Add linux-next specific files for 20110831
[linux-2.6/next.git] / fs / jffs2 / background.c
blob404111b016c93324535b4551dd2239f35c398966
1 /*
2 * JFFS2 -- Journalling Flash File System, Version 2.
4 * Copyright © 2001-2007 Red Hat, Inc.
5 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
7 * Created by David Woodhouse <dwmw2@infradead.org>
9 * For licensing information, see the file 'LICENCE' in this directory.
13 #include <linux/kernel.h>
14 #include <linux/jffs2.h>
15 #include <linux/mtd/mtd.h>
16 #include <linux/completion.h>
17 #include <linux/sched.h>
18 #include <linux/freezer.h>
19 #include <linux/kthread.h>
20 #include "nodelist.h"
23 static int jffs2_garbage_collect_thread(void *);
25 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
27 assert_spin_locked(&c->erase_completion_lock);
28 if (c->gc_task && jffs2_thread_should_wake(c))
29 send_sig(SIGHUP, c->gc_task, 1);
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)
35 struct task_struct *tsk;
36 int ret = 0;
38 BUG_ON(c->gc_task);
40 init_completion(&c->gc_thread_start);
41 init_completion(&c->gc_thread_exit);
43 tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
44 if (IS_ERR(tsk)) {
45 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %ld\n", -PTR_ERR(tsk));
46 complete(&c->gc_thread_exit);
47 ret = PTR_ERR(tsk);
48 } else {
49 /* Wait for it... */
50 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", tsk->pid));
51 wait_for_completion(&c->gc_thread_start);
52 ret = tsk->pid;
55 return ret;
58 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
60 int wait = 0;
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 wait = 1;
67 spin_unlock(&c->erase_completion_lock);
68 if (wait)
69 wait_for_completion(&c->gc_thread_exit);
72 static int jffs2_garbage_collect_thread(void *_c)
74 struct jffs2_sb_info *c = _c;
76 allow_signal(SIGKILL);
77 allow_signal(SIGSTOP);
78 allow_signal(SIGCONT);
80 c->gc_task = current;
81 complete(&c->gc_thread_start);
83 set_user_nice(current, 10);
85 set_freezable();
86 for (;;) {
87 allow_signal(SIGHUP);
88 again:
89 spin_lock(&c->erase_completion_lock);
90 if (!jffs2_thread_should_wake(c)) {
91 set_current_state (TASK_INTERRUPTIBLE);
92 spin_unlock(&c->erase_completion_lock);
93 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
94 schedule();
95 } else
96 spin_unlock(&c->erase_completion_lock);
99 /* Problem - immediately after bootup, the GCD spends a lot
100 * of time in places like jffs2_kill_fragtree(); so much so
101 * that userspace processes (like gdm and X) are starved
102 * despite plenty of cond_resched()s and renicing. Yield()
103 * doesn't help, either (presumably because userspace and GCD
104 * are generally competing for a higher latency resource -
105 * disk).
106 * This forces the GCD to slow the hell down. Pulling an
107 * inode in with read_inode() is much preferable to having
108 * the GC thread get there first. */
109 schedule_timeout_interruptible(msecs_to_jiffies(50));
111 if (kthread_should_stop()) {
112 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): kthread_stop() called.\n"));
113 goto die;
116 /* Put_super will send a SIGKILL and then wait on the sem.
118 while (signal_pending(current) || freezing(current)) {
119 siginfo_t info;
120 unsigned long signr;
122 if (try_to_freeze())
123 goto again;
125 signr = dequeue_signal_lock(current, &current->blocked, &info);
127 switch(signr) {
128 case SIGSTOP:
129 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
130 set_current_state(TASK_STOPPED);
131 schedule();
132 break;
134 case SIGKILL:
135 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
136 goto die;
138 case SIGHUP:
139 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
140 break;
141 default:
142 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
145 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
146 disallow_signal(SIGHUP);
148 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
149 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
150 printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
151 goto die;
154 die:
155 spin_lock(&c->erase_completion_lock);
156 c->gc_task = NULL;
157 spin_unlock(&c->erase_completion_lock);
158 complete_and_exit(&c->gc_thread_exit, 0);