xfs: validate acl count
[linux-2.6.git] / fs / jffs2 / background.c
1 /*
2  * JFFS2 -- Journalling Flash File System, Version 2.
3  *
4  * Copyright © 2001-2007 Red Hat, Inc.
5  * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
6  *
7  * Created by David Woodhouse <dwmw2@infradead.org>
8  *
9  * For licensing information, see the file 'LICENCE' in this directory.
10  *
11  */
12
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"
21
22
23 static int jffs2_garbage_collect_thread(void *);
24
25 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
26 {
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);
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         struct task_struct *tsk;
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         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;
53         }
54
55         return ret;
56 }
57
58 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
59 {
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;
66         }
67         spin_unlock(&c->erase_completion_lock);
68         if (wait)
69                 wait_for_completion(&c->gc_thread_exit);
70 }
71
72 static int jffs2_garbage_collect_thread(void *_c)
73 {
74         struct jffs2_sb_info *c = _c;
75
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         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);
97                         
98
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));
110
111                 if (kthread_should_stop()) {
112                         D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread():  kthread_stop() called.\n"));
113                         goto die;
114                 }
115
116                 /* Put_super will send a SIGKILL and then wait on the sem.
117                  */
118                 while (signal_pending(current) || freezing(current)) {
119                         siginfo_t info;
120                         unsigned long signr;
121
122                         if (try_to_freeze())
123                                 goto again;
124
125                         signr = dequeue_signal_lock(current, &current->blocked, &info);
126
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;
133
134                         case SIGKILL:
135                                 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
136                                 goto die;
137
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));
143                         }
144                 }
145                 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
146                 disallow_signal(SIGHUP);
147
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;
152                 }
153         }
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);
159 }