = NULL;
+			save_callback(task);
+		}
+
+		/*
+		 * Perform the next FSM step.
+		 * tk_action may be NULL when the task has been killed
+		 * by someone else.
+		 */
+		if (!RPC_IS_QUEUED(task)) {
+			if (task->tk_action == NULL)
+				break;
+			task->tk_action(task);
+		}
+
+		/*
+		 * Lockless check for whether task is sleeping or not.
+		 */
+		if (!RPC_IS_QUEUED(task))
+			continue;
+		rpc_clear_running(task);
+		if (RPC_IS_ASYNC(task)) {
+			/* Careful! we may have raced... */
+			if (RPC_IS_QUEUED(task))
+				return;
+			if (rpc_test_and_set_running(task))
+				return;
+			continue;
+		}
+
+		/* sync task: sleep here */
+		dprintk("RPC: %5u sync task going to sleep\n", task->tk_pid);
+		status = out_of_line_wait_on_bit(&task->tk_runstate,
+				RPC_TASK_QUEUED, rpc_wait_bit_killable,
+				TASK_KILLABLE);
+		if (status == -ERESTARTSYS) {
+			/*
+			 * When a sync task receives a signal, it exits with
+			 * -ERESTARTSYS. In order to catch any callbacks that
+			 * clean up after sleeping on some queue, we don't
+			 * break the loop here, but go around once more.
+			 */
+			dprintk("RPC: %5u got signal\n", task->tk_pid);
+			task->tk_flags |= RPC_TASK_KILLED;
+			rpc_exit(task, -ERESTARTSYS);
+			rpc_wake_up_task(task);
+		}
+		rpc_set_running(task);
+		dprintk("RPC: %5u sync task resuming\n", task->tk_pid);
+	}
+
+	dprintk("RPC: %5u return %d, status %d\n", task->tk_pid, status,
+			task->tk_status);
+	/* Release all resources associated with the task */
+	rpc_release_task(task);
+}
+
+/*
+ * User-visible entry point to the scheduler.
+ *
+ * This may be called recursively if e.g. an async NFS task updates
+ * the attributes and finds that dirty pages must be flushed.
+ * NOTE: Upon exit of this function the task is guaranteed to be
+ *	 released. In particular note that tk_release() will have
+ *	 been called, so your task memory may have been freed.
+ */
+void rpc_execute(struct rpc_task *task)
+{
+	rpc_set_active(task);
+	rpc_set_running(task);
+	__rpc_execute(task);
+}
+
+static void rpc_async_schedule(struct work_struct *work)
+{
+	__rpc_execute(container_of(work, struct rpc_task, u.tk_work));
+}
+
+struct rpc_buffer {
+	size_t	len;
+	char	data[];
+};
+
+/**
+ * rpc_malloc - allocate an RPC buffer
+ * @task: RPC task that will use this buffer
+ * @size: requested byte size
+ *
+ * To prevent rpciod from hanging, this allocator never sleeps,
+ * returning NULL if the request cannot be serviced immediately.
+ * The caller can arrange to sleep in a way that is safe for rpciod.
+ *
+ * Most requests are 'small' (under 2KiB) and can be serviced from a
+ * mempool, ensuring that NFS reads and writes can always proceed,
+ * and that there is good locality of reference for these buffers.
+ *
+ * In order to avoid memory starvation triggering more writebacks of
+ * NFS requests, we avoid using GFP_KERNEL.
+ */
+void *rpc_malloc(struct rpc_task *task, size_t size)
+{
+	struct rpc_buffer *buf;
+	gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
+
+	size += sizeof(struct rpc_buffer);
+	if (size <= RPC_BUFFER_MAXSIZE)
+		buf = mempool_alloc(rpc_buffer_mempool, gfp);
+	else
+		buf = kmalloc(size, gfp);
+
+	if (!buf)
+		return NULL;
+
+	buf->len = size;
+	dprintk("RPC: %5u allocated buffer of size %zu at %p\n",
+			task->tk_pid, size, buf);
+	return &buf->data;
+}
+EXPORT_SYMBOL_GPL(rpc_malloc);
+
+/**
+ * rpc_free - free buffer allocated via rpc_malloc
+ * @buffer: buffer to free
+ *
+ */
+void rpc_free(void *buffer)
+{
+	size_t size;
+	struct rpc_buffer *buf;
+
+	if (!buffer)
+		return;
+
+	buf = container_of(buffer, struct rpc_buffer, data);
+	size = buf->len;
+
+	dprintk("RPC:       freeing buffer of size %zu at %p\n",
+			size, buf);
+
+	if (size <= RPC_BUFFER_MAXSIZE)
+		mempool_free(buf, rpc_buffer_mempool);
+	else
+		kfree(buf);
+}
+EXPORT_SYMBOL_GPL(rpc_free);
+
+/*
+ * Creation and deletion of RPC task structures
+ */
+static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *task_setup_data)
+{
+	memset(task, 0, sizeof(*task));
+	atomic_set(&task->tk_count, 1);
+	task->tk_flags  = task_setup_data->flags;
+	task->tk_ops = task_setup_data->callback_ops;
+	task->tk_calldata = task_setup_data->callback_data;
+	INIT_LIST_HEAD(&task->tk_task);
+
+	/* Initialize retry counters */
+	task->tk_garb_retry = 2;
+	task->tk_cred_retry = 2;
+
+	task->tk_priority = task_setup_data->priority - RPC_PRIORITY_LOW;
+	task->tk_owner = current->tgid;
+
+	/* Initialize workqueue for async tasks */
+	task->tk_workqueue = task_setup_data->workqueue;
+
+	task->tk_client = task_setup_data->rpc_client;
+	if (task->tk_client != NULL) {
+		kref_get(&task->tk_client->cl_kref);
+		if (task->tk_client->cl_softrtry)
+			task->tk_flags |= RPC_TASK_SOFT;
+	}
+
+	if (task->tk_ops->rpc_call_prepare != NULL)
+		task->tk_action = rpc_prepare_task;
+
+	if (task_setup_data->rpc_message != NULL) {
+		task->tk_msg.rpc_proc = task_setup_data->rpc_message->rpc_proc;
+		task->tk_msg.rpc_argp = task_setup_data->rpc_message->rpc_argp;
+		task->tk_msg.rpc_resp = task_setup_data->rpc_message->rpc_resp;
+		/* Bind the user cred */
+		rpcauth_bindcred(task, task_setup_data->rpc_message->rpc_cred, task_setup_data->flags);
+		if (task->tk_action == NULL)
+			rpc_call_start(task);
+	}
+
+	/* starting timestamp */
+	task->tk_start = jiffies;
+
+	dprintk("RPC:       new task initialized, procpid %u\n",
+				task_pid_nr(current));
+}
+
+static struct rpc_task *
+rpc_alloc_task(void)
+{
+	return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
+}
+
+/*
+ * Create a new task for the specified client.
+ */
+struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data)
+{
+	struct rpc_task	*task = setup_data->task;
+	unsigned short flags = 0;
+
+	if (task == NULL) {
+		task = rpc_alloc_task();
+		if (task == NULL)
+			goto out;
+		flags = RPC_TASK_DYNAMIC;
+	}
+
+	rpc_init_task(task, setup_data);
+
+	task->tk_flags |= flags;
+	dprintk("RPC:       allocated task %p\n", task);
+out:
+	return task;
+}
+
+static void rpc_free_task(struct rpc_task *task)
+{
+	const struct rpc_call_ops *tk_ops = task->tk_ops;
+	void *calldata = task->tk_calldata;
+
+	if (task->tk_flags & RPC_TASK_DYNAMIC) {
+		dprintk("RPC: %5u freeing task\n", task->tk_pid);
+		mempool_free(task, rpc_task_mempool);
+	}
+	rpc_release_calldata(tk_ops, calldata);
+}
+
+static void rpc_async_release(struct work_struct *work)
+{
+	rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
+}
+
+void rpc_put_task(struct rpc_task *task)
+{
+	if (!atomic_dec_and_test(&task->tk_count))
+		return;
+	/* Release resources */
+	if (task->tk_rqstp)
+		xprt_release(task);
+	if (task->tk_msg.rpc_cred)
+		rpcauth_unbindcred(task);
+	if (task->tk_client) {
+		rpc_release_client(task->tk_client);
+		task->tk_client = NULL;
+	}
+	if (task->tk_workqueue != NULL) {
+		INIT_WORK(&task->u.tk_work, rpc_async_release);
+		queue_work(task->tk_workqueue, &task->u.tk_work);
+	} else
+		rpc_free_task(task);
+}
+EXPORT_SYMBOL_GPL(rpc_put_task);
+
+static void rpc_release_task(struct rpc_task *task)
+{
+#ifdef RPC_DEBUG
+	BUG_ON(task->tk_magic != RPC_TASK_MAGIC_ID);
+#endif
+	dprintk("RPC: %5u release task\n", task->tk_pid);
+
+	if (!list_empty(&task->tk_task)) {
+		struct rpc_clnt *clnt = task->tk_client;
+		/* Remove from client task list */
+		spin_lock(&clnt->cl_lock);
+		list_del(&task->tk_task);
+		spin_unlock(&clnt->cl_lock);
+	}
+	BUG_ON (RPC_IS_QUEUED(task));
+
+#ifdef RPC_DEBUG
+	task->tk_magic = 0;
+#endif
+	/* Wake up anyone who is waiting for task completion */
+	rpc_mark_complete_task(task);
+
+	rpc_put_task(task);
+}
+
+/*
+ * Kill all tasks for the given client.
+ * XXX: kill their descendants as well?
+ */
+void rpc_killall_tasks(struct rpc_clnt *clnt)
+{
+	struct rpc_task	*rovr;
+
+
+	if (list_empty(&clnt->cl_tasks))
+		return;
+	dprintk("RPC:       killing all tasks for client %p\n", clnt);
+	/*
+	 * Spin lock all_tasks to prevent changes...
+	 */
+	spin_lock(&clnt->cl_lock);
+	list_for_each_entry(rovr, &clnt->cl_tasks, tk_task) {
+		if (! RPC_IS_ACTIVATED(rovr))
+			continue;
+		if (!(rovr->tk_flags & RPC_TASK_KILLED)) {
+			rovr->tk_flags |= RPC_TASK_KILLED;
+			rpc_exit(rovr, -EIO);
+			rpc_wake_up_task(rovr);
+		}
+	}
+	spin_unlock(&clnt->cl_lock);
+}
+EXPORT_SYMBOL_GPL(rpc_killall_tasks);
+
+int rpciod_up(void)
+{
+	return try_module_get(THIS_MODULE) ? 0 : -EINVAL;
+}
+
+void rpciod_down(void)
+{
+	module_put(THIS_MODULE);
+}
+
+/*
+ * Start up the rpciod workqueue.
+ */
+static int rpciod_start(void)
+{
+	struct workqueue_struct *wq;
+
+	/*
+	 * Create the rpciod thread and wait for it to start.
+	 */
+	dprintk("RPC:       creating workqueue rpciod\n");
+	wq = create_workqueue("rpciod");
+	rpciod_workqueue = wq;
+	return rpciod_workqueue != NULL;
+}
+
+static void rpciod_stop(void)
+{
+	struct workqueue_struct *wq = NULL;
+
+	if (rpciod_workqueue == NULL)
+		return;
+	dprintk("RPC:       destroying workqueue rpciod\n");
+
+	wq = rpciod_workqueue;
+	rpciod_workqueue = NULL;
+	destroy_workqueue(wq);
+}
+
+void
+rpc_destroy_mempool(void)
+{
+	rpciod_stop();
+	if (rpc_buffer_mempool)
+		mempool_destroy(rpc_buffer_mempool);
+	if (rpc_task_mempool)
+		mempool_destroy(rpc_task_mempool);
+	if (rpc_task_slabp)
+		kmem_cache_destroy(rpc_task_slabp);
+	if (rpc_buffer_slabp)
+		kmem_cache_destroy(rpc_buffer_slabp);
+	rpc_destroy_wait_queue(&delay_queue);
+}
+
+int
+rpc_init_mempool(void)
+{
+	/*
+	 * The following is not strictly a mempool initialisation,
+	 * but there is no harm in doing it here
+	 */
+	rpc_init_wait_queue(&delay_queue, "delayq");
+	if (!rpciod_start())
+		goto err_nomem;
+
+	rpc_task_slabp = kmem_cache_create("rpc_tasks",
+					     sizeof(struct rpc_task),
+					     0, SLAB_HWCACHE_ALIGN,
+					     NULL);
+	if (!rpc_task_slabp)
+		goto err_nomem;
+	rpc_buffer_slabp = kmem_cache_create("rpc_buffers",
+					     RPC_BUFFER_MAXSIZE,
+					     0, SLAB_HWCACHE_ALIGN,
+					     NULL);
+	if (!rpc_buffer_slabp)
+		goto err_nomem;
+	rpc_task_mempool = mempool_create_slab_pool(RPC_TASK_POOLSIZE,
+						    rpc_task_slabp);
+	if (!rpc_task_mempool)
+		goto err_nomem;
+	rpc_buffer_mempool = mempool_create_slab_pool(RPC_BUFFER_POOLSIZE,
+						      rpc_buffer_slabp);
+	if (!rpc_buffer_mempool)
+		goto err_nomem;
+	return 0;
+err_nomem:
+	rpc_destroy_mempool();
+	return -ENOMEM;
+}