Commit | Line | Data |
---|---|---|
31153d81 YZ |
1 | /* |
2 | * Copyright (C) 2008 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 "ref-cache.h" | |
22 | #include "transaction.h" | |
23 | ||
d352ac68 CM |
24 | /* |
25 | * leaf refs are used to cache the information about which extents | |
26 | * a given leaf has references on. This allows us to process that leaf | |
27 | * in btrfs_drop_snapshot without needing to read it back from disk. | |
28 | */ | |
29 | ||
30 | /* | |
31 | * kmalloc a leaf reference struct and update the counters for the | |
32 | * total ref cache size | |
33 | */ | |
bcc63abb Y |
34 | struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root, |
35 | int nr_extents) | |
31153d81 YZ |
36 | { |
37 | struct btrfs_leaf_ref *ref; | |
bcc63abb | 38 | size_t size = btrfs_leaf_ref_size(nr_extents); |
31153d81 | 39 | |
bcc63abb | 40 | ref = kmalloc(size, GFP_NOFS); |
31153d81 | 41 | if (ref) { |
bcc63abb Y |
42 | spin_lock(&root->fs_info->ref_cache_lock); |
43 | root->fs_info->total_ref_cache_size += size; | |
44 | spin_unlock(&root->fs_info->ref_cache_lock); | |
45 | ||
31153d81 YZ |
46 | memset(ref, 0, sizeof(*ref)); |
47 | atomic_set(&ref->usage, 1); | |
017e5369 | 48 | INIT_LIST_HEAD(&ref->list); |
31153d81 YZ |
49 | } |
50 | return ref; | |
51 | } | |
52 | ||
d352ac68 CM |
53 | /* |
54 | * free a leaf reference struct and update the counters for the | |
55 | * total ref cache size | |
56 | */ | |
bcc63abb | 57 | void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) |
31153d81 YZ |
58 | { |
59 | if (!ref) | |
60 | return; | |
61 | WARN_ON(atomic_read(&ref->usage) == 0); | |
62 | if (atomic_dec_and_test(&ref->usage)) { | |
bcc63abb Y |
63 | size_t size = btrfs_leaf_ref_size(ref->nritems); |
64 | ||
31153d81 YZ |
65 | BUG_ON(ref->in_tree); |
66 | kfree(ref); | |
bcc63abb Y |
67 | |
68 | spin_lock(&root->fs_info->ref_cache_lock); | |
69 | root->fs_info->total_ref_cache_size -= size; | |
70 | spin_unlock(&root->fs_info->ref_cache_lock); | |
31153d81 YZ |
71 | } |
72 | } | |
73 | ||
017e5369 | 74 | static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr, |
31153d81 YZ |
75 | struct rb_node *node) |
76 | { | |
d397712b CM |
77 | struct rb_node **p = &root->rb_node; |
78 | struct rb_node *parent = NULL; | |
31153d81 | 79 | struct btrfs_leaf_ref *entry; |
31153d81 | 80 | |
d397712b | 81 | while (*p) { |
31153d81 YZ |
82 | parent = *p; |
83 | entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node); | |
31153d81 | 84 | |
017e5369 | 85 | if (bytenr < entry->bytenr) |
31153d81 | 86 | p = &(*p)->rb_left; |
017e5369 | 87 | else if (bytenr > entry->bytenr) |
31153d81 YZ |
88 | p = &(*p)->rb_right; |
89 | else | |
90 | return parent; | |
91 | } | |
bcc63abb | 92 | |
31153d81 | 93 | entry = rb_entry(node, struct btrfs_leaf_ref, rb_node); |
31153d81 YZ |
94 | rb_link_node(node, parent, p); |
95 | rb_insert_color(node, root); | |
96 | return NULL; | |
97 | } | |
98 | ||
017e5369 | 99 | static struct rb_node *tree_search(struct rb_root *root, u64 bytenr) |
31153d81 | 100 | { |
d397712b | 101 | struct rb_node *n = root->rb_node; |
31153d81 | 102 | struct btrfs_leaf_ref *entry; |
31153d81 | 103 | |
d397712b | 104 | while (n) { |
31153d81 YZ |
105 | entry = rb_entry(n, struct btrfs_leaf_ref, rb_node); |
106 | WARN_ON(!entry->in_tree); | |
107 | ||
017e5369 | 108 | if (bytenr < entry->bytenr) |
31153d81 | 109 | n = n->rb_left; |
017e5369 | 110 | else if (bytenr > entry->bytenr) |
31153d81 YZ |
111 | n = n->rb_right; |
112 | else | |
113 | return n; | |
114 | } | |
115 | return NULL; | |
116 | } | |
117 | ||
e4657689 ZY |
118 | int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen, |
119 | int shared) | |
31153d81 | 120 | { |
31153d81 YZ |
121 | struct btrfs_leaf_ref *ref = NULL; |
122 | struct btrfs_leaf_ref_tree *tree = root->ref_tree; | |
123 | ||
e4657689 ZY |
124 | if (shared) |
125 | tree = &root->fs_info->shared_ref_tree; | |
31153d81 YZ |
126 | if (!tree) |
127 | return 0; | |
128 | ||
129 | spin_lock(&tree->lock); | |
d397712b | 130 | while (!list_empty(&tree->list)) { |
bcc63abb | 131 | ref = list_entry(tree->list.next, struct btrfs_leaf_ref, list); |
e4657689 | 132 | BUG_ON(ref->tree != tree); |
bcc63abb Y |
133 | if (ref->root_gen > max_root_gen) |
134 | break; | |
e4657689 ZY |
135 | if (!xchg(&ref->in_tree, 0)) { |
136 | cond_resched_lock(&tree->lock); | |
137 | continue; | |
138 | } | |
bcc63abb | 139 | |
31153d81 | 140 | rb_erase(&ref->rb_node, &tree->root); |
017e5369 | 141 | list_del_init(&ref->list); |
31153d81 YZ |
142 | |
143 | spin_unlock(&tree->lock); | |
bcc63abb | 144 | btrfs_free_leaf_ref(root, ref); |
31153d81 YZ |
145 | cond_resched(); |
146 | spin_lock(&tree->lock); | |
147 | } | |
148 | spin_unlock(&tree->lock); | |
149 | return 0; | |
150 | } | |
151 | ||
d352ac68 CM |
152 | /* |
153 | * find the leaf ref for a given extent. This returns the ref struct with | |
154 | * a usage reference incremented | |
155 | */ | |
31153d81 | 156 | struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root, |
017e5369 | 157 | u64 bytenr) |
31153d81 YZ |
158 | { |
159 | struct rb_node *rb; | |
160 | struct btrfs_leaf_ref *ref = NULL; | |
161 | struct btrfs_leaf_ref_tree *tree = root->ref_tree; | |
e4657689 ZY |
162 | again: |
163 | if (tree) { | |
164 | spin_lock(&tree->lock); | |
165 | rb = tree_search(&tree->root, bytenr); | |
166 | if (rb) | |
167 | ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node); | |
168 | if (ref) | |
169 | atomic_inc(&ref->usage); | |
170 | spin_unlock(&tree->lock); | |
171 | if (ref) | |
172 | return ref; | |
173 | } | |
174 | if (tree != &root->fs_info->shared_ref_tree) { | |
175 | tree = &root->fs_info->shared_ref_tree; | |
176 | goto again; | |
177 | } | |
178 | return NULL; | |
31153d81 YZ |
179 | } |
180 | ||
d352ac68 CM |
181 | /* |
182 | * add a fully filled in leaf ref struct | |
183 | * remove all the refs older than a given root generation | |
184 | */ | |
e4657689 ZY |
185 | int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref, |
186 | int shared) | |
31153d81 YZ |
187 | { |
188 | int ret = 0; | |
189 | struct rb_node *rb; | |
31153d81 | 190 | struct btrfs_leaf_ref_tree *tree = root->ref_tree; |
31153d81 | 191 | |
e4657689 ZY |
192 | if (shared) |
193 | tree = &root->fs_info->shared_ref_tree; | |
194 | ||
31153d81 | 195 | spin_lock(&tree->lock); |
017e5369 | 196 | rb = tree_insert(&tree->root, ref->bytenr, &ref->rb_node); |
31153d81 YZ |
197 | if (rb) { |
198 | ret = -EEXIST; | |
199 | } else { | |
31153d81 | 200 | atomic_inc(&ref->usage); |
e4657689 ZY |
201 | ref->tree = tree; |
202 | ref->in_tree = 1; | |
017e5369 | 203 | list_add_tail(&ref->list, &tree->list); |
31153d81 YZ |
204 | } |
205 | spin_unlock(&tree->lock); | |
206 | return ret; | |
207 | } | |
208 | ||
d352ac68 CM |
209 | /* |
210 | * remove a single leaf ref from the tree. This drops the ref held by the tree | |
211 | * only | |
212 | */ | |
31153d81 YZ |
213 | int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) |
214 | { | |
e4657689 ZY |
215 | struct btrfs_leaf_ref_tree *tree; |
216 | ||
217 | if (!xchg(&ref->in_tree, 0)) | |
218 | return 0; | |
31153d81 | 219 | |
e4657689 | 220 | tree = ref->tree; |
31153d81 | 221 | spin_lock(&tree->lock); |
31153d81 | 222 | |
31153d81 | 223 | rb_erase(&ref->rb_node, &tree->root); |
017e5369 | 224 | list_del_init(&ref->list); |
31153d81 YZ |
225 | |
226 | spin_unlock(&tree->lock); | |
227 | ||
bcc63abb | 228 | btrfs_free_leaf_ref(root, ref); |
31153d81 YZ |
229 | return 0; |
230 | } |