bcache: Kill op->cl

This isn't used for waiting asynchronously anymore - so this is a fairly
trivial refactoring.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index b58c2bc..d0968e8 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -143,7 +143,7 @@
 		struct btree_op op;
 		struct keylist keys;
 
-		bch_btree_op_init_stack(&op);
+		bch_btree_op_init(&op, -1);
 		bch_keylist_init(&keys);
 
 		op.type = BTREE_REPLACE;
@@ -156,7 +156,6 @@
 			atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin);
 
 		bch_btree_insert(&op, dc->disk.c, &keys, NULL);
-		closure_sync(&op.cl);
 
 		if (op.insert_collision)
 			trace_bcache_writeback_collision(&w->key);
@@ -457,7 +456,7 @@
 {
 	struct sectors_dirty_init op;
 
-	bch_btree_op_init_stack(&op.op);
+	bch_btree_op_init(&op.op, -1);
 	op.inode = dc->disk.id;
 
 	bch_btree_map_keys(&op.op, dc->disk.c, &KEY(op.inode, 0, 0),