fs/jffs2/background.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright (C) 2001 Red Hat, Inc.
   5  *
   6  * Created by David Woodhouse <dwmw2@cambridge.redhat.com>
   7  *
   8  * The original JFFS, from which the design for JFFS2 was derived,
   9  * was designed and implemented by Axis Communications AB.
  10  *
  11  * The contents of this file are subject to the Red Hat eCos Public
  12  * License Version 1.1 (the "Licence"); you may not use this file
  13  * except in compliance with the Licence.  You may obtain a copy of
  14  * the Licence at http://www.redhat.com/
  15  *
  16  * Software distributed under the Licence is distributed on an "AS IS"
  17  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
  18  * See the Licence for the specific language governing rights and
  19  * limitations under the Licence.
  20  *
  21  * The Original Code is JFFS2 - Journalling Flash File System, version 2
  22  *
  23  * Alternatively, the contents of this file may be used under the
  24  * terms of the GNU General Public License version 2 (the "GPL"), in
  25  * which case the provisions of the GPL are applicable instead of the
  26  * above.  If you wish to allow the use of your version of this file
  27  * only under the terms of the GPL and not to allow others to use your
  28  * version of this file under the RHEPL, indicate your decision by
  29  * deleting the provisions above and replace them with the notice and
  30  * other provisions required by the GPL.  If you do not delete the
  31  * provisions above, a recipient may use your version of this file
  32  * under either the RHEPL or the GPL.
  33  *
  34  * $Id: background.c,v 1.16 2001/10/08 09:22:38 dwmw2 Exp $
  35  *
  36  */
  37
  38 #define __KERNEL_SYSCALLS__
  39
  40 #include <linux/kernel.h>
  41 #include <linux/sched.h>
  42 #include <linux/unistd.h>
  43 #include <linux/jffs2.h>
  44 #include <linux/mtd/mtd.h>
  45 #include <linux/interrupt.h>
  46 #include <linux/completion.h>
  47 #include "nodelist.h"
  48
  49
  50 static int jffs2_garbage_collect_thread(void *);
  51 static int thread_should_wake(struct jffs2_sb_info *c);
  52
  53 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
  54 {
  55         spin_lock_bh(&c->erase_completion_lock);
  56         if (c->gc_task && thread_should_wake(c))
  57                 send_sig(SIGHUP, c->gc_task, 1);
  58         spin_unlock_bh(&c->erase_completion_lock);
  59 }
  60
  61 /* This must only ever be called when no GC thread is currently running */
  62 int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
  63 {
  64         pid_t pid;
  65         int ret = 0;
  66
  67         if (c->gc_task)
  68                 BUG();
  69
  70         init_MUTEX_LOCKED(&c->gc_thread_start);
  71         init_completion(&c->gc_thread_exit);
  72
  73         pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES);
  74         if (pid < 0) {
  75                 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid);
  76                 complete(&c->gc_thread_exit);
  77                 ret = pid;
  78         } else {
  79                 /* Wait for it... */
  80                 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid));
  81                 down(&c->gc_thread_start);
  82         }
  83
  84         return ret;
  85 }
  86
  87 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
  88 {
  89         spin_lock_bh(&c->erase_completion_lock);
  90         if (c->gc_task) {
  91                 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
  92                 send_sig(SIGKILL, c->gc_task, 1);
  93         }
  94         spin_unlock_bh(&c->erase_completion_lock);
  95         wait_for_completion(&c->gc_thread_exit);
  96 }
  97
  98 static int jffs2_garbage_collect_thread(void *_c)
  99 {
 100         struct jffs2_sb_info *c = _c;
 101
 102         daemonize();
 103         current->tty = NULL;
 104         c->gc_task = current;
 105         up(&c->gc_thread_start);
 106
 107         sprintf(current->comm, "jffs2_gcd_mtd%d", c->mtd->index);
 108
 109         /* FIXME in the 2.2 backport */
 110         current->nice = 10;
 111
 112         for (;;) {
 113                 spin_lock_irq(&current->sigmask_lock);
 114                 siginitsetinv (&current->blocked, sigmask(SIGHUP) | sigmask(SIGKILL) | sigmask(SIGSTOP) | sigmask(SIGCONT));
 115                 recalc_sigpending(current);
 116                 spin_unlock_irq(&current->sigmask_lock);
 117
 118                 if (!thread_should_wake(c)) {
 119                         set_current_state (TASK_INTERRUPTIBLE);
 120                         D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
 121                         /* Yes, there's a race here; we checked thread_should_wake() before
 122                            setting current->state to TASK_INTERRUPTIBLE. But it doesn't
 123                            matter - We don't care if we miss a wakeup, because the GC thread
 124                            is only an optimisation anyway. */
 125                         schedule();
 126                 }
 127
 128                 if (current->need_resched)
 129                         schedule();
 130
 131                 /* Put_super will send a SIGKILL and then wait on the sem.
 132                  */
 133                 while (signal_pending(current)) {
 134                         siginfo_t info;
 135                         unsigned long signr;
 136
 137                         spin_lock_irq(&current->sigmask_lock);
 138                         signr = dequeue_signal(&current->blocked, &info);
 139                         spin_unlock_irq(&current->sigmask_lock);
 140
 141                         switch(signr) {
 142                         case SIGSTOP:
 143                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
 144                                 set_current_state(TASK_STOPPED);
 145                                 schedule();
 146                                 break;
 147
 148                         case SIGKILL:
 149                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
 150                                 spin_lock_bh(&c->erase_completion_lock);
 151                                 c->gc_task = NULL;
 152                                 spin_unlock_bh(&c->erase_completion_lock);
 153                                 complete_and_exit(&c->gc_thread_exit, 0);
 154
 155                         case SIGHUP:
 156                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
 157                                 break;
 158                         default:
 159                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
 160
 161                         }
 162                 }
 163                 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
 164                 spin_lock_irq(&current->sigmask_lock);
 165                 siginitsetinv (&current->blocked, sigmask(SIGKILL) | sigmask(SIGSTOP) | sigmask(SIGCONT));
 166                 recalc_sigpending(current);
 167                 spin_unlock_irq(&current->sigmask_lock);
 168
 169                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
 170                 jffs2_garbage_collect_pass(c);
 171         }
 172 }
 173
 174 static int thread_should_wake(struct jffs2_sb_info *c)
 175 {
 176         D1(printk(KERN_DEBUG "thread_should_wake(): nr_free_blocks %d, nr_erasing_blocks %d, dirty_size 0x%x\n",
 177                   c->nr_free_blocks, c->nr_erasing_blocks, c->dirty_size));
 178         if (c->nr_free_blocks + c->nr_erasing_blocks < JFFS2_RESERVED_BLOCKS_GCTRIGGER &&
 179             c->dirty_size > c->sector_size)
 180                 return 1;
 181         else
 182                 return 0;
 183 }