diff options
Diffstat (limited to 'fs/btrfs/ref-cache.c')
| -rw-r--r-- | fs/btrfs/ref-cache.c | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/fs/btrfs/ref-cache.c b/fs/btrfs/ref-cache.c new file mode 100644 index 000000000000..95a9faeb9dc4 --- /dev/null +++ b/fs/btrfs/ref-cache.c @@ -0,0 +1,226 @@ +/* + * Copyright (C) 2008 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include <linux/sched.h> +#include "ctree.h" +#include "ref-cache.h" +#include "transaction.h" + +struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(int nr_extents) +{ + struct btrfs_leaf_ref *ref; + + ref = kmalloc(btrfs_leaf_ref_size(nr_extents), GFP_NOFS); + if (ref) { + memset(ref, 0, sizeof(*ref)); + atomic_set(&ref->usage, 1); + } + return ref; +} + +void btrfs_free_leaf_ref(struct btrfs_leaf_ref *ref) +{ + if (!ref) + return; + WARN_ON(atomic_read(&ref->usage) == 0); + if (atomic_dec_and_test(&ref->usage)) { + BUG_ON(ref->in_tree); + kfree(ref); + } +} + +static int comp_keys(struct btrfs_key *k1, struct btrfs_key *k2) +{ + if (k1->objectid > k2->objectid) + return 1; + if (k1->objectid < k2->objectid) + return -1; + if (k1->type > k2->type) + return 1; + if (k1->type < k2->type) + return -1; + if (k1->offset > k2->offset) + return 1; + if (k1->offset < k2->offset) + return -1; + return 0; +} + +static struct rb_node *tree_insert(struct rb_root *root, struct btrfs_key *key, + struct rb_node *node) +{ + struct rb_node ** p = &root->rb_node; + struct rb_node * parent = NULL; + struct btrfs_leaf_ref *entry; + int ret; + + while(*p) { + parent = *p; + entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node); + WARN_ON(!entry->in_tree); + + ret = comp_keys(key, &entry->key); + if (ret < 0) + p = &(*p)->rb_left; + else if (ret > 0) + p = &(*p)->rb_right; + else + return parent; + } + + entry = rb_entry(node, struct btrfs_leaf_ref, rb_node); + entry->in_tree = 1; + rb_link_node(node, parent, p); + rb_insert_color(node, root); + return NULL; +} + +static struct rb_node *tree_search(struct rb_root *root, struct btrfs_key *key) +{ + struct rb_node * n = root->rb_node; + struct btrfs_leaf_ref *entry; + int ret; + + while(n) { + entry = rb_entry(n, struct btrfs_leaf_ref, rb_node); + WARN_ON(!entry->in_tree); + + ret = comp_keys(key, &entry->key); + if (ret < 0) + n = n->rb_left; + else if (ret > 0) + n = n->rb_right; + else + return n; + } + return NULL; +} + +int btrfs_remove_leaf_refs(struct btrfs_root *root) +{ + struct rb_node *rb; + struct btrfs_leaf_ref *ref = NULL; + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + + if (!tree) + return 0; + + spin_lock(&tree->lock); + while(!btrfs_leaf_ref_tree_empty(tree)) { + tree->last = NULL; + rb = rb_first(&tree->root); + ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node); + rb_erase(&ref->rb_node, &tree->root); + ref->in_tree = 0; + + spin_unlock(&tree->lock); + + btrfs_free_leaf_ref(ref); + + cond_resched(); + spin_lock(&tree->lock); + } + spin_unlock(&tree->lock); + return 0; +} + +struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root, + struct btrfs_key *key) +{ + struct rb_node *rb; + struct btrfs_leaf_ref *ref = NULL; + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + + if (!tree) + return NULL; + + spin_lock(&tree->lock); + if (tree->last && comp_keys(key, &tree->last->key) == 0) { + ref = tree->last; + } else { + rb = tree_search(&tree->root, key); + if (rb) { + ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node); + tree->last = ref; + } + } + if (ref) + atomic_inc(&ref->usage); + spin_unlock(&tree->lock); + return ref; +} + +int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) +{ + int ret = 0; + struct rb_node *rb; + size_t size = btrfs_leaf_ref_size(ref->nritems); + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + struct btrfs_transaction *trans = root->fs_info->running_transaction; + + spin_lock(&tree->lock); + rb = tree_insert(&tree->root, &ref->key, &ref->rb_node); + if (rb) { + ret = -EEXIST; + } else { + spin_lock(&root->fs_info->ref_cache_lock); + root->fs_info->total_ref_cache_size += size; + if (trans && tree->generation == trans->transid) + root->fs_info->running_ref_cache_size += size; + spin_unlock(&root->fs_info->ref_cache_lock); + + tree->last = ref; + atomic_inc(&ref->usage); + } + spin_unlock(&tree->lock); + return ret; +} + +int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) +{ + size_t size = btrfs_leaf_ref_size(ref->nritems); + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + struct btrfs_transaction *trans = root->fs_info->running_transaction; + + BUG_ON(!ref->in_tree); + spin_lock(&tree->lock); + + spin_lock(&root->fs_info->ref_cache_lock); + root->fs_info->total_ref_cache_size -= size; + if (trans && tree->generation == trans->transid) + root->fs_info->running_ref_cache_size -= size; + spin_unlock(&root->fs_info->ref_cache_lock); + + if (tree->last == ref) { + struct rb_node *next = rb_next(&ref->rb_node); + if (next) { + tree->last = rb_entry(next, struct btrfs_leaf_ref, + rb_node); + } else + tree->last = NULL; + } + + rb_erase(&ref->rb_node, &tree->root); + ref->in_tree = 0; + + spin_unlock(&tree->lock); + + btrfs_free_leaf_ref(ref); + return 0; +} + |