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/sched.h>
20#include "ctree.h"
21#include "disk-io.h"
22#include "print-tree.h"
23#include "transaction.h"
24#include "locking.h"
25
26/*
27 * Defrag all the leaves in a given btree.
28 * Read all the leaves and try to get key order to
29 * better reflect disk order
30 */
31
32int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
33			struct btrfs_root *root)
34{
35	struct btrfs_path *path = NULL;
36	struct btrfs_key key;
37	int ret = 0;
38	int wret;
39	int level;
40	int next_key_ret = 0;
41	u64 last_ret = 0;
42	u64 min_trans = 0;
43
44	if (root->fs_info->extent_root == root) {
45		/*
46		 * there's recursion here right now in the tree locking,
47		 * we can't defrag the extent root without deadlock
48		 */
49		goto out;
50	}
51
52	if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
53		goto out;
54
55	path = btrfs_alloc_path();
56	if (!path)
57		return -ENOMEM;
58
59	level = btrfs_header_level(root->node);
60
61	if (level == 0)
62		goto out;
63
64	if (root->defrag_progress.objectid == 0) {
65		struct extent_buffer *root_node;
66		u32 nritems;
67
68		root_node = btrfs_lock_root_node(root);
69		btrfs_set_lock_blocking(root_node);
70		nritems = btrfs_header_nritems(root_node);
71		root->defrag_max.objectid = 0;
72		/* from above we know this is not a leaf */
73		btrfs_node_key_to_cpu(root_node, &root->defrag_max,
74				      nritems - 1);
75		btrfs_tree_unlock(root_node);
76		free_extent_buffer(root_node);
77		memset(&key, 0, sizeof(key));
78	} else {
79		memcpy(&key, &root->defrag_progress, sizeof(key));
80	}
81
82	path->keep_locks = 1;
83
84	ret = btrfs_search_forward(root, &key, path, min_trans);
85	if (ret < 0)
86		goto out;
87	if (ret > 0) {
88		ret = 0;
89		goto out;
90	}
91	btrfs_release_path(path);
92	wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
93
94	if (wret < 0) {
95		ret = wret;
96		goto out;
97	}
98	if (!path->nodes[1]) {
99		ret = 0;
100		goto out;
101	}
102	path->slots[1] = btrfs_header_nritems(path->nodes[1]);
103	next_key_ret = btrfs_find_next_key(root, path, &key, 1,
104					   min_trans);
105	ret = btrfs_realloc_node(trans, root,
106				 path->nodes[1], 0,
107				 &last_ret,
108				 &root->defrag_progress);
109	if (ret) {
110		WARN_ON(ret == -EAGAIN);
111		goto out;
112	}
113	if (next_key_ret == 0) {
114		memcpy(&root->defrag_progress, &key, sizeof(key));
115		ret = -EAGAIN;
116	}
117out:
118	btrfs_free_path(path);
119	if (ret == -EAGAIN) {
120		if (root->defrag_max.objectid > root->defrag_progress.objectid)
121			goto done;
122		if (root->defrag_max.type > root->defrag_progress.type)
123			goto done;
124		if (root->defrag_max.offset > root->defrag_progress.offset)
125			goto done;
126		ret = 0;
127	}
128done:
129	if (ret != -EAGAIN) {
130		memset(&root->defrag_progress, 0,
131		       sizeof(root->defrag_progress));
132		root->defrag_trans_start = trans->transid;
133	}
134	return ret;
135}
136