bcachefs: trans->restarted

Start tracking when btree transactions have been restarted - and assert
that we're always calling bch2_trans_begin() immediately after
transaction restart.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/btree_cache.c

@@ -655,8 +655,10 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c,
 	 * Parent node must be locked, else we could read in a btree node that's
 	 * been freed:
 	 */
-	if (iter && !bch2_btree_node_relock(iter, level + 1))
+	if (iter && !bch2_btree_node_relock(iter, level + 1)) {
+		btree_trans_restart(iter->trans);
 		return ERR_PTR(-EINTR);
+	}
 
 	b = bch2_btree_node_mem_alloc(c);
 	if (IS_ERR(b))
@@ -695,11 +697,15 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c,
 
 	if (iter &&
 	    (!bch2_trans_relock(iter->trans) ||
-	     !bch2_btree_iter_relock_intent(iter)))
+	     !bch2_btree_iter_relock_intent(iter))) {
+		BUG_ON(!iter->trans->restarted);
 		return ERR_PTR(-EINTR);
+	}
 
-	if (!six_relock_type(&b->c.lock, lock_type, seq))
+	if (!six_relock_type(&b->c.lock, lock_type, seq)) {
+		btree_trans_restart(iter->trans);
 		return ERR_PTR(-EINTR);
+	}
 
 	return b;
 }
@@ -824,7 +830,7 @@ struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_iter *
 
 		if (!btree_node_lock(b, k->k.p, level, iter, lock_type,
 				     lock_node_check_fn, (void *) k, trace_ip)) {
-			if (b->hash_val != btree_ptr_hash_val(k))
+			if (!trans->restarted)
 				goto retry;
 			return ERR_PTR(-EINTR);
 		}
@@ -840,6 +846,7 @@ struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_iter *
 							      trace_ip,
 							      iter->btree_id,
 							      &iter->real_pos);
+			btree_trans_restart(trans);
 			return ERR_PTR(-EINTR);
 		}
 	}
@@ -858,8 +865,10 @@ struct btree *bch2_btree_node_get(struct btree_trans *trans, struct btree_iter *
 		 */
 		if (iter &&
 		    (!bch2_trans_relock(trans) ||
-		     !bch2_btree_iter_relock_intent(iter)))
+		     !bch2_btree_iter_relock_intent(iter))) {
+			BUG_ON(!trans->restarted);
 			return ERR_PTR(-EINTR);
+		}
 
 		if (!six_relock_type(&b->c.lock, lock_type, seq))
 			goto retry;

fs/bcachefs/btree_gc.c

@@ -1735,7 +1735,8 @@ static int bch2_gc_btree_gens(struct bch_fs *c, enum btree_id btree_id)
 				   BTREE_ITER_NOT_EXTENTS|
 				   BTREE_ITER_ALL_SNAPSHOTS);
 
-	while ((k = bch2_btree_iter_peek(iter)).k &&
+	while ((bch2_trans_begin(&trans),
+		k = bch2_btree_iter_peek(iter)).k &&
 	       !(ret = bkey_err(k))) {
 		c->gc_gens_pos = iter->pos;
 

fs/bcachefs/btree_iter.c

@@ -316,7 +316,7 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos,
 	}
 
 	if (unlikely(deadlock_iter)) {
-		trace_trans_restart_would_deadlock(iter->trans->ip, ip,
+		trace_trans_restart_would_deadlock(trans->ip, ip,
 				trans->in_traverse_all, reason,
 				deadlock_iter->btree_id,
 				btree_iter_type(deadlock_iter),
@@ -324,6 +324,7 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos,
 				iter->btree_id,
 				btree_iter_type(iter),
 				&pos);
+		btree_trans_restart(trans);
 		return false;
 	}
 
@@ -404,6 +405,7 @@ bool bch2_btree_iter_relock_intent(struct btree_iter *iter)
 					? iter->l[l].b->c.lock.state.seq
 					: 0);
 			btree_iter_set_dirty(iter, BTREE_ITER_NEED_TRAVERSE);
+			btree_trans_restart(iter->trans);
 			return false;
 		}
 	}
@@ -414,7 +416,11 @@ bool bch2_btree_iter_relock_intent(struct btree_iter *iter)
 __flatten
 bool bch2_btree_iter_relock(struct btree_iter *iter, unsigned long trace_ip)
 {
-	return btree_iter_get_locks(iter, false, trace_ip);
+	bool ret = btree_iter_get_locks(iter, false, trace_ip);
+
+	if (!ret)
+		btree_trans_restart(iter->trans);
+	return ret;
 }
 
 bool __bch2_btree_iter_upgrade(struct btree_iter *iter,
@@ -457,6 +463,8 @@ bool __bch2_btree_iter_upgrade(struct btree_iter *iter,
 			btree_iter_get_locks(linked, true, _THIS_IP_);
 		}
 
+	if (iter->should_be_locked)
+		btree_trans_restart(iter->trans);
 	return false;
 }
 
@@ -505,11 +513,15 @@ bool bch2_trans_relock(struct btree_trans *trans)
 {
 	struct btree_iter *iter;
 
+	if (unlikely(trans->restarted))
+		return false;
+
 	trans_for_each_iter(trans, iter)
 		if (btree_iter_should_be_locked(iter) &&
 		    !bch2_btree_iter_relock(iter, _RET_IP_)) {
 			trace_trans_restart_relock(trans->ip, _RET_IP_,
 					iter->btree_id, &iter->real_pos);
+			BUG_ON(!trans->restarted);
 			return false;
 		}
 	return true;
@@ -1088,11 +1100,12 @@ static int lock_root_check_fn(struct six_lock *lock, void *p)
 	return b == *rootp ? 0 : -1;
 }
 
-static inline int btree_iter_lock_root(struct btree_iter *iter,
+static inline int btree_iter_lock_root(struct btree_trans *trans,
+				       struct btree_iter *iter,
 				       unsigned depth_want,
 				       unsigned long trace_ip)
 {
-	struct bch_fs *c = iter->trans->c;
+	struct bch_fs *c = trans->c;
 	struct btree *b, **rootp = &c->btree_roots[iter->btree_id].b;
 	enum six_lock_type lock_type;
 	unsigned i;
@@ -1120,8 +1133,11 @@ static inline int btree_iter_lock_root(struct btree_iter *iter,
 		if (unlikely(!btree_node_lock(b, SPOS_MAX, iter->level,
 					      iter, lock_type,
 					      lock_root_check_fn, rootp,
-					      trace_ip)))
-			return -EINTR;
+					      trace_ip))) {
+			if (trans->restarted)
+				return -EINTR;
+			continue;
+		}
 
 		if (likely(b == READ_ONCE(*rootp) &&
 			   b->c.level == iter->level &&
@@ -1199,10 +1215,10 @@ static noinline void btree_node_mem_ptr_set(struct btree_iter *iter,
 		btree_node_unlock(iter, plevel);
 }
 
-static __always_inline int btree_iter_down(struct btree_iter *iter,
+static __always_inline int btree_iter_down(struct btree_trans *trans,
+					   struct btree_iter *iter,
 					   unsigned long trace_ip)
 {
-	struct btree_trans *trans  = iter->trans;
 	struct bch_fs *c = trans->c;
 	struct btree_iter_level *l = &iter->l[iter->level];
 	struct btree *b;
@@ -1257,6 +1273,8 @@ static int __btree_iter_traverse_all(struct btree_trans *trans, int ret,
 
 	trans->in_traverse_all = true;
 retry_all:
+	trans->restarted = false;
+
 	nr_sorted = 0;
 
 	trans_for_each_iter(trans, iter) {
@@ -1319,11 +1337,11 @@ static int __btree_iter_traverse_all(struct btree_trans *trans, int ret,
 	}
 
 	if (hweight64(trans->iters_live) > 1)
-		ret = -EINTR;
+		ret = btree_trans_restart(trans);
 	else
 		trans_for_each_iter(trans, iter)
 			if (iter->flags & BTREE_ITER_KEEP_UNTIL_COMMIT) {
-				ret = -EINTR;
+				ret = btree_trans_restart(trans);
 				break;
 			}
 out:
@@ -1414,8 +1432,8 @@ static int btree_iter_traverse_one(struct btree_iter *iter,
 	 */
 	while (iter->level > depth_want) {
 		ret = btree_iter_node(iter, iter->level)
-			? btree_iter_down(iter, trace_ip)
-			: btree_iter_lock_root(iter, depth_want, trace_ip);
+			? btree_iter_down(trans, iter, trace_ip)
+			: btree_iter_lock_root(trans, iter, depth_want, trace_ip);
 		if (unlikely(ret)) {
 			if (ret == 1) {
 				/*
@@ -1443,6 +1461,7 @@ static int btree_iter_traverse_one(struct btree_iter *iter,
 
 	iter->uptodate = BTREE_ITER_NEED_PEEK;
 out:
+	BUG_ON((ret == -EINTR) != !!trans->restarted);
 	trace_iter_traverse(trans->ip, trace_ip,
 			    btree_iter_type(iter) == BTREE_ITER_CACHED,
 			    iter->btree_id, &iter->real_pos, ret);
@@ -1589,6 +1608,8 @@ static void btree_iter_set_search_pos(struct btree_iter *iter, struct bpos new_p
 	int cmp = bpos_cmp(new_pos, iter->real_pos);
 	unsigned l = iter->level;
 
+	EBUG_ON(iter->trans->restarted);
+
 	if (!cmp)
 		goto out;
 
@@ -2158,6 +2179,8 @@ struct btree_iter *__bch2_trans_get_iter(struct btree_trans *trans,
 	struct btree_iter *iter, *best = NULL;
 	struct bpos real_pos, pos_min = POS_MIN;
 
+	EBUG_ON(trans->restarted);
+
 	if ((flags & BTREE_ITER_TYPE) != BTREE_ITER_NODES &&
 	    btree_node_type_is_extents(btree_id) &&
 	    !(flags & BTREE_ITER_NOT_EXTENTS) &&
@@ -2322,6 +2345,7 @@ void *bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
 
 		if (old_bytes) {
 			trace_trans_restart_mem_realloced(trans->ip, _RET_IP_, new_bytes);
+			btree_trans_restart(trans);
 			return ERR_PTR(-EINTR);
 		}
 	}
@@ -2396,6 +2420,8 @@ void bch2_trans_reset(struct btree_trans *trans, unsigned flags)
 	if (!(flags & TRANS_RESET_NOTRAVERSE) &&
 	    trans->iters_linked)
 		bch2_btree_iter_traverse_all(trans);
+
+	trans->restarted = false;
 }
 
 static void bch2_trans_alloc_iters(struct btree_trans *trans, struct bch_fs *c)

fs/bcachefs/btree_iter.h

@@ -117,6 +117,14 @@ bool bch2_btree_iter_relock(struct btree_iter *, unsigned long);
 bool bch2_trans_relock(struct btree_trans *);
 void bch2_trans_unlock(struct btree_trans *);
 
+__always_inline
+static inline int btree_trans_restart(struct btree_trans *trans)
+{
+	trans->restarted = true;
+	bch2_trans_unlock(trans);
+	return -EINTR;
+}
+
 bool __bch2_btree_iter_upgrade(struct btree_iter *, unsigned);
 
 static inline bool bch2_btree_iter_upgrade(struct btree_iter *iter,

fs/bcachefs/btree_key_cache.c

@@ -215,7 +215,7 @@ static int btree_key_cache_fill(struct btree_trans *trans,
 
 	if (!bch2_btree_node_relock(ck_iter, 0)) {
 		trace_transaction_restart_ip(trans->ip, _THIS_IP_);
-		ret = -EINTR;
+		ret = btree_trans_restart(trans);
 		goto err;
 	}
 
@@ -234,6 +234,10 @@ static int btree_key_cache_fill(struct btree_trans *trans,
 		}
 	}
 
+	/*
+	 * XXX: not allowed to be holding read locks when we take a write lock,
+	 * currently
+	 */
 	bch2_btree_node_lock_write(ck_iter->l[0].b, ck_iter);
 	if (new_k) {
 		kfree(ck->k);
@@ -300,10 +304,8 @@ int bch2_btree_iter_traverse_cached(struct btree_iter *iter)
 
 		if (!btree_node_lock((void *) ck, iter->pos, 0, iter, lock_want,
 				     bkey_cached_check_fn, iter, _THIS_IP_)) {
-			if (ck->key.btree_id != iter->btree_id ||
-			    bpos_cmp(ck->key.pos, iter->pos)) {
+			if (!trans->restarted)
 				goto retry;
-			}
 
 			trace_transaction_restart_ip(trans->ip, _THIS_IP_);
 			ret = -EINTR;
@@ -323,10 +325,10 @@ int bch2_btree_iter_traverse_cached(struct btree_iter *iter)
 	iter->l[0].b		= (void *) ck;
 fill:
 	if (!ck->valid && !(iter->flags & BTREE_ITER_CACHED_NOFILL)) {
-		if (!btree_node_intent_locked(iter, 0))
-			bch2_btree_iter_upgrade(iter, 1);
-		if (!btree_node_intent_locked(iter, 0)) {
+		if (!iter->locks_want &&
+		    !!__bch2_btree_iter_upgrade(iter, 1)) {
 			trace_transaction_restart_ip(trans->ip, _THIS_IP_);
+			BUG_ON(!trans->restarted);
 			ret = -EINTR;
 			goto err;
 		}
@@ -342,9 +344,12 @@ int bch2_btree_iter_traverse_cached(struct btree_iter *iter)
 	iter->uptodate = BTREE_ITER_NEED_PEEK;
 
 	if ((iter->flags & BTREE_ITER_INTENT) &&
-	    !iter->locks_want &&
-	    __bch2_btree_iter_upgrade(iter, 1))
+	    !bch2_btree_iter_upgrade(iter, 1)) {
+		BUG_ON(!trans->restarted);
 		ret = -EINTR;
+	}
+
+	BUG_ON(!ret && !btree_node_locked(iter, 0));
 
 	return ret;
 err:

fs/bcachefs/btree_types.h

@@ -380,9 +380,10 @@ struct btree_trans {
 	int			srcu_idx;
 
 	u8			nr_updates;
-	unsigned		used_mempool:1;
-	unsigned		error:1;
-	unsigned		in_traverse_all:1;
+	bool			used_mempool:1;
+	bool			error:1;
+	bool			in_traverse_all:1;
+	bool			restarted:1;
 	/*
 	 * For when bch2_trans_update notices we'll be splitting a compressed
 	 * extent:

fs/bcachefs/btree_update_interior.c

@@ -1006,6 +1006,7 @@ bch2_btree_update_start(struct btree_iter *iter, unsigned level,
 
 		if (flags & BTREE_INSERT_JOURNAL_RECLAIM) {
 			bch2_btree_update_free(as);
+			btree_trans_restart(trans);
 			return ERR_PTR(ret);
 		}
 

fs/bcachefs/btree_update_leaf.c

@@ -384,6 +384,7 @@ bch2_trans_commit_write_locked(struct btree_trans *trans,
 
 	if (race_fault()) {
 		trace_trans_restart_fault_inject(trans->ip, trace_ip);
+		trans->restarted = true;
 		return -EINTR;
 	}
 
@@ -520,10 +521,17 @@ static noinline int maybe_do_btree_merge(struct btree_trans *trans, struct btree
 		u64s_delta -= !bkey_deleted(old.k) ? old.k->u64s : 0;
 	}
 
-	return u64s_delta <= 0
-		? (bch2_foreground_maybe_merge(trans, iter, iter->level,
-				trans->flags & ~BTREE_INSERT_NOUNLOCK) ?: -EINTR)
-		: 0;
+	if (u64s_delta > 0)
+		return 0;
+
+	ret = bch2_foreground_maybe_merge(trans, iter, iter->level,
+				trans->flags & ~BTREE_INSERT_NOUNLOCK);
+	if (!ret) {
+		ret = -EINTR;
+		trans->restarted = true;
+	}
+
+	return ret;
 }
 
 /*
@@ -587,6 +595,7 @@ static inline int do_bch2_trans_commit(struct btree_trans *trans,
 					trace_trans_restart_upgrade(trans->ip, trace_ip,
 								    iter->btree_id,
 								    &iter->real_pos);
+					trans->restarted = true;
 					return -EINTR;
 				}
 			} else {
@@ -696,6 +705,7 @@ int bch2_trans_commit_error(struct btree_trans *trans,
 			trace_trans_restart_btree_node_split(trans->ip, trace_ip,
 							     i->iter->btree_id,
 							     &i->iter->real_pos);
+			trans->restarted = true;
 			ret = -EINTR;
 		}
 		break;
@@ -704,7 +714,7 @@ int bch2_trans_commit_error(struct btree_trans *trans,
 
 		ret = bch2_replicas_delta_list_mark(c, trans->fs_usage_deltas);
 		if (ret)
-			return ret;
+			break;
 
 		if (bch2_trans_relock(trans))
 			return 0;
@@ -716,12 +726,15 @@ int bch2_trans_commit_error(struct btree_trans *trans,
 		bch2_trans_unlock(trans);
 
 		if ((trans->flags & BTREE_INSERT_JOURNAL_RECLAIM) &&
-		    !(trans->flags & BTREE_INSERT_JOURNAL_RESERVED))
-			return -EAGAIN;
+		    !(trans->flags & BTREE_INSERT_JOURNAL_RESERVED)) {
+			trans->restarted = true;
+			ret = -EAGAIN;
+			break;
+		}
 
 		ret = bch2_trans_journal_res_get(trans, JOURNAL_RES_GET_CHECK);
 		if (ret)
-			return ret;
+			break;
 
 		if (bch2_trans_relock(trans))
 			return 0;
@@ -737,7 +750,7 @@ int bch2_trans_commit_error(struct btree_trans *trans,
 		wait_event_freezable(c->journal.reclaim_wait,
 				     (ret = journal_reclaim_wait_done(c)));
 		if (ret < 0)
-			return ret;
+			break;
 
 		if (bch2_trans_relock(trans))
 			return 0;
@@ -750,6 +763,7 @@ int bch2_trans_commit_error(struct btree_trans *trans,
 		break;
 	}
 
+	BUG_ON((ret == EINTR || ret == -EAGAIN) && !trans->restarted);
 	BUG_ON(ret == -ENOSPC && (flags & BTREE_INSERT_NOFAIL));
 
 	return ret;
@@ -972,6 +986,7 @@ int __bch2_trans_commit(struct btree_trans *trans)
 			trace_trans_restart_upgrade(trans->ip, _RET_IP_,
 						    i->iter->btree_id,
 						    &i->iter->pos);
+			trans->restarted = true;
 			ret = -EINTR;
 			goto out;
 		}
@@ -994,6 +1009,7 @@ int __bch2_trans_commit(struct btree_trans *trans)
 			goto err;
 	}
 retry:
+	BUG_ON(trans->restarted);
 	memset(&trans->journal_res, 0, sizeof(trans->journal_res));
 
 	ret = do_bch2_trans_commit(trans, &i, _RET_IP_);