ext4: report error to userspace by netlink

hulk inclusion
category: feature
bugzilla: 34592
CVE: NA

-------------------------------------------------

Implement the ext3/ext4 file system error report.

This patch is used to implement abnormal alarm of ext3/ext4 filesystem.
You can archieve this by setting "FILESYSTEM_MONITOR" or "FILESYSTEM_ALARM"
on in configuration file. With this setting, alarm will be raised when
ext3/ext4 file system expection occurs.

Signed-off-by: Zhao Minmin <zhaominmin1@huawei.com>
Reviewed-by: Yi Zhang <yi.zhang@huawei.com>
Link: http://hulk.huawei.com/pipermail/kernel.openeuler/2016-March/009711.html


Signed-off-by: Wang Hui <john.wanghui@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

[yebin: cherry-pick this patch from redhat-7.5, commit 13848b1856c1]

Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Wenan Mao <maowenan@huawei.com>
Reviewed-by: Yi Zhang <yi.zhang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>