fs/btrfs/ref-cache.c

   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
  24 struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root,
  25                                             int nr_extents)
  26 {
  27         struct btrfs_leaf_ref *ref;
  28         size_t size = btrfs_leaf_ref_size(nr_extents);
  29
  30         ref = kmalloc(size, GFP_NOFS);
  31         if (ref) {
  32                 spin_lock(&root->fs_info->ref_cache_lock);
  33                 root->fs_info->total_ref_cache_size += size;
  34                 spin_unlock(&root->fs_info->ref_cache_lock);
  35
  36                 memset(ref, 0, sizeof(*ref));
  37                 atomic_set(&ref->usage, 1);
  38                 INIT_LIST_HEAD(&ref->list);
  39         }
  40         return ref;
  41 }
  42
  43 void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
  44 {
  45         if (!ref)
  46                 return;
  47         WARN_ON(atomic_read(&ref->usage) == 0);
  48         if (atomic_dec_and_test(&ref->usage)) {
  49                 size_t size = btrfs_leaf_ref_size(ref->nritems);
  50
  51                 BUG_ON(ref->in_tree);
  52                 kfree(ref);
  53
  54                 spin_lock(&root->fs_info->ref_cache_lock);
  55                 root->fs_info->total_ref_cache_size -= size;
  56                 spin_unlock(&root->fs_info->ref_cache_lock);
  57         }
  58 }
  59
  60 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
  61                                    struct rb_node *node)
  62 {
  63         struct rb_node ** p = &root->rb_node;
  64         struct rb_node * parent = NULL;
  65         struct btrfs_leaf_ref *entry;
  66
  67         while(*p) {
  68                 parent = *p;
  69                 entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node);
  70                 WARN_ON(!entry->in_tree);
  71
  72                 if (bytenr < entry->bytenr)
  73                         p = &(*p)->rb_left;
  74                 else if (bytenr > entry->bytenr)
  75                         p = &(*p)->rb_right;
  76                 else
  77                         return parent;
  78         }
  79
  80         entry = rb_entry(node, struct btrfs_leaf_ref, rb_node);
  81         entry->in_tree = 1;
  82         rb_link_node(node, parent, p);
  83         rb_insert_color(node, root);
  84         return NULL;
  85 }
  86
  87 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
  88 {
  89         struct rb_node * n = root->rb_node;
  90         struct btrfs_leaf_ref *entry;
  91
  92         while(n) {
  93                 entry = rb_entry(n, struct btrfs_leaf_ref, rb_node);
  94                 WARN_ON(!entry->in_tree);
  95
  96                 if (bytenr < entry->bytenr)
  97                         n = n->rb_left;
  98                 else if (bytenr > entry->bytenr)
  99                         n = n->rb_right;
 100                 else
 101                         return n;
 102         }
 103         return NULL;
 104 }
 105
 106 int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen)
 107 {
 108         struct btrfs_leaf_ref *ref = NULL;
 109         struct btrfs_leaf_ref_tree *tree = root->ref_tree;
 110
 111         if (!tree)
 112                 return 0;
 113
 114         spin_lock(&tree->lock);
 115         while(!list_empty(&tree->list)) {
 116                 ref = list_entry(tree->list.next, struct btrfs_leaf_ref, list);
 117                 BUG_ON(!ref->in_tree);
 118                 if (ref->root_gen > max_root_gen)
 119                         break;
 120
 121                 rb_erase(&ref->rb_node, &tree->root);
 122                 ref->in_tree = 0;
 123                 list_del_init(&ref->list);
 124
 125                 spin_unlock(&tree->lock);
 126                 btrfs_free_leaf_ref(root, ref);
 127                 cond_resched();
 128                 spin_lock(&tree->lock);
 129         }
 130         spin_unlock(&tree->lock);
 131         return 0;
 132 }
 133
 134 struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root,
 135                                              u64 bytenr)
 136 {
 137         struct rb_node *rb;
 138         struct btrfs_leaf_ref *ref = NULL;
 139         struct btrfs_leaf_ref_tree *tree = root->ref_tree;
 140
 141         if (!tree)
 142                 return NULL;
 143
 144         spin_lock(&tree->lock);
 145         rb = tree_search(&tree->root, bytenr);
 146         if (rb)
 147                 ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node);
 148         if (ref)
 149                 atomic_inc(&ref->usage);
 150         spin_unlock(&tree->lock);
 151         return ref;
 152 }
 153
 154 int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
 155 {
 156         int ret = 0;
 157         struct rb_node *rb;
 158         struct btrfs_leaf_ref_tree *tree = root->ref_tree;
 159
 160         spin_lock(&tree->lock);
 161         rb = tree_insert(&tree->root, ref->bytenr, &ref->rb_node);
 162         if (rb) {
 163                 ret = -EEXIST;
 164         } else {
 165                 atomic_inc(&ref->usage);
 166                 list_add_tail(&ref->list, &tree->list);
 167         }
 168         spin_unlock(&tree->lock);
 169         return ret;
 170 }
 171
 172 int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
 173 {
 174         struct btrfs_leaf_ref_tree *tree = root->ref_tree;
 175
 176         BUG_ON(!ref->in_tree);
 177         spin_lock(&tree->lock);
 178
 179         rb_erase(&ref->rb_node, &tree->root);
 180         ref->in_tree = 0;
 181         list_del_init(&ref->list);
 182
 183         spin_unlock(&tree->lock);
 184
 185         btrfs_free_leaf_ref(root, ref);
 186         return 0;
 187 }