ext4: always panic when errors=panic is specified

In the Linux kernel, the following vulnerability has been resolved:

ext4: always panic when errors=panic is specified

Before commit 014c9caa29d3 ("ext4: make ext4_abort() use

__ext4_error()"), the following series of commands would trigger a

panic:

1. mount /dev/sda -o ro,errors=panic test

2. mount /dev/sda -o remount,abort test

After commit 014c9caa29d3, remounting a file system using the test

mount option "abort" will no longer trigger a panic. This commit will

restore the behaviour immediately before commit 014c9caa29d3.

(However, note that the Linux kernel's behavior has not been

consistent; some previous kernel versions, including 5.4 and 4.19

similarly did not panic after using the mount option "abort".)

This also makes a change to long-standing behaviour; namely, the

following series commands will now cause a panic, when previously it

did not:

1. mount /dev/sda -o ro,errors=panic test

2. echo test > /sys/fs/ext4/sda/trigger_fs_error

However, this makes ext4's behaviour much more consistent, so this is

a good thing.