Commit 861cd0f6 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Write lock btree node in key cache fills 



this addresses a key cache coherency bug

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent baf13d83

fs/bcachefs/btree_key_cache.c

+22 −12
Original line number Diff line number Diff line
@@ -197,7 +197,9 @@ bkey_cached_reuse(struct btree_key_cache *c) 
	return ck;

}



static int btree_key_cache_create(struct btree_trans *trans, struct btree_path *path,

static int btree_key_cache_create(struct btree_trans *trans,

				  struct btree_path *path,

				  struct btree_path *ck_path,

				  struct bkey_s_c k)

{

	struct bch_fs *c = trans->c;
@@ -217,7 +219,7 @@ static int btree_key_cache_create(struct btree_trans *trans, struct btree_path * 
	key_u64s = min(256U, (key_u64s * 3) / 2);

	key_u64s = roundup_pow_of_two(key_u64s);



	struct bkey_cached *ck = bkey_cached_alloc(trans, path, key_u64s);

	struct bkey_cached *ck = bkey_cached_alloc(trans, ck_path, key_u64s);

	int ret = PTR_ERR_OR_ZERO(ck);

	if (ret)

		return ret;
@@ -226,19 +228,19 @@ static int btree_key_cache_create(struct btree_trans *trans, struct btree_path * 
		ck = bkey_cached_reuse(bc);

		if (unlikely(!ck)) {

			bch_err(c, "error allocating memory for key cache item, btree %s",

				bch2_btree_id_str(path->btree_id));

				bch2_btree_id_str(ck_path->btree_id));

			return -BCH_ERR_ENOMEM_btree_key_cache_create;

		}

	}



	ck->c.level		= 0;

	ck->c.btree_id		= path->btree_id;

	ck->key.btree_id	= path->btree_id;

	ck->key.pos		= path->pos;

	ck->c.btree_id		= ck_path->btree_id;

	ck->key.btree_id	= ck_path->btree_id;

	ck->key.pos		= ck_path->pos;

	ck->flags		= 1U << BKEY_CACHED_ACCESSED;



	if (unlikely(key_u64s > ck->u64s)) {

		mark_btree_node_locked_noreset(path, 0, BTREE_NODE_UNLOCKED);

		mark_btree_node_locked_noreset(ck_path, 0, BTREE_NODE_UNLOCKED);



		struct bkey_i *new_k = allocate_dropping_locks(trans, ret,

				kmalloc(key_u64s * sizeof(u64), _gfp));
@@ -258,22 +260,29 @@ static int btree_key_cache_create(struct btree_trans *trans, struct btree_path * 


	bkey_reassemble(ck->k, k);



	ret = bch2_btree_node_lock_write(trans, path, &path_l(path)->b->c);

	if (unlikely(ret))

		goto err;



	ret = rhashtable_lookup_insert_fast(&bc->table, &ck->hash, bch2_btree_key_cache_params);



	bch2_btree_node_unlock_write(trans, path, path_l(path)->b);



	if (unlikely(ret)) /* raced with another fill? */

		goto err;



	atomic_long_inc(&bc->nr_keys);

	six_unlock_write(&ck->c.lock);



	enum six_lock_type lock_want = __btree_lock_want(path, 0);

	enum six_lock_type lock_want = __btree_lock_want(ck_path, 0);

	if (lock_want == SIX_LOCK_read)

		six_lock_downgrade(&ck->c.lock);

	btree_path_cached_set(trans, path, ck, (enum btree_node_locked_type) lock_want);

	path->uptodate = BTREE_ITER_UPTODATE;

	btree_path_cached_set(trans, ck_path, ck, (enum btree_node_locked_type) lock_want);

	ck_path->uptodate = BTREE_ITER_UPTODATE;

	return 0;

err:

	bkey_cached_free(bc, ck);

	mark_btree_node_locked_noreset(path, 0, BTREE_NODE_UNLOCKED);

	mark_btree_node_locked_noreset(ck_path, 0, BTREE_NODE_UNLOCKED);



	return ret;

}
@@ -293,6 +302,7 @@ static noinline int btree_key_cache_fill(struct btree_trans *trans, 
	int ret;



	bch2_trans_iter_init(trans, &iter, ck_path->btree_id, ck_path->pos,

			     BTREE_ITER_intent|

			     BTREE_ITER_key_cache_fill|

			     BTREE_ITER_cached_nofill);

	iter.flags &= ~BTREE_ITER_with_journal;
@@ -306,7 +316,7 @@ static noinline int btree_key_cache_fill(struct btree_trans *trans, 
	if (unlikely(ret))

		goto out;



	ret = btree_key_cache_create(trans, ck_path, k);

	ret = btree_key_cache_create(trans, btree_iter_path(trans, &iter), ck_path, k);

	if (ret)

		goto err;