From 5510a4af521c34df339fcceb0f26ace5b1090ad6 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Sun, 26 Nov 2023 18:31:11 -0500 Subject: [PATCH] bcachefs: Fix split_race livelock bch2_btree_update_start() calculates which nodes are going to have to be split/rewritten, so that we know how many nodes to reserve and how deep in the tree we have to take locks. But btree node merges require inserting two keys into the parent node, not just splits. Signed-off-by: Kent Overstreet --- fs/bcachefs/btree_update_interior.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/bcachefs/btree_update_interior.c b/fs/bcachefs/btree_update_interior.c index d08efd6d958e..d68fb01944b1 100644 --- a/fs/bcachefs/btree_update_interior.c +++ b/fs/bcachefs/btree_update_interior.c @@ -1071,8 +1071,12 @@ bch2_btree_update_start(struct btree_trans *trans, struct btree_path *path, break; } + /* + * Always check for space for two keys, even if we won't have to + * split at prior level - it might have been a merge instead: + */ if (bch2_btree_node_insert_fits(c, path->l[update_level].b, - BKEY_BTREE_PTR_U64s_MAX * (1 + split))) + BKEY_BTREE_PTR_U64s_MAX * 2)) break; split = path->l[update_level].b->nr.live_u64s > BTREE_SPLIT_THRESHOLD(c);