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

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
 *
 * 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.
6088c058	5	* Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
1da177e4 LT	6	*
	7	* Created by David Woodhouse <dwmw2@infradead.org>
	8	*
	9	* For licensing information, see the file 'LICENCE' in this directory.
	10	*
1da177e4 LT	11	*/
	12
	13	#include <linux/kernel.h>
	14	#include <linux/jffs2.h>
	15	#include <linux/mtd/mtd.h>
	16	#include <linux/completion.h>
4e57b681	17	#include <linux/sched.h>
7dfb7103	18	#include <linux/freezer.h>
91e0955b	19	#include <linux/kthread.h>
1da177e4 LT	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	{
acb64a43	27	assert_spin_locked(&c->erase_completion_lock);
ef53cb02 DW	28	if (c->gc_task && jffs2_thread_should_wake(c))
ef53cb02 DW	29	send_sig(SIGHUP, c->gc_task, 1);
1da177e4 LT	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	{
91e0955b	35	struct task_struct *tsk;
1da177e4 LT	36	int ret = 0;
1da177e4 LT	37
4b4d1cc7	38	BUG_ON(c->gc_task);
1da177e4	39
fff7afd7	40	init_completion(&c->gc_thread_start);
1da177e4 LT	41	init_completion(&c->gc_thread_exit);
1da177e4 LT	42
91e0955b GL	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));
1da177e4	46	complete(&c->gc_thread_exit);
91e0955b	47	ret = PTR_ERR(tsk);
1da177e4 LT	48	} else {
1da177e4 LT	49	/* Wait for it... */
91e0955b	50	D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", tsk->pid));
fff7afd7	51	wait_for_completion(&c->gc_thread_start);
91e0955b	52	ret = tsk->pid;
1da177e4	53	}
182ec4ee	54
1da177e4 LT	55	return ret;
	56	}
	57
	58	void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
	59	{
e2d48b1a	60	int wait = 0;
1da177e4 LT	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);
e2d48b1a	65	wait = 1;
1da177e4 LT	66	}
1da177e4 LT	67	spin_unlock(&c->erase_completion_lock);
e2d48b1a TG	68	if (wait)
e2d48b1a TG	69	wait_for_completion(&c->gc_thread_exit);
1da177e4 LT	70	}
	71
	72	static int jffs2_garbage_collect_thread(void *_c)
	73	{
	74	struct jffs2_sb_info *c = _c;
	75
1da177e4 LT	76	allow_signal(SIGKILL);
	77	allow_signal(SIGSTOP);
	78	allow_signal(SIGCONT);
	79
	80	c->gc_task = current;
fff7afd7	81	complete(&c->gc_thread_start);
1da177e4 LT	82
	83	set_user_nice(current, 10);
	84
83144186	85	set_freezable();
1da177e4 LT	86	for (;;) {
1da177e4 LT	87	allow_signal(SIGHUP);
e716dd36	88	again:
b27cf88e	89	spin_lock(&c->erase_completion_lock);
1da177e4 LT	90	if (!jffs2_thread_should_wake(c)) {
1da177e4 LT	91	set_current_state (TASK_INTERRUPTIBLE);
b27cf88e	92	spin_unlock(&c->erase_completion_lock);
1da177e4	93	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
1da177e4	94	schedule();
b27cf88e DW	95	} else
	96	spin_unlock(&c->erase_completion_lock);
	97
1da177e4	98
efab0b5d AS	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));
1da177e4	110
91e0955b GL	111	if (kthread_should_stop()) {
	112	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): kthread_stop() called.\n"));
	113	goto die;
	114	}
	115
182ec4ee	116	/* Put_super will send a SIGKILL and then wait on the sem.
1da177e4	117	*/
e136e769	118	while (signal_pending(current) \|\| freezing(current)) {
1da177e4 LT	119	siginfo_t info;
	120	unsigned long signr;
	121
e716dd36 DW	122	if (try_to_freeze())
	123	goto again;
	124
1da177e4 LT	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	}