linux/fs/jbd2
Theodore Ts'o d76a3a7711 ext4/jbd2: don't wait (forever) for stale tid caused by wraparound
In the case where an inode has a very stale transaction id (tid) in
i_datasync_tid or i_sync_tid, it's possible that after a very large
(2**31) number of transactions, that the tid number space might wrap,
causing tid_geq()'s calculations to fail.

Commit deeeaf13 "jbd2: fix fsync() tid wraparound bug", later modified
by commit e7b04ac0 "jbd2: don't wake kjournald unnecessarily",
attempted to fix this problem, but it only avoided kjournald spinning
forever by fixing the logic in jbd2_log_start_commit().

Unfortunately, in the codepaths in fs/ext4/fsync.c and fs/ext4/inode.c
that might call jbd2_log_start_commit() with a stale tid, those
functions will subsequently call jbd2_log_wait_commit() with the same
stale tid, and then wait for a very long time.  To fix this, we
replace the calls to jbd2_log_start_commit() and
jbd2_log_wait_commit() with a call to a new function,
jbd2_complete_transaction(), which will correctly handle stale tid's.

As a bonus, jbd2_complete_transaction() will avoid locking
j_state_lock for writing unless a commit needs to be started.  This
should have a small (but probably not measurable) improvement for
ext4's scalability.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Reported-by: George Barnett <gbarnett@atlassian.com>
Cc: stable@vger.kernel.org
2013-04-03 22:02:52 -04:00
..
checkpoint.c jbd2: remove bh_state lock from checkpointing code 2012-03-13 22:45:25 -04:00
commit.c jbd2: track request delay statistics 2013-02-06 22:30:23 -05:00
journal.c ext4/jbd2: don't wait (forever) for stale tid caused by wraparound 2013-04-03 22:02:52 -04:00
Kconfig jbd2: Grab a reference to the crc32c driver if necessary 2012-05-27 07:50:56 -04:00
Makefile
recovery.c jbd2: check return value of blkdev_issue_flush() 2012-08-17 09:56:17 -04:00
revoke.c jbd2: checksum revocation blocks 2012-05-27 08:08:24 -04:00
transaction.c jbd2: fix use after free in jbd2_journal_dirty_metadata() 2013-03-11 13:24:56 -04:00