[deliverable/linux.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 "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);

	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));

		/* 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>
1da177e4 LT	18	#include "nodelist.h"
	19
	20
	21	static int jffs2_garbage_collect_thread(void *);
	22
	23	void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
	24	{
	25	spin_lock(&c->erase_completion_lock);
ef53cb02 DW	26	if (c->gc_task && jffs2_thread_should_wake(c))
ef53cb02 DW	27	send_sig(SIGHUP, c->gc_task, 1);
1da177e4 LT	28	spin_unlock(&c->erase_completion_lock);
	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	{
	34	pid_t pid;
	35	int ret = 0;
	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);
	41
	42	pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS\|CLONE_FILES);
	43	if (pid < 0) {
	44	printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid);
	45	complete(&c->gc_thread_exit);
	46	ret = pid;
	47	} else {
	48	/* Wait for it... */
	49	D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid));
fff7afd7	50	wait_for_completion(&c->gc_thread_start);
1da177e4	51	}
182ec4ee	52
1da177e4 LT	53	return ret;
	54	}
	55
	56	void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
	57	{
e2d48b1a	58	int wait = 0;
1da177e4 LT	59	spin_lock(&c->erase_completion_lock);
	60	if (c->gc_task) {
	61	D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
	62	send_sig(SIGKILL, c->gc_task, 1);
e2d48b1a	63	wait = 1;
1da177e4 LT	64	}
1da177e4 LT	65	spin_unlock(&c->erase_completion_lock);
e2d48b1a TG	66	if (wait)
e2d48b1a TG	67	wait_for_completion(&c->gc_thread_exit);
1da177e4 LT	68	}
	69
	70	static int jffs2_garbage_collect_thread(void *_c)
	71	{
	72	struct jffs2_sb_info *c = _c;
	73
	74	daemonize("jffs2_gcd_mtd%d", c->mtd->index);
	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
182ec4ee	110	/* Put_super will send a SIGKILL and then wait on the sem.
1da177e4	111	*/
e136e769	112	while (signal_pending(current) \|\| freezing(current)) {
1da177e4 LT	113	siginfo_t info;
	114	unsigned long signr;
	115
e716dd36 DW	116	if (try_to_freeze())
	117	goto again;
	118
1da177e4 LT	119	signr = dequeue_signal_lock(current, &current->blocked, &info);
	120
	121	switch(signr) {
	122	case SIGSTOP:
	123	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
	124	set_current_state(TASK_STOPPED);
	125	schedule();
	126	break;
	127
	128	case SIGKILL:
	129	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
	130	goto die;
	131
	132	case SIGHUP:
	133	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
	134	break;
	135	default:
	136	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
	137	}
	138	}
	139	/* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
	140	disallow_signal(SIGHUP);
	141
	142	D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
	143	if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
	144	printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
	145	goto die;
	146	}
	147	}
	148	die:
	149	spin_lock(&c->erase_completion_lock);
	150	c->gc_task = NULL;
	151	spin_unlock(&c->erase_completion_lock);
	152	complete_and_exit(&c->gc_thread_exit, 0);
	153	}