We may not need to pull in a btree node when walking backpointers - don't do so unnecessarily when using backpointer_get_key().
It'll still fall back to backpointer_get_node() in a few situations, including btree roots (where an iterator can't point at just the key), and races due to the interior update path not having deleted a backpointer to an old node yet. Signed-off-by: Kent Overstreet <[email protected]> --- fs/bcachefs/backpointers.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c index ebeb6a5ff9d2..655be2332742 100644 --- a/fs/bcachefs/backpointers.c +++ b/fs/bcachefs/backpointers.c @@ -244,27 +244,31 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans, if (unlikely(bp.v->btree_id >= btree_id_nr_alive(c))) return bkey_s_c_null; - if (likely(!bp.v->level)) { - bch2_trans_node_iter_init(trans, iter, - bp.v->btree_id, - bp.v->pos, - 0, 0, - iter_flags); - struct bkey_s_c k = bch2_btree_iter_peek_slot(iter); - if (bkey_err(k)) { - bch2_trans_iter_exit(trans, iter); - return k; - } + bch2_trans_node_iter_init(trans, iter, + bp.v->btree_id, + bp.v->pos, + 0, + bp.v->level, + iter_flags); + struct bkey_s_c k = bch2_btree_iter_peek_slot(iter); + if (bkey_err(k)) { + bch2_trans_iter_exit(trans, iter); + return k; + } - if (k.k && - extent_matches_bp(c, bp.v->btree_id, bp.v->level, k, bp)) - return k; + if (k.k && + extent_matches_bp(c, bp.v->btree_id, bp.v->level, k, bp)) + return k; - bch2_trans_iter_exit(trans, iter); + bch2_trans_iter_exit(trans, iter); + + if (!bp.v->level) { int ret = backpointer_target_not_found(trans, bp, k, last_flushed); return ret ? bkey_s_c_err(ret) : bkey_s_c_null; } else { struct btree *b = bch2_backpointer_get_node(trans, bp, iter, last_flushed); + if (b == ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node)) + return bkey_s_c_null; if (IS_ERR_OR_NULL(b)) return ((struct bkey_s_c) { .k = ERR_CAST(b) }); -- 2.45.2
