ext4: always panic when errors=panic is specified

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.

Cc: stable@kernel.org
Fixes: 014c9caa29d3 ("ext4: make ext4_abort() use __ext4_error()")
Signed-off-by: Ye Bin <yebin10@huawei.com>
Link: https://lore.kernel.org/r/20210401081903.3421208-1-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>