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   1 /* kafsasyncd.c: AFS asynchronous operation daemon
   2  *
   3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  *
  11  *
  12  * The AFS async daemon is used to the following:
  13  * - probe "dead" servers to see whether they've come back to life yet.
  14  * - probe "live" servers that we haven't talked to for a while to see if they are better
  15  *   candidates for serving than what we're currently using
  16  * - poll volume location servers to keep up to date volume location lists
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/sched.h>
  22 #include <linux/completion.h>
  23 #include "cell.h"
  24 #include "server.h"
  25 #include "volume.h"
  26 #include "kafsasyncd.h"
  27 #include "kafstimod.h"
  28 #include <rxrpc/call.h>
  29 #include <asm/errno.h>
  30 #include "internal.h"
  31
  32 static DECLARE_COMPLETION(kafsasyncd_alive);
  33 static DECLARE_COMPLETION(kafsasyncd_dead);
  34 static DECLARE_WAIT_QUEUE_HEAD(kafsasyncd_sleepq);
  35 static struct task_struct *kafsasyncd_task;
  36 static int kafsasyncd_die;
  37
  38 static int kafsasyncd(void *arg);
  39
  40 static LIST_HEAD(kafsasyncd_async_attnq);
  41 static LIST_HEAD(kafsasyncd_async_busyq);
  42 static DEFINE_SPINLOCK(kafsasyncd_async_lock);
  43
  44 static void kafsasyncd_null_call_attn_func(struct rxrpc_call *call)
  45 {
  46 }
  47
  48 static void kafsasyncd_null_call_error_func(struct rxrpc_call *call)
  49 {
  50 }
  51
  52 /*****************************************************************************/
  53 /*
  54  * start the async daemon
  55  */
  56 int afs_kafsasyncd_start(void)
  57 {
  58         int ret;
  59
  60         ret = kernel_thread(kafsasyncd, NULL, 0);
  61         if (ret < 0)
  62                 return ret;
  63
  64         wait_for_completion(&kafsasyncd_alive);
  65
  66         return ret;
  67 } /* end afs_kafsasyncd_start() */
  68
  69 /*****************************************************************************/
  70 /*
  71  * stop the async daemon
  72  */
  73 void afs_kafsasyncd_stop(void)
  74 {
  75         /* get rid of my daemon */
  76         kafsasyncd_die = 1;
  77         wake_up(&kafsasyncd_sleepq);
  78         wait_for_completion(&kafsasyncd_dead);
  79
  80 } /* end afs_kafsasyncd_stop() */
  81
  82 /*****************************************************************************/
  83 /*
  84  * probing daemon
  85  */
  86 static int kafsasyncd(void *arg)
  87 {
  88         struct afs_async_op *op;
  89         int die;
  90
  91         DECLARE_WAITQUEUE(myself, current);
  92
  93         kafsasyncd_task = current;
  94
  95         printk("kAFS: Started kafsasyncd %d\n", current->pid);
  96
  97         daemonize("kafsasyncd");
  98
  99         complete(&kafsasyncd_alive);
 100
 101         /* loop around looking for things to attend to */
 102         do {
 103                 set_current_state(TASK_INTERRUPTIBLE);
 104                 add_wait_queue(&kafsasyncd_sleepq, &myself);
 105
 106                 for (;;) {
 107                         if (!list_empty(&kafsasyncd_async_attnq) ||
 108                             signal_pending(current) ||
 109                             kafsasyncd_die)
 110                                 break;
 111
 112                         schedule();
 113                         set_current_state(TASK_INTERRUPTIBLE);
 114                 }
 115
 116                 remove_wait_queue(&kafsasyncd_sleepq, &myself);
 117                 set_current_state(TASK_RUNNING);
 118
 119                 try_to_freeze();
 120
 121                 /* discard pending signals */
 122                 afs_discard_my_signals();
 123
 124                 die = kafsasyncd_die;
 125
 126                 /* deal with the next asynchronous operation requiring
 127                  * attention */
 128                 if (!list_empty(&kafsasyncd_async_attnq)) {
 129                         struct afs_async_op *op;
 130
 131                         _debug("@@@ Begin Asynchronous Operation");
 132
 133                         op = NULL;
 134                         spin_lock(&kafsasyncd_async_lock);
 135
 136                         if (!list_empty(&kafsasyncd_async_attnq)) {
 137                                 op = list_entry(kafsasyncd_async_attnq.next,
 138                                                 struct afs_async_op, link);
 139                                 list_move_tail(&op->link,
 140                                               &kafsasyncd_async_busyq);
 141                         }
 142
 143                         spin_unlock(&kafsasyncd_async_lock);
 144
 145                         _debug("@@@ Operation %p {%p}\n",
 146                                op, op ? op->ops : NULL);
 147
 148                         if (op)
 149                                 op->ops->attend(op);
 150
 151                         _debug("@@@ End Asynchronous Operation");
 152                 }
 153
 154         } while(!die);
 155
 156         /* need to kill all outstanding asynchronous operations before
 157          * exiting */
 158         kafsasyncd_task = NULL;
 159         spin_lock(&kafsasyncd_async_lock);
 160
 161         /* fold the busy and attention queues together */
 162         list_splice_init(&kafsasyncd_async_busyq,
 163                          &kafsasyncd_async_attnq);
 164
 165         /* dequeue kafsasyncd from all their wait queues */
 166         list_for_each_entry(op, &kafsasyncd_async_attnq, link) {
 167                 op->call->app_attn_func = kafsasyncd_null_call_attn_func;
 168                 op->call->app_error_func = kafsasyncd_null_call_error_func;
 169                 remove_wait_queue(&op->call->waitq, &op->waiter);
 170         }
 171
 172         spin_unlock(&kafsasyncd_async_lock);
 173
 174         /* abort all the operations */
 175         while (!list_empty(&kafsasyncd_async_attnq)) {
 176                 op = list_entry(kafsasyncd_async_attnq.next, struct afs_async_op, link);
 177                 list_del_init(&op->link);
 178
 179                 rxrpc_call_abort(op->call, -EIO);
 180                 rxrpc_put_call(op->call);
 181                 op->call = NULL;
 182
 183                 op->ops->discard(op);
 184         }
 185
 186         /* and that's all */
 187         _leave("");
 188         complete_and_exit(&kafsasyncd_dead, 0);
 189
 190 } /* end kafsasyncd() */
 191
 192 /*****************************************************************************/
 193 /*
 194  * begin an operation
 195  * - place operation on busy queue
 196  */
 197 void afs_kafsasyncd_begin_op(struct afs_async_op *op)
 198 {
 199         _enter("");
 200
 201         spin_lock(&kafsasyncd_async_lock);
 202
 203         init_waitqueue_entry(&op->waiter, kafsasyncd_task);
 204         add_wait_queue(&op->call->waitq, &op->waiter);
 205
 206         list_move_tail(&op->link, &kafsasyncd_async_busyq);
 207
 208         spin_unlock(&kafsasyncd_async_lock);
 209
 210         _leave("");
 211 } /* end afs_kafsasyncd_begin_op() */
 212
 213 /*****************************************************************************/
 214 /*
 215  * request attention for an operation
 216  * - move to attention queue
 217  */
 218 void afs_kafsasyncd_attend_op(struct afs_async_op *op)
 219 {
 220         _enter("");
 221
 222         spin_lock(&kafsasyncd_async_lock);
 223
 224         list_move_tail(&op->link, &kafsasyncd_async_attnq);
 225
 226         spin_unlock(&kafsasyncd_async_lock);
 227
 228         wake_up(&kafsasyncd_sleepq);
 229
 230         _leave("");
 231 } /* end afs_kafsasyncd_attend_op() */
 232
 233 /*****************************************************************************/
 234 /*
 235  * terminate an operation
 236  * - remove from either queue
 237  */
 238 void afs_kafsasyncd_terminate_op(struct afs_async_op *op)
 239 {
 240         _enter("");
 241
 242         spin_lock(&kafsasyncd_async_lock);
 243
 244         if (!list_empty(&op->link)) {
 245                 list_del_init(&op->link);
 246                 remove_wait_queue(&op->call->waitq, &op->waiter);
 247         }
 248
 249         spin_unlock(&kafsasyncd_async_lock);
 250
 251         wake_up(&kafsasyncd_sleepq);
 252
 253         _leave("");
 254 } /* end afs_kafsasyncd_terminate_op() */