+ return eb;
+}
+
+static void add_root_to_dirty_list(struct btrfs_root *root)
+{
+ if (root->track_dirty && list_empty(&root->dirty_list)) {
+ list_add(&root->dirty_list,
+ &root->fs_info->dirty_cowonly_roots);
+ }
+}
+
+int btrfs_copy_root(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct extent_buffer *buf,
+ struct extent_buffer **cow_ret, u64 new_root_objectid)
+{
+ struct extent_buffer *cow;
+ u32 nritems;
+ int ret = 0;
+ int level;
+ struct btrfs_key first_key;
+ struct btrfs_root *new_root;
+
+ new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
+ if (!new_root)
+ return -ENOMEM;
+
+ memcpy(new_root, root, sizeof(*new_root));
+ new_root->root_key.objectid = new_root_objectid;
+
+ WARN_ON(root->ref_cows && trans->transid !=
+ root->fs_info->running_transaction->transid);
+ WARN_ON(root->ref_cows && trans->transid != root->last_trans);
+
+ level = btrfs_header_level(buf);
+ nritems = btrfs_header_nritems(buf);
+ if (nritems) {
+ if (level == 0)
+ btrfs_item_key_to_cpu(buf, &first_key, 0);
+ else
+ btrfs_node_key_to_cpu(buf, &first_key, 0);
+ } else {
+ first_key.objectid = 0;
+ }
+ cow = btrfs_alloc_free_block(trans, new_root, buf->len,
+ new_root_objectid,
+ trans->transid, first_key.objectid,
+ level, buf->start, 0);
+ if (IS_ERR(cow)) {
+ kfree(new_root);
+ return PTR_ERR(cow);
+ }
+
+ copy_extent_buffer(cow, buf, 0, 0, cow->len);
+ btrfs_set_header_bytenr(cow, cow->start);
+ btrfs_set_header_generation(cow, trans->transid);
+ btrfs_set_header_owner(cow, new_root_objectid);
+ btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
+
+ WARN_ON(btrfs_header_generation(buf) > trans->transid);
+ ret = btrfs_inc_ref(trans, new_root, buf);
+ kfree(new_root);
+
+ if (ret)
+ return ret;
+
+ btrfs_mark_buffer_dirty(cow);
+ *cow_ret = cow;
+ return 0;
+}
+
+int __btrfs_cow_block(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct extent_buffer *buf,
+ struct extent_buffer *parent, int parent_slot,
+ struct extent_buffer **cow_ret,
+ u64 search_start, u64 empty_size)
+{
+ u64 root_gen;
+ struct extent_buffer *cow;
+ u32 nritems;
+ int ret = 0;
+ int different_trans = 0;
+ int level;
+ int unlock_orig = 0;
+ struct btrfs_key first_key;
+
+ if (*cow_ret == buf)
+ unlock_orig = 1;
+
+ WARN_ON(!btrfs_tree_locked(buf));
+
+ if (root->ref_cows) {
+ root_gen = trans->transid;
+ } else {
+ root_gen = 0;
+ }
+ WARN_ON(root->ref_cows && trans->transid !=
+ root->fs_info->running_transaction->transid);
+ WARN_ON(root->ref_cows && trans->transid != root->last_trans);
+
+ level = btrfs_header_level(buf);
+ nritems = btrfs_header_nritems(buf);
+ if (nritems) {
+ if (level == 0)
+ btrfs_item_key_to_cpu(buf, &first_key, 0);
+ else
+ btrfs_node_key_to_cpu(buf, &first_key, 0);
+ } else {
+ first_key.objectid = 0;
+ }
+ cow = btrfs_alloc_free_block(trans, root, buf->len,
+ root->root_key.objectid,
+ root_gen, first_key.objectid, level,
+ search_start, empty_size);
+ if (IS_ERR(cow))
+ return PTR_ERR(cow);
+
+ copy_extent_buffer(cow, buf, 0, 0, cow->len);
+ btrfs_set_header_bytenr(cow, cow->start);
+ btrfs_set_header_generation(cow, trans->transid);
+ btrfs_set_header_owner(cow, root->root_key.objectid);
+ btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
+
+ WARN_ON(btrfs_header_generation(buf) > trans->transid);
+ if (btrfs_header_generation(buf) != trans->transid) {
+ different_trans = 1;
+ ret = btrfs_inc_ref(trans, root, buf);
+ if (ret)
+ return ret;
+ } else {
+ clean_tree_block(trans, root, buf);
+ }
+
+ if (buf == root->node) {
+ WARN_ON(parent && parent != buf);
+ root_gen = btrfs_header_generation(buf);
+
+ spin_lock(&root->node_lock);
+ root->node = cow;
+ extent_buffer_get(cow);
+ spin_unlock(&root->node_lock);
+
+ if (buf != root->commit_root) {
+ btrfs_free_extent(trans, root, buf->start,
+ buf->len, root->root_key.objectid,
+ root_gen, 0, 0, 1);
+ }
+ free_extent_buffer(buf);
+ add_root_to_dirty_list(root);
+ } else {
+ root_gen = btrfs_header_generation(parent);
+ btrfs_set_node_blockptr(parent, parent_slot,
+ cow->start);
+ WARN_ON(trans->transid == 0);
+ btrfs_set_node_ptr_generation(parent, parent_slot,
+ trans->transid);
+ btrfs_mark_buffer_dirty(parent);
+ WARN_ON(btrfs_header_generation(parent) != trans->transid);
+ btrfs_free_extent(trans, root, buf->start, buf->len,
+ btrfs_header_owner(parent), root_gen,
+ 0, 0, 1);
+ }
+ if (unlock_orig)
+ btrfs_tree_unlock(buf);
+ free_extent_buffer(buf);
+ btrfs_mark_buffer_dirty(cow);
+ *cow_ret = cow;
+ return 0;