diff options
Diffstat (limited to 'fs/btrfs/ref-cache.c')
| -rw-r--r-- | fs/btrfs/ref-cache.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/fs/btrfs/ref-cache.c b/fs/btrfs/ref-cache.c new file mode 100644 index 00000000000..272b9890c98 --- /dev/null +++ b/fs/btrfs/ref-cache.c @@ -0,0 +1,187 @@ +/* + * 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(struct btrfs_root *root, + int nr_extents) +{ + struct btrfs_leaf_ref *ref; + size_t size = btrfs_leaf_ref_size(nr_extents); + + ref = kmalloc(size, GFP_NOFS); + if (ref) { + spin_lock(&root->fs_info->ref_cache_lock); + root->fs_info->total_ref_cache_size += size; + spin_unlock(&root->fs_info->ref_cache_lock); + + memset(ref, 0, sizeof(*ref)); + atomic_set(&ref->usage, 1); + INIT_LIST_HEAD(&ref->list); + } + return ref; +} + +void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) +{ + if (!ref) + return; + WARN_ON(atomic_read(&ref->usage) == 0); + if (atomic_dec_and_test(&ref->usage)) { + size_t size = btrfs_leaf_ref_size(ref->nritems); + + BUG_ON(ref->in_tree); + kfree(ref); + + spin_lock(&root->fs_info->ref_cache_lock); + root->fs_info->total_ref_cache_size -= size; + spin_unlock(&root->fs_info->ref_cache_lock); + } +} + +static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr, + struct rb_node *node) +{ + struct rb_node ** p = &root->rb_node; + struct rb_node * parent = NULL; + struct btrfs_leaf_ref *entry; + + while(*p) { + parent = *p; + entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node); + WARN_ON(!entry->in_tree); + + if (bytenr < entry->bytenr) + p = &(*p)->rb_left; + else if (bytenr > entry->bytenr) + 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, u64 bytenr) +{ + struct rb_node * n = root->rb_node; + struct btrfs_leaf_ref *entry; + + while(n) { + entry = rb_entry(n, struct btrfs_leaf_ref, rb_node); + WARN_ON(!entry->in_tree); + + if (bytenr < entry->bytenr) + n = n->rb_left; + else if (bytenr > entry->bytenr) + n = n->rb_right; + else + return n; + } + return NULL; +} + +int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen) +{ + struct btrfs_leaf_ref *ref = NULL; + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + + if (!tree) + return 0; + + spin_lock(&tree->lock); + while(!list_empty(&tree->list)) { + ref = list_entry(tree->list.next, struct btrfs_leaf_ref, list); + BUG_ON(!ref->in_tree); + if (ref->root_gen > max_root_gen) + break; + + rb_erase(&ref->rb_node, &tree->root); + ref->in_tree = 0; + list_del_init(&ref->list); + + spin_unlock(&tree->lock); + btrfs_free_leaf_ref(root, 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, + u64 bytenr) +{ + 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); + rb = tree_search(&tree->root, bytenr); + if (rb) + ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node); + 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; + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + + spin_lock(&tree->lock); + rb = tree_insert(&tree->root, ref->bytenr, &ref->rb_node); + if (rb) { + ret = -EEXIST; + } else { + atomic_inc(&ref->usage); + list_add_tail(&ref->list, &tree->list); + } + spin_unlock(&tree->lock); + return ret; +} + +int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) +{ + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + + BUG_ON(!ref->in_tree); + spin_lock(&tree->lock); + + rb_erase(&ref->rb_node, &tree->root); + ref->in_tree = 0; + list_del_init(&ref->list); + + spin_unlock(&tree->lock); + + btrfs_free_leaf_ref(root, ref); + return 0; +} |