Commit 2e9940d4 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Handle cached data LRU wraparound 



We only have 48 bits for the LRU time field, which is insufficient to
prevent wraparound.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent cff07e27

fs/bcachefs/alloc_background.c

+41 −5
Original line number Diff line number Diff line
@@ -2019,6 +2019,21 @@ static int invalidate_one_bucket(struct btree_trans *trans, 
	goto out;

}



static struct bkey_s_c next_lru_key(struct btree_trans *trans, struct btree_iter *iter,

				    struct bch_dev *ca, bool *wrapped)

{

	struct bkey_s_c k;

again:

	k = bch2_btree_iter_peek_upto(iter, lru_pos(ca->dev_idx, U64_MAX, LRU_TIME_MAX));

	if (!k.k && !*wrapped) {

		bch2_btree_iter_set_pos(iter, lru_pos(ca->dev_idx, 0, 0));

		*wrapped = true;

		goto again;

	}



	return k;

}



static void bch2_do_invalidates_work(struct work_struct *work)

{

	struct bch_fs *c = container_of(work, struct bch_fs, invalidate_work);
@@ -2032,12 +2047,33 @@ static void bch2_do_invalidates_work(struct work_struct *work) 
	for_each_member_device(c, ca) {

		s64 nr_to_invalidate =

			should_invalidate_buckets(ca, bch2_dev_usage_read(ca));

		struct btree_iter iter;

		bool wrapped = false;



		bch2_trans_iter_init(trans, &iter, BTREE_ID_lru,

				     lru_pos(ca->dev_idx, 0,

					     ((bch2_current_io_time(c, READ) + U32_MAX) &

					      LRU_TIME_MAX)), 0);



		ret = for_each_btree_key_upto(trans, iter, BTREE_ID_lru,

				lru_pos(ca->dev_idx, 0, 0),

				lru_pos(ca->dev_idx, U64_MAX, LRU_TIME_MAX),

				BTREE_ITER_intent, k,

			invalidate_one_bucket(trans, &iter, k, &nr_to_invalidate));

		while (true) {

			bch2_trans_begin(trans);



			struct bkey_s_c k = next_lru_key(trans, &iter, ca, &wrapped);

			ret = bkey_err(k);

			if (bch2_err_matches(ret, BCH_ERR_transaction_restart))

				continue;

			if (ret)

				break;

			if (!k.k)

				break;



			ret = invalidate_one_bucket(trans, &iter, k, &nr_to_invalidate);

			if (ret)

				break;



			bch2_btree_iter_advance(&iter);

		}

		bch2_trans_iter_exit(trans, &iter);



		if (ret < 0) {

			bch2_dev_put(ca);