git.oblomov.eu Git - linux-2.6/blob - 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         }
  33         return ref;
  34 }
  35
  36 void btrfs_free_leaf_ref(struct btrfs_leaf_ref *ref)
  37 {
  38         if (!ref)
  39                 return;
  40         WARN_ON(atomic_read(&ref->usage) == 0);
  41         if (atomic_dec_and_test(&ref->usage)) {
  42                 BUG_ON(ref->in_tree);
  43                 kfree(ref);
  44         }
  45 }
  46
  47 static int comp_keys(struct btrfs_key *k1, struct btrfs_key *k2)
  48 {
  49         if (k1->objectid > k2->objectid)
  50                 return 1;
  51         if (k1->objectid < k2->objectid)
  52                 return -1;
  53         if (k1->type > k2->type)
  54                 return 1;
  55         if (k1->type < k2->type)
  56                 return -1;
  57         if (k1->offset > k2->offset)
  58                 return 1;
  59         if (k1->offset < k2->offset)
  60                 return -1;
  61         return 0;
  62 }
  63
  64 static struct rb_node *tree_insert(struct rb_root *root, struct btrfs_key *key,
  65                                    struct rb_node *node)
  66 {
  67         struct rb_node ** p = &root->rb_node;
  68         struct rb_node * parent = NULL;
  69         struct btrfs_leaf_ref *entry;
  70         int ret;
  71
  72         while(*p) {
  73                 parent = *p;
  74                 entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node);
  75                 WARN_ON(!entry->in_tree);
  76
  77                 ret = comp_keys(key, &entry->key);
  78                 if (ret < 0)
  79                         p = &(*p)->rb_left;
  80                 else if (ret > 0)
  81                         p = &(*p)->rb_right;
  82                 else
  83                         return parent;
  84         }
  85
  86         entry = rb_entry(node, struct btrfs_leaf_ref, rb_node);
  87         entry->in_tree = 1;
  88         rb_link_node(node, parent, p);
  89         rb_insert_color(node, root);
  90         return NULL;
  91 }
  92
  93 static struct rb_node *tree_search(struct rb_root *root, struct btrfs_key *key)
  94 {
  95         struct rb_node * n = root->rb_node;
  96         struct btrfs_leaf_ref *entry;
  97         int ret;
  98
  99         while(n) {
 100                 entry = rb_entry(n, struct btrfs_leaf_ref, rb_node);
 101                 WARN_ON(!entry->in_tree);
 102
 103                 ret = comp_keys(key, &entry->key);
 104                 if (ret < 0)
 105                         n = n->rb_left;
 106                 else if (ret > 0)
 107                         n = n->rb_right;
 108                 else
 109                         return n;
 110         }
 111         return NULL;
 112 }
 113
 114 int btrfs_remove_leaf_refs(struct btrfs_root *root)
 115 {
 116         struct rb_node *rb;
 117         struct btrfs_leaf_ref *ref = NULL;
 118         struct btrfs_leaf_ref_tree *tree = root->ref_tree;
 119
 120         if (!tree)
 121                 return 0;
 122
 123         spin_lock(&tree->lock);
 124         while(!btrfs_leaf_ref_tree_empty(tree)) {
 125                 tree->last = NULL;
 126                 rb = rb_first(&tree->root);
 127                 ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node);
 128                 rb_erase(&ref->rb_node, &tree->root);
 129                 ref->in_tree = 0;
 130
 131                 spin_unlock(&tree->lock);
 132
 133                 btrfs_free_leaf_ref(ref);
 134
 135                 cond_resched();
 136                 spin_lock(&tree->lock);
 137         }
 138         spin_unlock(&tree->lock);
 139         return 0;
 140 }
 141
 142 struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root,
 143                                              struct btrfs_key *key)
 144 {
 145         struct rb_node *rb;
 146         struct btrfs_leaf_ref *ref = NULL;
 147         struct btrfs_leaf_ref_tree *tree = root->ref_tree;
 148
 149         if (!tree)
 150                 return NULL;
 151
 152         spin_lock(&tree->lock);
 153         if (tree->last && comp_keys(key, &tree->last->key) == 0) {
 154                 ref = tree->last;
 155         } else {
 156                 rb = tree_search(&tree->root, key);
 157                 if (rb) {
 158                         ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node);
 159                         tree->last = ref;
 160                 }
 161         }
 162         if (ref)
 163                 atomic_inc(&ref->usage);
 164         spin_unlock(&tree->lock);
 165         return ref;
 166 }
 167
 168 int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
 169 {
 170         int ret = 0;
 171         struct rb_node *rb;
 172         size_t size = btrfs_leaf_ref_size(ref->nritems);
 173         struct btrfs_leaf_ref_tree *tree = root->ref_tree;
 174         struct btrfs_transaction *trans = root->fs_info->running_transaction;
 175
 176         spin_lock(&tree->lock);
 177         rb = tree_insert(&tree->root, &ref->key, &ref->rb_node);
 178         if (rb) {
 179                 ret = -EEXIST;
 180         } else {
 181                 spin_lock(&root->fs_info->ref_cache_lock);
 182                 root->fs_info->total_ref_cache_size += size;
 183                 if (trans && tree->generation == trans->transid)
 184                         root->fs_info->running_ref_cache_size += size;
 185                 spin_unlock(&root->fs_info->ref_cache_lock);
 186
 187                 tree->last = ref;
 188                 atomic_inc(&ref->usage);
 189         }
 190         spin_unlock(&tree->lock);
 191         return ret;
 192 }
 193
 194 int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
 195 {
 196         size_t size = btrfs_leaf_ref_size(ref->nritems);
 197         struct btrfs_leaf_ref_tree *tree = root->ref_tree;
 198         struct btrfs_transaction *trans = root->fs_info->running_transaction;
 199
 200         BUG_ON(!ref->in_tree);
 201         spin_lock(&tree->lock);
 202
 203         spin_lock(&root->fs_info->ref_cache_lock);
 204         root->fs_info->total_ref_cache_size -= size;
 205         if (trans && tree->generation == trans->transid)
 206                 root->fs_info->running_ref_cache_size -= size;
 207         spin_unlock(&root->fs_info->ref_cache_lock);
 208
 209         if (tree->last == ref) {
 210                 struct rb_node *next = rb_next(&ref->rb_node);
 211                 if (next) {
 212                         tree->last = rb_entry(next, struct btrfs_leaf_ref,
 213                                               rb_node);
 214                 } else
 215                         tree->last = NULL;
 216         }
 217
 218         rb_erase(&ref->rb_node, &tree->root);
 219         ref->in_tree = 0;
 220
 221         spin_unlock(&tree->lock);
 222
 223         btrfs_free_leaf_ref(ref);
 224         return 0;
 225 }
 226