fs/afs/kafsasyncd.c

   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                 /* discard pending signals */
 120                 afs_discard_my_signals();
 121
 122                 die = kafsasyncd_die;
 123
 124                 /* deal with the next asynchronous operation requiring
 125                  * attention */
 126                 if (!list_empty(&kafsasyncd_async_attnq)) {
 127                         struct afs_async_op *op;
 128
 129                         _debug("@@@ Begin Asynchronous Operation");
 130
 131                         op = NULL;
 132                         spin_lock(&kafsasyncd_async_lock);
 133
 134                         if (!list_empty(&kafsasyncd_async_attnq)) {
 135                                 op = list_entry(kafsasyncd_async_attnq.next,
 136                                                 struct afs_async_op, link);
 137                                 list_del(&op->link);
 138                                 list_add_tail(&op->link,
 139                                               &kafsasyncd_async_busyq);
 140                         }
 141
 142                         spin_unlock(&kafsasyncd_async_lock);
 143
 144                         _debug("@@@ Operation %p {%p}\n",
 145                                op, op ? op->ops : NULL);
 146
 147                         if (op)
 148                                 op->ops->attend(op);
 149
 150                         _debug("@@@ End Asynchronous Operation");
 151                 }
 152
 153         } while(!die);
 154
 155         /* need to kill all outstanding asynchronous operations before
 156          * exiting */
 157         kafsasyncd_task = NULL;
 158         spin_lock(&kafsasyncd_async_lock);
 159
 160         /* fold the busy and attention queues together */
 161         list_splice_init(&kafsasyncd_async_busyq,
 162                          &kafsasyncd_async_attnq);
 163
 164         /* dequeue kafsasyncd from all their wait queues */
 165         list_for_each_entry(op, &kafsasyncd_async_attnq, link) {
 166                 op->call->app_attn_func = kafsasyncd_null_call_attn_func;
 167                 op->call->app_error_func = kafsasyncd_null_call_error_func;
 168                 remove_wait_queue(&op->call->waitq, &op->waiter);
 169         }
 170
 171         spin_unlock(&kafsasyncd_async_lock);
 172
 173         /* abort all the operations */
 174         while (!list_empty(&kafsasyncd_async_attnq)) {
 175                 op = list_entry(kafsasyncd_async_attnq.next, struct afs_async_op, link);
 176                 list_del_init(&op->link);
 177
 178                 rxrpc_call_abort(op->call, -EIO);
 179                 rxrpc_put_call(op->call);
 180                 op->call = NULL;
 181
 182                 op->ops->discard(op);
 183         }
 184
 185         /* and that's all */
 186         _leave("");
 187         complete_and_exit(&kafsasyncd_dead, 0);
 188
 189 } /* end kafsasyncd() */
 190
 191 /*****************************************************************************/
 192 /*
 193  * begin an operation
 194  * - place operation on busy queue
 195  */
 196 void afs_kafsasyncd_begin_op(struct afs_async_op *op)
 197 {
 198         _enter("");
 199
 200         spin_lock(&kafsasyncd_async_lock);
 201
 202         init_waitqueue_entry(&op->waiter, kafsasyncd_task);
 203         add_wait_queue(&op->call->waitq, &op->waiter);
 204
 205         list_del(&op->link);
 206         list_add_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_del(&op->link);
 225         list_add_tail(&op->link, &kafsasyncd_async_attnq);
 226
 227         spin_unlock(&kafsasyncd_async_lock);
 228
 229         wake_up(&kafsasyncd_sleepq);
 230
 231         _leave("");
 232 } /* end afs_kafsasyncd_attend_op() */
 233
 234 /*****************************************************************************/
 235 /*
 236  * terminate an operation
 237  * - remove from either queue
 238  */
 239 void afs_kafsasyncd_terminate_op(struct afs_async_op *op)
 240 {
 241         _enter("");
 242
 243         spin_lock(&kafsasyncd_async_lock);
 244
 245         if (!list_empty(&op->link)) {
 246                 list_del_init(&op->link);
 247                 remove_wait_queue(&op->call->waitq, &op->waiter);
 248         }
 249
 250         spin_unlock(&kafsasyncd_async_lock);
 251
 252         wake_up(&kafsasyncd_sleepq);
 253
 254         _leave("");
 255 } /* end afs_kafsasyncd_terminate_op() */