Commit 2b3e79fe authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Don't use bch2_btree_node_lock_write_nofail() in btree split path 



It turns out - btree splits happen with the rest of the transaction
still locked, to avoid unnecessary restarts, which means using nofail
doesn't work here - we can deadlock.

Fortunately, we now have the ability to return errors here.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 1189bdda

fs/bcachefs/btree_update_interior.c

+26 −15
Original line number Diff line number Diff line
@@ -1280,23 +1280,29 @@ static void bch2_btree_set_root_inmem(struct bch_fs *c, struct btree *b) 
	bch2_recalc_btree_reserve(c);

}



static void bch2_btree_set_root(struct btree_update *as,

static int bch2_btree_set_root(struct btree_update *as,

			       struct btree_trans *trans,

			       struct btree_path *path,

				struct btree *b)

			       struct btree *b,

			       bool nofail)

{

	struct bch_fs *c = as->c;

	struct btree *old;



	trace_and_count(c, btree_node_set_root, trans, b);



	old = btree_node_root(c, b);

	struct btree *old = btree_node_root(c, b);



	/*

	 * Ensure no one is using the old root while we switch to the

	 * new root:

	 */

	if (nofail) {

		bch2_btree_node_lock_write_nofail(trans, path, &old->c);

	} else {

		int ret = bch2_btree_node_lock_write(trans, path, &old->c);

		if (ret)

			return ret;

	}



	bch2_btree_set_root_inmem(c, b);
@@ -1310,6 +1316,7 @@ static void bch2_btree_set_root(struct btree_update *as, 
	 * depend on the new root would have to update the new root.

	 */

	bch2_btree_node_unlock_write(trans, path, old);

	return 0;

}



/* Interior node updates: */
@@ -1652,15 +1659,16 @@ static int btree_split(struct btree_update *as, struct btree_trans *trans, 
	if (parent) {

		/* Split a non root node */

		ret = bch2_btree_insert_node(as, trans, path, parent, &as->parent_keys);

		if (ret)

			goto err;

	} else if (n3) {

		bch2_btree_set_root(as, trans, trans->paths + path, n3);

		ret = bch2_btree_set_root(as, trans, trans->paths + path, n3, false);

	} else {

		/* Root filled up but didn't need to be split */

		bch2_btree_set_root(as, trans, trans->paths + path, n1);

		ret = bch2_btree_set_root(as, trans, trans->paths + path, n1, false);

	}



	if (ret)

		goto err;



	if (n3) {

		bch2_btree_update_get_open_buckets(as, n3);

		bch2_btree_node_write(c, n3, SIX_LOCK_intent, 0);
@@ -1863,7 +1871,9 @@ static void __btree_increase_depth(struct btree_update *as, struct btree_trans * 
	bch2_keylist_add(&as->parent_keys, &b->key);

	btree_split_insert_keys(as, trans, path_idx, n, &as->parent_keys);



	bch2_btree_set_root(as, trans, path, n);

	int ret = bch2_btree_set_root(as, trans, path, n, true);

	BUG_ON(ret);



	bch2_btree_update_get_open_buckets(as, n);

	bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);

	bch2_trans_node_add(trans, path, n);
@@ -2106,12 +2116,13 @@ int bch2_btree_node_rewrite(struct btree_trans *trans, 
	if (parent) {

		bch2_keylist_add(&as->parent_keys, &n->key);

		ret = bch2_btree_insert_node(as, trans, iter->path, parent, &as->parent_keys);

		if (ret)

			goto err;

	} else {

		bch2_btree_set_root(as, trans, btree_iter_path(trans, iter), n);

		ret = bch2_btree_set_root(as, trans, btree_iter_path(trans, iter), n, false);

	}



	if (ret)

		goto err;



	bch2_btree_update_get_open_buckets(as, n);

	bch2_btree_node_write(c, n, SIX_LOCK_intent, 0);