jbd2: protect all log tail updates with j_checkpoint_mutex
commit
a78bb11d7acd525623c6a0c2ff4e213d527573fa upstream.
There are some log tail updates that are not protected by j_checkpoint_mutex.
Some of these are harmless because they happen during startup or shutdown but
updates in jbd2_journal_commit_transaction() and jbd2_journal_flush() can
really race with other log tail updates (e.g. someone doing
jbd2_journal_flush() with someone running jbd2_cleanup_journal_tail()). So
protect all log tail updates with j_checkpoint_mutex.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
[bwh: Backported to 3.2:
- Adjust context
- Add unlock on the error path in jbd2_journal_flush()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Bartosz Kwitniewski <zerg2000@astral.org.pl>