We may sometimes read from uninitialized memory; we know, and that's ok. We check if a btree node has been reused before waiting on any outstanding IO.
Signed-off-by: Kent Overstreet <[email protected]> --- fs/bcachefs/btree_update_interior.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/fs/bcachefs/btree_update_interior.c b/fs/bcachefs/btree_update_interior.c index d3e0cf01ba37..67f1e3202835 100644 --- a/fs/bcachefs/btree_update_interior.c +++ b/fs/bcachefs/btree_update_interior.c @@ -649,6 +649,14 @@ static int btree_update_nodes_written_trans(struct btree_trans *trans, return 0; } +/* If the node has been reused, we might be reading uninitialized memory - that's fine: */ +static noinline __no_kmsan_checks bool btree_node_seq_matches(struct btree *b, __le64 seq) +{ + struct btree_node *b_data = READ_ONCE(b->data); + + return (b_data ? b_data->keys.seq : 0) == seq; +} + static void btree_update_nodes_written(struct btree_update *as) { struct bch_fs *c = as->c; @@ -677,17 +685,9 @@ static void btree_update_nodes_written(struct btree_update *as) * on disk: */ for (i = 0; i < as->nr_old_nodes; i++) { - __le64 seq; - b = as->old_nodes[i]; - bch2_trans_begin(trans); - btree_node_lock_nopath_nofail(trans, &b->c, SIX_LOCK_read); - seq = b->data ? b->data->keys.seq : 0; - six_unlock_read(&b->c.lock); - bch2_trans_unlock_long(trans); - - if (seq == as->old_nodes_seq[i]) + if (btree_node_seq_matches(b, as->old_nodes_seq[i])) wait_on_bit_io(&b->flags, BTREE_NODE_write_in_flight_inner, TASK_UNINTERRUPTIBLE); } -- 2.49.0
