MySQL 无法启动，因为“mysqld：找不到文件：'./mysql/plugin.frm' (errno: 13)”

Question

我正在使用 Ubuntu Server 13.10 和 MySQL 5.5 设置一个新的 LAMP 服务器，并且正在将 mysql 数据库迁移到新服务器时，我意识到 mysql 服务器没有运行。几天前我检查时一切都很好。当我尝试从命令行启动服务器时，我得到了这个：

@Ubuntu:~$ sudo mysqld start
[sudo] password for XXX:
140402 10:32:07 [Warning] Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
140402 10:32:07 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
140402 10:32:07 [Note] Plugin 'FEDERATED' is disabled.
mysqld: Can't find file: './mysql/plugin.frm' (errno: 13)
140402 10:32:07 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
140402 10:32:07 InnoDB: The InnoDB memory heap is disabled
140402 10:32:07 InnoDB: Mutexes and rw_locks use GCC atomic builtins
140402 10:32:07 InnoDB: Compressed tables use zlib 1.2.8
140402 10:32:07 InnoDB: Using Linux native AIO
140402 10:32:07 InnoDB: Initializing buffer pool, size = 128.0M
140402 10:32:07 InnoDB: Completed initialization of buffer pool
140402 10:32:07 InnoDB: Operating system error number 13 in a file operation.
InnoDB: The error means mysqld does not have the access rights to
InnoDB: the directory.
InnoDB: File name ./ibdata1
InnoDB: File operation call: 'create'.
InnoDB: Cannot continue operation.

当我尝试这个时：

XXX@Ubuntu-SHS:~$ sudo /etc/init.d/mysql restart
* Stopping MySQL database server mysqld [ OK ]
* Starting MySQL database server mysqld [fail]

错误日志中没有任何内容。更新：注意到所有目录和文件/var/lib/mysql都已更改为所有者/组的 messagebus。是这样吗？我的其他设置显示所有内容为mysql mysql。