ext2: return error when fail to allocating memory in ioctl

Currently, we do not check memory allocation
result for ei->i_block_alloc_info in ioctl,
this patch checks it and returns error in
failure case.

Link: https://lore.kernel.org/r/20191023135643.28837-1-cgxu519@mykernel.netSigned-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext2/ioctl.c

@@ -145,10 +145,13 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		if (ei->i_block_alloc_info){
 			struct ext2_reserve_window_node *rsv = &ei->i_block_alloc_info->rsv_window_node;
 			rsv->rsv_goal_size = rsv_window_size;
+		} else {
+			ret = -ENOMEM;
 		}
+
 		mutex_unlock(&ei->truncate_mutex);
 		mnt_drop_write_file(filp);
-		return 0;
+		return ret;
 	}
 	default:
 		return -ENOTTY;