async-thread.c

/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/kthread.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/freezer.h>
#include "async-thread.h"

#define WORK_QUEUED_BIT 0
#define WORK_DONE_BIT 1
#define WORK_ORDER_DONE_BIT 2
#define WORK_HIGH_PRIO_BIT 3

/*
 * container for the kthread task pointer and the list of pending work
 * One of these is allocated per thread.
 */
struct btrfs_worker_thread {
	/* pool we belong to */
	struct btrfs_workers *workers;

	/* list of struct btrfs_work that are waiting for service */
	struct list_head pending;
	struct list_head prio_pending;

	/* list of worker threads from struct btrfs_workers */
	struct list_head worker_list;

	/* kthread */
	struct task_struct *task;

	/* number of things on the pending list */
	atomic_t num_pending;

	/* reference counter for this struct */
	atomic_t refs;

	unsigned long sequence;

	/* protects the pending list. */
	spinlock_t lock;

	/* set to non-zero when this thread is already awake and kicking */
	int working;

	/* are we currently idle */
	int idle;
};

static int __btrfs_start_workers(struct btrfs_workers *workers);

/*
 * btrfs_start_workers uses kthread_run, which can block waiting for memory