Btrfs: remove unused ftrace include
[linux-2.6] / fs / jffs2 / background.c
1 /*
2  * JFFS2 -- Journalling Flash File System, Version 2.
3  *
4  * Copyright © 2001-2007 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  */
11
12 #include <linux/kernel.h>
13 #include <linux/jffs2.h>
14 #include <linux/mtd/mtd.h>
15 #include <linux/completion.h>
16 #include <linux/sched.h>
17 #include <linux/freezer.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         BUG_ON(c->gc_task);
38
39         init_completion(&c->gc_thread_start);
40         init_completion(&c->gc_thread_exit);
41
42         pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES);
43         if (pid < 0) {
44                 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid);
45                 complete(&c->gc_thread_exit);
46                 ret = pid;
47         } else {
48                 /* Wait for it... */
49                 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid));
50                 wait_for_completion(&c->gc_thread_start);
51         }
52
53         return ret;
54 }
55
56 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
57 {
58         int wait = 0;
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                 wait = 1;
64         }
65         spin_unlock(&c->erase_completion_lock);
66         if (wait)
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         complete(&c->gc_thread_start);
81
82         set_user_nice(current, 10);
83
84         set_freezable();
85         for (;;) {
86                 allow_signal(SIGHUP);
87         again:
88                 spin_lock(&c->erase_completion_lock);
89                 if (!jffs2_thread_should_wake(c)) {
90                         set_current_state (TASK_INTERRUPTIBLE);
91                         spin_unlock(&c->erase_completion_lock);
92                         D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
93                         schedule();
94                 } else
95                         spin_unlock(&c->erase_completion_lock);
96                         
97
98                 /* Problem - immediately after bootup, the GCD spends a lot
99                  * of time in places like jffs2_kill_fragtree(); so much so
100                  * that userspace processes (like gdm and X) are starved
101                  * despite plenty of cond_resched()s and renicing.  Yield()
102                  * doesn't help, either (presumably because userspace and GCD
103                  * are generally competing for a higher latency resource -
104                  * disk).
105                  * This forces the GCD to slow the hell down.   Pulling an
106                  * inode in with read_inode() is much preferable to having
107                  * the GC thread get there first. */
108                 schedule_timeout_interruptible(msecs_to_jiffies(50));
109
110                 /* Put_super will send a SIGKILL and then wait on the sem.
111                  */
112                 while (signal_pending(current) || freezing(current)) {
113                         siginfo_t info;
114                         unsigned long signr;
115
116                         if (try_to_freeze())
117                                 goto again;
118
119                         signr = dequeue_signal_lock(current, &current->blocked, &info);
120
121                         switch(signr) {
122                         case SIGSTOP:
123                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
124                                 set_current_state(TASK_STOPPED);
125                                 schedule();
126                                 break;
127
128                         case SIGKILL:
129                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
130                                 goto die;
131
132                         case SIGHUP:
133                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
134                                 break;
135                         default:
136                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
137                         }
138                 }
139                 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
140                 disallow_signal(SIGHUP);
141
142                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
143                 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
144                         printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
145                         goto die;
146                 }
147         }
148  die:
149         spin_lock(&c->erase_completion_lock);
150         c->gc_task = NULL;
151         spin_unlock(&c->erase_completion_lock);
152         complete_and_exit(&c->gc_thread_exit, 0);
153 }