ext4: report error to userspace by netlink

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8TNRU


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 openeuler, commit 6636f443]
conflicts :
fs/ext4/super.c
fs/ext4/ext4.h

Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>

Conflicts:
	fs/ext4/super.c

Signed-off-by: Baokun Li <libaokun1@huawei.com>