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   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@infradead.org>
   7  *
   8  * For licensing information, see the file 'LICENCE' in this directory.
   9  *
  10  * $Id: background.c,v 1.50 2004/11/16 20:36:10 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 "nodelist.h"
  19
  20
  21 static int jffs2_garbage_collect_thread(void *);
  22
  23 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
  24 {
  25         spin_lock(&c->erase_completion_lock);
  26         if (c->gc_task && jffs2_thread_should_wake(c))
  27                 send_sig(SIGHUP, c->gc_task, 1);
  28         spin_unlock(&c->erase_completion_lock);
  29 }
  30
  31 /* This must only ever be called when no GC thread is currently running */
  32 int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
  33 {
  34         pid_t pid;
  35         int ret = 0;
  36
  37         if (c->gc_task)
  38                 BUG();
  39
  40         init_MUTEX_LOCKED(&c->gc_thread_start);
  41         init_completion(&c->gc_thread_exit);
  42
  43         pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES);
  44         if (pid < 0) {
  45                 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid);
  46                 complete(&c->gc_thread_exit);
  47                 ret = pid;
  48         } else {
  49                 /* Wait for it... */
  50                 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid));
  51                 down(&c->gc_thread_start);
  52         }
  53
  54         return ret;
  55 }
  56
  57 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
  58 {
  59         spin_lock(&c->erase_completion_lock);
  60         if (c->gc_task) {
  61                 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
  62                 send_sig(SIGKILL, c->gc_task, 1);
  63         }
  64         spin_unlock(&c->erase_completion_lock);
  65         wait_for_completion(&c->gc_thread_exit);
  66 }
  67
  68 static int jffs2_garbage_collect_thread(void *_c)
  69 {
  70         struct jffs2_sb_info *c = _c;
  71
  72         daemonize("jffs2_gcd_mtd%d", c->mtd->index);
  73         allow_signal(SIGKILL);
  74         allow_signal(SIGSTOP);
  75         allow_signal(SIGCONT);
  76
  77         c->gc_task = current;
  78         up(&c->gc_thread_start);
  79
  80         set_user_nice(current, 10);
  81
  82         for (;;) {
  83                 allow_signal(SIGHUP);
  84
  85                 if (!jffs2_thread_should_wake(c)) {
  86                         set_current_state (TASK_INTERRUPTIBLE);
  87                         D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
  88                         /* Yes, there's a race here; we checked jffs2_thread_should_wake()
  89                            before setting current->state to TASK_INTERRUPTIBLE. But it doesn't
  90                            matter - We don't care if we miss a wakeup, because the GC thread
  91                            is only an optimisation anyway. */
  92                         schedule();
  93                 }
  94
  95                 if (try_to_freeze(0))
  96                         continue;
  97
  98                 cond_resched();
  99
 100                 /* Put_super will send a SIGKILL and then wait on the sem.
 101                  */
 102                 while (signal_pending(current)) {
 103                         siginfo_t info;
 104                         unsigned long signr;
 105
 106                         signr = dequeue_signal_lock(current, &current->blocked, &info);
 107
 108                         switch(signr) {
 109                         case SIGSTOP:
 110                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
 111                                 set_current_state(TASK_STOPPED);
 112                                 schedule();
 113                                 break;
 114
 115                         case SIGKILL:
 116                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
 117                                 goto die;
 118
 119                         case SIGHUP:
 120                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
 121                                 break;
 122                         default:
 123                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
 124                         }
 125                 }
 126                 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
 127                 disallow_signal(SIGHUP);
 128
 129                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
 130                 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
 131                         printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
 132                         goto die;
 133                 }
 134         }
 135  die:
 136         spin_lock(&c->erase_completion_lock);
 137         c->gc_task = NULL;
 138         spin_unlock(&c->erase_completion_lock);
 139         complete_and_exit(&c->gc_thread_exit, 0);
 140 }