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Commit 17e21a9f authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcache: Have btree_split() insert into parent directly 



The flow control in btree_insert_node() was... fragile... before,
this'll use more stack (but since our btrees are never more than depth
1, that shouldn't matter) and it should be significantly clearer and
less fragile.

Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
parent 65d22e91

drivers/md/bcache/btree.c

+39 −46
Original line number Diff line number Diff line
@@ -2025,15 +2025,16 @@ static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op, 


static int btree_split(struct btree *b, struct btree_op *op,

		       struct keylist *insert_keys,

		       struct keylist *parent_keys,

		       struct bkey *replace_key)

{

	bool split;

	struct btree *n1, *n2 = NULL, *n3 = NULL;

	uint64_t start_time = local_clock();

	struct closure cl;

	struct keylist parent_keys;



	closure_init_stack(&cl);

	bch_keylist_init(&parent_keys);



	n1 = btree_node_alloc_replacement(b, true);

	if (IS_ERR(n1))
@@ -2078,7 +2079,7 @@ static int btree_split(struct btree *b, struct btree_op *op, 


		bkey_copy_key(&n2->key, &b->key);



		bch_keylist_add(parent_keys, &n2->key);

		bch_keylist_add(&parent_keys, &n2->key);

		bch_btree_node_write(n2, &cl);

		rw_unlock(true, n2);

	} else {
@@ -2087,33 +2088,39 @@ static int btree_split(struct btree *b, struct btree_op *op, 
		bch_btree_insert_keys(n1, op, insert_keys, replace_key);

	}



	bch_keylist_add(parent_keys, &n1->key);

	bch_keylist_add(&parent_keys, &n1->key);

	bch_btree_node_write(n1, &cl);



	if (n3) {

		/* Depth increases, make a new root */



		bkey_copy_key(&n3->key, &MAX_KEY);

		bch_btree_insert_keys(n3, op, parent_keys, NULL);

		bch_btree_insert_keys(n3, op, &parent_keys, NULL);

		bch_btree_node_write(n3, &cl);



		closure_sync(&cl);

		bch_btree_set_root(n3);

		rw_unlock(true, n3);



		btree_node_free(b);

	} else if (!b->parent) {

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



		bch_keylist_reset(parent_keys);

		closure_sync(&cl);

		bch_btree_set_root(n1);



		btree_node_free(b);

	} else {

		/* Split a non root node */

		closure_sync(&cl);

		make_btree_freeing_key(b, parent_keys->top);

		bch_keylist_push(parent_keys);

		make_btree_freeing_key(b, parent_keys.top);

		bch_keylist_push(&parent_keys);



		btree_node_free(b);



		bch_btree_insert_node(b->parent, op, &parent_keys, NULL, NULL);

		BUG_ON(!bch_keylist_empty(&parent_keys));

	}



	rw_unlock(true, n1);

	btree_node_free(b);



	bch_time_stats_update(&b->c->btree_split_time, start_time);
@@ -2139,46 +2146,32 @@ static int bch_btree_insert_node(struct btree *b, struct btree_op *op, 
				 atomic_t *journal_ref,

				 struct bkey *replace_key)

{

	int ret = 0;

	struct keylist split_keys;



	bch_keylist_init(&split_keys);



	do {

	BUG_ON(b->level && replace_key);



	if (should_split(b)) {

		if (current->bio_list) {

			op->lock = b->c->root->level + 1;

				ret = -EAGAIN;

			return -EAGAIN;

		} else if (op->lock <= b->c->root->level) {

			op->lock = b->c->root->level + 1;

				ret = -EINTR;

			return -EINTR;

		} else {

				struct btree *parent = b->parent;



				ret = btree_split(b, op, insert_keys,

						  &split_keys, replace_key);

				insert_keys = &split_keys;

				replace_key = NULL;

				b = parent;

				if (!ret)

					ret = -EINTR;

			/* Invalidated all iterators */

			return btree_split(b, op, insert_keys, replace_key) ?:

				-EINTR;

		}

	} else {

		BUG_ON(write_block(b) != b->sets[b->nsets].data);



			if (bch_btree_insert_keys(b, op, insert_keys,

						  replace_key)) {

		if (bch_btree_insert_keys(b, op, insert_keys, replace_key)) {

			if (!b->level)

				bch_btree_leaf_dirty(b, journal_ref);

			else

				bch_btree_node_write_sync(b);

		}

		}

	} while (!bch_keylist_empty(&split_keys));



	return ret;

		return 0;

	}

}



int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,