Merge commit 'v2.6.29-rc1' into perfcounters/core

Conflicts:
	include/linux/kernel_stat.h

1 files changed, 230 insertions, 0 deletions

diff --git a/fs/btrfs/ref-cache.c b/fs/btrfs/ref-cache.c
new file mode 100644
index 000000000000..6f0acc4c9eab
--- /dev/null
+++ b/fs/btrfs/ref-cache.c
@@ -0,0 +1,230 @@
+/*
+ * 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"
+
+/*
+ * 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(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;
+}
+
+/*
+ * 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 btrfs_leaf_ref *entry;
+
+        while (*p) {
+                parent = *p;
+                entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node);
+
+                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);
+        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,
+                           int shared)
+{
+        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 (!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);
+                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;
+}
+
+/*
+ * 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;
+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;
+}
+
+/*
+ * 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;
+        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 {
+                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)
+{
+        struct btrfs_leaf_ref_tree *tree;
+
+        if (!xchg(&ref->in_tree, 0))
+                return 0;
+
+        tree = ref->tree;
+        spin_lock(&tree->lock);
+
+        rb_erase(&ref->rb_node, &tree->root);
+        list_del_init(&ref->list);
+
+        spin_unlock(&tree->lock);
+
+        btrfs_free_leaf_ref(root, ref);
+        return 0;
+}