linux-ext4 - Re: [PATCH 1/2] jbd2: don't call get_bh() before calling __jbd2_journal_remove

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Message-ID: <CAGZGoEd0TcJccE-RAZ1+mevWJiWE-Fm1AVeN8=-GiZHg-O38pg@mail.gmail.com>
Date:	Wed, 3 Sep 2014 15:54:39 +0800
From:	Yuanhan Liu <yliu.null@...il.com>
To:	"Theodore Ts'o" <tytso@....edu>
Cc:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 1/2] jbd2: don't call get_bh() before calling __jbd2_journal_remove_checkpoint()

<resend due to malformed email>

On Wed, Sep 3, 2014 at 6:46 AM, Theodore Ts'o <tytso@....edu> wrote:
> The __jbd2_journal_remove_checkpoint() doesn't require an elevated
> b_count; indeed, until the jh structure gets released by the call to
> jbd2_journal_put_journal_head(), the bh's b_count is elevated by
> virtue of the existence of the jh structure.
>
> Suggested-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Theodore Ts'o <tytso@....edu>
> ---
>  fs/jbd2/checkpoint.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
> index 22fcd50..cb6e17c 100644
> --- a/fs/jbd2/checkpoint.c
> +++ b/fs/jbd2/checkpoint.c
> @@ -100,11 +100,8 @@ static int __try_to_free_cp_buf(struct journal_head *jh)
>                  * Get our reference so that bh cannot be freed before
>                  * we unlock it
>                  */

I guess you need drop those comments as well.

        --yliu
> -               get_bh(bh);
>                 JBUFFER_TRACE(jh, "remove from checkpoint list");
>                 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
> -               BUFFER_TRACE(bh, "release");
> -               __brelse(bh);
>         }
>         return ret;
--
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