Btrfs: drop WARN_ON from btrfs_add_leaf_ref
[linux-2.6] / fs / btrfs / tree-defrag.c
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 int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
27                         struct btrfs_root *root, int cache_only)
28 {
29         struct btrfs_path *path = NULL;
30         struct btrfs_key key;
31         int ret = 0;
32         int wret;
33         int level;
34         int orig_level;
35         int is_extent = 0;
36         int next_key_ret = 0;
37         u64 last_ret = 0;
38         u64 min_trans = 0;
39
40         if (cache_only)
41                 goto out;
42
43         if (root->fs_info->extent_root == root) {
44                 /*
45                  * there's recursion here right now in the tree locking,
46                  * we can't defrag the extent root without deadlock
47                  */
48                 goto out;
49         }
50
51         if (root->ref_cows == 0 && !is_extent)
52                 goto out;
53
54         if (btrfs_test_opt(root, SSD))
55                 goto out;
56
57         path = btrfs_alloc_path();
58         if (!path)
59                 return -ENOMEM;
60
61         level = btrfs_header_level(root->node);
62         orig_level = level;
63
64         if (level == 0) {
65                 goto out;
66         }
67         if (root->defrag_progress.objectid == 0) {
68                 struct extent_buffer *root_node;
69                 u32 nritems;
70
71                 root_node = btrfs_lock_root_node(root);
72                 nritems = btrfs_header_nritems(root_node);
73                 root->defrag_max.objectid = 0;
74                 /* from above we know this is not a leaf */
75                 btrfs_node_key_to_cpu(root_node, &root->defrag_max,
76                                       nritems - 1);
77                 btrfs_tree_unlock(root_node);
78                 free_extent_buffer(root_node);
79                 memset(&key, 0, sizeof(key));
80         } else {
81                 memcpy(&key, &root->defrag_progress, sizeof(key));
82         }
83
84         path->keep_locks = 1;
85         if (cache_only)
86                 min_trans = root->defrag_trans_start;
87
88         ret = btrfs_search_forward(root, &key, NULL, path,
89                                    cache_only, min_trans);
90         if (ret < 0)
91                 goto out;
92         if (ret > 0) {
93                 ret = 0;
94                 goto out;
95         }
96         btrfs_release_path(root, path);
97         wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
98
99         if (wret < 0) {
100                 ret = wret;
101                 goto out;
102         }
103         if (!path->nodes[1]) {
104                 ret = 0;
105                 goto out;
106         }
107         path->slots[1] = btrfs_header_nritems(path->nodes[1]);
108         next_key_ret = btrfs_find_next_key(root, path, &key, 1, cache_only,
109                                            min_trans);
110         ret = btrfs_realloc_node(trans, root,
111                                  path->nodes[1], 0,
112                                  cache_only, &last_ret,
113                                  &root->defrag_progress);
114         WARN_ON(ret && ret != -EAGAIN);
115         if (next_key_ret == 0) {
116                 memcpy(&root->defrag_progress, &key, sizeof(key));
117                 ret = -EAGAIN;
118         }
119
120         btrfs_release_path(root, path);
121         if (is_extent)
122                 btrfs_extent_post_op(trans, root);
123 out:
124         if (is_extent)
125                 mutex_unlock(&root->fs_info->alloc_mutex);
126
127         if (path)
128                 btrfs_free_path(path);
129         if (ret == -EAGAIN) {
130                 if (root->defrag_max.objectid > root->defrag_progress.objectid)
131                         goto done;
132                 if (root->defrag_max.type > root->defrag_progress.type)
133                         goto done;
134                 if (root->defrag_max.offset > root->defrag_progress.offset)
135                         goto done;
136                 ret = 0;
137         }
138 done:
139         if (ret != -EAGAIN) {
140                 memset(&root->defrag_progress, 0,
141                        sizeof(root->defrag_progress));
142                 root->defrag_trans_start = trans->transid;
143         }
144         return ret;
145 }