ext4: save the error code which triggered an ext4_error() in the superblock

mainline inclusion
from mainline-v5.6-rc1
commit 878520ac
category: bugfix
bugzilla: 46758
CVE: NA

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

This allows the cause of an ext4_error() report to be categorized
based on whether it was triggered due to an I/O error, or an memory
allocation error, or other possible causes.  Most errors are caused by
a detected file system inconsistency, so the default code stored in
the superblock will be EXT4_ERR_EFSCORRUPTED.

Link: https://lore.kernel.org/r/20191204032335.7683-1-tytso@mit.edu


Signed-off-by: Theodore Ts'o <tytso@mit.edu>

conflicts:
fs/ext4/ext4.h
fs/ext4/inode.c
fs/ext4/namei.c

Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>