Commit 9cf6b84b authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS 



Incorrectly handled transaction restarts can be a source of heisenbugs;
add a mode where we randomly inject them to shake them out.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 9f734cd0

fs/bcachefs/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -61,6 +61,13 @@ config BCACHEFS_DEBUG 
	The resulting code will be significantly slower than normal; you

	probably shouldn't select this option unless you're a developer.



config BCACHEFS_INJECT_TRANSACTION_RESTARTS

	bool "Randomly inject transaction restarts"

	depends on BCACHEFS_DEBUG

	help

	Randomly inject transaction restarts in a few core paths - may have a

	significant performance penalty



config BCACHEFS_TESTS

	bool "bcachefs unit and performance tests"

	depends on BCACHEFS_FS

fs/bcachefs/btree_iter.c

+32 −1
Original line number Diff line number Diff line
@@ -2357,6 +2357,12 @@ struct bkey_s_c bch2_btree_iter_peek_max(struct btree_iter *iter, struct bpos en 
	bch2_btree_iter_verify_entry_exit(iter);

	EBUG_ON((iter->flags & BTREE_ITER_filter_snapshots) && bkey_eq(end, POS_MAX));



	ret = trans_maybe_inject_restart(trans, _RET_IP_);

	if (unlikely(ret)) {

		k = bkey_s_c_err(ret);

		goto out_no_locked;

	}



	if (iter->update_path) {

		bch2_path_put_nokeep(trans, iter->update_path,

				     iter->flags & BTREE_ITER_intent);
@@ -2622,6 +2628,12 @@ struct bkey_s_c bch2_btree_iter_peek_prev_min(struct btree_iter *iter, struct bp 
	bch2_btree_iter_verify_entry_exit(iter);

	EBUG_ON((iter->flags & BTREE_ITER_filter_snapshots) && bpos_eq(end, POS_MIN));



	int ret = trans_maybe_inject_restart(trans, _RET_IP_);

	if (unlikely(ret)) {

		k = bkey_s_c_err(ret);

		goto out_no_locked;

	}



	while (1) {

		k = __bch2_btree_iter_peek_prev(iter, search_key);

		if (unlikely(!k.k))
@@ -2749,6 +2761,12 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter) 
	bch2_btree_iter_verify_entry_exit(iter);

	EBUG_ON(btree_iter_path(trans, iter)->level && (iter->flags & BTREE_ITER_with_key_cache));



	ret = trans_maybe_inject_restart(trans, _RET_IP_);

	if (unlikely(ret)) {

		k = bkey_s_c_err(ret);

		goto out_no_locked;

	}



	/* extents can't span inode numbers: */

	if ((iter->flags & BTREE_ITER_is_extents) &&

	    unlikely(iter->pos.offset == KEY_OFFSET_MAX)) {
@@ -3106,6 +3124,10 @@ void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size) 


	WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);



	ret = trans_maybe_inject_restart(trans, _RET_IP_);

	if (ret)

		return ERR_PTR(ret);



	struct btree_transaction_stats *s = btree_trans_stats(trans);

	s->max_mem = max(s->max_mem, new_bytes);
@@ -3163,7 +3185,8 @@ void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size) 


	if (old_bytes) {

		trace_and_count(c, trans_restart_mem_realloced, trans, _RET_IP_, new_bytes);

		return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_mem_realloced));

		return ERR_PTR(btree_trans_restart_ip(trans,

					BCH_ERR_transaction_restart_mem_realloced, _RET_IP_));

	}

out_change_top:

	p = trans->mem + trans->mem_top;
@@ -3271,6 +3294,14 @@ u32 bch2_trans_begin(struct btree_trans *trans) 


	trans->last_begin_ip = _RET_IP_;



#ifdef CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS

	if (trans->restarted) {

		trans->restart_count_this_trans++;

	} else {

		trans->restart_count_this_trans = 0;

	}

#endif



	trans_set_locked(trans, false);



	if (trans->restarted) {

fs/bcachefs/btree_iter.h

+12 −0
Original line number Diff line number Diff line
@@ -355,6 +355,18 @@ static int btree_trans_restart(struct btree_trans *trans, int err) 
	return btree_trans_restart_ip(trans, err, _THIS_IP_);

}



static inline int trans_maybe_inject_restart(struct btree_trans *trans, unsigned long ip)

{

#ifdef CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS

	if (!(ktime_get_ns() & ~(~0ULL << min(63, (10 + trans->restart_count_this_trans))))) {

		trace_and_count(trans->c, trans_restart_injected, trans, ip);

		return btree_trans_restart_ip(trans,

					BCH_ERR_transaction_restart_fault_inject, ip);

	}

#endif

	return 0;

}



bool bch2_btree_node_upgrade(struct btree_trans *,

			     struct btree_path *, unsigned);

fs/bcachefs/btree_trans_commit.c

+4 −0
Original line number Diff line number Diff line
@@ -999,6 +999,10 @@ int __bch2_trans_commit(struct btree_trans *trans, unsigned flags) 


	bch2_trans_verify_not_unlocked_or_in_restart(trans);



	ret = trans_maybe_inject_restart(trans, _RET_IP_);

	if (unlikely(ret))

		goto out_reset;



	if (!trans->nr_updates &&

	    !trans->journal_entries_u64s)

		goto out_reset;

fs/bcachefs/btree_types.h

+3 −0
Original line number Diff line number Diff line
@@ -509,6 +509,9 @@ struct btree_trans { 
	bool			notrace_relock_fail:1;

	enum bch_errcode	restarted:16;

	u32			restart_count;

#ifdef CONFIG_BCACHEFS_INJECT_TRANSACTION_RESTARTS

	u32			restart_count_this_trans;

#endif



	u64			last_begin_time;

	unsigned long		last_begin_ip;