Received-SPF: pass (google.com: best guess record for domain of linux-ext4-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 6 Feb 2020 12:03:35 +0100
From:   Jan Kara <jack@suse.cz>
To:     "zhangyi (F)" <yi.zhang@huawei.com>
Cc:     jack@suse.cz, tytso@mit.edu, linux-ext4@vger.kernel.org,
        luoshijie1@huawei.com, zhangxiaoxu5@huawei.com
Subject: Re: [PATCH 1/2] jbd2: move the clearing of b_modified flag to the
 journal_unmap_buffer()
Message-ID: <20200206110335.GA3994@quack2.suse.cz>
References: <20200203140458.37397-1-yi.zhang@huawei.com>
 <20200203140458.37397-2-yi.zhang@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200203140458.37397-2-yi.zhang@huawei.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-ext4-owner@vger.kernel.org
Precedence: bulk

On Mon 03-02-20 22:04:57, zhangyi (F) wrote:
> There is no need to delay the clearing of b_modified flag to the
> transaction committing time when unmapping the journalled buffer, so
> just move it to the journal_unmap_buffer().
> 
> Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>

Thanks for the patch. It looks good, just one small comment below:

> diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> index e77a5a0b4e46..a479cbf8ae54 100644
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -2337,11 +2337,7 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
>  		set_buffer_freed(bh);
>  		if (journal->j_running_transaction && buffer_jbddirty(bh))
>  			jh->b_next_transaction = journal->j_running_transaction;
> -		spin_unlock(&journal->j_list_lock);
> -		spin_unlock(&jh->b_state_lock);
> -		write_unlock(&journal->j_state_lock);
> -		jbd2_journal_put_journal_head(jh);
> -		return 0;
> +		may_free = 0;

I'd rather add b_modified clearing here than trying to reuse the tail of
the function. Because this condition is different from the other ones that
end up in zap_buffer_locked - here we really want to keep bh and jh mostly
intact.
								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR