fs/jffs2.org/background.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright (C) 2001-2003 Red Hat, Inc.
   5  *
   6  * Created by David Woodhouse <dwmw2@redhat.com>
   7  *
   8  * For licensing information, see the file 'LICENCE' in this directory.
   9  *
  10  * $Id: background.c,v 1.49 2004/07/13 08:56:40 dwmw2 Exp $
  11  *
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/jffs2.h>
  16 #include <linux/mtd/mtd.h>
  17 #include <linux/completion.h>
  18 #include <linux/suspend.h>
  19 #include "nodelist.h"
  20
  21
  22 static int jffs2_garbage_collect_thread(void *);
  23
  24 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
  25 {
  26         spin_lock(&c->erase_completion_lock);
  27         if (c->gc_task && jffs2_thread_should_wake(c))
  28                 send_sig(SIGHUP, c->gc_task, 1);
  29         spin_unlock(&c->erase_completion_lock);
  30 }
  31
  32 /* This must only ever be called when no GC thread is currently running */
  33 int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
  34 {
  35         pid_t pid;
  36         int ret = 0;
  37
  38         if (c->gc_task)
  39                 BUG();
  40
  41         init_MUTEX_LOCKED(&c->gc_thread_start);
  42         init_completion(&c->gc_thread_exit);
  43
  44         pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES);
  45         if (pid < 0) {
  46                 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid);
  47                 complete(&c->gc_thread_exit);
  48                 ret = pid;
  49         } else {
  50                 /* Wait for it... */
  51                 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid));
  52                 down(&c->gc_thread_start);
  53         }
  54
  55         return ret;
  56 }
  57
  58 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
  59 {
  60         spin_lock(&c->erase_completion_lock);
  61         if (c->gc_task) {
  62                 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
  63                 send_sig(SIGKILL, c->gc_task, 1);
  64         }
  65         spin_unlock(&c->erase_completion_lock);
  66         wait_for_completion(&c->gc_thread_exit);
  67 }
  68
  69 static int jffs2_garbage_collect_thread(void *_c)
  70 {
  71         struct jffs2_sb_info *c = _c;
  72
  73         daemonize("jffs2_gcd_mtd%d", c->mtd->index);
  74         allow_signal(SIGKILL);
  75         allow_signal(SIGSTOP);
  76         allow_signal(SIGCONT);
  77
  78         c->gc_task = current;
  79         up(&c->gc_thread_start);
  80
  81         set_user_nice(current, 10);
  82
  83         for (;;) {
  84                 allow_signal(SIGHUP);
  85
  86                 if (!jffs2_thread_should_wake(c)) {
  87                         set_current_state (TASK_INTERRUPTIBLE);
  88                         D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
  89                         /* Yes, there's a race here; we checked jffs2_thread_should_wake()
  90                            before setting current->state to TASK_INTERRUPTIBLE. But it doesn't
  91                            matter - We don't care if we miss a wakeup, because the GC thread
  92                            is only an optimisation anyway. */
  93                         schedule();
  94                 }
  95
  96                 if (current->flags & PF_FREEZE) {
  97                         refrigerator(0);
  98                         /* refrigerator() should recalc sigpending for us
  99                            but doesn't. No matter - allow_signal() will. */
 100                         continue;
 101                 }
 102
 103                 cond_resched();
 104
 105                 /* Put_super will send a SIGKILL and then wait on the sem.
 106                  */
 107                 while (signal_pending(current)) {
 108                         siginfo_t info;
 109                         unsigned long signr;
 110
 111                         signr = dequeue_signal_lock(current, &current->blocked, &info);
 112
 113                         switch(signr) {
 114                         case SIGSTOP:
 115                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
 116                                 set_current_state(TASK_STOPPED);
 117                                 schedule();
 118                                 break;
 119
 120                         case SIGKILL:
 121                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
 122                                 goto die;
 123
 124                         case SIGHUP:
 125                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
 126                                 break;
 127                         default:
 128                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
 129                         }
 130                 }
 131                 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
 132                 disallow_signal(SIGHUP);
 133
 134                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
 135                 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
 136                         printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
 137                         goto die;
 138                 }
 139         }
 140  die:
 141         spin_lock(&c->erase_completion_lock);
 142         c->gc_task = NULL;
 143         spin_unlock(&c->erase_completion_lock);
 144         complete_and_exit(&c->gc_thread_exit, 0);
 145 }