btrfs: delayed-ref: pass delayed_refs directly to btrfs_select_ref_head

Since trans is only used for referring to delayed_refs, there is no need
to pass it instead of delayed_refs to btrfs_select_ref_head().  No
functional change.
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/delayed-ref.c

@@ -353,16 +353,13 @@ int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq)
 	return ret;
 }
 
-struct btrfs_delayed_ref_head *
-btrfs_select_ref_head(struct btrfs_trans_handle *trans)
+struct btrfs_delayed_ref_head *btrfs_select_ref_head(
+		struct btrfs_delayed_ref_root *delayed_refs)
 {
-	struct btrfs_delayed_ref_root *delayed_refs;
 	struct btrfs_delayed_ref_head *head;
 	u64 start;
 	bool loop = false;
 
-	delayed_refs = &trans->transaction->delayed_refs;
-
 again:
 	start = delayed_refs->run_delayed_start;
 	head = find_ref_head(delayed_refs, start, 1);

fs/btrfs/delayed-ref.h

@@ -263,8 +263,8 @@ static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 }
 
 
-struct btrfs_delayed_ref_head *
-btrfs_select_ref_head(struct btrfs_trans_handle *trans);
+struct btrfs_delayed_ref_head *btrfs_select_ref_head(
+		struct btrfs_delayed_ref_root *delayed_refs);
 
 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);
 

fs/btrfs/extent-tree.c

@@ -2511,7 +2511,7 @@ static struct btrfs_delayed_ref_head *btrfs_obtain_ref_head(
 	int ret;
 
 	spin_lock(&delayed_refs->lock);
-	head = btrfs_select_ref_head(trans);
+	head = btrfs_select_ref_head(delayed_refs);
 	if (!head) {
 		spin_unlock(&delayed_refs->lock);
 		return head;