bcache: Convert bucket_wait to wait_queue_head_t

At one point we did do fancy asynchronous waiting stuff with
bucket_wait, but that's all gone (and bucket_wait is used a lot less
than it used to be). So use the standard primitives.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 9a164cd..84398a8 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -427,7 +427,7 @@
 
 	lockdep_assert_held(&bch_register_lock);
 
-	if (bch_bucket_alloc_set(c, WATERMARK_METADATA, &k.key, 1, &cl))
+	if (bch_bucket_alloc_set(c, WATERMARK_METADATA, &k.key, 1, true))
 		return 1;
 
 	SET_KEY_SIZE(&k.key, c->sb.bucket_size);
@@ -565,7 +565,7 @@
 		p->magic	= pset_magic(ca);
 		p->csum		= bch_crc64(&p->magic, bucket_bytes(ca) - 8);
 
-		bucket = bch_bucket_alloc(ca, WATERMARK_PRIO, &cl);
+		bucket = bch_bucket_alloc(ca, WATERMARK_PRIO, true);
 		BUG_ON(bucket == -1);
 
 		mutex_unlock(&ca->set->bucket_lock);
@@ -1439,6 +1439,7 @@
 	closure_init_unlocked(&c->sb_write);
 	mutex_init(&c->bucket_lock);
 	init_waitqueue_head(&c->try_wait);
+	init_waitqueue_head(&c->bucket_wait);
 	closure_init_unlocked(&c->uuid_write);
 	spin_lock_init(&c->sort_time_lock);
 	mutex_init(&c->sort_lock);
@@ -1608,7 +1609,7 @@
 			goto err_unlock_gc;
 
 		err = "cannot allocate new btree root";
-		c->root = bch_btree_node_alloc(c, 0, &op.cl);
+		c->root = bch_btree_node_alloc(c, 0);
 		if (IS_ERR_OR_NULL(c->root))
 			goto err_unlock_gc;