/* kafsasyncd.c: AFS asynchronous operation daemon
*
* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*
* The AFS async daemon is used to the following:
* - probe "dead" servers to see whether they've come back to life yet.
* - probe "live" servers that we haven't talked to for a while to see if they are better
* candidates for serving than what we're currently using
* - poll volume location servers to keep up to date volume location lists
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/freezer.h>
#include "cell.h"
#include "server.h"
#include "volume.h"
#include "kafsasyncd.h"
#include "kafstimod.h"
#include <rxrpc/call.h>
#include <asm/errno.h>
#include "internal.h"
static DECLARE_COMPLETION(kafsasyncd_alive);
static DECLARE_COMPLETION(kafsasyncd_dead);
static DECLARE_WAIT_QUEUE_HEAD(kafsasyncd_sleepq);
static struct task_struct *kafsasyncd_task;
static int kafsasyncd_die;
static int kafsasyncd(void *arg);
static LIST_HEAD(kafsasyncd_async_attnq);
static LIST_HEAD(kafsasyncd_async_busyq);
static DEFINE_SPINLOCK(kafsasyncd_async_lock);
static void kafsasyncd_null_call_attn_func(struct rxrpc_call *call)
{
}
static void kafsasyncd_null_call_error_func(struct rxrpc_call *call)
{
}
/*****************************************************************************/
/*
* start the async daemon
*/
int afs_kafsasyncd_start(void)
{
int ret;
ret = kernel_thread(kafsasyncd, NULL, 0);
if (ret < 0)
return ret;
wait_for_completion(&kafsasyncd_alive);
return ret;
} /* end afs_kafsasyncd_start() */
/*****************************************************************************/
/*
* stop the async daemon
*/
void afs_kafsasyncd_stop(void)
{
/* get rid of my daemon */
kafsasyncd_die = 1;
wake_up(&kafsasyncd_sleepq);
wait_for_completion(&kafsasyncd_dead);
} /* end afs_kafsasyncd_stop() */
/*****************************************************************************/
/*
* probing daemon
*/
static int kafsasyncd(void *arg)
{
struct afs_async_op *op;
int die;
DECLARE_WAITQUEUE(myself, current);
kafsasyncd_task = current;
printk("kAFS: Started kafsasyncd %d\n", current->pid);
daemonize("kafsasyncd");
complete(&kafsasyncd_alive);
/* loop around looking for things to attend to */
do {
set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&kafsasyncd_sleepq, &myself);
for (;;) {
if (!list_empty(&kafsasyncd_async_attnq) ||
signal_pending(current) ||
kafsasyncd_die)
break;
schedule();
set_current_state(TASK_INTERRUPTIBLE);
}
remove_wait_queue(&kafsasyncd_sleepq, &myself);
set_current_state(TASK_RUNNING);
try_to_freeze();
/* discard pending signals */
afs_discard_my_signals();
die = kafsasyncd_die;
/* deal with the next asynchronous operation requiring
* attention */
if (!list_empty(&kafsasyncd_async_attnq)) {
struct afs_async_op *op;
_debug("@@@ Begin Asynchronous Operation");
op = NULL;
spin_lock(&kafsasyncd_async_lock);
if (!list_empty(&kafsasyncd_async_attnq)) {
op = list_entry(kafsasyncd_async_attnq.next,
struct afs_async_op, link);
list_move_tail(&op->link,
&kafsasyncd_async_busyq);
}
spin_unlock(&kafsasyncd_async_lock);
_debug("@@@ Operation %p {%p}\n",
op, op ? op->ops : NULL);
if (op)
op->ops->attend(op);
_debug("@@@ End Asynchronous Operation");
}
} while(!die);
/* need to kill all outstanding asynchronous operations before
* exiting */
kafsasyncd_task = NULL;
spin_lock(&kafsasyncd_async_lock);
/* fold the busy and attention queues together */
list_splice_init(&kafsasyncd_async_busyq,
&kafsasyncd_async_attnq);
/* dequeue kafsasyncd from all their wait queues */
list_for_each_entry(op, &kafsasyncd_async_attnq, link) {
op->call->app_attn_func = kafsasyncd_null_call_attn_func;
op->call->app_error_func = kafsasyncd_null_call_error_func;
remove_wait_queue(&op->call->waitq, &op->waiter);
}
spin_unlock(&kafsasyncd_async_lock);
/* abort all the operations */
while (!list_empty(&kafsasyncd_async_attnq)) {
op = list_entry(kafsasyncd_async_attnq.next, struct afs_async_op, link);
list_del_init(&op->link);
rxrpc_call_abort(op->call, -EIO);
rxrpc_put_call(op->call);
op->call = NULL;
op->ops->discard(op);
}
/* and that's all */
_leave("");
complete_and_exit(&kafsasyncd_dead, 0);
} /* end kafsasyncd() */
/*****************************************************************************/
/*
* begin an operation
* - place operation on busy queue
*/
void afs_kafsasyncd_begin_op(struct afs_async_op *op)
{
_enter("");
spin_lock(&kafsasyncd_async_lock);
init_waitqueue_entry(&op->waiter, kafsasyncd_task);
add_wait_queue(&op->call->waitq, &op->waiter);
list_move_tail(&op->link, &kafsasyncd_async_busyq);
spin_unlock(&kafsasyncd_async_lock);
_leave("");
} /* end afs_kafsasyncd_begin_op() */
/*****************************************************************************/
/*
* request attention for an operation
* - move to attention queue
*/
void afs_kafsasyncd_attend_op(struct afs_async_op *op)
{
_enter("");
spin_lock(&kafsasyncd_async_lock);
list_move_tail(&op->link, &kafsasyncd_async_attnq);
spin_unlock(&kafsasyncd_async_lock);
wake_up(&kafsasyncd_sleepq);
_leave("");
} /* end afs_kafsasyncd_attend_op() */
/*****************************************************************************/
/*
* terminate an operation
* - remove from either queue
*/
void afs_kafsasyncd_terminate_op(struct afs_async_op *op)
{
_enter("");
spin_lock(&kafsasyncd_async_lock);
if (!list_empty(&op->link)) {
list_del_init(&op->link);
remove_wait_queue(&op->call->waitq, &op->waiter);
}
spin_unlock(&kafsasyncd_async_lock);
wake_up(&kafsasyncd_sleepq);
_leave("");
} /* end afs_kafsasyncd_terminate_op() */
