diff options
| author | Kent Overstreet <kent.overstreet@gmail.com> | 2020-06-02 19:41:47 -0400 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2023-10-22 17:08:40 -0400 |
| commit | f96c0df4dbb0ed845bbc51f341d00bc90368c93c (patch) | |
| tree | e2e2caa6a99307007fc44f0167ec537896847c33 /fs/bcachefs/btree_iter.c | |
| parent | 495aabede3ff594c5eda98cb9f4463502cb48cad (diff) | |
bcachefs: Fix a deadlock in bch2_btree_node_get_sibling()
There was a bad interaction with bch2_btree_iter_set_pos_same_leaf(),
which can leave a btree node locked that is just outside iter->pos,
breaking the lock ordering checks in __bch2_btree_node_lock(). Ideally
we should get rid of this corner case, but for now fix it locally with
verbose comments.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/btree_iter.c')
| -rw-r--r-- | fs/bcachefs/btree_iter.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c index f7de2def58df..43ea3ceafcf2 100644 --- a/fs/bcachefs/btree_iter.c +++ b/fs/bcachefs/btree_iter.c @@ -205,8 +205,9 @@ bool __bch2_btree_node_lock(struct btree *b, struct bpos pos, if (!linked->nodes_locked) continue; - /* * Must lock btree nodes in key order: */ - if (__btree_iter_cmp(iter->btree_id, pos, linked) < 0) + /* Must lock btree nodes in key order: */ + if ((cmp_int(iter->btree_id, linked->btree_id) ?: + bkey_cmp(pos, linked->pos)) < 0) ret = false; /* @@ -1320,6 +1321,16 @@ void bch2_btree_iter_set_pos_same_leaf(struct btree_iter *iter, struct bpos new_ btree_iter_advance_to_pos(iter, l, -1); + /* + * XXX: + * keeping a node locked that's outside (even just outside) iter->pos + * breaks __bch2_btree_node_lock(). This seems to only affect + * bch2_btree_node_get_sibling so for now it's fixed there, but we + * should try to get rid of this corner case. + * + * (this behaviour is currently needed for BTREE_INSERT_NOUNLOCK) + */ + if (bch2_btree_node_iter_end(&l->iter) && btree_iter_pos_after_node(iter, l->b)) btree_iter_set_dirty(iter, BTREE_ITER_NEED_TRAVERSE); @@ -2195,6 +2206,7 @@ void bch2_trans_init(struct btree_trans *trans, struct bch_fs *c, bch2_trans_preload_mem(trans, expected_mem_bytes); #ifdef CONFIG_BCACHEFS_DEBUG + trans->pid = current->pid; mutex_lock(&c->btree_trans_lock); list_add(&trans->list, &c->btree_trans_list); mutex_unlock(&c->btree_trans_lock); @@ -2233,7 +2245,7 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct bch_fs *c) mutex_lock(&c->btree_trans_lock); list_for_each_entry(trans, &c->btree_trans_list, list) { - pr_buf(out, "%ps\n", (void *) trans->ip); + pr_buf(out, "%i %ps\n", trans->pid, (void *) trans->ip); trans_for_each_iter(trans, iter) { if (!iter->nodes_locked) |