e2fsck: update j_tail_sequence after recovery

When journal is released, s_sequence is set to j_tail_sequence.
But, currently, even if the recovery process is successfully completed,
the j_tail_sequence and, finally, s_sequence are never changed. By this,
when we repeat doing power-off the device suddenly and executing e2fsck
without full scan before mount, the s_sequence number will never change
and, in a very rare case, newly generated journal logs will be
surprisingly grafted to the old journal logs. In this case, out-of-date
metadata log can be replayed on the filesystem area and the filesystem
can be crashed unintentionally by journal recovery process. Therefore,
we need to update j_tail_sequence after recovery process is successfully
completed in e2fsck.

Youngjin had repeated this test and found the problem. With our test,
the filesystem crash occurred within 4 hours.

Signed-off-by: Youngjin Gil <youngjin.gil@samsung.com>
Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

e2fsck/journal.c

@@ -948,6 +948,8 @@ static errcode_t recover_ext3_journal(e2fsck_t ctx)
 		mark_buffer_dirty(journal->j_sb_buffer);
 	}
 
+	journal->j_tail_sequence = journal->j_transaction_sequence;
+
 errout:
 	journal_destroy_revoke(journal);
 	journal_destroy_revoke_caches();