Btrfs: pass delayed_refs directly to btrfs_find_delayed_ref_head

All we need is @delayed_refs, all callers have get it ahead of calling
btrfs_find_delayed_ref_head since lock needs to be acquired firstly,
there is no reason to deference it again inside the function.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 8299601..db70659 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1284,7 +1284,7 @@
 		 */
 		delayed_refs = &trans->transaction->delayed_refs;
 		spin_lock(&delayed_refs->lock);
-		head = btrfs_find_delayed_ref_head(trans, bytenr);
+		head = btrfs_find_delayed_ref_head(delayed_refs, bytenr);
 		if (head) {
 			if (!mutex_trylock(&head->mutex)) {
 				atomic_inc(&head->node.refs);