ap/os/linux/linux-3.4.x/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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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 <linux/syscalls.h>
#include "nodelist.h"

/* quick gc wait timeout 60 seconds*/
#define QUICK_GC_TIMEOUT_MS  60000

struct jffs2_quick_gc_manager {
	char * name;
	struct jffs2_sb_info *c;
	struct completion  *waiting;
	 struct semaphore wait_sem;
};

static struct jffs2_quick_gc_manager jffs2_quick_gc_mtd[] = { 
                                                  {"imagefs", NULL, NULL}, 
                                                  {"resource", NULL, NULL},
                                                  {"nvrofs", NULL, NULL}
                                                };


static struct jffs2_quick_gc_manager * jffs2_quick_gc_find_manager(const char *mtd_name)
{
	int i;
	struct jffs2_quick_gc_manager *m = NULL;

	for(i=0; i<sizeof(jffs2_quick_gc_mtd)/sizeof(jffs2_quick_gc_mtd[0]); i++) {
		if(strcmp(mtd_name, jffs2_quick_gc_mtd[i].name) == 0)
			m = &jffs2_quick_gc_mtd[i];
	}

	return m;
}

static int jffs2_quick_gc_clean_manager(struct jffs2_sb_info *c)
{
	int i;

	for(i=0; i<sizeof(jffs2_quick_gc_mtd)/sizeof(jffs2_quick_gc_mtd[0]); i++) {
		if(strcmp(c->mtd->name, jffs2_quick_gc_mtd[i].name) == 0)
			jffs2_quick_gc_mtd[i].c = NULL;
	}

	return 0;
}

int quick_gc_wait_done(const char *mtd_name)
{
	struct jffs2_sb_info *c = NULL;
	struct jffs2_quick_gc_manager *m = NULL;
	struct completion waiting_done;

	m = jffs2_quick_gc_find_manager(mtd_name);
	BUG_ON(!m);

	c = m->c;
	if(c == NULL)
		return 1; /*partition not exist or not rw mode*/
	if(!c->gc_task)
		return 1; /*no gc_task, not  rw mode*/
	BUG_ON(m->waiting); /*must no waiting*/

	down(&(m->wait_sem));
	spin_lock(&c->erase_completion_lock);
	if(jffs2_thread_should_wake(c)) {
		m->waiting = &waiting_done;
		init_completion(m->waiting);
		printk(KERN_ALERT "[zgp] %s quick gc waiting start\n", c->mtd->name);
		jffs2_quick_garbage_collect_trigger(c);
		spin_unlock(&c->erase_completion_lock);
		wait_for_completion_timeout(m->waiting, msecs_to_jiffies(QUICK_GC_TIMEOUT_MS));
		m->waiting = NULL;
		printk(KERN_ALERT "[zgp] %s quick gc waiting return\n", c->mtd->name);
		up(&(m->wait_sem));
		return 1;
	}
	spin_unlock(&c->erase_completion_lock);
	up(&(m->wait_sem));

	return 1;
}

SYSCALL_DEFINE1(jffs2_quick_gc_wait_done, int __user, partition_no)
{
	BUG_ON(partition_no >= sizeof(jffs2_quick_gc_mtd)/sizeof(jffs2_quick_gc_mtd[0]));

	//printk(KERN_ALERT "[zgp]syscall %s wait done GC\n ", jffs2_quick_gc_mtd[partition_no].name);

	return quick_gc_wait_done(jffs2_quick_gc_mtd[partition_no].name);
}

void jffs2_quick_gc_done(struct jffs2_sb_info *c)
{
	struct jffs2_quick_gc_manager *m = NULL;

	assert_spin_locked(&c->erase_completion_lock);

	m = jffs2_quick_gc_find_manager(c->mtd->name);
	BUG_ON(!m);

	if(m->waiting) {
		//printk(KERN_ALERT "[zgp] mtd %s quck gc done\n", c->mtd->name);
		complete(m->waiting);
	}
}

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)) {
		//c->quick_gcblock_count = 0;
		send_sig(SIGHUP, c->gc_task, 1);
	}
}

/* add quick garbage collect trigger zgp*/
void jffs2_quick_garbage_collect_trigger(struct jffs2_sb_info *c)
{
	assert_spin_locked(&c->erase_completion_lock);
	if (c->gc_task) {
		c->quick_wait = 1;
		c->quick_gcblock_count = 0;
		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);

	for(ret = 0; ret < sizeof(jffs2_quick_gc_mtd)/sizeof(jffs2_quick_gc_mtd[0]); ret++) {
		if(strcmp(c->mtd->name, jffs2_quick_gc_mtd[ret].name) == 0) {
			c->flags |= JFFS2_SB_FLAG_QUICK_GC;
			c->quick_gcblock_count = 0;
			c->quick_wait = 0;
			jffs2_quick_gc_mtd[ret].c = c;
			sema_init(&(jffs2_quick_gc_mtd[ret].wait_sem), 1);
			//printk(KERN_ALERT "[zgp]partition %s enable quick GC\n ", c->mtd->name);
		}
	}

	tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
	if (IS_ERR(tsk)) {
		pr_warn("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... */
		jffs2_dbg(1, "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;
	struct jffs2_quick_gc_manager *m = NULL;

	if(c->flags & JFFS2_SB_FLAG_QUICK_GC) {
		m = jffs2_quick_gc_find_manager(c->mtd->name);
		BUG_ON(!m);
		BUG_ON(m->waiting); /*some one wait for GC*/
	}

	spin_lock(&c->erase_completion_lock);
	if (c->gc_task) {
		jffs2_dbg(1, "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);

	if(c->flags & JFFS2_SB_FLAG_QUICK_GC)
		jffs2_quick_gc_clean_manager(c);

}

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);
			if (c->flags & JFFS2_SB_FLAG_QUICK_GC) {
				printk(KERN_ALERT "[zgp] mtd %s quck gc done and sleep,gcblock_cnt:%d\n", c->mtd->name, c->quick_gcblock_count);
				jffs2_quick_gc_done(c);
			}
			spin_unlock(&c->erase_completion_lock);
			jffs2_dbg(1, "%s(): sleeping...\n", __func__);
			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. */
		if (c->flags & JFFS2_SB_FLAG_QUICK_GC) {
			if(c->quick_wait != 2)
				schedule_timeout_interruptible(msecs_to_jiffies(10));
		} else
			schedule_timeout_interruptible(msecs_to_jiffies(50));

		if (kthread_should_stop()) {
			jffs2_dbg(1, "%s(): kthread_stop() called\n", __func__);
			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:
				jffs2_dbg(1, "%s(): SIGSTOP received\n",
					  __func__);
				set_current_state(TASK_STOPPED);
				schedule();
				break;

			case SIGKILL:
				jffs2_dbg(1, "%s(): SIGKILL received\n",
					  __func__);
				goto die;

			case SIGHUP:
				jffs2_dbg(1, "%s(): SIGHUP received\n",
					  __func__);
				break;
			default:
				jffs2_dbg(1, "%s(): signal %ld received\n",
					  __func__, signr);
			}
		}
		/* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
		disallow_signal(SIGHUP);

		jffs2_dbg(1, "%s(): pass\n", __func__);
		if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
			pr_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);
}