diff options
| author | Kent Overstreet <kent.overstreet@linux.dev> | 2025-05-10 21:42:37 +0300 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2025-05-15 00:05:19 +0300 |
| commit | b1c71cb492bb26dc883b11b5bd085d2467508f84 (patch) | |
| tree | 02cddd08af95e0a26eabc7a7f95646e94bc7020e | |
| parent | cd52cc3544e400e53e6d4b7bfc5263e7a867b5ab (diff) | |
| download | linux-b1c71cb492bb26dc883b11b5bd085d2467508f84.tar.xz | |
bcachefs: Fix broken btree_path lock invariants in next_node()
This fixes btree locking assert pops users were seeing during evacuate:
https://github.com/koverstreet/bcachefs/issues/878
May 09 22:45:02 sharon kernel: bcachefs (68116e25-fa2d-4c6f-86c7-e8b431d792ae): bch2_btree_insert_node(): node not locked at level 1
May 09 22:45:02 sharon kernel: bch2_btree_node_rewrite [bcachefs]: watermark=btree no_check_rw alloc l=0-1 mode=none nodes_written=0 cl.remaining=2 journal_seq=0
May 09 22:45:02 sharon kernel: path: idx 1 ref 1:0 S B btree=alloc level=0 pos 0:3699637:0 0:3698012:1-0:3699637:0 bch2_move_btree.isra.0+0x1db/0x490 [bcachefs] uptodate 0 locks_want 2
May 09 22:45:02 sharon kernel: l=0 locks intent seq 4 node ffff8bd700c93600
May 09 22:45:02 sharon kernel: l=1 locks unlocked seq 1712 node ffff8bd6fd5e7a00
May 09 22:45:02 sharon kernel: l=2 locks unlocked seq 2295 node ffff8bd6cc725400
May 09 22:45:02 sharon kernel: l=3 locks unlocked seq 0 node 0000000000000000
Evacuate walks btree nodes with bch2_btree_iter_next_node() and rewrites
them, bch2_btree_update_start() upgrades the path to take intent locks
as far as it needs to.
But next_node() does low level unlock/relock calls on individual nodes,
and didn't handle the case where a path is supposed to be holding
multiple intent locks. If a path has locks_want > 1, it needs to be
either holding locks on all the btree nodes (at each level) requested,
or none of them.
Fix this with a bch2_btree_path_downgrade().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
| -rw-r--r-- | fs/bcachefs/btree_iter.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c index 59fa527ac685..9c9bc7b6c712 100644 --- a/fs/bcachefs/btree_iter.c +++ b/fs/bcachefs/btree_iter.c @@ -1971,6 +1971,12 @@ struct btree *bch2_btree_iter_next_node(struct btree_trans *trans, struct btree_ return NULL; } + /* + * We don't correctly handle nodes with extra intent locks here: + * downgrade so we don't violate locking invariants + */ + bch2_btree_path_downgrade(trans, path); + if (!bch2_btree_node_relock(trans, path, path->level + 1)) { __bch2_btree_path_unlock(trans, path); path->l[path->level].b = ERR_PTR(-BCH_ERR_no_btree_node_relock); |