bcachefs: bch2_trans_get_iter() no longer returns errors

Since we now always preallocate the maximum number of iterators when we
initialize a btree transaction, getting an iterator never fails - we can
delete a fair amount of error path code.

This patch also simplifies the iterator allocation code a bit.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

12 files changed, 46 insertions, 222 deletions

diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 96cc5394295e..7a95fcc0b244 100644
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -346,7 +346,7 @@ void bch2_btree_trans_verify_locks(struct btree_trans *trans)
 {
 	struct btree_iter *iter;
 
-	trans_for_each_iter_all(trans, iter)
+	trans_for_each_iter(trans, iter)
 		bch2_btree_iter_verify_locks(iter);
 }
 #else
@@ -2002,110 +2002,37 @@ int bch2_trans_iter_free(struct btree_trans *trans,
 	return bch2_trans_iter_put(trans, iter);
 }
 
-#if 0
-static int bch2_trans_realloc_iters(struct btree_trans *trans,
-				    unsigned new_size)
+noinline __cold
+static void btree_trans_iter_alloc_fail(struct btree_trans *trans)
 {
-	void *p, *new_iters, *new_updates, *new_updates2;
-	size_t iters_bytes;
-	size_t updates_bytes;
-
-	new_size = roundup_pow_of_two(new_size);
-
-	BUG_ON(new_size > BTREE_ITER_MAX);
-
-	if (new_size <= trans->size)
-		return 0;
-
-	BUG_ON(trans->used_mempool);
-
-	bch2_trans_unlock(trans);
 
-	iters_bytes	= sizeof(struct btree_iter) * new_size;
-	updates_bytes	= sizeof(struct btree_insert_entry) * new_size;
-
-	p = kmalloc(iters_bytes +
-		    updates_bytes +
-		    updates_bytes, GFP_NOFS);
-	if (p)
-		goto success;
-
-	p = mempool_alloc(&trans->c->btree_iters_pool, GFP_NOFS);
-	new_size = BTREE_ITER_MAX;
-
-	trans->used_mempool = true;
-success:
-	new_iters	= p; p += iters_bytes;
-	new_updates	= p; p += updates_bytes;
-	new_updates2	= p; p += updates_bytes;
-
-	memcpy(new_iters, trans->iters,
-	       sizeof(struct btree_iter) * trans->nr_iters);
-	memcpy(new_updates, trans->updates,
-	       sizeof(struct btree_insert_entry) * trans->nr_updates);
-	memcpy(new_updates2, trans->updates2,
-	       sizeof(struct btree_insert_entry) * trans->nr_updates2);
-
-	if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG))
-		memset(trans->iters, POISON_FREE,
-		       sizeof(struct btree_iter) * trans->nr_iters +
-		       sizeof(struct btree_insert_entry) * trans->nr_iters);
-
-	kfree(trans->iters);
-
-	trans->iters		= new_iters;
-	trans->updates		= new_updates;
-	trans->updates2		= new_updates2;
-	trans->size		= new_size;
-
-	if (trans->iters_live) {
-		trace_trans_restart_iters_realloced(trans->ip, trans->size);
-		return -EINTR;
-	}
+	struct btree_iter *iter;
 
-	return 0;
+	trans_for_each_iter(trans, iter)
+		pr_err("iter: btree %s pos %llu:%llu%s%s%s %ps",
+		       bch2_btree_ids[iter->btree_id],
+		       iter->pos.inode,
+		       iter->pos.offset,
+		       (trans->iters_live & (1ULL << iter->idx)) ? " live" : "",
+		       (trans->iters_touched & (1ULL << iter->idx)) ? " touched" : "",
+		       iter->flags & BTREE_ITER_KEEP_UNTIL_COMMIT ? " keep" : "",
+		       (void *) iter->ip_allocated);
+	panic("trans iter oveflow\n");
 }
-#endif
 
 static struct btree_iter *btree_trans_iter_alloc(struct btree_trans *trans)
 {
-	unsigned idx = __ffs64(~trans->iters_linked);
-
-	if (idx < trans->nr_iters)
-		goto got_slot;
-
-	if (trans->nr_iters == trans->size) {
-		struct btree_iter *iter;
-
-		BUG_ON(trans->size < BTREE_ITER_MAX);
-
-		trans_for_each_iter(trans, iter) {
-			pr_err("iter: btree %s pos %llu:%llu%s%s%s %ps",
-			       bch2_btree_ids[iter->btree_id],
-			       iter->pos.inode,
-			       iter->pos.offset,
-			       (trans->iters_live & (1ULL << iter->idx)) ? " live" : "",
-			       (trans->iters_touched & (1ULL << iter->idx)) ? " touched" : "",
-			       iter->flags & BTREE_ITER_KEEP_UNTIL_COMMIT ? " keep" : "",
-			       (void *) iter->ip_allocated);
-		}
+	unsigned idx;
 
-		panic("trans iter oveflow\n");
-#if 0
-		ret = bch2_trans_realloc_iters(trans, trans->size * 2);
-		if (ret)
-			return ERR_PTR(ret);
-#endif
-	}
+	if (unlikely(trans->iters_linked ==
+		     ~((~0ULL << 1) << (BTREE_ITER_MAX - 1))))
+		btree_trans_iter_alloc_fail(trans);
 
-	idx = trans->nr_iters++;
-	BUG_ON(trans->nr_iters > trans->size);
+	idx = __ffs64(~trans->iters_linked);
 
-	trans->iters[idx].idx = idx;
-got_slot:
-	BUG_ON(trans->iters_linked & (1ULL << idx));
-	trans->iters_linked |= 1ULL << idx;
-	trans->iters[idx].flags = 0;
+	trans->iters_linked	|= 1ULL << idx;
+	trans->iters[idx].idx	 = idx;
+	trans->iters[idx].flags	 = 0;
 	return &trans->iters[idx];
 }
 
@@ -2141,8 +2068,6 @@ static struct btree_iter *__btree_trans_get_iter(struct btree_trans *trans,
 {
 	struct btree_iter *iter, *best = NULL;
 
-	BUG_ON(trans->nr_iters > BTREE_ITER_MAX);
-
 	trans_for_each_iter(trans, iter) {
 		if (btree_iter_type(iter) != (flags & BTREE_ITER_TYPE))
 			continue;
@@ -2160,16 +2085,10 @@ static struct btree_iter *__btree_trans_get_iter(struct btree_trans *trans,
 
 	if (!best) {
 		iter = btree_trans_iter_alloc(trans);
-		if (IS_ERR(iter))
-			return iter;
-
 		bch2_btree_iter_init(trans, iter, btree_id, pos, flags);
 	} else if ((trans->iters_live & (1ULL << best->idx)) ||
 		   (best->flags & BTREE_ITER_KEEP_UNTIL_COMMIT)) {
 		iter = btree_trans_iter_alloc(trans);
-		if (IS_ERR(iter))
-			return iter;
-
 		btree_iter_copy(iter, best);
 	} else {
 		iter = best;
@@ -2203,9 +2122,8 @@ struct btree_iter *__bch2_trans_get_iter(struct btree_trans *trans,
 	struct btree_iter *iter =
 		__btree_trans_get_iter(trans, btree_id, pos, flags);
 
-	if (!IS_ERR(iter))
-		__bch2_btree_iter_set_pos(iter, pos,
-			btree_node_type_is_extents(btree_id));
+	__bch2_btree_iter_set_pos(iter, pos,
+		btree_node_type_is_extents(btree_id));
 	return iter;
 }
 
@@ -2221,7 +2139,6 @@ struct btree_iter *bch2_trans_get_node_iter(struct btree_trans *trans,
 				       flags|BTREE_ITER_NODES);
 	unsigned i;
 
-	BUG_ON(IS_ERR(iter));
 	BUG_ON(bkey_cmp(iter->pos, pos));
 
 	iter->locks_want = locks_want;
@@ -2241,9 +2158,6 @@ struct btree_iter *__bch2_trans_copy_iter(struct btree_trans *trans,
 	struct btree_iter *iter;
 
 	iter = btree_trans_iter_alloc(trans);
-	if (IS_ERR(iter))
-		return iter;
-
 	btree_iter_copy(iter, src);
 
 	trans->iters_live |= 1ULL << iter->idx;
@@ -2318,7 +2232,6 @@ void bch2_trans_reset(struct btree_trans *trans, unsigned flags)
 
 	trans->iters_touched &= trans->iters_live;
 
-	trans->need_reset		= 0;
 	trans->nr_updates		= 0;
 	trans->nr_updates2		= 0;
 	trans->mem_top			= 0;
@@ -2339,9 +2252,8 @@ void bch2_trans_reset(struct btree_trans *trans, unsigned flags)
 
 static void bch2_trans_alloc_iters(struct btree_trans *trans, struct bch_fs *c)
 {
-	unsigned new_size = BTREE_ITER_MAX;
-	size_t iters_bytes	= sizeof(struct btree_iter) * new_size;
-	size_t updates_bytes	= sizeof(struct btree_insert_entry) * new_size;
+	size_t iters_bytes	= sizeof(struct btree_iter) * BTREE_ITER_MAX;
+	size_t updates_bytes	= sizeof(struct btree_insert_entry) * BTREE_ITER_MAX;
 	void *p = NULL;
 
 	BUG_ON(trans->used_mempool);
@@ -2355,7 +2267,6 @@ static void bch2_trans_alloc_iters(struct btree_trans *trans, struct bch_fs *c)
 	trans->iters		= p; p += iters_bytes;
 	trans->updates		= p; p += updates_bytes;
 	trans->updates2		= p; p += updates_bytes;
-	trans->size		= new_size;
 }
 
 void bch2_trans_init(struct btree_trans *trans, struct bch_fs *c,
diff --git a/fs/bcachefs/btree_iter.h b/fs/bcachefs/btree_iter.h
index f7a73619c85b..ee8c4346aadb 100644
--- a/fs/bcachefs/btree_iter.h
+++ b/fs/bcachefs/btree_iter.h
@@ -48,21 +48,16 @@ static inline int btree_iter_err(const struct btree_iter *iter)
 
 /* Iterate over iters within a transaction: */
 
-#define trans_for_each_iter_all(_trans, _iter)				\
-	for (_iter = (_trans)->iters;					\
-	     _iter < (_trans)->iters + (_trans)->nr_iters;		\
-	     _iter++)
-
 static inline struct btree_iter *
 __trans_next_iter(struct btree_trans *trans, unsigned idx)
 {
-	EBUG_ON(idx < trans->nr_iters && trans->iters[idx].idx != idx);
-
-	for (; idx < trans->nr_iters; idx++)
-		if (trans->iters_linked & (1ULL << idx))
-			return &trans->iters[idx];
+	u64 l = trans->iters_linked >> idx;
+	if (!l)
+		return NULL;
 
-	return NULL;
+	idx += __ffs64(l);
+	EBUG_ON(trans->iters[idx].idx != idx);
+	return &trans->iters[idx];
 }
 
 #define trans_for_each_iter(_trans, _iter)				\
@@ -240,10 +235,9 @@ static inline int bkey_err(struct bkey_s_c k)
 
 #define for_each_btree_key(_trans, _iter, _btree_id,			\
 			   _start, _flags, _k, _ret)			\
-	for ((_ret) = PTR_ERR_OR_ZERO((_iter) =				\
-			bch2_trans_get_iter((_trans), (_btree_id),	\
-					    (_start), (_flags))) ?:	\
-		      PTR_ERR_OR_ZERO(((_k) =				\
+	for ((_iter) = bch2_trans_get_iter((_trans), (_btree_id),	\
+					   (_start), (_flags)),		\
+	     (_ret) = PTR_ERR_OR_ZERO(((_k) =				\
 			__bch2_btree_iter_peek(_iter, _flags)).k);	\
 	     !_ret && (_k).k;						\
 	     (_ret) = PTR_ERR_OR_ZERO(((_k) =				\
@@ -270,9 +264,7 @@ bch2_trans_get_iter(struct btree_trans *trans, enum btree_id btree_id,
 {
 	struct btree_iter *iter =
 		__bch2_trans_get_iter(trans, btree_id, pos, flags);
-
-	if (!IS_ERR(iter))
-		iter->ip_allocated = _THIS_IP_;
+	iter->ip_allocated = _THIS_IP_;
 	return iter;
 }
 
@@ -284,10 +276,8 @@ bch2_trans_copy_iter(struct btree_trans *trans, struct btree_iter *src)
 	struct btree_iter *iter =
 		__bch2_trans_copy_iter(trans, src);
 
-	if (!IS_ERR(iter))
-		iter->ip_allocated = _THIS_IP_;
+	iter->ip_allocated = _THIS_IP_;
 	return iter;
-
 }
 
 struct btree_iter *bch2_trans_get_node_iter(struct btree_trans *,
diff --git a/fs/bcachefs/btree_key_cache.c b/fs/bcachefs/btree_key_cache.c
index 3ed7d3778aca..c3fead003a23 100644
--- a/fs/bcachefs/btree_key_cache.c
+++ b/fs/bcachefs/btree_key_cache.c
@@ -169,9 +169,6 @@ static int btree_key_cache_fill(struct btree_trans *trans,
 
 	iter = bch2_trans_get_iter(trans, ck->key.btree_id,
 				   ck->key.pos, BTREE_ITER_SLOTS);
-	if (IS_ERR(iter))
-		return PTR_ERR(iter);
-
 	k = bch2_btree_iter_peek_slot(iter);
 	ret = bkey_err(k);
 	if (ret) {
@@ -325,18 +322,11 @@ static int btree_key_cache_flush_pos(struct btree_trans *trans,
 	b_iter = bch2_trans_get_iter(trans, key.btree_id, key.pos,
 				     BTREE_ITER_SLOTS|
 				     BTREE_ITER_INTENT);
-	ret = PTR_ERR_OR_ZERO(b_iter);
-	if (ret)
-		goto out;
-
 	c_iter = bch2_trans_get_iter(trans, key.btree_id, key.pos,
 				     BTREE_ITER_CACHED|
 				     BTREE_ITER_CACHED_NOFILL|
 				     BTREE_ITER_CACHED_NOCREATE|
 				     BTREE_ITER_INTENT);
-	ret = PTR_ERR_OR_ZERO(c_iter);
-	if (ret)
-		goto out;
 retry:
 	ret = bch2_btree_iter_traverse(c_iter);
 	if (ret)
diff --git a/fs/bcachefs/btree_types.h b/fs/bcachefs/btree_types.h
index cf59f1224741..15af60e92820 100644
--- a/fs/bcachefs/btree_types.h
+++ b/fs/bcachefs/btree_types.h
@@ -357,20 +357,17 @@ struct btree_trans {
 	unsigned long		ip;
 	int			srcu_idx;
 
-	u64			iters_linked;
-	u64			iters_live;
-	u64			iters_touched;
-
-	u8			nr_iters;
 	u8			nr_updates;
 	u8			nr_updates2;
-	u8			size;
 	unsigned		used_mempool:1;
 	unsigned		error:1;
 	unsigned		nounlock:1;
-	unsigned		need_reset:1;
 	unsigned		in_traverse_all:1;
 
+	u64			iters_linked;
+	u64			iters_live;
+	u64			iters_touched;
+
 	unsigned		mem_top;
 	unsigned		mem_bytes;
 	void			*mem;
diff --git a/fs/bcachefs/btree_update_leaf.c b/fs/bcachefs/btree_update_leaf.c
index d1196ce70058..f35cdbfb43c5 100644
--- a/fs/bcachefs/btree_update_leaf.c
+++ b/fs/bcachefs/btree_update_leaf.c
@@ -717,7 +717,7 @@ static void bch2_trans_update2(struct btree_trans *trans,
 
 	BUG_ON(iter->uptodate > BTREE_ITER_NEED_PEEK);
 
-	EBUG_ON(trans->nr_updates2 >= trans->nr_iters);
+	EBUG_ON(trans->nr_updates2 >= BTREE_ITER_MAX);
 
 	iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
 
@@ -750,8 +750,6 @@ static int extent_update_to_keys(struct btree_trans *trans,
 		return 0;
 
 	iter = bch2_trans_copy_iter(trans, orig_iter);
-	if (IS_ERR(iter))
-		return PTR_ERR(iter);
 
 	iter->flags |= BTREE_ITER_INTENT;
 	__bch2_btree_iter_set_pos(iter, insert->k.p, false);
@@ -770,10 +768,6 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 	int ret = 0;
 
 	iter = bch2_trans_get_iter(trans, btree_id, start, BTREE_ITER_INTENT);
-	ret = PTR_ERR_OR_ZERO(iter);
-	if (ret)
-		return ret;
-
 	k = bch2_btree_iter_peek_with_updates(iter);
 
 	while (k.k && !(ret = bkey_err(k))) {
@@ -782,8 +776,6 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 
 		if (bkey_cmp(bkey_start_pos(k.k), start) < 0) {
 			update_iter = bch2_trans_copy_iter(trans, iter);
-			if ((ret = PTR_ERR_OR_ZERO(update_iter)))
-				goto err;
 
 			update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
 			if ((ret = PTR_ERR_OR_ZERO(update)))
@@ -799,8 +791,6 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 
 		if (bkey_cmp(k.k->p, end) > 0) {
 			update_iter = bch2_trans_copy_iter(trans, iter);
-			if ((ret = PTR_ERR_OR_ZERO(update_iter)))
-				goto err;
 
 			update = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
 			if ((ret = PTR_ERR_OR_ZERO(update)))
@@ -814,8 +804,6 @@ static int extent_handle_overwrites(struct btree_trans *trans,
 			bch2_trans_iter_put(trans, update_iter);
 		} else {
 			update_iter = bch2_trans_copy_iter(trans, iter);
-			if ((ret = PTR_ERR_OR_ZERO(update_iter)))
-				goto err;
 
 			update = bch2_trans_kmalloc(trans, sizeof(struct bkey));
 			if ((ret = PTR_ERR_OR_ZERO(update)))
@@ -847,8 +835,6 @@ int __bch2_trans_commit(struct btree_trans *trans)
 	unsigned u64s;
 	int ret = 0;
 
-	BUG_ON(trans->need_reset);
-
 	if (!trans->nr_updates)
 		goto out_noupdates;
 
@@ -1041,10 +1027,6 @@ int bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
 		 */
 		if (trans->iters_live & (1ULL << i->iter->idx)) {
 			i->iter = bch2_trans_copy_iter(trans, i->iter);
-			if (IS_ERR(i->iter)) {
-				trans->need_reset = true;
-				return PTR_ERR(i->iter);
-			}
 
 			i->iter->flags |= BTREE_ITER_KEEP_UNTIL_COMMIT;
 			bch2_trans_iter_put(trans, i->iter);
@@ -1054,7 +1036,7 @@ int bch2_trans_update(struct btree_trans *trans, struct btree_iter *iter,
 		bch2_btree_iter_set_pos(i->iter, n.k->k.p);
 	}
 
-	EBUG_ON(trans->nr_updates >= trans->nr_iters);
+	EBUG_ON(trans->nr_updates >= BTREE_ITER_MAX);
 
 	array_insert_item(trans->updates, trans->nr_updates,
 			  i - trans->updates, n);
@@ -1069,8 +1051,6 @@ int __bch2_btree_insert(struct btree_trans *trans,
 
 	iter = bch2_trans_get_iter(trans, id, bkey_start_pos(&k->k),
 				   BTREE_ITER_INTENT);
-	if (IS_ERR(iter))
-		return PTR_ERR(iter);
 
 	ret   = bch2_btree_iter_traverse(iter) ?:
 		bch2_trans_update(trans, iter, k, 0);
@@ -1117,9 +1097,6 @@ int bch2_btree_delete_range_trans(struct btree_trans *trans, enum btree_id id,
 	int ret = 0;
 
 	iter = bch2_trans_get_iter(trans, id, start, BTREE_ITER_INTENT);
-	ret = PTR_ERR_OR_ZERO(iter);
-	if (ret)
-		return ret;
 retry:
 	while ((k = bch2_btree_iter_peek(iter)).k &&
 	       !(ret = bkey_err(k)) &&
diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c
index be65f2e78a62..1b1200c55134 100644
--- a/fs/bcachefs/buckets.c
+++ b/fs/bcachefs/buckets.c
@@ -1576,9 +1576,6 @@ static int trans_get_key(struct btree_trans *trans,
 
 	*iter = bch2_trans_get_iter(trans, btree_id, pos,
 				    flags|BTREE_ITER_INTENT);
-	if (IS_ERR(*iter))
-		return PTR_ERR(*iter);
-
 	*k = __bch2_btree_iter_peek(*iter, flags);
 	ret = bkey_err(*k);
 	if (ret)
@@ -1606,9 +1603,6 @@ static int bch2_trans_start_alloc_update(struct btree_trans *trans, struct btree
 					   BTREE_ITER_CACHED|
 					   BTREE_ITER_CACHED_NOFILL|
 					   BTREE_ITER_INTENT);
-		if (IS_ERR(iter))
-			return PTR_ERR(iter);
-
 		ret = bch2_btree_iter_traverse(iter);
 		if (ret) {
 			bch2_trans_iter_put(trans, iter);
diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c
index fe3dd53ab51a..4acf71cce7e8 100644
--- a/fs/bcachefs/fs-io.c
+++ b/fs/bcachefs/fs-io.c
@@ -2492,10 +2492,7 @@ static long bchfs_fcollapse_finsert(struct bch_inode_info *inode,
 	src = bch2_trans_get_iter(&trans, BTREE_ID_EXTENTS,
 			POS(inode->v.i_ino, src_start >> 9),
 			BTREE_ITER_INTENT);
-	BUG_ON(IS_ERR_OR_NULL(src));
-
 	dst = bch2_trans_copy_iter(&trans, src);
-	BUG_ON(IS_ERR_OR_NULL(dst));
 
 	while (1) {
 		struct disk_reservation disk_res =
diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index 7449819d8eac..39f872de0c18 100644
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -230,7 +230,6 @@ static int hash_check_duplicates(struct btree_trans *trans,
 		return 0;
 
 	iter = bch2_trans_copy_iter(trans, h->chain);
-	BUG_ON(IS_ERR(iter));
 
 	for_each_btree_key_continue(iter, 0, k2, ret) {
 		if (bkey_cmp(k2.k->p, k.k->p) >= 0)
@@ -265,10 +264,8 @@ static void hash_set_chain_start(struct btree_trans *trans,
 		hash_stop_chain(trans, h);
 
 	if (!hole) {
-		if (!h->chain) {
+		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;
 	}
@@ -440,9 +437,6 @@ static int bch2_fix_overlapping_extent(struct btree_trans *trans,
 	bch2_cut_front(cut_at, u);
 
 	u_iter = bch2_trans_copy_iter(trans, iter);
-	ret = PTR_ERR_OR_ZERO(u_iter);
-	if (ret)
-		return ret;
 
 	/*
 	 * We don't want to go through the
diff --git a/fs/bcachefs/inode.c b/fs/bcachefs/inode.c
index 82099e5a48d8..bf1c7319669c 100644
--- a/fs/bcachefs/inode.c
+++ b/fs/bcachefs/inode.c
@@ -302,9 +302,6 @@ struct btree_iter *bch2_inode_peek(struct btree_trans *trans,
 
 	iter = bch2_trans_get_iter(trans, BTREE_ID_INODES, POS(0, inum),
 				   BTREE_ITER_CACHED|flags);
-	if (IS_ERR(iter))
-		return iter;
-
 	k = bch2_btree_iter_peek_cached(iter);
 	ret = bkey_err(k);
 	if (ret)
@@ -640,9 +637,6 @@ int bch2_inode_find_by_inum_trans(struct btree_trans *trans, u64 inode_nr,
 
 	iter = bch2_trans_get_iter(trans, BTREE_ID_INODES,
 			POS(0, inode_nr), BTREE_ITER_CACHED);
-	if (IS_ERR(iter))
-		return PTR_ERR(iter);
-
 	k = bch2_btree_iter_peek_cached(iter);
 	ret = bkey_err(k);
 	if (ret)
diff --git a/fs/bcachefs/io.c b/fs/bcachefs/io.c
index b61964a27544..4549629ac002 100644
--- a/fs/bcachefs/io.c
+++ b/fs/bcachefs/io.c
@@ -197,8 +197,6 @@ static int sum_sector_overwrites(struct btree_trans *trans,
 	*delta = 0;
 
 	iter = bch2_trans_copy_iter(trans, extent_iter);
-	if (IS_ERR(iter))
-		return PTR_ERR(iter);
 
 	for_each_btree_key_continue(iter, BTREE_ITER_SLOTS, old, ret) {
 		if (!may_allocate &&
@@ -1789,9 +1787,6 @@ static int __bch2_rbio_narrow_crcs(struct btree_trans *trans,
 
 	iter = bch2_trans_get_iter(trans, BTREE_ID_EXTENTS, rbio->pos,
 				   BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
-	if ((ret = PTR_ERR_OR_ZERO(iter)))
-		goto out;
-
 	k = bch2_btree_iter_peek_slot(iter);
 	if ((ret = bkey_err(k)))
 		goto out;
@@ -1999,10 +1994,6 @@ int __bch2_read_indirect_extent(struct btree_trans *trans,
 	iter = bch2_trans_get_iter(trans, BTREE_ID_REFLINK,
 				   POS(0, reflink_offset),
 				   BTREE_ITER_SLOTS);
-	ret = PTR_ERR_OR_ZERO(iter);
-	if (ret)
-		return ret;
-
 	k = bch2_btree_iter_peek_slot(iter);
 	ret = bkey_err(k);
 	if (ret)
diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
index a837d9eb0f6d..d24cef2bf1aa 100644
--- a/fs/bcachefs/recovery.c
+++ b/fs/bcachefs/recovery.c
@@ -443,9 +443,6 @@ retry:
 		bch2_cut_back(atomic_end, split);
 
 		split_iter = bch2_trans_copy_iter(&trans, iter);
-		ret = PTR_ERR_OR_ZERO(split_iter);
-		if (ret)
-			goto err;
 
 		/*
 		 * It's important that we don't go through the
@@ -502,8 +499,6 @@ static int __bch2_journal_replay_key(struct btree_trans *trans,
 	iter = bch2_trans_get_node_iter(trans, id, k->k.p,
 					BTREE_MAX_DEPTH, level,
 					BTREE_ITER_INTENT);
-	if (IS_ERR(iter))
-		return PTR_ERR(iter);
 
 	/*
 	 * iter->flags & BTREE_ITER_IS_EXTENTS triggers the update path to run
@@ -538,8 +533,7 @@ static int __bch2_alloc_replay_key(struct btree_trans *trans, struct bkey_i *k)
 				   BTREE_ITER_CACHED|
 				   BTREE_ITER_CACHED_NOFILL|
 				   BTREE_ITER_INTENT);
-	ret =   PTR_ERR_OR_ZERO(iter) ?:
-		bch2_trans_update(trans, iter, k, BTREE_TRIGGER_NORUN);
+	ret = bch2_trans_update(trans, iter, k, BTREE_TRIGGER_NORUN);
 	bch2_trans_iter_put(trans, iter);
 	return ret;
 }
diff --git a/fs/bcachefs/str_hash.h b/fs/bcachefs/str_hash.h
index dea9b7252b88..1ecf72c9487c 100644
--- a/fs/bcachefs/str_hash.h
+++ b/fs/bcachefs/str_hash.h
@@ -205,8 +205,6 @@ int bch2_hash_needs_whiteout(struct btree_trans *trans,
 	int ret;
 
 	iter = bch2_trans_copy_iter(trans, start);
-	if (IS_ERR(iter))
-		return PTR_ERR(iter);
 
 	bch2_btree_iter_next_slot(iter);
 
@@ -253,11 +251,8 @@ int bch2_hash_set(struct btree_trans *trans,
 		}
 
 		if (!slot &&
-		    !(flags & BCH_HASH_SET_MUST_REPLACE)) {
+		    !(flags & BCH_HASH_SET_MUST_REPLACE))
 			slot = bch2_trans_copy_iter(trans, iter);
-			if (IS_ERR(slot))
-				return PTR_ERR(slot);
-		}
 
 		if (k.k->type != KEY_TYPE_whiteout)
 			goto not_found;