fs/jffs2/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 1.44 2003/10/08 13:29:55 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 static int thread_should_wake(struct jffs2_sb_info *c);
  24
  25 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
  26 {
  27         spin_lock(&c->erase_completion_lock);
  28         if (c->gc_task && thread_should_wake(c))
  29                 send_sig(SIGHUP, c->gc_task, 1);
  30         spin_unlock(&c->erase_completion_lock);
  31 }
  32
  33 /* This must only ever be called when no GC thread is currently running */
  34 int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
  35 {
  36         pid_t pid;
  37         int ret = 0;
  38
  39         if (c->gc_task)
  40                 BUG();
  41
  42         init_MUTEX_LOCKED(&c->gc_thread_start);
  43         init_completion(&c->gc_thread_exit);
  44
  45         pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES);
  46         if (pid < 0) {
  47                 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid);
  48                 complete(&c->gc_thread_exit);
  49                 ret = pid;
  50         } else {
  51                 /* Wait for it... */
  52                 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid));
  53                 down(&c->gc_thread_start);
  54         }
  55
  56         return ret;
  57 }
  58
  59 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
  60 {
  61         spin_lock(&c->erase_completion_lock);
  62         if (c->gc_task) {
  63                 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
  64                 send_sig(SIGKILL, c->gc_task, 1);
  65         }
  66         spin_unlock(&c->erase_completion_lock);
  67         wait_for_completion(&c->gc_thread_exit);
  68 }
  69
  70 static int jffs2_garbage_collect_thread(void *_c)
  71 {
  72         struct jffs2_sb_info *c = _c;
  73
  74         daemonize("jffs2_gcd_mtd%d", c->mtd->index);
  75         allow_signal(SIGKILL);
  76         allow_signal(SIGSTOP);
  77         allow_signal(SIGCONT);
  78
  79         c->gc_task = current;
  80         up(&c->gc_thread_start);
  81
  82         set_user_nice(current, 10);
  83
  84         for (;;) {
  85                 allow_signal(SIGHUP);
  86
  87                 if (!thread_should_wake(c)) {
  88                         set_current_state (TASK_INTERRUPTIBLE);
  89                         D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
  90                         /* Yes, there's a race here; we checked thread_should_wake() before
  91                            setting current->state to TASK_INTERRUPTIBLE. But it doesn't
  92                            matter - We don't care if we miss a wakeup, because the GC thread
  93                            is only an optimisation anyway. */
  94                         schedule();
  95                 }
  96
  97                 if (current->flags & PF_FREEZE) {
  98                         refrigerator(0);
  99                         /* refrigerator() should recalc sigpending for us
 100                            but doesn't. No matter - allow_signal() will. */
 101                         continue;
 102                 }
 103
 104                 cond_resched();
 105
 106                 /* Put_super will send a SIGKILL and then wait on the sem.
 107                  */
 108                 while (signal_pending(current)) {
 109                         siginfo_t info;
 110                         unsigned long signr;
 111
 112                         signr = dequeue_signal_lock(current, &current->blocked, &info);
 113
 114                         switch(signr) {
 115                         case SIGSTOP:
 116                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
 117                                 set_current_state(TASK_STOPPED);
 118                                 schedule();
 119                                 break;
 120
 121                         case SIGKILL:
 122                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
 123                                 goto die;
 124
 125                         case SIGHUP:
 126                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
 127                                 break;
 128                         default:
 129                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
 130                         }
 131                 }
 132                 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
 133                 disallow_signal(SIGHUP);
 134
 135                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
 136                 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
 137                         printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
 138                         goto die;
 139                 }
 140         }
 141  die:
 142         spin_lock(&c->erase_completion_lock);
 143         c->gc_task = NULL;
 144         spin_unlock(&c->erase_completion_lock);
 145         complete_and_exit(&c->gc_thread_exit, 0);
 146 }
 147
 148 static int thread_should_wake(struct jffs2_sb_info *c)
 149 {
 150         int ret = 0;
 151         uint32_t dirty;
 152
 153         if (c->unchecked_size) {
 154                 D1(printk(KERN_DEBUG "thread_should_wake(): unchecked_size %d, checked_ino #%d\n",
 155                           c->unchecked_size, c->checked_ino));
 156                 return 1;
 157         }
 158
 159         /* dirty_size contains blocks on erase_pending_list
 160          * those blocks are counted in c->nr_erasing_blocks.
 161          * If one block is actually erased, it is not longer counted as dirty_space
 162          * but it is counted in c->nr_erasing_blocks, so we add it and subtract it
 163          * with c->nr_erasing_blocks * c->sector_size again.
 164          * Blocks on erasable_list are counted as dirty_size, but not in c->nr_erasing_blocks
 165          * This helps us to force gc and pick eventually a clean block to spread the load.
 166          */
 167         dirty = c->dirty_size + c->erasing_size - c->nr_erasing_blocks * c->sector_size;
 168
 169         if (c->nr_free_blocks + c->nr_erasing_blocks < c->resv_blocks_gctrigger &&
 170                         (dirty > c->nospc_dirty_size))
 171                 ret = 1;
 172
 173         D1(printk(KERN_DEBUG "thread_should_wake(): nr_free_blocks %d, nr_erasing_blocks %d, dirty_size 0x%x: %s\n",
 174                   c->nr_free_blocks, c->nr_erasing_blocks, c->dirty_size, ret?"yes":"no"));
 175
 176         return ret;
 177 }