jbd2: Factor out common parts of stopping and restarting a handle

mainline inclusion
from mainline-5.5-rc1
commit ec8b6f60
category: bugfix
bugzilla: 25031
CVE: NA
---------------------------

jbd2__journal_restart() has quite some code that is common with
jbd2_journal_stop(). Factor this functionality into stop_this_handle()
helper and use it from both functions. Note that this also drops
t_handle_lock protection from jbd2__journal_restart() as
jbd2_journal_stop() does the same thing without it.

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191105164437.32602-17-jack@suse.cz


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

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>