Commit a56da697 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Fix bch2_trans_put() 

reference: https://github.com/koverstreet/bcachefs/issues/692



trans->ref is the reference used by the cycle detector, which walks
btree_trans objects of other threads to walk the graph of held locks and
issue wakeups when an abort is required.

We have to wait for the ref to go to 1 before freeing trans->paths or
clearing trans->locking_wait.task.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 0a2a507d

fs/bcachefs/btree_iter.c

+8 −3
Original line number Diff line number Diff line
@@ -3161,6 +3161,7 @@ struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx) 
list_add_done:

	seqmutex_unlock(&c->btree_trans_lock);

got_trans:

	trans->ref.closure_get_happened = false;

	trans->c		= c;

	trans->last_begin_time	= local_clock();

	trans->fn_idx		= fn_idx;
@@ -3235,7 +3236,6 @@ void bch2_trans_put(struct btree_trans *trans) 
	trans_for_each_update(trans, i)

		__btree_path_put(trans->paths + i->path, true);

	trans->nr_updates	= 0;

	trans->locking_wait.task = NULL;



	check_btree_paths_leaked(trans);
@@ -3256,6 +3256,13 @@ void bch2_trans_put(struct btree_trans *trans) 
	if (unlikely(trans->journal_replay_not_finished))

		bch2_journal_keys_put(c);



	/*

	 * trans->ref protects trans->locking_wait.task, btree_paths arary; used

	 * by cycle detector

	 */

	closure_sync(&trans->ref);

	trans->locking_wait.task = NULL;



	unsigned long *paths_allocated = trans->paths_allocated;

	trans->paths_allocated	= NULL;

	trans->paths		= NULL;
@@ -3273,8 +3280,6 @@ void bch2_trans_put(struct btree_trans *trans) 
		trans = this_cpu_xchg(c->btree_trans_bufs->trans, trans);



	if (trans) {

		closure_sync(&trans->ref);



		seqmutex_lock(&c->btree_trans_lock);

		list_del(&trans->list);

		seqmutex_unlock(&c->btree_trans_lock);