-#if 0
-/*
- * when dropping snapshots, we generate a ton of delayed refs, and it makes
- * sense not to join the transaction while it is trying to flush the current
- * queue of delayed refs out.
- *
- * This is used by the drop snapshot code only
- */
-static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
-{
- DEFINE_WAIT(wait);
-
- mutex_lock(&info->trans_mutex);
- while (info->running_transaction &&
- info->running_transaction->delayed_refs.flushing) {
- prepare_to_wait(&info->transaction_wait, &wait,
- TASK_UNINTERRUPTIBLE);
- mutex_unlock(&info->trans_mutex);
-
- schedule();
-
- mutex_lock(&info->trans_mutex);
- finish_wait(&info->transaction_wait, &wait);
- }
- mutex_unlock(&info->trans_mutex);
- return 0;
-}
-
-/*
- * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
- * all of them
- */
-int btrfs_drop_dead_root(struct btrfs_root *root)
-{
- struct btrfs_trans_handle *trans;
- struct btrfs_root *tree_root = root->fs_info->tree_root;
- unsigned long nr;
- int ret;
-
- while (1) {
- /*
- * we don't want to jump in and create a bunch of
- * delayed refs if the transaction is starting to close
- */
- wait_transaction_pre_flush(tree_root->fs_info);
- trans = btrfs_start_transaction(tree_root, 1);
-
- /*
- * we've joined a transaction, make sure it isn't
- * closing right now
- */
- if (trans->transaction->delayed_refs.flushing) {
- btrfs_end_transaction(trans, tree_root);
- continue;
- }
-
- ret = btrfs_drop_snapshot(trans, root);
- if (ret != -EAGAIN)
- break;
-
- ret = btrfs_update_root(trans, tree_root,
- &root->root_key,
- &root->root_item);
- if (ret)
- break;
-
- nr = trans->blocks_used;
- ret = btrfs_end_transaction(trans, tree_root);
- BUG_ON(ret);
-
- btrfs_btree_balance_dirty(tree_root, nr);
- cond_resched();
- }
- BUG_ON(ret);
-
- ret = btrfs_del_root(trans, tree_root, &root->root_key);
- BUG_ON(ret);
-
- nr = trans->blocks_used;
- ret = btrfs_end_transaction(trans, tree_root);
- BUG_ON(ret);
-
- free_extent_buffer(root->node);
- free_extent_buffer(root->commit_root);
- kfree(root);
-
- btrfs_btree_balance_dirty(tree_root, nr);
- return ret;
-}
-#endif
-