FreeBSD/Linux Kernel Cross Reference
sys/fs/jffs2/background.c

     /*
      * JFFS2 -- Journalling Flash File System, Version 2.
      *
      * Copyright (C) 2001 Red Hat, Inc.
      *
      * Created by David Woodhouse <dwmw2@cambridge.redhat.com>
      *
      * The original JFFS, from which the design for JFFS2 was derived,
      * was designed and implemented by Axis Communications AB.
     *
     * The contents of this file are subject to the Red Hat eCos Public
     * License Version 1.1 (the "Licence"); you may not use this file
     * except in compliance with the Licence.  You may obtain a copy of
     * the Licence at http://www.redhat.com/
     *
     * Software distributed under the Licence is distributed on an "AS IS"
     * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
     * See the Licence for the specific language governing rights and
     * limitations under the Licence.
     *
     * The Original Code is JFFS2 - Journalling Flash File System, version 2
     *
     * Alternatively, the contents of this file may be used under the
     * terms of the GNU General Public License version 2 (the "GPL"), in
     * which case the provisions of the GPL are applicable instead of the
     * above.  If you wish to allow the use of your version of this file
     * only under the terms of the GPL and not to allow others to use your
     * version of this file under the RHEPL, indicate your decision by
     * deleting the provisions above and replace them with the notice and
     * other provisions required by the GPL.  If you do not delete the
     * provisions above, a recipient may use your version of this file
     * under either the RHEPL or the GPL.
     *
     * $Id: background.c,v 1.16 2001/10/08 09:22:38 dwmw2 Exp $
     *
     */
    
    #define __KERNEL_SYSCALLS__
    
    #include <linux/kernel.h>
    #include <linux/sched.h>
    #include <linux/unistd.h>
    #include <linux/jffs2.h>
    #include <linux/mtd/mtd.h>
    #include <linux/interrupt.h>
    #include <linux/completion.h>
    #include "nodelist.h"
    
    
    static int jffs2_garbage_collect_thread(void *);
    static int thread_should_wake(struct jffs2_sb_info *c);
    
    void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
    {
            spin_lock_bh(&c->erase_completion_lock);
            if (c->gc_task && thread_should_wake(c))
                    send_sig(SIGHUP, c->gc_task, 1);
            spin_unlock_bh(&c->erase_completion_lock);
    }
    
    /* This must only ever be called when no GC thread is currently running */
    int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
    {
            pid_t pid;
            int ret = 0;
    
            if (c->gc_task)
                    BUG();
    
            init_MUTEX_LOCKED(&c->gc_thread_start);
            init_completion(&c->gc_thread_exit);
    
            pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES);
            if (pid < 0) {
                    printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid);
                    complete(&c->gc_thread_exit);
                    ret = pid;
            } else {
                    /* Wait for it... */
                    D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid));
                    down(&c->gc_thread_start);
            }
     
            return ret;
    }
    
    void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
    {
            spin_lock_bh(&c->erase_completion_lock);
            if (c->gc_task) {
                    D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
                    send_sig(SIGKILL, c->gc_task, 1);
            }
            spin_unlock_bh(&c->erase_completion_lock);
            wait_for_completion(&c->gc_thread_exit);
    }
    
    static int jffs2_garbage_collect_thread(void *_c)
    {
           struct jffs2_sb_info *c = _c;
   
           daemonize();
           current->tty = NULL;
           c->gc_task = current;
           up(&c->gc_thread_start);
   
           sprintf(current->comm, "jffs2_gcd_mtd%d", c->mtd->index);
   
           /* FIXME in the 2.2 backport */
           current->nice = 10;
   
           for (;;) {
                   spin_lock_irq(&current->sigmask_lock);
                   siginitsetinv (&current->blocked, sigmask(SIGHUP) | sigmask(SIGKILL) | sigmask(SIGSTOP) | sigmask(SIGCONT));
                   recalc_sigpending(current);
                   spin_unlock_irq(&current->sigmask_lock);
   
                   if (!thread_should_wake(c)) {
                           set_current_state (TASK_INTERRUPTIBLE);
                           D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
                           /* Yes, there's a race here; we checked thread_should_wake() before
                              setting current->state to TASK_INTERRUPTIBLE. But it doesn't
                              matter - We don't care if we miss a wakeup, because the GC thread
                              is only an optimisation anyway. */
                           schedule();
                   }
                   
                   if (current->need_resched)
                           schedule();
   
                   /* Put_super will send a SIGKILL and then wait on the sem. 
                    */
                   while (signal_pending(current)) {
                           siginfo_t info;
                           unsigned long signr;
   
                           spin_lock_irq(&current->sigmask_lock);
                           signr = dequeue_signal(&current->blocked, &info);
                           spin_unlock_irq(&current->sigmask_lock);
   
                           switch(signr) {
                           case SIGSTOP:
                                   D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
                                   set_current_state(TASK_STOPPED);
                                   schedule();
                                   break;
   
                           case SIGKILL:
                                   D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
                                   spin_lock_bh(&c->erase_completion_lock);
                                   c->gc_task = NULL;
                                   spin_unlock_bh(&c->erase_completion_lock);
                                   complete_and_exit(&c->gc_thread_exit, 0);
   
                           case SIGHUP:
                                   D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
                                   break;
                           default:
                                   D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
   
                           }
                   }
                   /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
                   spin_lock_irq(&current->sigmask_lock);
                   siginitsetinv (&current->blocked, sigmask(SIGKILL) | sigmask(SIGSTOP) | sigmask(SIGCONT));
                   recalc_sigpending(current);
                   spin_unlock_irq(&current->sigmask_lock);
   
                   D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
                   jffs2_garbage_collect_pass(c);
           }
   }
   
   static int thread_should_wake(struct jffs2_sb_info *c)
   {
           D1(printk(KERN_DEBUG "thread_should_wake(): nr_free_blocks %d, nr_erasing_blocks %d, dirty_size 0x%x\n", 
                     c->nr_free_blocks, c->nr_erasing_blocks, c->dirty_size));
           if (c->nr_free_blocks + c->nr_erasing_blocks < JFFS2_RESERVED_BLOCKS_GCTRIGGER &&
               c->dirty_size > c->sector_size)
                   return 1;
           else 
                   return 0;
   }

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