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bcachefs: bch2_gc_btree() should not use btree_root_lock

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btree_root_lock is for the root keys in btree_root, not the pointers to
the nodes themselves; this fixes a lock ordering issue between
btree_root_lock and btree node locks.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-07-04 21:02:16 -04:00
parent f236ea4bca
commit 1841027c7d
1 changed files with 22 additions and 8 deletions
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30
fs/bcachefs/btree_gc.c
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@ -641,16 +641,30 @@ static int bch2_gc_btree(struct btree_trans *trans, enum btree_id btree, bool in
target_depth = 0;
/* root */
mutex_lock(&c->btree_root_lock);
struct btree *b = bch2_btree_id_root(c, btree)->b;
if (!btree_node_fake(b)) {
do {
retry_root:
bch2_trans_begin(trans);
struct btree_iter iter;
bch2_trans_node_iter_init(trans, &iter, btree, POS_MIN,
0, bch2_btree_id_root(c, btree)->b->c.level, 0);
struct btree *b = bch2_btree_iter_peek_node(&iter);
ret = PTR_ERR_OR_ZERO(b);
if (ret)
goto err_root;
if (b != btree_node_root(c, b)) {
bch2_trans_iter_exit(trans, &iter);
goto retry_root;
}
gc_pos_set(c, gc_pos_btree(btree, b->c.level + 1, SPOS_MAX));
ret = lockrestart_do(trans,
bch2_gc_mark_key(trans, b->c.btree_id, b->c.level + 1,
NULL, NULL, bkey_i_to_s_c(&b->key), initial));
struct bkey_s_c k = bkey_i_to_s_c(&b->key);
ret = bch2_gc_mark_key(trans, btree, b->c.level + 1, NULL, NULL, k, initial);
level = b->c.level;
}
mutex_unlock(&c->btree_root_lock);
err_root:
bch2_trans_iter_exit(trans, &iter);
} while (bch2_err_matches(ret, BCH_ERR_transaction_restart));
if (ret)
return ret;