On Wed, May 20, 2020 at 03:31:19PM +0200, Jan Kara wrote:
> When reserved transaction handle is unused, we subtract its reserved
> credits in __jbd2_journal_unreserve_handle() called from
> jbd2_journal_stop(). However this function forgets to remove reserved
> credits from transaction->t_outstanding_credits and thus the transaction
> space that was reserved remains effectively leaked. The leaked
> transaction space can be quite significant in some cases and leads to
> unnecessarily small transactions and thus reducing throughput of the
> journalling machinery. E.g. fsmark workload creating lots of 4k files
> was observed to have about 20% lower throughput due to this when ext4 is
> mounted with dioread_nolock mount option.
>
> Subtract reserved credits from t_outstanding_credits as well.
>
> CC: stable@xxxxxxxxxxxxxxx
> Fixes: 8f7d89f36829 ("jbd2: transaction reservation support")
> Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
Thanks, applied.
- Ted
