Btrfs: fix NULL pointer after aborting a transaction (f094ac32) · Commits · 戴 / test

While doing cleanup work on an aborted transaction, we've set the global running transaction pointer to NULL _before_ waiting all other transaction handles to finish, so others'd hit NULL pointer crash when referencing the global running transaction pointer. This first sets a hint to avoid new transaction handle joining, then waits other existing handles to abort or finish so that we can safely set the above global pointer to NULL. Signed-off-by:

Liu Bo <bo.li.liu@oracle.com> Signed-off-by:

Josef Bacik <jbacik@fusionio.com>

fs/btrfs/transaction.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -1447,6 +1447,7 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans,
		struct btrfs_root *root, int err)
		{
		struct btrfs_transaction *cur_trans = trans->transaction;
		DEFINE_WAIT(wait);

		WARN_ON(trans->use_count > 1);

		@@ -1455,8 +1456,13 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans,
		spin_lock(&root->fs_info->trans_lock);
		list_del_init(&cur_trans->list);
		if (cur_trans == root->fs_info->running_transaction) {
		root->fs_info->trans_no_join = 1;
		spin_unlock(&root->fs_info->trans_lock);
		wait_event(cur_trans->writer_wait,
		atomic_read(&cur_trans->num_writers) == 1);

		spin_lock(&root->fs_info->trans_lock);
		root->fs_info->running_transaction = NULL;
		root->fs_info->trans_no_join = 0;
		}
		spin_unlock(&root->fs_info->trans_lock);

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