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