[linux-2.6-block.git] / fs / btrfs / transaction.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/module.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"

static int total_trans = 0;
extern struct kmem_cache *btrfs_trans_handle_cachep;
extern struct kmem_cache *btrfs_transaction_cachep;

static struct workqueue_struct *trans_wq;

#define BTRFS_ROOT_TRANS_TAG 0

static void put_transaction(struct btrfs_transaction *transaction)
{
	WARN_ON(transaction->use_count == 0);
	transaction->use_count--;
	if (transaction->use_count == 0) {
		WARN_ON(total_trans == 0);
		total_trans--;
		list_del_init(&transaction->list);
		memset(transaction, 0, sizeof(*transaction));
		kmem_cache_free(btrfs_transaction_cachep, transaction);
	}
}

static int join_transaction(struct btrfs_root *root)
{
	struct btrfs_transaction *cur_trans;
	cur_trans = root->fs_info->running_transaction;
	if (!cur_trans) {
		cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
					     GFP_NOFS);
		total_trans++;
		BUG_ON(!cur_trans);
		root->fs_info->generation++;
		root->fs_info->running_transaction = cur_trans;
		cur_trans->num_writers = 0;
		cur_trans->transid = root->fs_info->generation;
		init_waitqueue_head(&cur_trans->writer_wait);
		init_waitqueue_head(&cur_trans->commit_wait);
		cur_trans->in_commit = 0;
		cur_trans->use_count = 1;
		cur_trans->commit_done = 0;
		cur_trans->start_time = get_seconds();
		list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
		init_bit_radix(&cur_trans->dirty_pages);
	}
	cur_trans->num_writers++;
	return 0;
}

struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
						   int num_blocks)
{
	struct btrfs_trans_handle *h =
		kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
	int ret;
	u64 running_trans_id;

	mutex_lock(&root->fs_info->trans_mutex);
	ret = join_transaction(root);
	BUG_ON(ret);
	running_trans_id = root->fs_info->running_transaction->transid;

	if (root != root->fs_info->tree_root && root->last_trans <
	    running_trans_id) {
		if (root->root_item.refs != 0) {
			radix_tree_tag_set(&root->fs_info->fs_roots_radix,
					   (unsigned long)root->root_key.objectid,
					   BTRFS_ROOT_TRANS_TAG);
			root->commit_root = root->node;
			get_bh(root->node);
		} else {
			WARN_ON(1);
		}
	}
	root->last_trans = running_trans_id;
	h->transid = running_trans_id;
	h->transaction = root->fs_info->running_transaction;
	h->blocks_reserved = num_blocks;
	h->blocks_used = 0;
	h->block_group = NULL;
	root->fs_info->running_transaction->use_count++;
	mutex_unlock(&root->fs_info->trans_mutex);
	return h;
}

int btrfs_end_transaction(struct btrfs_trans_handle *trans,
			  struct btrfs_root *root)
{
	struct btrfs_transaction *cur_trans;

	mutex_lock(&root->fs_info->trans_mutex);
	cur_trans = root->fs_info->running_transaction;
	WARN_ON(cur_trans->num_writers < 1);
	if (waitqueue_active(&cur_trans->writer_wait))
		wake_up(&cur_trans->writer_wait);
	cur_trans->num_writers--;
	put_transaction(cur_trans);
	mutex_unlock(&root->fs_info->trans_mutex);
	memset(trans, 0, sizeof(*trans));
	kmem_cache_free(btrfs_trans_handle_cachep, trans);
	return 0;
}


int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
				     struct btrfs_root *root)
{
	unsigned long gang[16];
	int ret;
	int i;
	int err;
	int werr = 0;
	struct page *page;
	struct radix_tree_root *dirty_pages;
	struct inode *btree_inode = root->fs_info->btree_inode;

	if (!trans || !trans->transaction) {
		return filemap_write_and_wait(btree_inode->i_mapping);
	}
	dirty_pages = &trans->transaction->dirty_pages;
	while(1) {
		ret = find_first_radix_bit(dirty_pages, gang,
					   0, ARRAY_SIZE(gang));
		if (!ret)
			break;
		for (i = 0; i < ret; i++) {
			/* FIXME EIO */
			clear_radix_bit(dirty_pages, gang[i]);
			page = find_lock_page(btree_inode->i_mapping,
					      gang[i]);
			if (!page)
				continue;
			err = write_one_page(page, 0);
			if (err)
				werr = err;
			page_cache_release(page);
		}
	}
	err = filemap_fdatawait(btree_inode->i_mapping);
	if (err)
		werr = err;
	return werr;
}

int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
			    struct btrfs_root *root)
{
	int ret;
	u64 old_extent_block;
	struct btrfs_fs_info *fs_info = root->fs_info;
	struct btrfs_root *tree_root = fs_info->tree_root;
	struct btrfs_root *extent_root = fs_info->extent_root;

	btrfs_write_dirty_block_groups(trans, extent_root);
	while(1) {
		old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
		if (old_extent_block == bh_blocknr(extent_root->node))
			break;
		btrfs_set_root_blocknr(&extent_root->root_item,
				       bh_blocknr(extent_root->node));
		ret = btrfs_update_root(trans, tree_root,
					&extent_root->root_key,
					&extent_root->root_item);
		BUG_ON(ret);
		btrfs_write_dirty_block_groups(trans, extent_root);
	}
	return 0;
}

static int wait_for_commit(struct btrfs_root *root,
			   struct btrfs_transaction *commit)
{
	DEFINE_WAIT(wait);
	while(!commit->commit_done) {
		prepare_to_wait(&commit->commit_wait, &wait,
				TASK_UNINTERRUPTIBLE);
		if (commit->commit_done)
			break;
		mutex_unlock(&root->fs_info->trans_mutex);
		schedule();
		mutex_lock(&root->fs_info->trans_mutex);
	}
	finish_wait(&commit->commit_wait, &wait);
	return 0;
}

struct dirty_root {
	struct list_head list;
	struct btrfs_key snap_key;
	struct buffer_head *commit_root;
	struct btrfs_root *root;
	int free_on_drop;
};

int btrfs_add_dead_root(struct btrfs_root *root, struct list_head *dead_list)
{
	struct dirty_root *dirty;

	dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
	if (!dirty)
		return -ENOMEM;
	memcpy(&dirty->snap_key, &root->root_key, sizeof(root->root_key));
	dirty->commit_root = root->node;
	dirty->root = root;
	dirty->free_on_drop = 1;
	list_add(&dirty->list, dead_list);
	return 0;
}

static int add_dirty_roots(struct btrfs_trans_handle *trans,
			   struct radix_tree_root *radix,
			   struct list_head *list)
{
	struct dirty_root *dirty;
	struct btrfs_root *gang[8];
	struct btrfs_root *root;
	struct btrfs_root_item tmp_item;
	int i;
	int ret;
	int err = 0;
	u32 refs;

	while(1) {
		ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
						 ARRAY_SIZE(gang),
						 BTRFS_ROOT_TRANS_TAG);
		if (ret == 0)
			break;
		for (i = 0; i < ret; i++) {
			root = gang[i];
			radix_tree_tag_clear(radix,
				     (unsigned long)root->root_key.objectid,
				     BTRFS_ROOT_TRANS_TAG);
			if (root->commit_root == root->node) {
				WARN_ON(bh_blocknr(root->node) !=
					btrfs_root_blocknr(&root->root_item));
				brelse(root->commit_root);
				root->commit_root = NULL;
				continue;
			}
			dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
			BUG_ON(!dirty);
			memcpy(&dirty->snap_key, &root->root_key,
			       sizeof(root->root_key));
			dirty->commit_root = root->commit_root;
			root->commit_root = NULL;
			dirty->root = root;
			dirty->free_on_drop = 0;
			memcpy(&tmp_item, &root->root_item, sizeof(tmp_item));

			root->root_key.offset = root->fs_info->generation;
			btrfs_set_root_blocknr(&root->root_item,
					       bh_blocknr(root->node));
			err = btrfs_insert_root(trans, root->fs_info->tree_root,
						&root->root_key,
						&root->root_item);
			if (err)
				break;

			refs = btrfs_root_refs(&tmp_item);
			btrfs_set_root_refs(&tmp_item, refs - 1);
			err = btrfs_update_root(trans, root->fs_info->tree_root,
						&dirty->snap_key,
						&tmp_item);

			BUG_ON(err);
			if (refs == 1)
				list_add(&dirty->list, list);
			else
				kfree(dirty);
		}
	}
	return err;
}

static int drop_dirty_roots(struct btrfs_root *tree_root,
			    struct list_head *list)
{
	struct dirty_root *dirty;
	struct btrfs_trans_handle *trans;
	int ret = 0;
	while(!list_empty(list)) {
		mutex_lock(&tree_root->fs_info->fs_mutex);
		dirty = list_entry(list->next, struct dirty_root, list);
		list_del_init(&dirty->list);

		trans = btrfs_start_transaction(tree_root, 1);
		ret = btrfs_drop_snapshot(trans, dirty->root,
					  dirty->commit_root);
		BUG_ON(ret);
		ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
		if (ret)
			break;
		ret = btrfs_end_transaction(trans, tree_root);
		BUG_ON(ret);

		if (dirty->free_on_drop)
			kfree(dirty->root);
		kfree(dirty);
		mutex_unlock(&tree_root->fs_info->fs_mutex);
		btrfs_btree_balance_dirty(tree_root);
	}
	return ret;
}

int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root)
{
	int ret = 0;
	struct btrfs_transaction *cur_trans;
	struct btrfs_transaction *prev_trans = NULL;
	struct list_head dirty_fs_roots;
	DEFINE_WAIT(wait);

	INIT_LIST_HEAD(&dirty_fs_roots);

	mutex_lock(&root->fs_info->trans_mutex);
	if (trans->transaction->in_commit) {
		cur_trans = trans->transaction;
		trans->transaction->use_count++;
		btrfs_end_transaction(trans, root);
		ret = wait_for_commit(root, cur_trans);
		BUG_ON(ret);
		put_transaction(cur_trans);
		mutex_unlock(&root->fs_info->trans_mutex);
		return 0;
	}
	cur_trans = trans->transaction;
	trans->transaction->in_commit = 1;
	while (trans->transaction->num_writers > 1) {
		WARN_ON(cur_trans != trans->transaction);
		prepare_to_wait(&trans->transaction->writer_wait, &wait,
				TASK_UNINTERRUPTIBLE);
		if (trans->transaction->num_writers <= 1)
			break;
		mutex_unlock(&root->fs_info->trans_mutex);
		schedule();
		mutex_lock(&root->fs_info->trans_mutex);
		finish_wait(&trans->transaction->writer_wait, &wait);
	}
	finish_wait(&trans->transaction->writer_wait, &wait);
	WARN_ON(cur_trans != trans->transaction);
	ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
			      &dirty_fs_roots);
	BUG_ON(ret);

	ret = btrfs_commit_tree_roots(trans, root);
	BUG_ON(ret);

	cur_trans = root->fs_info->running_transaction;
	root->fs_info->running_transaction = NULL;
	if (cur_trans->list.prev != &root->fs_info->trans_list) {
		prev_trans = list_entry(cur_trans->list.prev,
					struct btrfs_transaction, list);
		if (prev_trans->commit_done)
			prev_trans = NULL;
		else
			prev_trans->use_count++;
	}
	mutex_unlock(&root->fs_info->trans_mutex);
	mutex_unlock(&root->fs_info->fs_mutex);
	ret = btrfs_write_and_wait_transaction(trans, root);
	if (prev_trans) {
		mutex_lock(&root->fs_info->trans_mutex);
		wait_for_commit(root, prev_trans);
		put_transaction(prev_trans);
		mutex_unlock(&root->fs_info->trans_mutex);
	}
	btrfs_set_super_generation(root->fs_info->disk_super,
				   cur_trans->transid);
	BUG_ON(ret);
	write_ctree_super(trans, root);

	mutex_lock(&root->fs_info->fs_mutex);
	btrfs_finish_extent_commit(trans, root);
	mutex_lock(&root->fs_info->trans_mutex);
	cur_trans->commit_done = 1;
	wake_up(&cur_trans->commit_wait);
	put_transaction(cur_trans);
	put_transaction(cur_trans);
	if (root->fs_info->closing)
		list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
	else
		list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
	mutex_unlock(&root->fs_info->trans_mutex);
	kmem_cache_free(btrfs_trans_handle_cachep, trans);

	if (root->fs_info->closing) {
		mutex_unlock(&root->fs_info->fs_mutex);
		drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
		mutex_lock(&root->fs_info->fs_mutex);
	}
	return ret;
}

void btrfs_transaction_cleaner(struct work_struct *work)
{
	struct btrfs_fs_info *fs_info = container_of(work,
						     struct btrfs_fs_info,
						     trans_work.work);

	struct btrfs_root *root = fs_info->tree_root;
	struct btrfs_transaction *cur;
	struct btrfs_trans_handle *trans;
	struct list_head dirty_roots;
	unsigned long now;
	unsigned long delay = HZ * 30;
	int ret;

	INIT_LIST_HEAD(&dirty_roots);
	mutex_lock(&root->fs_info->fs_mutex);
	mutex_lock(&root->fs_info->trans_mutex);
	cur = root->fs_info->running_transaction;
	if (!cur) {
		mutex_unlock(&root->fs_info->trans_mutex);
		goto out;
	}
	now = get_seconds();
	if (now < cur->start_time || now - cur->start_time < 30) {
		mutex_unlock(&root->fs_info->trans_mutex);
		delay = HZ * 5;
		goto out;
	}
	mutex_unlock(&root->fs_info->trans_mutex);
	trans = btrfs_start_transaction(root, 1);
	ret = btrfs_commit_transaction(trans, root);
out:
	mutex_unlock(&root->fs_info->fs_mutex);

	mutex_lock(&root->fs_info->trans_mutex);
	list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
	mutex_unlock(&root->fs_info->trans_mutex);

	if (!list_empty(&dirty_roots)) {
		drop_dirty_roots(root, &dirty_roots);
	}
	btrfs_transaction_queue_work(root, delay);
}

void btrfs_transaction_queue_work(struct btrfs_root *root, int delay)
{
	queue_delayed_work(trans_wq, &root->fs_info->trans_work, delay);
}

void btrfs_transaction_flush_work(struct btrfs_root *root)
{
	cancel_rearming_delayed_workqueue(trans_wq, &root->fs_info->trans_work);
	flush_workqueue(trans_wq);
}

void __init btrfs_init_transaction_sys(void)
{
	trans_wq = create_workqueue("btrfs");
}

void __exit btrfs_exit_transaction_sys(void)
{
	destroy_workqueue(trans_wq);
}
Commit	Line	Data
	1	/*
	2	* Copyright (C) 2007 Oracle. All rights reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public
	6	* License v2 as published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	11	* General Public License for more details.
	12	*
	13	* You should have received a copy of the GNU General Public
	14	* License along with this program; if not, write to the
	15	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	16	* Boston, MA 021110-1307, USA.
	17	*/
	18
	19	#include <linux/module.h>
	20	#include <linux/fs.h>
	21	#include <linux/sched.h>
	22	#include "ctree.h"
	23	#include "disk-io.h"
	24	#include "transaction.h"
	25
	26	static int total_trans = 0;
	27	extern struct kmem_cache *btrfs_trans_handle_cachep;
	28	extern struct kmem_cache *btrfs_transaction_cachep;
	29
	30	static struct workqueue_struct *trans_wq;
	31
	32	#define BTRFS_ROOT_TRANS_TAG 0
	33
	34	static void put_transaction(struct btrfs_transaction *transaction)
	35	{
	36	WARN_ON(transaction->use_count == 0);
	37	transaction->use_count--;
	38	if (transaction->use_count == 0) {
	39	WARN_ON(total_trans == 0);
	40	total_trans--;
	41	list_del_init(&transaction->list);
	42	memset(transaction, 0, sizeof(*transaction));
	43	kmem_cache_free(btrfs_transaction_cachep, transaction);
	44	}
	45	}
	46
	47	static int join_transaction(struct btrfs_root *root)
	48	{
	49	struct btrfs_transaction *cur_trans;
	50	cur_trans = root->fs_info->running_transaction;
	51	if (!cur_trans) {
	52	cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
	53	GFP_NOFS);
	54	total_trans++;
	55	BUG_ON(!cur_trans);
	56	root->fs_info->generation++;
	57	root->fs_info->running_transaction = cur_trans;
	58	cur_trans->num_writers = 0;
	59	cur_trans->transid = root->fs_info->generation;
	60	init_waitqueue_head(&cur_trans->writer_wait);
	61	init_waitqueue_head(&cur_trans->commit_wait);
	62	cur_trans->in_commit = 0;
	63	cur_trans->use_count = 1;
	64	cur_trans->commit_done = 0;
	65	cur_trans->start_time = get_seconds();
	66	list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
	67	init_bit_radix(&cur_trans->dirty_pages);
	68	}
	69	cur_trans->num_writers++;
	70	return 0;
	71	}
	72
	73	struct btrfs_trans_handle btrfs_start_transaction(struct btrfs_root root,
	74	int num_blocks)
	75	{
	76	struct btrfs_trans_handle *h =
	77	kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
	78	int ret;
	79	u64 running_trans_id;
	80
	81	mutex_lock(&root->fs_info->trans_mutex);
	82	ret = join_transaction(root);
	83	BUG_ON(ret);
	84	running_trans_id = root->fs_info->running_transaction->transid;
	85
	86	if (root != root->fs_info->tree_root && root->last_trans <
	87	running_trans_id) {
	88	if (root->root_item.refs != 0) {
	89	radix_tree_tag_set(&root->fs_info->fs_roots_radix,
	90	(unsigned long)root->root_key.objectid,
	91	BTRFS_ROOT_TRANS_TAG);
	92	root->commit_root = root->node;
	93	get_bh(root->node);
	94	} else {
	95	WARN_ON(1);
	96	}
	97	}
	98	root->last_trans = running_trans_id;
	99	h->transid = running_trans_id;
	100	h->transaction = root->fs_info->running_transaction;
	101	h->blocks_reserved = num_blocks;
	102	h->blocks_used = 0;
	103	h->block_group = NULL;
	104	root->fs_info->running_transaction->use_count++;
	105	mutex_unlock(&root->fs_info->trans_mutex);
	106	return h;
	107	}
	108
	109	int btrfs_end_transaction(struct btrfs_trans_handle *trans,
	110	struct btrfs_root *root)
	111	{
	112	struct btrfs_transaction *cur_trans;
	113
	114	mutex_lock(&root->fs_info->trans_mutex);
	115	cur_trans = root->fs_info->running_transaction;
	116	WARN_ON(cur_trans->num_writers < 1);
	117	if (waitqueue_active(&cur_trans->writer_wait))
	118	wake_up(&cur_trans->writer_wait);
	119	cur_trans->num_writers--;
	120	put_transaction(cur_trans);
	121	mutex_unlock(&root->fs_info->trans_mutex);
	122	memset(trans, 0, sizeof(*trans));
	123	kmem_cache_free(btrfs_trans_handle_cachep, trans);
	124	return 0;
	125	}
	126
	127
	128	int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
	129	struct btrfs_root *root)
	130	{
	131	unsigned long gang[16];
	132	int ret;
	133	int i;
	134	int err;
	135	int werr = 0;
	136	struct page *page;
	137	struct radix_tree_root *dirty_pages;
	138	struct inode *btree_inode = root->fs_info->btree_inode;
	139
	140	if (!trans \|\| !trans->transaction) {
	141	return filemap_write_and_wait(btree_inode->i_mapping);
	142	}
	143	dirty_pages = &trans->transaction->dirty_pages;
	144	while(1) {
	145	ret = find_first_radix_bit(dirty_pages, gang,
	146	0, ARRAY_SIZE(gang));
	147	if (!ret)
	148	break;
	149	for (i = 0; i < ret; i++) {
	150	/* FIXME EIO */
	151	clear_radix_bit(dirty_pages, gang[i]);
	152	page = find_lock_page(btree_inode->i_mapping,
	153	gang[i]);
	154	if (!page)
	155	continue;
	156	err = write_one_page(page, 0);
	157	if (err)
	158	werr = err;
	159	page_cache_release(page);
	160	}
	161	}
	162	err = filemap_fdatawait(btree_inode->i_mapping);
	163	if (err)
	164	werr = err;
	165	return werr;
	166	}
	167
	168	int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
	169	struct btrfs_root *root)
	170	{
	171	int ret;
	172	u64 old_extent_block;
	173	struct btrfs_fs_info *fs_info = root->fs_info;
	174	struct btrfs_root *tree_root = fs_info->tree_root;
	175	struct btrfs_root *extent_root = fs_info->extent_root;
	176
	177	btrfs_write_dirty_block_groups(trans, extent_root);
	178	while(1) {
	179	old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
	180	if (old_extent_block == bh_blocknr(extent_root->node))
	181	break;
	182	btrfs_set_root_blocknr(&extent_root->root_item,
	183	bh_blocknr(extent_root->node));
	184	ret = btrfs_update_root(trans, tree_root,
	185	&extent_root->root_key,
	186	&extent_root->root_item);
	187	BUG_ON(ret);
	188	btrfs_write_dirty_block_groups(trans, extent_root);
	189	}
	190	return 0;
	191	}
	192
	193	static int wait_for_commit(struct btrfs_root *root,
	194	struct btrfs_transaction *commit)
	195	{
	196	DEFINE_WAIT(wait);
	197	while(!commit->commit_done) {
	198	prepare_to_wait(&commit->commit_wait, &wait,
	199	TASK_UNINTERRUPTIBLE);
	200	if (commit->commit_done)
	201	break;
	202	mutex_unlock(&root->fs_info->trans_mutex);
	203	schedule();
	204	mutex_lock(&root->fs_info->trans_mutex);
	205	}
	206	finish_wait(&commit->commit_wait, &wait);
	207	return 0;
	208	}
	209
	210	struct dirty_root {
	211	struct list_head list;
	212	struct btrfs_key snap_key;
	213	struct buffer_head *commit_root;
	214	struct btrfs_root *root;
	215	int free_on_drop;
	216	};
	217
	218	int btrfs_add_dead_root(struct btrfs_root root, struct list_head dead_list)
	219	{
	220	struct dirty_root *dirty;
	221
	222	dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
	223	if (!dirty)
	224	return -ENOMEM;
	225	memcpy(&dirty->snap_key, &root->root_key, sizeof(root->root_key));
	226	dirty->commit_root = root->node;
	227	dirty->root = root;
	228	dirty->free_on_drop = 1;
	229	list_add(&dirty->list, dead_list);
	230	return 0;
	231	}
	232
	233	static int add_dirty_roots(struct btrfs_trans_handle *trans,
	234	struct radix_tree_root *radix,
	235	struct list_head *list)
	236	{
	237	struct dirty_root *dirty;
	238	struct btrfs_root *gang[8];
	239	struct btrfs_root *root;
	240	struct btrfs_root_item tmp_item;
	241	int i;
	242	int ret;
	243	int err = 0;
	244	u32 refs;
	245
	246	while(1) {
	247	ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
	248	ARRAY_SIZE(gang),
	249	BTRFS_ROOT_TRANS_TAG);
	250	if (ret == 0)
	251	break;
	252	for (i = 0; i < ret; i++) {
	253	root = gang[i];
	254	radix_tree_tag_clear(radix,
	255	(unsigned long)root->root_key.objectid,
	256	BTRFS_ROOT_TRANS_TAG);
	257	if (root->commit_root == root->node) {
	258	WARN_ON(bh_blocknr(root->node) !=
	259	btrfs_root_blocknr(&root->root_item));
	260	brelse(root->commit_root);
	261	root->commit_root = NULL;
	262	continue;
	263	}
	264	dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
	265	BUG_ON(!dirty);
	266	memcpy(&dirty->snap_key, &root->root_key,
	267	sizeof(root->root_key));
	268	dirty->commit_root = root->commit_root;
	269	root->commit_root = NULL;
	270	dirty->root = root;
	271	dirty->free_on_drop = 0;
	272	memcpy(&tmp_item, &root->root_item, sizeof(tmp_item));
	273
	274	root->root_key.offset = root->fs_info->generation;
	275	btrfs_set_root_blocknr(&root->root_item,
	276	bh_blocknr(root->node));
	277	err = btrfs_insert_root(trans, root->fs_info->tree_root,
	278	&root->root_key,
	279	&root->root_item);
	280	if (err)
	281	break;
	282
	283	refs = btrfs_root_refs(&tmp_item);
	284	btrfs_set_root_refs(&tmp_item, refs - 1);
	285	err = btrfs_update_root(trans, root->fs_info->tree_root,
	286	&dirty->snap_key,
	287	&tmp_item);
	288
	289	BUG_ON(err);
	290	if (refs == 1)
	291	list_add(&dirty->list, list);
	292	else
	293	kfree(dirty);
	294	}
	295	}
	296	return err;
	297	}
	298
	299	static int drop_dirty_roots(struct btrfs_root *tree_root,
	300	struct list_head *list)
	301	{
	302	struct dirty_root *dirty;
	303	struct btrfs_trans_handle *trans;
	304	int ret = 0;
	305	while(!list_empty(list)) {
	306	mutex_lock(&tree_root->fs_info->fs_mutex);
	307	dirty = list_entry(list->next, struct dirty_root, list);
	308	list_del_init(&dirty->list);
	309
	310	trans = btrfs_start_transaction(tree_root, 1);
	311	ret = btrfs_drop_snapshot(trans, dirty->root,
	312	dirty->commit_root);
	313	BUG_ON(ret);
	314	ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
	315	if (ret)
	316	break;
	317	ret = btrfs_end_transaction(trans, tree_root);
	318	BUG_ON(ret);
	319
	320	if (dirty->free_on_drop)
	321	kfree(dirty->root);
	322	kfree(dirty);
	323	mutex_unlock(&tree_root->fs_info->fs_mutex);
	324	btrfs_btree_balance_dirty(tree_root);
	325	}
	326	return ret;
	327	}
	328
	329	int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
	330	struct btrfs_root *root)
	331	{
	332	int ret = 0;
	333	struct btrfs_transaction *cur_trans;
	334	struct btrfs_transaction *prev_trans = NULL;
	335	struct list_head dirty_fs_roots;
	336	DEFINE_WAIT(wait);
	337
	338	INIT_LIST_HEAD(&dirty_fs_roots);
	339
	340	mutex_lock(&root->fs_info->trans_mutex);
	341	if (trans->transaction->in_commit) {
	342	cur_trans = trans->transaction;
	343	trans->transaction->use_count++;
	344	btrfs_end_transaction(trans, root);
	345	ret = wait_for_commit(root, cur_trans);
	346	BUG_ON(ret);
	347	put_transaction(cur_trans);
	348	mutex_unlock(&root->fs_info->trans_mutex);
	349	return 0;
	350	}
	351	cur_trans = trans->transaction;
	352	trans->transaction->in_commit = 1;
	353	while (trans->transaction->num_writers > 1) {
	354	WARN_ON(cur_trans != trans->transaction);
	355	prepare_to_wait(&trans->transaction->writer_wait, &wait,
	356	TASK_UNINTERRUPTIBLE);
	357	if (trans->transaction->num_writers <= 1)
	358	break;
	359	mutex_unlock(&root->fs_info->trans_mutex);
	360	schedule();
	361	mutex_lock(&root->fs_info->trans_mutex);
	362	finish_wait(&trans->transaction->writer_wait, &wait);
	363	}
	364	finish_wait(&trans->transaction->writer_wait, &wait);
	365	WARN_ON(cur_trans != trans->transaction);
	366	ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
	367	&dirty_fs_roots);
	368	BUG_ON(ret);
	369
	370	ret = btrfs_commit_tree_roots(trans, root);
	371	BUG_ON(ret);
	372
	373	cur_trans = root->fs_info->running_transaction;
	374	root->fs_info->running_transaction = NULL;
	375	if (cur_trans->list.prev != &root->fs_info->trans_list) {
	376	prev_trans = list_entry(cur_trans->list.prev,
	377	struct btrfs_transaction, list);
	378	if (prev_trans->commit_done)
	379	prev_trans = NULL;
	380	else
	381	prev_trans->use_count++;
	382	}
	383	mutex_unlock(&root->fs_info->trans_mutex);
	384	mutex_unlock(&root->fs_info->fs_mutex);
	385	ret = btrfs_write_and_wait_transaction(trans, root);
	386	if (prev_trans) {
	387	mutex_lock(&root->fs_info->trans_mutex);
	388	wait_for_commit(root, prev_trans);
	389	put_transaction(prev_trans);
	390	mutex_unlock(&root->fs_info->trans_mutex);
	391	}
	392	btrfs_set_super_generation(root->fs_info->disk_super,
	393	cur_trans->transid);
	394	BUG_ON(ret);
	395	write_ctree_super(trans, root);
	396
	397	mutex_lock(&root->fs_info->fs_mutex);
	398	btrfs_finish_extent_commit(trans, root);
	399	mutex_lock(&root->fs_info->trans_mutex);
	400	cur_trans->commit_done = 1;
	401	wake_up(&cur_trans->commit_wait);
	402	put_transaction(cur_trans);
	403	put_transaction(cur_trans);
	404	if (root->fs_info->closing)
	405	list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
	406	else
	407	list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
	408	mutex_unlock(&root->fs_info->trans_mutex);
	409	kmem_cache_free(btrfs_trans_handle_cachep, trans);
	410
	411	if (root->fs_info->closing) {
	412	mutex_unlock(&root->fs_info->fs_mutex);
	413	drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
	414	mutex_lock(&root->fs_info->fs_mutex);
	415	}
	416	return ret;
	417	}
	418
	419	void btrfs_transaction_cleaner(struct work_struct *work)
	420	{
	421	struct btrfs_fs_info *fs_info = container_of(work,
	422	struct btrfs_fs_info,
	423	trans_work.work);
	424
	425	struct btrfs_root *root = fs_info->tree_root;
	426	struct btrfs_transaction *cur;
	427	struct btrfs_trans_handle *trans;
	428	struct list_head dirty_roots;
	429	unsigned long now;
	430	unsigned long delay = HZ * 30;
	431	int ret;
	432
	433	INIT_LIST_HEAD(&dirty_roots);
	434	mutex_lock(&root->fs_info->fs_mutex);
	435	mutex_lock(&root->fs_info->trans_mutex);
	436	cur = root->fs_info->running_transaction;
	437	if (!cur) {
	438	mutex_unlock(&root->fs_info->trans_mutex);
	439	goto out;
	440	}
	441	now = get_seconds();
	442	if (now < cur->start_time \|\| now - cur->start_time < 30) {
	443	mutex_unlock(&root->fs_info->trans_mutex);
	444	delay = HZ * 5;
	445	goto out;
	446	}
	447	mutex_unlock(&root->fs_info->trans_mutex);
	448	trans = btrfs_start_transaction(root, 1);
	449	ret = btrfs_commit_transaction(trans, root);
	450	out:
	451	mutex_unlock(&root->fs_info->fs_mutex);
	452
	453	mutex_lock(&root->fs_info->trans_mutex);
	454	list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
	455	mutex_unlock(&root->fs_info->trans_mutex);
	456
	457	if (!list_empty(&dirty_roots)) {
	458	drop_dirty_roots(root, &dirty_roots);
	459	}
	460	btrfs_transaction_queue_work(root, delay);
	461	}
	462
	463	void btrfs_transaction_queue_work(struct btrfs_root *root, int delay)
	464	{
	465	queue_delayed_work(trans_wq, &root->fs_info->trans_work, delay);
	466	}
	467
	468	void btrfs_transaction_flush_work(struct btrfs_root *root)
	469	{
	470	cancel_rearming_delayed_workqueue(trans_wq, &root->fs_info->trans_work);
	471	flush_workqueue(trans_wq);
	472	}
	473
	474	void __init btrfs_init_transaction_sys(void)
	475	{
	476	trans_wq = create_workqueue("btrfs");
	477	}
	478
	479	void __exit btrfs_exit_transaction_sys(void)
	480	{
	481	destroy_workqueue(trans_wq);
	482	}
	483