From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: linux-ext4@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH 2/2] jbd2: Avoid leaking transaction credits when unreserving handle
Date: Thu, 28 May 2020 22:44:01 -0400 [thread overview]
Message-ID: <20200529024401.GH228632@mit.edu> (raw)
In-Reply-To: <20200520133119.1383-3-jack@suse.cz>
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@vger.kernel.org
> Fixes: 8f7d89f36829 ("jbd2: transaction reservation support")
> Reviewed-by: Andreas Dilger <adilger@dilger.ca>
> Signed-off-by: Jan Kara <jack@suse.cz>
Thanks, applied.
- Ted
next prev parent reply other threads:[~2020-05-29 2:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-20 13:31 [PATCH 0/2 v2] jbd2: Fix leaked transaction credits Jan Kara
2020-05-20 13:31 ` [PATCH 1/2] ext4: Drop ext4_journal_free_reserved() Jan Kara
2020-05-20 19:29 ` Andreas Dilger
2020-05-29 2:43 ` Theodore Y. Ts'o
2020-05-20 13:31 ` [PATCH 2/2] jbd2: Avoid leaking transaction credits when unreserving handle Jan Kara
2020-05-29 2:44 ` Theodore Y. Ts'o [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-05-18 9:21 [PATCH 0/2] jbd2: Fix leaked transaction credits Jan Kara
2020-05-18 9:21 ` [PATCH 2/2] jbd2: Avoid leaking transaction credits when unreserving handle Jan Kara
2020-05-20 0:44 ` Andreas Dilger
2020-05-20 13:27 ` Jan Kara
2020-05-22 0:12 ` Sasha Levin
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