Merge git://git.infradead.org/~dwmw2/rbtree-2.6
[linux-2.6] / 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@infradead.org>
7  *
8  * For licensing information, see the file 'LICENCE' in this directory.
9  *
10  * $Id: background.c,v 1.54 2005/05/20 21:37:12 gleixner 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/sched.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         BUG_ON(c->gc_task);
39
40         init_completion(&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                 wait_for_completion(&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         int wait = 0;
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                 wait = 1;
65         }
66         spin_unlock(&c->erase_completion_lock);
67         if (wait)
68                 wait_for_completion(&c->gc_thread_exit);
69 }
70
71 static int jffs2_garbage_collect_thread(void *_c)
72 {
73         struct jffs2_sb_info *c = _c;
74
75         daemonize("jffs2_gcd_mtd%d", c->mtd->index);
76         allow_signal(SIGKILL);
77         allow_signal(SIGSTOP);
78         allow_signal(SIGCONT);
79
80         c->gc_task = current;
81         complete(&c->gc_thread_start);
82
83         set_user_nice(current, 10);
84
85         for (;;) {
86                 allow_signal(SIGHUP);
87
88                 if (!jffs2_thread_should_wake(c)) {
89                         set_current_state (TASK_INTERRUPTIBLE);
90                         D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
91                         /* Yes, there's a race here; we checked jffs2_thread_should_wake()
92                            before setting current->state to TASK_INTERRUPTIBLE. But it doesn't
93                            matter - We don't care if we miss a wakeup, because the GC thread
94                            is only an optimisation anyway. */
95                         schedule();
96                 }
97
98                 if (try_to_freeze())
99                         continue;
100
101                 cond_resched();
102
103                 /* Put_super will send a SIGKILL and then wait on the sem.
104                  */
105                 while (signal_pending(current)) {
106                         siginfo_t info;
107                         unsigned long signr;
108
109                         signr = dequeue_signal_lock(current, &current->blocked, &info);
110
111                         switch(signr) {
112                         case SIGSTOP:
113                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
114                                 set_current_state(TASK_STOPPED);
115                                 schedule();
116                                 break;
117
118                         case SIGKILL:
119                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
120                                 goto die;
121
122                         case SIGHUP:
123                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
124                                 break;
125                         default:
126                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
127                         }
128                 }
129                 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
130                 disallow_signal(SIGHUP);
131
132                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
133                 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
134                         printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
135                         goto die;
136                 }
137         }
138  die:
139         spin_lock(&c->erase_completion_lock);
140         c->gc_task = NULL;
141         spin_unlock(&c->erase_completion_lock);
142         complete_and_exit(&c->gc_thread_exit, 0);
143 }