jbd2: clear JBD2_ABORT flag before journal_reset to update log tail info when load journal

If the journal is dirty when the filesystem is mounted, jbd2 will replay
the journal but the journal superblock will not be updated by
journal_reset() because JBD2_ABORT flag is still set (it was set in
journal_init_common()). This is problematic because when a new transaction
is then committed, it will be recorded in block 1 (journal->j_tail was set
to 1 in journal_reset()). If unclean shutdown happens again before the
journal superblock is updated, the new recorded transaction will not be
replayed during the next mount (because of stale sb->s_start and
sb->s_sequence values) which can lead to filesystem corruption.

Fixes: 85e0c4e8 ("jbd2: if the journal is aborted then don't allow update of the log tail")
Signed-off-by: Kai Li <li.kai4@h3c.com>
Link: https://lore.kernel.org/r/20200111022542.5008-1-li.kai4@h3c.com


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