bcache: Convert sorting to btree_keys

More work to disentangle various code from struct btree

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 2128ee1..b14f34a 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -480,9 +480,9 @@
 
 	/* If not a leaf node, always sort */
 	if (b->level && b->keys.nsets)
-		bch_btree_sort(b, &b->c->sort);
+		bch_btree_sort(&b->keys, &b->c->sort);
 	else
-		bch_btree_sort_lazy(b, &b->c->sort);
+		bch_btree_sort_lazy(&b->keys, &b->c->sort);
 
 	/*
 	 * do verify if there was more than one set initially (i.e. we did a
@@ -1087,7 +1087,7 @@
 {
 	struct btree *n = bch_btree_node_alloc(b->c, b->level, wait);
 	if (!IS_ERR_OR_NULL(n)) {
-		bch_btree_sort_into(b, n, &b->c->sort);
+		bch_btree_sort_into(&b->keys, &n->keys, &b->c->sort);
 		bkey_copy_key(&n->key, &b->key);
 	}