1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
/*
* JFFS2 -- Journalling Flash File System, Version 2.
*
* Copyright © 2001-2007 Red Hat, Inc.
*
* Created by David Woodhouse <dwmw2@infradead.org>
*
* For licensing information, see the file 'LICENCE' in this directory.
*
*/
#include <linux/kernel.h>
#include <linux/jffs2.h>
#include <linux/mtd/mtd.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/freezer.h>
#include "nodelist.h"
static int jffs2_garbage_collect_thread(void *);
void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
{
spin_lock(&c->erase_completion_lock);
if (c->gc_task && jffs2_thread_should_wake(c))
send_sig(SIGHUP, c->gc_task, 1);
spin_unlock(&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;
BUG_ON(c->gc_task);
init_completion(&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));
wait_for_completion(&c->gc_thread_start);
}
return ret;
}
void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
{
int wait = 0;
spin_lock(&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);
wait = 1;
}
spin_unlock(&c->erase_completion_lock);
if (wait)
wait_for_completion(&c->gc_thread_exit);
}
static int jffs2_garbage_collect_thread(void *_c)
{
struct jffs2_sb_info *c = _c;
daemonize("jffs2_gcd_mtd%d", c->mtd->index);
allow_signal(SIGKILL);
allow_signal(SIGSTOP);
allow_signal(SIGCONT);
c->gc_task = current;
complete(&c->gc_thread_start);
set_user_nice(current, 10);
for (;;) {
allow_signal(SIGHUP);
again:
if (!jffs2_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 jffs2_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();
}
/* This thread is purely an optimisation. But if it runs when
other things could be running, it actually makes things a
lot worse. Use yield() and put it at the back of the runqueue
every time. Especially during boot, pulling an inode in
with read_inode() is much preferable to having the GC thread
get there first. */
yield();
/* Put_super will send a SIGKILL and then wait on the sem.
*/
while (signal_pending(current)) {
siginfo_t info;
unsigned long signr;
if (try_to_freeze())
goto again;
signr = dequeue_signal_lock(current, ¤t->blocked, &info);
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"));
goto die;
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. */
disallow_signal(SIGHUP);
D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
goto die;
}
}
die:
spin_lock(&c->erase_completion_lock);
c->gc_task = NULL;
spin_unlock(&c->erase_completion_lock);
complete_and_exit(&c->gc_thread_exit, 0);
}
|
