linux-ext4 - Re: [PATCH] jbd2: Avoid long hold times of j_state

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Message-ID: <20181030144410.GG15839@thunk.org>
Date:   Tue, 30 Oct 2018 10:44:10 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-ext4@...r.kernel.org, Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH] jbd2: Avoid long hold times of j_state_lock while
 committing a transaction

On Tue, Oct 16, 2018 at 11:42:48AM +0200, Jan Kara wrote:
> We can hold j_state_lock for writing at the beginning of
> jbd2_journal_commit_transaction() for a rather long time (reportedly for
> 30 ms) due cleaning revoke bits of all revoked buffers under it. The
> handling of revoke tables as well as cleaning of t_reserved_list, and
> checkpoint lists does not need j_state_lock for anything. Furthermore
> the transaction is in T_LOCKED state and we waited for all outstanding
> handles so nobody is going to be adding anything to the transaction.
> 
> Just drop the lock for unnecessary operations.
> 
> Reported-and-tested-by: Adrian Hunter <adrian.hunter@...el.com>
> Suggested-by: "Theodore Y. Ts'o" <tytso@....edu>
> Signed-off-by: Jan Kara <jack@...e.cz>

Applied, thanks.

					- Ted