bcachefs: trans_for_each_iter()

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

16 files changed, 255 insertions, 248 deletions

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index 436eb1e1ab07..3549f0f54624 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -945,7 +945,7 @@ static int bch2_invalidate_one_bucket2(struct btree_trans *trans,
 	bch2_btree_iter_set_pos(iter, POS(ca->dev_idx, b));
 retry:
 	k = bch2_btree_iter_peek_slot(iter);
-	ret = btree_iter_err(k);
+	ret = bkey_err(k);
 	if (ret)
 		return ret;
 
diff --git a/fs/bcachefs/btree_cache.c b/fs/bcachefs/btree_cache.c
index 65fc82fba071..55aaa3e4aa84 100644
--- a/fs/bcachefs/btree_cache.c
+++ b/fs/bcachefs/btree_cache.c
@@ -814,7 +814,7 @@ struct btree *bch2_btree_node_get_sibling(struct bch_fs *c,
 		 * We might have got -EINTR because trylock failed, and we're
 		 * holding other locks that would cause us to deadlock:
 		 */
-		for_each_linked_btree_iter(iter, linked)
+		trans_for_each_iter(iter->trans, linked)
 			if (btree_iter_cmp(iter, linked) < 0)
 				__bch2_btree_iter_unlock(linked);
 
@@ -839,13 +839,13 @@ struct btree *bch2_btree_node_get_sibling(struct bch_fs *c,
 			}
 		}
 
-		bch2_btree_iter_relock(iter);
+		bch2_btree_trans_relock(iter->trans);
 	}
 out:
 	if (btree_lock_want(iter, level + 1) == BTREE_NODE_UNLOCKED)
 		btree_node_unlock(iter, level + 1);
 
-	bch2_btree_iter_verify_locks(iter);
+	bch2_btree_trans_verify_locks(iter->trans);
 
 	BUG_ON((!may_drop_locks || !IS_ERR(ret)) &&
 	       (iter->uptodate >= BTREE_ITER_NEED_RELOCK ||
diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 5280e77f548f..f018ca7999f7 100644
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -70,7 +70,7 @@ void bch2_btree_node_unlock_write(struct btree *b, struct btree_iter *iter)
 	EBUG_ON(iter->l[b->level].b != b);
 	EBUG_ON(iter->l[b->level].lock_seq + 1 != b->lock.state.seq);
 
-	for_each_btree_iter_with_node(iter, b, linked)
+	trans_for_each_iter_with_node(iter->trans, b, linked)
 		linked->l[b->level].lock_seq += 2;
 
 	six_unlock_write(&b->lock);
@@ -83,7 +83,7 @@ void __bch2_btree_node_lock_write(struct btree *b, struct btree_iter *iter)
 
 	EBUG_ON(btree_node_read_locked(iter, b->level));
 
-	for_each_linked_btree_iter(iter, linked)
+	trans_for_each_iter(iter->trans, linked)
 		if (linked->l[b->level].b == b &&
 		    btree_node_read_locked(linked, b->level))
 			readers++;
@@ -187,7 +187,8 @@ static inline bool btree_iter_get_locks(struct btree_iter *iter,
 	if (iter->uptodate == BTREE_ITER_NEED_RELOCK)
 		iter->uptodate = BTREE_ITER_NEED_PEEK;
 
-	bch2_btree_iter_verify_locks(iter);
+	bch2_btree_trans_verify_locks(iter->trans);
+
 	return iter->uptodate < BTREE_ITER_NEED_RELOCK;
 }
 
@@ -202,7 +203,7 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos,
 	bool ret = true;
 
 	/* Check if it's safe to block: */
-	for_each_btree_iter(iter, linked) {
+	trans_for_each_iter(iter->trans, linked) {
 		if (!linked->nodes_locked)
 			continue;
 
@@ -262,7 +263,7 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos,
 /* Btree iterator locking: */
 
 #ifdef CONFIG_BCACHEFS_DEBUG
-void __bch2_btree_iter_verify_locks(struct btree_iter *iter)
+void bch2_btree_iter_verify_locks(struct btree_iter *iter)
 {
 	unsigned l;
 
@@ -279,35 +280,23 @@ void __bch2_btree_iter_verify_locks(struct btree_iter *iter)
 	}
 }
 
-void bch2_btree_iter_verify_locks(struct btree_iter *iter)
+void bch2_btree_trans_verify_locks(struct btree_trans *trans)
 {
-	struct btree_iter *linked;
-
-	for_each_btree_iter(iter, linked)
-		__bch2_btree_iter_verify_locks(linked);
+	struct btree_iter *iter;
 
+	trans_for_each_iter(trans, iter)
+		bch2_btree_iter_verify_locks(iter);
 }
 #endif
 
 __flatten
-static bool __bch2_btree_iter_relock(struct btree_iter *iter)
+static bool bch2_btree_iter_relock(struct btree_iter *iter)
 {
 	return iter->uptodate >= BTREE_ITER_NEED_RELOCK
 		? btree_iter_get_locks(iter, false)
 		: true;
 }
 
-bool bch2_btree_iter_relock(struct btree_iter *iter)
-{
-	struct btree_iter *linked;
-	bool ret = true;
-
-	for_each_btree_iter(iter, linked)
-		ret &= __bch2_btree_iter_relock(linked);
-
-	return ret;
-}
-
 bool __bch2_btree_iter_upgrade(struct btree_iter *iter,
 			       unsigned new_locks_want)
 {
@@ -325,8 +314,9 @@ bool __bch2_btree_iter_upgrade(struct btree_iter *iter,
 	 * on iterators that might lock ancestors before us to avoid getting
 	 * -EINTR later:
 	 */
-	for_each_linked_btree_iter(iter, linked)
-		if (linked->btree_id == iter->btree_id &&
+	trans_for_each_iter(iter->trans, linked)
+		if (linked != iter &&
+		    linked->btree_id == iter->btree_id &&
 		    btree_iter_cmp(linked, iter) <= 0 &&
 		    linked->locks_want < new_locks_want) {
 			linked->locks_want = new_locks_want;
@@ -371,7 +361,7 @@ void __bch2_btree_iter_downgrade(struct btree_iter *iter,
 	 * might have had to modify locks_want on linked iterators due to lock
 	 * ordering:
 	 */
-	for_each_btree_iter(iter, linked) {
+	trans_for_each_iter(iter->trans, linked) {
 		unsigned new_locks_want = downgrade_to ?:
 			(linked->flags & BTREE_ITER_INTENT ? 1 : 0);
 
@@ -394,19 +384,40 @@ void __bch2_btree_iter_downgrade(struct btree_iter *iter,
 		}
 	}
 
-	bch2_btree_iter_verify_locks(iter);
+	bch2_btree_trans_verify_locks(iter->trans);
 }
 
 int bch2_btree_iter_unlock(struct btree_iter *iter)
 {
 	struct btree_iter *linked;
 
-	for_each_btree_iter(iter, linked)
+	trans_for_each_iter(iter->trans, linked)
 		__bch2_btree_iter_unlock(linked);
 
-	return iter->flags & BTREE_ITER_ERROR ? -EIO : 0;
+	return btree_iter_err(iter);
 }
 
+bool bch2_btree_trans_relock(struct btree_trans *trans)
+{
+	struct btree_iter *iter;
+	bool ret = true;
+
+	trans_for_each_iter(trans, iter)
+		ret &= bch2_btree_iter_relock(iter);
+
+	return ret;
+}
+
+void bch2_btree_trans_unlock(struct btree_trans *trans)
+{
+	struct btree_iter *iter;
+
+	trans_for_each_iter(trans, iter)
+		__bch2_btree_iter_unlock(iter);
+}
+
+/* Btree transaction locking: */
+
 /* Btree iterator: */
 
 #ifdef CONFIG_BCACHEFS_DEBUG
@@ -464,7 +475,7 @@ void bch2_btree_iter_verify(struct btree_iter *iter, struct btree *b)
 {
 	struct btree_iter *linked;
 
-	for_each_btree_iter_with_node(iter, b, linked)
+	trans_for_each_iter_with_node(iter->trans, b, linked)
 		__bch2_btree_iter_verify(linked, b);
 }
 
@@ -618,7 +629,7 @@ void bch2_btree_node_iter_fix(struct btree_iter *iter,
 		__bch2_btree_node_iter_fix(iter, b, node_iter, t,
 					  where, clobber_u64s, new_u64s);
 
-	for_each_btree_iter_with_node(iter, b, linked)
+	trans_for_each_iter_with_node(iter->trans, b, linked)
 		__bch2_btree_node_iter_fix(linked, b,
 					  &linked->l[b->level].iter, t,
 					  where, clobber_u64s, new_u64s);
@@ -776,7 +787,7 @@ void bch2_btree_iter_node_replace(struct btree_iter *iter, struct btree *b)
 	enum btree_node_locked_type t;
 	struct btree_iter *linked;
 
-	for_each_btree_iter(iter, linked)
+	trans_for_each_iter(iter->trans, linked)
 		if (btree_iter_pos_in_node(linked, b)) {
 			/*
 			 * bch2_btree_iter_node_drop() has already been called -
@@ -810,7 +821,7 @@ void bch2_btree_iter_node_drop(struct btree_iter *iter, struct btree *b)
 	iter->l[level].b = BTREE_ITER_NOT_END;
 	mark_btree_node_unlocked(iter, level);
 
-	for_each_btree_iter(iter, linked)
+	trans_for_each_iter(iter->trans, linked)
 		if (linked->l[level].b == b) {
 			__btree_node_unlock(linked, level);
 			linked->l[level].b = BTREE_ITER_NOT_END;
@@ -825,7 +836,7 @@ void bch2_btree_iter_reinit_node(struct btree_iter *iter, struct btree *b)
 {
 	struct btree_iter *linked;
 
-	for_each_btree_iter_with_node(iter, b, linked)
+	trans_for_each_iter_with_node(iter->trans, b, linked)
 		__btree_iter_init(linked, b->level);
 }
 
@@ -1005,7 +1016,7 @@ retry:
 		iter = iter->next;
 	} while (iter != sorted_iters);
 
-	ret = btree_iter_linked(iter) ? -EINTR : 0;
+	ret = btree_trans_has_multiple_iters(iter->trans) ? -EINTR : 0;
 out:
 	bch2_btree_cache_cannibalize_unlock(c);
 	return ret;
@@ -1051,7 +1062,7 @@ int __must_check __bch2_btree_iter_traverse(struct btree_iter *iter)
 	if (unlikely(iter->level >= BTREE_MAX_DEPTH))
 		return 0;
 
-	if (__bch2_btree_iter_relock(iter))
+	if (bch2_btree_iter_relock(iter))
 		return 0;
 
 	/*
@@ -1091,7 +1102,7 @@ int __must_check __bch2_btree_iter_traverse(struct btree_iter *iter)
 
 	iter->uptodate = BTREE_ITER_NEED_PEEK;
 
-	bch2_btree_iter_verify_locks(iter);
+	bch2_btree_trans_verify_locks(iter->trans);
 	__bch2_btree_iter_verify(iter, iter->l[iter->level].b);
 	return 0;
 }
@@ -1104,7 +1115,7 @@ int __must_check bch2_btree_iter_traverse(struct btree_iter *iter)
 	if (unlikely(ret))
 		ret = btree_iter_traverse_error(iter, ret);
 
-	BUG_ON(ret == -EINTR && !btree_iter_linked(iter));
+	BUG_ON(ret == -EINTR && !btree_trans_has_multiple_iters(iter->trans));
 
 	return ret;
 }
@@ -1117,7 +1128,7 @@ static inline void bch2_btree_iter_checks(struct btree_iter *iter,
 		(iter->btree_id == BTREE_ID_EXTENTS &&
 		 type != BTREE_ITER_NODES));
 
-	bch2_btree_iter_verify_locks(iter);
+	bch2_btree_trans_verify_locks(iter->trans);
 }
 
 /* Iterate across nodes (leaf and interior nodes) */
@@ -1619,7 +1630,7 @@ static void bch2_btree_iter_unlink(struct btree_iter *iter)
 	if (!btree_iter_linked(iter))
 		return;
 
-	for_each_linked_btree_iter(iter, linked)
+	trans_for_each_iter(iter->trans, linked)
 		if (linked->next == iter) {
 			linked->next = iter->next;
 			iter->next = iter;
@@ -1686,7 +1697,7 @@ int bch2_trans_iter_put(struct btree_trans *trans,
 			struct btree_iter *iter)
 {
 	ssize_t idx = btree_trans_iter_idx(trans, iter);
-	int ret = (iter->flags & BTREE_ITER_ERROR) ? -EIO : 0;
+	int ret = btree_iter_err(iter);
 
 	trans->iters_live	&= ~(1ULL << idx);
 	return ret;
@@ -1706,7 +1717,7 @@ static inline void __bch2_trans_iter_free(struct btree_trans *trans,
 int bch2_trans_iter_free(struct btree_trans *trans,
 			 struct btree_iter *iter)
 {
-	int ret = (iter->flags & BTREE_ITER_ERROR) ? -EIO : 0;
+	int ret = btree_iter_err(iter);
 
 	__bch2_trans_iter_free(trans, btree_trans_iter_idx(trans, iter));
 	return ret;
@@ -1715,7 +1726,7 @@ int bch2_trans_iter_free(struct btree_trans *trans,
 int bch2_trans_iter_free_on_commit(struct btree_trans *trans,
 				   struct btree_iter *iter)
 {
-	int ret = (iter->flags & BTREE_ITER_ERROR) ? -EIO : 0;
+	int ret = btree_iter_err(iter);
 
 	trans->iters_unlink_on_commit |=
 		1ULL << btree_trans_iter_idx(trans, iter);
@@ -1966,8 +1977,7 @@ int bch2_trans_unlock(struct btree_trans *trans)
 		unsigned idx = __ffs(iters);
 		struct btree_iter *iter = &trans->iters[idx];
 
-		if (iter->flags & BTREE_ITER_ERROR)
-			ret = -EIO;
+		ret = ret ?: btree_iter_err(iter);
 
 		__bch2_btree_iter_unlock(iter);
 		iters ^= 1 << idx;
diff --git a/fs/bcachefs/btree_iter.h b/fs/bcachefs/btree_iter.h
index 4be472e45310..70b5cc6ee5ab 100644
--- a/fs/bcachefs/btree_iter.h
+++ b/fs/bcachefs/btree_iter.h
@@ -23,11 +23,44 @@ static inline struct btree *btree_node_parent(struct btree_iter *iter,
 	return btree_iter_node(iter, b->level + 1);
 }
 
+static inline bool btree_trans_has_multiple_iters(const struct btree_trans *trans)
+{
+	return hweight64(trans->iters_linked) > 1;
+}
+
 static inline bool btree_iter_linked(const struct btree_iter *iter)
 {
 	return iter->next != iter;
 }
 
+static inline int btree_iter_err(const struct btree_iter *iter)
+{
+	return iter->flags & BTREE_ITER_ERROR ? -EIO : 0;
+}
+
+/* Iterate over iters within a transaction: */
+
+static inline struct btree_iter *
+__trans_next_iter(struct btree_trans *trans, struct btree_iter *iter)
+{
+	unsigned idx;
+
+	/* XXX expensive pointer subtraction: */
+
+	for (idx = iter - trans->iters;
+	     idx < trans->nr_iters;
+	     idx++)
+		if (trans->iters_linked & (1ULL << idx))
+			return &trans->iters[idx];
+
+	return NULL;
+}
+
+#define trans_for_each_iter(_trans, _iter)				\
+	for (_iter = (_trans)->iters;					\
+	     (_iter = __trans_next_iter((_trans), _iter));		\
+	     _iter++)
+
 static inline bool __iter_has_node(const struct btree_iter *iter,
 				   const struct btree *b)
 {
@@ -44,59 +77,39 @@ static inline bool __iter_has_node(const struct btree_iter *iter,
 }
 
 static inline struct btree_iter *
-__next_linked_iter(struct btree_iter *iter, struct btree_iter *linked)
+__trans_next_iter_with_node(struct btree_trans *trans, struct btree *b,
+			    struct btree_iter *iter)
 {
-	return linked->next != iter ? linked->next : NULL;
-}
+	unsigned idx;
 
-static inline struct btree_iter *
-__next_iter_with_node(struct btree_iter *iter, struct btree *b,
-		      struct btree_iter *linked)
-{
-	while (linked && !__iter_has_node(linked, b))
-		linked = __next_linked_iter(iter, linked);
+	/* XXX expensive pointer subtraction: */
+
+	for (idx = iter - trans->iters;
+	     idx < trans->nr_iters;
+	     idx++) {
+		if (!(trans->iters_linked & (1ULL << idx)))
+			continue;
 
-	return linked;
+		iter = &trans->iters[idx];
+		if (__iter_has_node(iter, b))
+			return iter;
+	}
+
+	return NULL;
 }
 
-/**
- * for_each_btree_iter - iterate over all iterators linked with @_iter,
- * including @_iter
- */
-#define for_each_btree_iter(_iter, _linked)				\
-	for ((_linked) = (_iter); (_linked);				\
-	     (_linked) = __next_linked_iter(_iter, _linked))
-
-/**
- * for_each_btree_iter_with_node - iterate over all iterators linked with @_iter
- * that also point to @_b
- *
- * @_b is assumed to be locked by @_iter
- *
- * Filters out iterators that don't have a valid btree_node iterator for @_b -
- * i.e. iterators for which bch2_btree_node_relock() would not succeed.
- */
-#define for_each_btree_iter_with_node(_iter, _b, _linked)		\
-	for ((_linked) = (_iter);					\
-	     ((_linked) = __next_iter_with_node(_iter, _b, _linked));	\
-	     (_linked) = __next_linked_iter(_iter, _linked))
-
-/**
- * for_each_linked_btree_iter - iterate over all iterators linked with @_iter,
- * _not_ including @_iter
- */
-#define for_each_linked_btree_iter(_iter, _linked)			\
-	for ((_linked) = (_iter)->next;					\
-	     (_linked) != (_iter);					\
-	     (_linked) = (_linked)->next)
+#define trans_for_each_iter_with_node(_trans, _b, _iter)		\
+	for (_iter = (_trans)->iters;					\
+	     (_iter = __trans_next_iter_with_node((_trans), (_b), _iter));\
+	     _iter++)
 
 #ifdef CONFIG_BCACHEFS_DEBUG
 void bch2_btree_iter_verify(struct btree_iter *, struct btree *);
-void bch2_btree_iter_verify_locks(struct btree_iter *);
+void bch2_btree_trans_verify_locks(struct btree_trans *);
 #else
 static inline void bch2_btree_iter_verify(struct btree_iter *iter,
 					  struct btree *b) {}
-static inline void bch2_btree_iter_verify_locks(struct btree_iter *iter) {}
+static inline void bch2_btree_trans_verify_locks(struct btree_trans *iter) {}
 #endif
 
 void bch2_btree_node_iter_fix(struct btree_iter *, struct btree *,
@@ -104,7 +117,9 @@ void bch2_btree_node_iter_fix(struct btree_iter *, struct btree *,
 			      unsigned, unsigned);
 
 int bch2_btree_iter_unlock(struct btree_iter *);
-bool bch2_btree_iter_relock(struct btree_iter *);
+
+bool bch2_btree_trans_relock(struct btree_trans *);
+void bch2_btree_trans_unlock(struct btree_trans *);
 
 bool __bch2_btree_iter_upgrade(struct btree_iter *, unsigned);
 bool __bch2_btree_iter_upgrade_nounlock(struct btree_iter *, unsigned);
@@ -252,7 +267,7 @@ static inline struct bkey_s_c __bch2_btree_iter_next(struct btree_iter *iter,
 	     !IS_ERR_OR_NULL((_k).k);					\
 	     (_k) = __bch2_btree_iter_next(_iter, _flags))
 
-static inline int btree_iter_err(struct bkey_s_c k)
+static inline int bkey_err(struct bkey_s_c k)
 {
 	return PTR_ERR_OR_ZERO(k.k);
 }
diff --git a/fs/bcachefs/btree_locking.h b/fs/bcachefs/btree_locking.h
index c036cd0458a4..37e09474fde4 100644
--- a/fs/bcachefs/btree_locking.h
+++ b/fs/bcachefs/btree_locking.h
@@ -163,8 +163,9 @@ static inline bool btree_node_lock_increment(struct btree_iter *iter,
 {
 	struct btree_iter *linked;
 
-	for_each_linked_btree_iter(iter, linked)
-		if (linked->l[level].b == b &&
+	trans_for_each_iter(iter->trans, linked)
+		if (linked != iter &&
+		    linked->l[level].b == b &&
 		    btree_node_locked_type(linked, level) >= want) {
 			six_lock_increment(&b->lock, want);
 			return true;
diff --git a/fs/bcachefs/btree_update_interior.c b/fs/bcachefs/btree_update_interior.c
index 8b96faf107f8..6e9a87c6b1be 100644
--- a/fs/bcachefs/btree_update_interior.c
+++ b/fs/bcachefs/btree_update_interior.c
@@ -246,7 +246,7 @@ void bch2_btree_node_free_inmem(struct bch_fs *c, struct btree *b,
 {
 	struct btree_iter *linked;
 
-	for_each_btree_iter(iter, linked)
+	trans_for_each_iter(iter->trans, linked)
 		BUG_ON(linked->l[b->level].b == b);
 
 	/*
@@ -1438,7 +1438,7 @@ static void btree_split(struct btree_update *as, struct btree *b,
 
 	bch2_btree_node_free_inmem(c, b, iter);
 
-	bch2_btree_iter_verify_locks(iter);
+	bch2_btree_trans_verify_locks(iter->trans);
 
 	bch2_time_stats_update(&c->times[BCH_TIME_btree_node_split],
 			       start_time);
@@ -1474,7 +1474,7 @@ bch2_btree_insert_keys_interior(struct btree_update *as, struct btree *b,
 
 	btree_update_updated_node(as, b);
 
-	for_each_btree_iter_with_node(iter, b, linked)
+	trans_for_each_iter_with_node(iter->trans, b, linked)
 		bch2_btree_node_iter_peek(&linked->l[b->level].iter, b);
 
 	bch2_btree_iter_verify(iter, b);
@@ -1559,7 +1559,7 @@ int bch2_btree_split_leaf(struct bch_fs *c, struct btree_iter *iter,
 	 * We already have a disk reservation and open buckets pinned; this
 	 * allocation must not block:
 	 */
-	for_each_btree_iter(iter, linked)
+	trans_for_each_iter(iter->trans, linked)
 		if (linked->btree_id == BTREE_ID_EXTENTS)
 			flags |= BTREE_INSERT_USE_RESERVE;
 
@@ -1571,10 +1571,10 @@ int bch2_btree_split_leaf(struct bch_fs *c, struct btree_iter *iter,
 		if (flags & BTREE_INSERT_NOUNLOCK)
 			return -EINTR;
 
-		bch2_btree_iter_unlock(iter);
+		bch2_btree_trans_unlock(iter->trans);
 		down_read(&c->gc_lock);
 
-		if (btree_iter_linked(iter))
+		if (!bch2_btree_trans_relock(iter->trans))
 			ret = -EINTR;
 	}
 
@@ -1753,7 +1753,7 @@ retry:
 	if (!(flags & BTREE_INSERT_GC_LOCK_HELD))
 		up_read(&c->gc_lock);
 out:
-	bch2_btree_iter_verify_locks(iter);
+	bch2_btree_trans_verify_locks(iter->trans);
 
 	/*
 	 * Don't downgrade locks here: we're called after successful insert,
@@ -2036,10 +2036,10 @@ int bch2_btree_node_update_key(struct bch_fs *c, struct btree_iter *iter,
 		return -EINTR;
 
 	if (!down_read_trylock(&c->gc_lock)) {
-		bch2_btree_iter_unlock(iter);
+		bch2_btree_trans_unlock(iter->trans);
 		down_read(&c->gc_lock);
 
-		if (!bch2_btree_iter_relock(iter)) {
+		if (!bch2_btree_trans_relock(iter->trans)) {
 			ret = -EINTR;
 			goto err;
 		}
@@ -2050,15 +2050,15 @@ int bch2_btree_node_update_key(struct bch_fs *c, struct btree_iter *iter,
 		/* bch2_btree_reserve_get will unlock */
 		ret = bch2_btree_cache_cannibalize_lock(c, &cl);
 		if (ret) {
-			ret = -EINTR;
-
-			bch2_btree_iter_unlock(iter);
+			bch2_btree_trans_unlock(iter->trans);
 			up_read(&c->gc_lock);
 			closure_sync(&cl);
 			down_read(&c->gc_lock);
 
-			if (!bch2_btree_iter_relock(iter))
+			if (!bch2_btree_trans_relock(iter->trans)) {
+				ret = -EINTR;
 				goto err;
+			}
 		}
 
 		new_hash = bch2_btree_node_mem_alloc(c);
@@ -2079,12 +2079,12 @@ int bch2_btree_node_update_key(struct bch_fs *c, struct btree_iter *iter,
 		if (ret != -EINTR)
 			goto err;
 
-		bch2_btree_iter_unlock(iter);
+		bch2_btree_trans_unlock(iter->trans);
 		up_read(&c->gc_lock);
 		closure_sync(&cl);
 		down_read(&c->gc_lock);
 
-		if (!bch2_btree_iter_relock(iter))
+		if (!bch2_btree_trans_relock(iter->trans))
 			goto err;
 	}
 
diff --git a/fs/bcachefs/btree_update_leaf.c b/fs/bcachefs/btree_update_leaf.c
index 45838db7b991..8b043d3c19ad 100644
--- a/fs/bcachefs/btree_update_leaf.c
+++ b/fs/bcachefs/btree_update_leaf.c
@@ -51,25 +51,6 @@ static void btree_trans_unlock_write(struct btree_trans *trans)
 		bch2_btree_node_unlock_write(i->iter->l[0].b, i->iter);
 }
 
-static bool btree_trans_relock(struct btree_trans *trans)
-{
-	struct btree_insert_entry *i;
-
-	trans_for_each_update_iter(trans, i)
-		return bch2_btree_iter_relock(i->iter);
-	return true;
-}
-
-static void btree_trans_unlock(struct btree_trans *trans)
-{
-	struct btree_insert_entry *i;
-
-	trans_for_each_update_iter(trans, i) {
-		bch2_btree_iter_unlock(i->iter);
-		break;
-	}
-}
-
 static inline int btree_trans_cmp(struct btree_insert_entry l,
 				  struct btree_insert_entry r)
 {
@@ -422,8 +403,6 @@ static inline void btree_insert_entry_checks(struct btree_trans *trans,
 
 		EBUG_ON((i->iter->flags & BTREE_ITER_IS_EXTENTS) &&
 			!(trans->flags & BTREE_INSERT_ATOMIC));
-
-		bch2_btree_iter_verify_locks(i->iter);
 	}
 
 	BUG_ON(debug_check_bkeys(c) &&
@@ -451,14 +430,14 @@ static int bch2_trans_journal_preres_get(struct btree_trans *trans)
 	if (ret != -EAGAIN)
 		return ret;
 
-	btree_trans_unlock(trans);
+	bch2_btree_trans_unlock(trans);
 
 	ret = bch2_journal_preres_get(&c->journal,
 			&trans->journal_preres, u64s, 0);
 	if (ret)
 		return ret;
 
-	if (!btree_trans_relock(trans)) {
+	if (!bch2_btree_trans_relock(trans)) {
 		trans_restart(" (iter relock after journal preres get blocked)");
 		return -EINTR;
 	}
@@ -617,12 +596,9 @@ static inline int do_btree_insert_at(struct btree_trans *trans,
 		 * have been traversed/locked, depending on what the caller was
 		 * doing:
 		 */
-		trans_for_each_update_iter(trans, i) {
-			for_each_btree_iter(i->iter, linked)
-				if (linked->uptodate < BTREE_ITER_NEED_RELOCK)
-					linked->flags |= BTREE_ITER_NOUNLOCK;
-			break;
-		}
+		trans_for_each_iter(trans, linked)
+			if (linked->uptodate < BTREE_ITER_NEED_RELOCK)
+				linked->flags |= BTREE_ITER_NOUNLOCK;
 	}
 
 	trans_for_each_update_iter(trans, i)
@@ -707,20 +683,20 @@ int bch2_trans_commit_error(struct btree_trans *trans,
 				return ret;
 		}
 
-		if (btree_trans_relock(trans))
+		if (bch2_btree_trans_relock(trans))
 			return 0;
 
 		trans_restart(" (iter relock after marking replicas)");
 		ret = -EINTR;
 		break;
 	case BTREE_INSERT_NEED_JOURNAL_RES:
-		btree_trans_unlock(trans);
+		bch2_btree_trans_unlock(trans);
 
 		ret = bch2_trans_journal_res_get(trans, JOURNAL_RES_GET_CHECK);
 		if (ret)
 			return ret;
 
-		if (btree_trans_relock(trans))
+		if (bch2_btree_trans_relock(trans))
 			return 0;
 
 		trans_restart(" (iter relock after journal res get blocked)");
@@ -785,10 +761,9 @@ static int __bch2_trans_commit(struct btree_trans *trans,
 			goto err;
 		}
 
-		if (i->iter->flags & BTREE_ITER_ERROR) {
-			ret = -EIO;
+		ret = btree_iter_err(i->iter);
+		if (ret)
 			goto err;
-		}
 	}
 
 	ret = do_btree_insert_at(trans, stopped_at);
@@ -802,16 +777,10 @@ static int __bch2_trans_commit(struct btree_trans *trans,
 		bch2_btree_iter_downgrade(i->iter);
 err:
 	/* make sure we didn't drop or screw up locks: */
-	trans_for_each_update_iter(trans, i) {
-		bch2_btree_iter_verify_locks(i->iter);
-		break;
-	}
+	bch2_btree_trans_verify_locks(trans);
 
-	trans_for_each_update_iter(trans, i) {
-		for_each_btree_iter(i->iter, linked)
-			linked->flags &= ~BTREE_ITER_NOUNLOCK;
-		break;
-	}
+	trans_for_each_iter(trans, linked)
+		linked->flags &= ~BTREE_ITER_NOUNLOCK;
 
 	return ret;
 }
@@ -847,13 +816,14 @@ int bch2_trans_commit(struct btree_trans *trans,
 
 	trans_for_each_update(trans, i)
 		btree_insert_entry_checks(trans, i);
+	bch2_btree_trans_verify_locks(trans);
 
 	if (unlikely(!(trans->flags & BTREE_INSERT_NOCHECK_RW) &&
 		     !percpu_ref_tryget(&c->writes))) {
 		if (likely(!(trans->flags & BTREE_INSERT_LAZY_RW)))
 			return -EROFS;
 
-		btree_trans_unlock(trans);
+		bch2_btree_trans_unlock(trans);
 
 		ret = bch2_fs_read_write_early(c);
 		if (ret)
@@ -861,7 +831,7 @@ int bch2_trans_commit(struct btree_trans *trans,
 
 		percpu_ref_get(&c->writes);
 
-		if (!btree_trans_relock(trans)) {
+		if (!bch2_btree_trans_relock(trans)) {
 			ret = -EINTR;
 			goto err;
 		}
@@ -962,7 +932,7 @@ int bch2_btree_delete_range(struct bch_fs *c, enum btree_id id,
 	iter = bch2_trans_get_iter(&trans, id, start, BTREE_ITER_INTENT);
 
 	while ((k = bch2_btree_iter_peek(iter)).k &&
-	       !(ret = btree_iter_err(k)) &&
+	       !(ret = bkey_err(k)) &&
 	       bkey_cmp(iter->pos, end) < 0) {
 		unsigned max_sectors = KEY_SIZE_MAX & (~0 << c->block_bits);
 		/* really shouldn't be using a bare, unpadded bkey_i */
diff --git a/fs/bcachefs/debug.c b/fs/bcachefs/debug.c
index 64e079280a9a..bb69a2acd8dd 100644
--- a/fs/bcachefs/debug.c
+++ b/fs/bcachefs/debug.c
@@ -226,7 +226,7 @@ static ssize_t bch2_read_btree(struct file *file, char __user *buf,
 	iter = bch2_trans_get_iter(&trans, i->id, i->from, BTREE_ITER_PREFETCH);
 	k = bch2_btree_iter_peek(iter);
 
-	while (k.k && !(err = btree_iter_err(k))) {
+	while (k.k && !(err = bkey_err(k))) {
 		bch2_bkey_val_to_text(&PBUF(i->buf), i->c, k);
 		i->bytes = strlen(i->buf);
 		BUG_ON(i->bytes >= PAGE_SIZE);
@@ -333,7 +333,7 @@ static ssize_t bch2_read_bfloat_failed(struct file *file, char __user *buf,
 	iter = bch2_trans_get_iter(&trans, i->id, i->from, BTREE_ITER_PREFETCH);
 
 	while ((k = bch2_btree_iter_peek(iter)).k &&
-	       !(err = btree_iter_err(k))) {
+	       !(err = bkey_err(k))) {
 		struct btree_iter_level *l = &iter->l[0];
 		struct bkey_packed *_k =
 			bch2_btree_node_iter_peek(&l->iter, l->b);
diff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c
index c33bcffa7871..5fc0025e66bf 100644
--- a/fs/bcachefs/ec.c
+++ b/fs/bcachefs/ec.c
@@ -426,7 +426,7 @@ int bch2_ec_read_extent(struct bch_fs *c, struct bch_read_bio *rbio)
 				   POS(0, stripe_idx),
 				   BTREE_ITER_SLOTS);
 	k = bch2_btree_iter_peek_slot(iter);
-	if (btree_iter_err(k) || k.k->type != KEY_TYPE_stripe) {
+	if (bkey_err(k) || k.k->type != KEY_TYPE_stripe) {
 		__bcache_io_error(c,
 			"error doing reconstruct read: stripe not found");
 		kfree(buf);
@@ -541,7 +541,7 @@ static int ec_stripe_mem_alloc(struct bch_fs *c,
 	if (!__ec_stripe_mem_alloc(c, idx, GFP_NOWAIT|__GFP_NOWARN))
 		return 0;
 
-	bch2_btree_iter_unlock(iter);
+	bch2_btree_trans_unlock(iter->trans);
 
 	if (!__ec_stripe_mem_alloc(c, idx, GFP_KERNEL))
 		return -EINTR;
@@ -750,7 +750,7 @@ static int ec_stripe_update_ptrs(struct bch_fs *c,
 				   BTREE_ITER_INTENT);
 
 	while ((k = bch2_btree_iter_peek(iter)).k &&
-	       !(ret = btree_iter_err(k)) &&
+	       !(ret = bkey_err(k)) &&
 	       bkey_cmp(bkey_start_pos(k.k), pos->p) < 0) {
 		idx = extent_matches_stripe(c, &s->key.v, k);
 		if (idx < 0) {
@@ -1170,7 +1170,7 @@ static int __bch2_stripe_write_key(struct btree_trans *trans,
 	bch2_btree_iter_set_pos(iter, POS(0, idx));
 
 	k = bch2_btree_iter_peek_slot(iter);
-	ret = btree_iter_err(k);
+	ret = bkey_err(k);
 	if (ret)
 		return ret;
 
diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c
index efc189c02db7..d865081d4a21 100644
--- a/fs/bcachefs/fs-io.c
+++ b/fs/bcachefs/fs-io.c
@@ -251,7 +251,7 @@ static int sum_sector_overwrites(struct btree_trans *trans,
 		 * carefully not advancing past @new and thus whatever leaf node
 		 * @_iter currently points to:
 		 */
-		BUG_ON(btree_iter_err(old));
+		BUG_ON(bkey_err(old));
 
 		if (allocating &&
 		    !*allocating &&
@@ -322,10 +322,10 @@ static int bch2_extent_update(struct btree_trans *trans,
 	if (i_sectors_delta ||
 	    new_i_size > inode->ei_inode.bi_size) {
 		if (c->opts.new_inode_updates) {
-			bch2_btree_iter_unlock(extent_iter);
+			bch2_btree_trans_unlock(trans);
 			mutex_lock(&inode->ei_update_lock);
 
-			if (!bch2_btree_iter_relock(extent_iter)) {
+			if (!bch2_btree_trans_relock(trans)) {
 				mutex_unlock(&inode->ei_update_lock);
 				return -EINTR;
 			}
@@ -921,10 +921,11 @@ static void readpage_bio_extend(struct readpages_iter *iter,
 	}
 }
 
-static void bchfs_read(struct bch_fs *c, struct btree_iter *iter,
+static void bchfs_read(struct btree_trans *trans, struct btree_iter *iter,
 		       struct bch_read_bio *rbio, u64 inum,
 		       struct readpages_iter *readpages_iter)
 {
+	struct bch_fs *c = trans->c;
 	struct bio *bio = &rbio->bio;
 	int flags = BCH_READ_RETRY_IF_STALE|
 		BCH_READ_MAY_PROMOTE;
@@ -943,7 +944,7 @@ static void bchfs_read(struct bch_fs *c, struct btree_iter *iter,
 		BUG_ON(!k.k);
 
 		if (IS_ERR(k.k)) {
-			int ret = bch2_btree_iter_unlock(iter);
+			int ret = btree_iter_err(iter);
 			BUG_ON(!ret);
 			bcache_io_error(c, bio, "btree IO error %i", ret);
 			bio_endio(bio);
@@ -951,7 +952,7 @@ static void bchfs_read(struct bch_fs *c, struct btree_iter *iter,
 		}
 
 		bkey_reassemble(&tmp.k, k);
-		bch2_btree_iter_unlock(iter);
+		bch2_btree_trans_unlock(trans);
 		k = bkey_i_to_s_c(&tmp.k);
 
 		if (readpages_iter) {
@@ -1030,7 +1031,8 @@ void bch2_readahead(struct readahead_control *ractl)
 		rbio->bio.bi_end_io = bch2_readpages_end_io;
 		__bio_add_page(&rbio->bio, page, PAGE_SIZE, 0);
 
-		bchfs_read(c, iter, rbio, inode->v.i_ino, &readpages_iter);
+		bchfs_read(&trans, iter, rbio, inode->v.i_ino,
+			   &readpages_iter);
 	}
 
 	bch2_pagecache_add_put(&inode->ei_pagecache_lock);
@@ -1054,7 +1056,7 @@ static void __bchfs_readpage(struct bch_fs *c, struct bch_read_bio *rbio,
 	iter = bch2_trans_get_iter(&trans, BTREE_ID_EXTENTS, POS_MIN,
 				   BTREE_ITER_SLOTS);
 
-	bchfs_read(c, iter, rbio, inum, NULL);
+	bchfs_read(&trans, iter, rbio, inum, NULL);
 
 	bch2_trans_exit(&trans);
 }
@@ -2098,7 +2100,7 @@ static int __bch2_fpunch(struct bch_fs *c, struct bch_inode_info *inode,
 				   BTREE_ITER_INTENT);
 
 	while ((k = bch2_btree_iter_peek(iter)).k &&
-	       !(ret = btree_iter_err(k)) &&
+	       !(ret = bkey_err(k)) &&
 	       bkey_cmp(iter->pos, end) < 0) {
 		struct disk_reservation disk_res =
 			bch2_disk_reservation_init(c, 0);
@@ -2437,14 +2439,14 @@ static long bch2_fcollapse(struct bch_inode_info *inode,
 
 		ret = bch2_btree_iter_traverse(dst);
 		if (ret)
-			goto btree_iter_err;
+			goto bkey_err;
 
 		bch2_btree_iter_set_pos(src,
 			POS(dst->pos.inode, dst->pos.offset + (len >> 9)));
 
 		k = bch2_btree_iter_peek_slot(src);
-		if ((ret = btree_iter_err(k)))
-			goto btree_iter_err;
+		if ((ret = bkey_err(k)))
+			goto bkey_err;
 
 		bkey_reassemble(&copy.k, k);
 
@@ -2465,7 +2467,7 @@ static long bch2_fcollapse(struct bch_inode_info *inode,
 				dst, &copy.k,
 				0, true, true, NULL);
 		bch2_disk_reservation_put(c, &disk_res);
-btree_iter_err:
+bkey_err:
 		if (ret == -EINTR)
 			ret = 0;
 		if (ret)
@@ -2559,8 +2561,8 @@ static long bch2_fallocate(struct bch_inode_info *inode, int mode,
 		struct bkey_s_c k;
 
 		k = bch2_btree_iter_peek_slot(iter);
-		if ((ret = btree_iter_err(k)))
-			goto btree_iter_err;
+		if ((ret = bkey_err(k)))
+			goto bkey_err;
 
 		/* already reserved */
 		if (k.k->type == KEY_TYPE_reservation &&
@@ -2591,7 +2593,7 @@ static long bch2_fallocate(struct bch_inode_info *inode, int mode,
 					&quota_res,
 					sectors, true);
 			if (unlikely(ret))
-				goto btree_iter_err;
+				goto bkey_err;
 		}
 
 		if (reservation.v.nr_replicas < replicas ||
@@ -2599,7 +2601,7 @@ static long bch2_fallocate(struct bch_inode_info *inode, int mode,
 			ret = bch2_disk_reservation_get(c, &disk_res, sectors,
 							replicas, 0);
 			if (unlikely(ret))
-				goto btree_iter_err;
+				goto bkey_err;
 
 			reservation.v.nr_replicas = disk_res.nr_replicas;
 		}
@@ -2608,7 +2610,7 @@ static long bch2_fallocate(struct bch_inode_info *inode, int mode,
 				&disk_res, &quota_res,
 				iter, &reservation.k_i,
 				0, true, true, NULL);
-btree_iter_err:
+bkey_err:
 		bch2_quota_reservation_put(c, inode, &quota_res);
 		bch2_disk_reservation_put(c, &disk_res);
 		if (ret == -EINTR)
diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index 41284d38db2f..c4d9d2761cdc 100644
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -33,9 +33,10 @@ static s64 bch2_count_inode_sectors(struct btree_trans *trans, u64 inum)
 	return bch2_trans_iter_free(trans, iter) ?: sectors;
 }
 
-static int remove_dirent(struct bch_fs *c, struct btree_iter *iter,
+static int remove_dirent(struct btree_trans *trans,
 			 struct bkey_s_c_dirent dirent)
 {
+	struct bch_fs *c = trans->c;
 	struct qstr name;
 	struct bch_inode_unpacked dir_inode;
 	struct bch_hash_info dir_hash_info;
@@ -52,8 +53,8 @@ static int remove_dirent(struct bch_fs *c, struct btree_iter *iter,
 	buf[name.len] = '\0';
 	name.name = buf;
 
-	/* Unlock iter so we don't deadlock, after copying name: */
-	bch2_btree_iter_unlock(iter);
+	/* Unlock so we don't deadlock, after copying name: */
+	bch2_btree_trans_unlock(trans);
 
 	ret = bch2_inode_find_by_inum(c, dir_inum, &dir_inode);
 	if (ret) {
@@ -143,29 +144,33 @@ static int walk_inode(struct bch_fs *c, struct inode_walker *w, u64 inum)
 
 struct hash_check {
 	struct bch_hash_info	info;
-	struct btree_trans	*trans;
 
 	/* start of current chain of hash collisions: */
 	struct btree_iter	*chain;
 
 	/* next offset in current chain of hash collisions: */
-	u64			next;
+	u64			chain_end;
 };
 
-static void hash_check_init(const struct bch_hash_desc desc,
-			    struct btree_trans *trans,
+static void hash_check_init(struct hash_check *h)
+{
+	h->chain = NULL;
+}
+
+static void hash_stop_chain(struct btree_trans *trans,
 			    struct hash_check *h)
 {
-	h->trans = trans;
-	h->chain = bch2_trans_get_iter(trans, desc.btree_id, POS_MIN, 0);
-	h->next = -1;
+	if (h->chain)
+		bch2_trans_iter_free(trans, h->chain);
+	h->chain = NULL;
 }
 
-static void hash_check_set_inode(struct hash_check *h, struct bch_fs *c,
+static void hash_check_set_inode(struct btree_trans *trans,
+				 struct hash_check *h,
 				 const struct bch_inode_unpacked *bi)
 {
-	h->info = bch2_hash_info_init(c, bi);
-	h->next = -1;
+	h->info = bch2_hash_info_init(trans->c, bi);
+	hash_stop_chain(trans, h);
 }
 
 static int hash_redo_key(const struct bch_hash_desc desc,
@@ -186,8 +191,6 @@ static int hash_redo_key(const struct bch_hash_desc desc,
 	if (ret)
 		goto err;
 
-	bch2_btree_iter_unlock(k_iter);
-
 	bch2_hash_set(trans, desc, &h->info, k_iter->pos.inode,
 		      tmp, BCH_HASH_SET_MUST_CREATE);
 	ret = bch2_trans_commit(trans, NULL, NULL,
@@ -232,7 +235,7 @@ static int hash_check_duplicates(struct btree_trans *trans,
 	if (!bkey_cmp(h->chain->pos, k_iter->pos))
 		return 0;
 
-	iter = bch2_trans_copy_iter(h->trans, h->chain);
+	iter = bch2_trans_copy_iter(trans, h->chain);
 	BUG_ON(IS_ERR(iter));
 
 	for_each_btree_key_continue(iter, 0, k2) {
@@ -252,23 +255,39 @@ static int hash_check_duplicates(struct btree_trans *trans,
 		}
 	}
 fsck_err:
-	bch2_trans_iter_free(h->trans, iter);
+	bch2_trans_iter_free(trans, iter);
 	return ret;
 }
 
-static bool key_has_correct_hash(const struct bch_hash_desc desc,
-				 struct hash_check *h, struct bch_fs *c,
-				 struct btree_iter *k_iter, struct bkey_s_c k)
+static void hash_set_chain_start(struct btree_trans *trans,
+			const struct bch_hash_desc desc,
+			struct hash_check *h,
+			struct btree_iter *k_iter, struct bkey_s_c k)
 {
-	u64 hash;
+	bool hole = (k.k->type != KEY_TYPE_whiteout &&
+		     k.k->type != desc.key_type);
 
-	if (k.k->type != KEY_TYPE_whiteout &&
-	    k.k->type != desc.key_type)
-		return true;
+	if (hole || k.k->p.offset > h->chain_end + 1)
+		hash_stop_chain(trans, h);
+
+	if (!hole) {
+		if (!h->chain) {
+			h->chain = bch2_trans_copy_iter(trans, k_iter);
+			BUG_ON(IS_ERR(h->chain));
+		}
+
+		h->chain_end = k.k->p.offset;
+	}
+}
+
+static bool key_has_correct_hash(struct btree_trans *trans,
+			const struct bch_hash_desc desc,
+			struct hash_check *h,
+			struct btree_iter *k_iter, struct bkey_s_c k)
+{
+	u64 hash;
 
-	if (k.k->p.offset != h->next)
-		bch2_btree_iter_copy(h->chain, k_iter);
-	h->next = k.k->p.offset + 1;
+	hash_set_chain_start(trans, desc, h, k_iter, k);
 
 	if (k.k->type != desc.key_type)
 		return true;
@@ -288,13 +307,7 @@ static int hash_check_key(struct btree_trans *trans,
 	u64 hashed;
 	int ret = 0;
 
-	if (k.k->type != KEY_TYPE_whiteout &&
-	    k.k->type != desc.key_type)
-		return 0;
-
-	if (k.k->p.offset != h->next)
-		bch2_btree_iter_copy(h->chain, k_iter);
-	h->next = k.k->p.offset + 1;
+	hash_set_chain_start(trans, desc, h, k_iter, k);
 
 	if (k.k->type != desc.key_type)
 		return 0;
@@ -332,7 +345,7 @@ static int check_dirent_hash(struct btree_trans *trans, struct hash_check *h,
 	unsigned len;
 	u64 hash;
 
-	if (key_has_correct_hash(bch2_dirent_hash_desc, h, c, iter, *k))
+	if (key_has_correct_hash(trans, bch2_dirent_hash_desc, h, iter, *k))
 		return 0;
 
 	len = bch2_dirent_name_bytes(bkey_s_c_to_dirent(*k));
@@ -526,7 +539,7 @@ static int check_dirents(struct bch_fs *c)
 	iter = bch2_trans_get_iter(&trans, BTREE_ID_DIRENTS,
 				   POS(BCACHEFS_ROOT_INO, 0), 0);
 
-	hash_check_init(bch2_dirent_hash_desc, &trans, &h);
+	hash_check_init(&h);
 
 	for_each_btree_key_continue(iter, 0, k) {
 		struct bkey_s_c_dirent d;
@@ -554,7 +567,7 @@ static int check_dirents(struct bch_fs *c)
 		}
 
 		if (w.first_this_inode && w.have_inode)
-			hash_check_set_inode(&h, c, &w.inode);
+			hash_check_set_inode(&trans, &h, &w.inode);
 
 		ret = check_dirent_hash(&trans, &h, iter, &k);
 		if (ret > 0) {
@@ -587,7 +600,7 @@ static int check_dirents(struct bch_fs *c)
 				".. dirent") ||
 		    fsck_err_on(memchr(d.v->d_name, '/', name_len), c,
 				"dirent name has invalid chars")) {
-			ret = remove_dirent(c, iter, d);
+			ret = remove_dirent(&trans, d);
 			if (ret)
 				goto err;
 			continue;
@@ -597,7 +610,7 @@ static int check_dirents(struct bch_fs *c)
 				"dirent points to own directory:\n%s",
 				(bch2_bkey_val_to_text(&PBUF(buf), c,
 						       k), buf))) {
-			ret = remove_dirent(c, iter, d);
+			ret = remove_dirent(&trans, d);
 			if (ret)
 				goto err;
 			continue;
@@ -614,7 +627,7 @@ static int check_dirents(struct bch_fs *c)
 				"dirent points to missing inode:\n%s",
 				(bch2_bkey_val_to_text(&PBUF(buf), c,
 						       k), buf))) {
-			ret = remove_dirent(c, iter, d);
+			ret = remove_dirent(&trans, d);
 			if (ret)
 				goto err;
 			continue;
@@ -650,6 +663,8 @@ static int check_dirents(struct bch_fs *c)
 
 		}
 	}
+
+	hash_stop_chain(&trans, &h);
 err:
 fsck_err:
 	return bch2_trans_exit(&trans) ?: ret;
@@ -677,7 +692,7 @@ static int check_xattrs(struct bch_fs *c)
 	iter = bch2_trans_get_iter(&trans, BTREE_ID_XATTRS,
 				   POS(BCACHEFS_ROOT_INO, 0), 0);
 
-	hash_check_init(bch2_xattr_hash_desc, &trans, &h);
+	hash_check_init(&h);
 
 	for_each_btree_key_continue(iter, 0, k) {
 		ret = walk_inode(c, &w, k.k->p.inode);
@@ -694,7 +709,7 @@ static int check_xattrs(struct bch_fs *c)
 		}
 
 		if (w.first_this_inode && w.have_inode)
-			hash_check_set_inode(&h, c, &w.inode);
+			hash_check_set_inode(&trans, &h, &w.inode);
 
 		ret = hash_check_key(&trans, bch2_xattr_hash_desc,
 				     &h, iter, k);
@@ -926,7 +941,7 @@ next:
 			if (fsck_err_on(inode_bitmap_test(&dirs_done, d_inum), c,
 					"directory %llu has multiple hardlinks",
 					d_inum)) {
-				ret = remove_dirent(c, iter, dirent);
+				ret = remove_dirent(&trans, dirent);
 				if (ret)
 					goto err;
 				continue;
@@ -972,7 +987,7 @@ up:
 		if (fsck_err_on(!inode_bitmap_test(&dirs_done, k.k->p.inode), c,
 				"unreachable directory found (inum %llu)",
 				k.k->p.inode)) {
-			bch2_btree_iter_unlock(iter);
+			bch2_btree_trans_unlock(&trans);
 
 			ret = reattach_inode(c, lostfound_inode, k.k->p.inode);
 			if (ret) {
@@ -1187,6 +1202,9 @@ static int check_inode(struct btree_trans *trans,
 	int ret = 0;
 
 	ret = bch2_inode_unpack(inode, &u);
+
+	bch2_btree_trans_unlock(trans);
+
 	if (bch2_fs_inconsistent_on(ret, c,
 			 "error unpacking inode %llu in fsck",
 			 inode.k->p.inode))
@@ -1306,7 +1324,7 @@ static int bch2_gc_walk_inodes(struct bch_fs *c,
 	nlinks_iter = genradix_iter_init(links, 0);
 
 	while ((k = bch2_btree_iter_peek(iter)).k &&
-	       !(ret2 = btree_iter_err(k))) {
+	       !(ret2 = bkey_err(k))) {
 peek_nlinks:	link = genradix_iter_peek(&nlinks_iter, links);
 
 		if (!link && (!k.k || iter->pos.inode >= range_end))
@@ -1326,12 +1344,6 @@ peek_nlinks:	link = genradix_iter_peek(&nlinks_iter, links);
 			link = &zero_links;
 
 		if (k.k && k.k->type == KEY_TYPE_inode) {
-			/*
-			 * Avoid potential deadlocks with iter for
-			 * truncate/rm/etc.:
-			 */
-			bch2_btree_iter_unlock(iter);
-
 			ret = check_inode(&trans, lostfound_inode, iter,
 					  bkey_s_c_to_inode(k), link);
 			BUG_ON(ret == -EINTR);
@@ -1402,7 +1414,7 @@ static int check_inodes_fast(struct bch_fs *c)
 	struct btree_iter *iter;
 	struct bkey_s_c k;
 	struct bkey_s_c_inode inode;
-	int ret = 0;
+	int ret = 0, ret2;
 
 	bch2_trans_init(&trans, c);
 
@@ -1426,12 +1438,9 @@ static int check_inodes_fast(struct bch_fs *c)
 		}
 	}
 
-	if (!ret)
-		ret = bch2_btree_iter_unlock(iter);
+	ret2 = bch2_trans_exit(&trans);
 
-	bch2_trans_exit(&trans);
-
-	return ret;
+	return ret ?: ret2;
 }
 
 /*
diff --git a/fs/bcachefs/inode.c b/fs/bcachefs/inode.c
index c6336e7a2a23..7be24865cc3f 100644
--- a/fs/bcachefs/inode.c
+++ b/fs/bcachefs/inode.c
@@ -323,7 +323,7 @@ again:
 	while (1) {
 		struct bkey_s_c k = bch2_btree_iter_peek_slot(iter);
 
-		ret = btree_iter_err(k);
+		ret = bkey_err(k);
 		if (ret)
 			return ret;
 
@@ -399,7 +399,7 @@ int bch2_inode_rm(struct bch_fs *c, u64 inode_nr)
 		struct bkey_s_c k = bch2_btree_iter_peek_slot(iter);
 		u32 bi_generation = 0;
 
-		ret = btree_iter_err(k);
+		ret = bkey_err(k);
 		if (ret)
 			break;
 
diff --git a/fs/bcachefs/io.c b/fs/bcachefs/io.c
index 62ee09121036..71481b9728f5 100644
--- a/fs/bcachefs/io.c
+++ b/fs/bcachefs/io.c
@@ -1279,7 +1279,7 @@ retry:
 	rbio->bio.bi_status = 0;
 
 	k = bch2_btree_iter_peek_slot(iter);
-	if (btree_iter_err(k))
+	if (bkey_err(k))
 		goto err;
 
 	bkey_reassemble(&tmp.k, k);
@@ -1332,7 +1332,7 @@ retry:
 
 		bkey_reassemble(&tmp.k, k);
 		k = bkey_i_to_s_c(&tmp.k);
-		bch2_btree_iter_unlock(iter);
+		bch2_btree_trans_unlock(&trans);
 
 		bytes = min_t(unsigned, bvec_iter.bi_size,
 			      (k.k->p.offset - bvec_iter.bi_sector) << 9);
@@ -1357,7 +1357,7 @@ retry:
 	 * If we get here, it better have been because there was an error
 	 * reading a btree node
 	 */
-	BUG_ON(!(iter->flags & BTREE_ITER_ERROR));
+	BUG_ON(!btree_iter_err(iter));
 	__bcache_io_error(c, "btree IO error");
 err:
 	rbio->bio.bi_status = BLK_STS_IOERR;
@@ -1893,7 +1893,7 @@ void bch2_read(struct bch_fs *c, struct bch_read_bio *rbio, u64 inode)
 		 */
 		bkey_reassemble(&tmp.k, k);
 		k = bkey_i_to_s_c(&tmp.k);
-		bch2_btree_iter_unlock(iter);
+		bch2_btree_trans_unlock(&trans);
 
 		bytes = min_t(unsigned, rbio->bio.bi_iter.bi_size,
 			      (k.k->p.offset - rbio->bio.bi_iter.bi_sector) << 9);
@@ -1915,7 +1915,7 @@ void bch2_read(struct bch_fs *c, struct bch_read_bio *rbio, u64 inode)
 	 * If we get here, it better have been because there was an error
 	 * reading a btree node
 	 */
-	BUG_ON(!(iter->flags & BTREE_ITER_ERROR));
+	BUG_ON(!btree_iter_err(iter));
 	bcache_io_error(c, &rbio->bio, "btree IO error");
 
 	bch2_trans_exit(&trans);
diff --git a/fs/bcachefs/migrate.c b/fs/bcachefs/migrate.c
index 2b63b07db2bc..98202fbabfaf 100644
--- a/fs/bcachefs/migrate.c
+++ b/fs/bcachefs/migrate.c
@@ -52,7 +52,7 @@ static int bch2_dev_usrdata_drop(struct bch_fs *c, unsigned dev_idx, int flags)
 
 
 	while ((k = bch2_btree_iter_peek(iter)).k &&
-	       !(ret = btree_iter_err(k))) {
+	       !(ret = bkey_err(k))) {
 		if (!bkey_extent_is_data(k.k) ||
 		    !bch2_extent_has_device(bkey_s_c_to_extent(k), dev_idx)) {
 			ret = bch2_mark_bkey_replicas(c, k);
diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
index 3f3e34e07f35..9793896bee77 100644
--- a/fs/bcachefs/move.c
+++ b/fs/bcachefs/move.c
@@ -77,7 +77,7 @@ static int bch2_migrate_index_update(struct bch_write_op *op)
 		bool did_work = false;
 		int nr;
 
-		ret = btree_iter_err(k);
+		ret = bkey_err(k);
 		if (ret)
 			break;
 
@@ -539,7 +539,7 @@ peek:
 
 		if (!k.k)
 			break;
-		ret = btree_iter_err(k);
+		ret = bkey_err(k);
 		if (ret)
 			break;
 		if (bkey_cmp(bkey_start_pos(k.k), end) >= 0)
diff --git a/fs/bcachefs/quota.c b/fs/bcachefs/quota.c
index f5dd13e92200..a4f75d53b42c 100644
--- a/fs/bcachefs/quota.c
+++ b/fs/bcachefs/quota.c
@@ -732,7 +732,7 @@ static int bch2_set_quota(struct super_block *sb, struct kqid qid,
 				   BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
 	k = bch2_btree_iter_peek_slot(iter);
 
-	ret = btree_iter_err(k);
+	ret = bkey_err(k);
 	if (unlikely(ret))
 		return ret;