[net-next-2.6.git] / fs / jffs2 / background.c

/*
 * 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 <linux/kthread.h>
#include "nodelist.h"


static int jffs2_garbage_collect_thread(void *);

void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
{
	assert_spin_locked(&c->erase_completion_lock);
	if (c->gc_task && jffs2_thread_should_wake(c))
		send_sig(SIGHUP, c->gc_task, 1);
}

/* This must only ever be called when no GC thread is currently running */
int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
{
	struct task_struct *tsk;
	int ret = 0;

	BUG_ON(c->gc_task);

	init_completion(&c->gc_thread_start);
	init_completion(&c->gc_thread_exit);

	tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
	if (IS_ERR(tsk)) {
		printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %ld\n", -PTR_ERR(tsk));
		complete(&c->gc_thread_exit);
		ret = PTR_ERR(tsk);
	} else {
		/* Wait for it... */
		D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", tsk->pid));
		wait_for_completion(&c->gc_thread_start);
		ret = tsk->pid;
	}

	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;

	allow_signal(SIGKILL);
	allow_signal(SIGSTOP);
	allow_signal(SIGCONT);

	c->gc_task = current;
	complete(&c->gc_thread_start);

	set_user_nice(current, 10);

	set_freezable();
	for (;;) {
		allow_signal(SIGHUP);
	again:
		spin_lock(&c->erase_completion_lock);
		if (!jffs2_thread_should_wake(c)) {
			set_current_state (TASK_INTERRUPTIBLE);
			spin_unlock(&c->erase_completion_lock);
			D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
			schedule();
		} else
			spin_unlock(&c->erase_completion_lock);
			

		/* Problem - immediately after bootup, the GCD spends a lot
		 * of time in places like jffs2_kill_fragtree(); so much so
		 * that userspace processes (like gdm and X) are starved
		 * despite plenty of cond_resched()s and renicing.  Yield()
		 * doesn't help, either (presumably because userspace and GCD
		 * are generally competing for a higher latency resource -
		 * disk).
		 * This forces the GCD to slow the hell down.   Pulling an
		 * inode in with read_inode() is much preferable to having
		 * the GC thread get there first. */
		schedule_timeout_interruptible(msecs_to_jiffies(50));

		if (kthread_should_stop()) {
			D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread():  kthread_stop() called.\n"));
			goto die;
		}

		/* Put_super will send a SIGKILL and then wait on the sem.
		 */
		while (signal_pending(current) || freezing(current)) {
			siginfo_t info;
			unsigned long signr;

			if (try_to_freeze())
				goto again;

			signr = dequeue_signal_lock(current, &current->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);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* JFFS2 -- Journalling Flash File System, Version 2.
	3	*
c00c310e	4	* Copyright © 2001-2007 Red Hat, Inc.
1da177e4 LT	5	*
	6	* Created by David Woodhouse <dwmw2@infradead.org>
	7	*
	8	* For licensing information, see the file 'LICENCE' in this directory.
	9	*
1da177e4 LT	10	*/
	11
	12	#include <linux/kernel.h>
	13	#include <linux/jffs2.h>
	14	#include <linux/mtd/mtd.h>
	15	#include <linux/completion.h>
4e57b681	16	#include <linux/sched.h>
7dfb7103	17	#include <linux/freezer.h>
91e0955b	18	#include <linux/kthread.h>
1da177e4 LT	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	{
acb64a43	26	assert_spin_locked(&c->erase_completion_lock);
ef53cb02 DW	27	if (c->gc_task && jffs2_thread_should_wake(c))
ef53cb02 DW	28	send_sig(SIGHUP, c->gc_task, 1);
1da177e4 LT	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	{
91e0955b	34	struct task_struct *tsk;
1da177e4 LT	35	int ret = 0;
1da177e4 LT	36
4b4d1cc7	37	BUG_ON(c->gc_task);
1da177e4	38
fff7afd7	39	init_completion(&c->gc_thread_start);
1da177e4 LT	40	init_completion(&c->gc_thread_exit);
1da177e4 LT	41
91e0955b GL	42	tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
	43	if (IS_ERR(tsk)) {
	44	printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %ld\n", -PTR_ERR(tsk));
1da177e4	45	complete(&c->gc_thread_exit);
91e0955b	46	ret = PTR_ERR(tsk);
1da177e4 LT	47	} else {
1da177e4 LT	48	/* Wait for it... */
91e0955b	49	D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", tsk->pid));
fff7afd7	50	wait_for_completion(&c->gc_thread_start);
91e0955b	51	ret = tsk->pid;
1da177e4	52	}
182ec4ee	53
1da177e4 LT	54	return ret;
	55	}
	56
	57	void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
	58	{
e2d48b1a	59	int wait = 0;
1da177e4 LT	60	spin_lock(&c->erase_completion_lock);
	61	if (c->gc_task) {
	62	D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
	63	send_sig(SIGKILL, c->gc_task, 1);
e2d48b1a	64	wait = 1;
1da177e4 LT	65	}
1da177e4 LT	66	spin_unlock(&c->erase_completion_lock);
e2d48b1a TG	67	if (wait)
e2d48b1a TG	68	wait_for_completion(&c->gc_thread_exit);
1da177e4 LT	69	}
	70
	71	static int jffs2_garbage_collect_thread(void *_c)
	72	{
	73	struct jffs2_sb_info *c = _c;
	74
1da177e4 LT	75	allow_signal(SIGKILL);
	76	allow_signal(SIGSTOP);
	77	allow_signal(SIGCONT);
	78
	79	c->gc_task = current;
fff7afd7	80	complete(&c->gc_thread_start);
1da177e4 LT	81
	82	set_user_nice(current, 10);
	83
83144186	84	set_freezable();
1da177e4 LT	85	for (;;) {
1da177e4 LT	86	allow_signal(SIGHUP);
e716dd36	87	again:
b27cf88e	88	spin_lock(&c->erase_completion_lock);
1da177e4 LT	89	if (!jffs2_thread_should_wake(c)) {
1da177e4 LT	90	set_current_state (TASK_INTERRUPTIBLE);
b27cf88e	91	spin_unlock(&c->erase_completion_lock);
1da177e4	92	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
1da177e4	93	schedule();
b27cf88e DW	94	} else
	95	spin_unlock(&c->erase_completion_lock);
	96
1da177e4	97
efab0b5d AS	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));
1da177e4	109
91e0955b GL	110	if (kthread_should_stop()) {
	111	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): kthread_stop() called.\n"));
	112	goto die;
	113	}
	114
182ec4ee	115	/* Put_super will send a SIGKILL and then wait on the sem.
1da177e4	116	*/
e136e769	117	while (signal_pending(current) \|\| freezing(current)) {
1da177e4 LT	118	siginfo_t info;
	119	unsigned long signr;
	120
e716dd36 DW	121	if (try_to_freeze())
	122	goto again;
	123
1da177e4 LT	124	signr = dequeue_signal_lock(current, &current->blocked, &info);
	125
	126	switch(signr) {
	127	case SIGSTOP:
	128	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
	129	set_current_state(TASK_STOPPED);
	130	schedule();
	131	break;
	132
	133	case SIGKILL:
	134	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
	135	goto die;
	136
	137	case SIGHUP:
	138	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
	139	break;
	140	default:
	141	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
	142	}
	143	}
	144	/* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
	145	disallow_signal(SIGHUP);
	146
	147	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
	148	if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
	149	printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
	150	goto die;
	151	}
	152	}
	153	die:
	154	spin_lock(&c->erase_completion_lock);
	155	c->gc_task = NULL;
	156	spin_unlock(&c->erase_completion_lock);
	157	complete_and_exit(&c->gc_thread_exit, 0);
	158	}