f2fs: remove unneeded return value of __insert_discard_tree()

We never use return value of __insert_discard_tree(), so remove it.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -1221,7 +1221,7 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
 	return err;
 }
 
-static struct discard_cmd *__insert_discard_tree(struct f2fs_sb_info *sbi,
+static void __insert_discard_tree(struct f2fs_sb_info *sbi,
 				struct block_device *bdev, block_t lstart,
 				block_t start, block_t len,
 				struct rb_node **insert_p,
@@ -1230,7 +1230,6 @@ static struct discard_cmd *__insert_discard_tree(struct f2fs_sb_info *sbi,
 	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
 	struct rb_node **p;
 	struct rb_node *parent = NULL;
-	struct discard_cmd *dc = NULL;
 	bool leftmost = true;
 
 	if (insert_p && insert_parent) {
@@ -1242,12 +1241,8 @@ static struct discard_cmd *__insert_discard_tree(struct f2fs_sb_info *sbi,
 	p = f2fs_lookup_rb_tree_for_insert(sbi, &dcc->root, &parent,
 							lstart, &leftmost);
 do_insert:
-	dc = __attach_discard_cmd(sbi, bdev, lstart, start, len, parent,
+	__attach_discard_cmd(sbi, bdev, lstart, start, len, parent,
 								p, leftmost);
-	if (!dc)
-		return NULL;
-
-	return dc;
 }
 
 static void __relocate_discard_cmd(struct discard_cmd_control *dcc,