#include "ref-cache.h"
#include "transaction.h"
-struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(int nr_extents)
+/*
+ * leaf refs are used to cache the information about which extents
+ * a given leaf has references on. This allows us to process that leaf
+ * in btrfs_drop_snapshot without needing to read it back from disk.
+ */
+
+/*
+ * kmalloc a leaf reference struct and update the counters for the
+ * total ref cache size
+ */
+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(btrfs_leaf_ref_size(nr_extents), GFP_NOFS);
+ 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_leaf_ref *ref)
+/*
+ * free a leaf reference struct and update the counters for the
+ * total ref cache size
+ */
+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 rb_node **p = &root->rb_node;
+ struct rb_node *parent = NULL;
struct btrfs_leaf_ref *entry;
- while(*p) {
+ 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
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 rb_node *n = root->rb_node;
struct btrfs_leaf_ref *entry;
- while(n) {
+ while (n) {
entry = rb_entry(n, struct btrfs_leaf_ref, rb_node);
WARN_ON(!entry->in_tree);
return NULL;
}
-int btrfs_remove_leaf_refs(struct btrfs_root *root)
+int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen,
+ int shared)
{
- struct rb_node *rb;
struct btrfs_leaf_ref *ref = NULL;
struct btrfs_leaf_ref_tree *tree = root->ref_tree;
+ if (shared)
+ tree = &root->fs_info->shared_ref_tree;
if (!tree)
return 0;
spin_lock(&tree->lock);
- while(!btrfs_leaf_ref_tree_empty(tree)) {
- rb = rb_first(&tree->root);
- ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node);
+ while (!list_empty(&tree->list)) {
+ ref = list_entry(tree->list.next, struct btrfs_leaf_ref, list);
+ BUG_ON(ref->tree != tree);
+ if (ref->root_gen > max_root_gen)
+ break;
+ if (!xchg(&ref->in_tree, 0)) {
+ cond_resched_lock(&tree->lock);
+ continue;
+ }
+
rb_erase(&ref->rb_node, &tree->root);
- ref->in_tree = 0;
list_del_init(&ref->list);
spin_unlock(&tree->lock);
-
- btrfs_free_leaf_ref(ref);
-
+ btrfs_free_leaf_ref(root, ref);
cond_resched();
spin_lock(&tree->lock);
}
return 0;
}
+/*
+ * find the leaf ref for a given extent. This returns the ref struct with
+ * a usage reference incremented
+ */
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;
+again:
+ if (tree) {
+ 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);
+ if (ref)
+ return ref;
+ }
+ if (tree != &root->fs_info->shared_ref_tree) {
+ tree = &root->fs_info->shared_ref_tree;
+ goto again;
+ }
+ return NULL;
}
-int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
+/*
+ * add a fully filled in leaf ref struct
+ * remove all the refs older than a given root generation
+ */
+int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref,
+ int shared)
{
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;
+ if (shared)
+ tree = &root->fs_info->shared_ref_tree;
+
spin_lock(&tree->lock);
rb = tree_insert(&tree->root, ref->bytenr, &ref->rb_node);
if (rb) {
ret = -EEXIST;
} else {
- spin_lock(&root->fs_info->ref_cache_lock);
- root->fs_info->total_ref_cache_size += size;
- spin_unlock(&root->fs_info->ref_cache_lock);
atomic_inc(&ref->usage);
+ ref->tree = tree;
+ ref->in_tree = 1;
list_add_tail(&ref->list, &tree->list);
}
spin_unlock(&tree->lock);
return ret;
}
+/*
+ * remove a single leaf ref from the tree. This drops the ref held by the tree
+ * only
+ */
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_leaf_ref_tree *tree;
- BUG_ON(!ref->in_tree);
+ if (!xchg(&ref->in_tree, 0))
+ return 0;
+
+ tree = ref->tree;
spin_lock(&tree->lock);
-
- spin_lock(&root->fs_info->ref_cache_lock);
- root->fs_info->total_ref_cache_size -= size;
- spin_unlock(&root->fs_info->ref_cache_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(ref);
+ btrfs_free_leaf_ref(root, ref);
return 0;
}
-
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff