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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 <linux/kthread.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 | 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, ¤t->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 | } |
160 |
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