bcachefs: trans->locked

Add a field for tracking whether a transaction object holds btree locks,
and assertions to verify state.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -999,6 +999,7 @@ static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 
 	bch2_trans_unlock(trans);
 	cond_resched();
+	trans->locked = true;
 
 	if (unlikely(trans->memory_allocation_failure)) {
 		struct closure cl;
@@ -3023,7 +3024,8 @@ u32 bch2_trans_begin(struct btree_trans *trans)
 	if (!trans->restarted &&
 	    (need_resched() ||
 	     time_after64(now, trans->last_begin_time + BTREE_TRANS_MAX_LOCK_HOLD_TIME_NS))) {
-		drop_locks_do(trans, (cond_resched(), 0));
+		bch2_trans_unlock(trans);
+		cond_resched();
 		now = local_clock();
 	}
 	trans->last_begin_time = now;
@@ -3033,6 +3035,8 @@ u32 bch2_trans_begin(struct btree_trans *trans)
 		bch2_trans_srcu_unlock(trans);
 
 	trans->last_begin_ip = _RET_IP_;
+	trans->locked  = true;
+
 	if (trans->restarted) {
 		bch2_btree_path_traverse_all(trans);
 		trans->notrace_relock_fail = false;
@@ -3090,7 +3094,7 @@ struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx)
 			 */
 			BUG_ON(pos_task &&
 			       pid == pos_task->pid &&
-			       bch2_trans_locked(pos));
+			       pos->locked);
 
 			if (pos_task && pid < pos_task->pid) {
 				list_add_tail(&trans->list, &pos->list);
@@ -3106,6 +3110,7 @@ struct btree_trans *__bch2_trans_get(struct bch_fs *c, unsigned fn_idx)
 	trans->last_begin_time	= local_clock();
 	trans->fn_idx		= fn_idx;
 	trans->locking_wait.task = current;
+	trans->locked		= true;
 	trans->journal_replay_not_finished =
 		unlikely(!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags)) &&
 		atomic_inc_not_zero(&c->journal_keys.ref);

fs/bcachefs/btree_iter.h

@@ -286,7 +286,6 @@ int bch2_trans_relock(struct btree_trans *);
 int bch2_trans_relock_notrace(struct btree_trans *);
 void bch2_trans_unlock(struct btree_trans *);
 void bch2_trans_unlock_long(struct btree_trans *);
-bool bch2_trans_locked(struct btree_trans *);
 
 static inline int trans_was_restarted(struct btree_trans *trans, u32 restart_count)
 {

fs/bcachefs/btree_locking.c

@@ -490,8 +490,6 @@ static inline bool btree_path_get_locks(struct btree_trans *trans,
 	if (path->uptodate == BTREE_ITER_NEED_RELOCK)
 		path->uptodate = BTREE_ITER_UPTODATE;
 
-	bch2_trans_verify_locks(trans);
-
 	return path->uptodate < BTREE_ITER_NEED_RELOCK;
 }
 
@@ -607,7 +605,9 @@ bool bch2_btree_path_relock_norestart(struct btree_trans *trans, struct btree_pa
 {
 	struct get_locks_fail f;
 
-	return btree_path_get_locks(trans, path, false, &f);
+	bool ret = btree_path_get_locks(trans, path, false, &f);
+	bch2_trans_verify_locks(trans);
+	return ret;
 }
 
 int __bch2_btree_path_relock(struct btree_trans *trans,
@@ -630,7 +630,9 @@ bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *trans,
 
 	path->locks_want = new_locks_want;
 
-	return btree_path_get_locks(trans, path, true, f);
+	bool ret = btree_path_get_locks(trans, path, true, f);
+	bch2_trans_verify_locks(trans);
+	return ret;
 }
 
 bool __bch2_btree_path_upgrade(struct btree_trans *trans,
@@ -638,8 +640,9 @@ bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 			       unsigned new_locks_want,
 			       struct get_locks_fail *f)
 {
-	if (bch2_btree_path_upgrade_noupgrade_sibs(trans, path, new_locks_want, f))
-		return true;
+	bool ret = bch2_btree_path_upgrade_noupgrade_sibs(trans, path, new_locks_want, f);
+	if (ret)
+		goto out;
 
 	/*
 	 * XXX: this is ugly - we'd prefer to not be mucking with other
@@ -673,8 +676,9 @@ bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 				btree_path_get_locks(trans, linked, true, NULL);
 			}
 	}
-
-	return false;
+out:
+	bch2_trans_verify_locks(trans);
+	return ret;
 }
 
 void __bch2_btree_path_downgrade(struct btree_trans *trans,
@@ -774,6 +778,8 @@ static inline int __bch2_trans_relock(struct btree_trans *trans, bool trace)
 
 	if (unlikely(trans->restarted))
 		return -((int) trans->restarted);
+	if (unlikely(trans->locked))
+		goto out;
 
 	trans_for_each_path(trans, path, i) {
 		struct get_locks_fail f;
@@ -783,6 +789,8 @@ static inline int __bch2_trans_relock(struct btree_trans *trans, bool trace)
 			return bch2_trans_relock_fail(trans, path, &f, trace);
 	}
 
+	trans->locked = true;
+out:
 	bch2_trans_verify_locks(trans);
 	return 0;
 }
@@ -800,11 +808,17 @@ int bch2_trans_relock_notrace(struct btree_trans *trans)
 void bch2_trans_unlock_noassert(struct btree_trans *trans)
 {
 	__bch2_trans_unlock(trans);
+
+	trans->locked = false;
+	trans->last_unlock_ip = _RET_IP_;
 }
 
 void bch2_trans_unlock(struct btree_trans *trans)
 {
 	__bch2_trans_unlock(trans);
+
+	trans->locked = false;
+	trans->last_unlock_ip = _RET_IP_;
 }
 
 void bch2_trans_unlock_long(struct btree_trans *trans)
@@ -813,17 +827,6 @@ void bch2_trans_unlock_long(struct btree_trans *trans)
 	bch2_trans_srcu_unlock(trans);
 }
 
-bool bch2_trans_locked(struct btree_trans *trans)
-{
-	struct btree_path *path;
-	unsigned i;
-
-	trans_for_each_path(trans, path, i)
-		if (path->nodes_locked)
-			return true;
-	return false;
-}
-
 int __bch2_trans_mutex_lock(struct btree_trans *trans,
 			    struct mutex *lock)
 {
@@ -865,6 +868,17 @@ void bch2_btree_path_verify_locks(struct btree_path *path)
 	}
 }
 
+static bool bch2_trans_locked(struct btree_trans *trans)
+{
+	struct btree_path *path;
+	unsigned i;
+
+	trans_for_each_path(trans, path, i)
+		if (path->nodes_locked)
+			return true;
+	return false;
+}
+
 void bch2_trans_verify_locks(struct btree_trans *trans)
 {
 	struct btree_path *path;

fs/bcachefs/btree_types.h

@@ -469,6 +469,8 @@ struct btree_trans {
 	u8			lock_must_abort;
 	bool			lock_may_not_fail:1;
 	bool			srcu_held:1;
+	bool			locked:1;
+	bool			write_locked:1;
 	bool			used_mempool:1;
 	bool			in_traverse_all:1;
 	bool			paths_sorted:1;
@@ -476,13 +478,13 @@ struct btree_trans {
 	bool			journal_transaction_names:1;
 	bool			journal_replay_not_finished:1;
 	bool			notrace_relock_fail:1;
-	bool			write_locked:1;
 	enum bch_errcode	restarted:16;
 	u32			restart_count;
 
 	u64			last_begin_time;
 	unsigned long		last_begin_ip;
 	unsigned long		last_restarted_ip;
+	unsigned long		last_unlock_ip;
 	unsigned long		srcu_lock_time;
 
 	const char		*fn;