linux-ext4 - Re: [PATCH 15/22] jbd2: Factor out common parts of stopping and restarting a handle

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Message-ID: <20191104123650.GB28764@mit.edu>
Date:   Mon, 4 Nov 2019 07:36:50 -0500
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-ext4@...r.kernel.org
Subject: Re: [PATCH 15/22] jbd2: Factor out common parts of stopping and
 restarting a handle

On Wed, Oct 23, 2019 at 06:17:24PM +0200, Jan Kara wrote:
> > What is j_state_lock protecting at this point?  There's only a 32-bit
> > read of j_commit_request at this point.
> 
> We could almost drop the lock. To be fully correct, we'd then need to use
> READ_ONCE here and WRITE_ONCE in places changing j_commit_request (reasons
> are well summarized in recent LWN series on how compiler can screw your
> unlocked reads and writes). So probably a fair cleanup but something I've
> decided to leave for later.

Fair enough; maybe leave a quick TODO comment so we remember that this
is an outstanding clean up?

						- Ted