linux-kernel - Re: [PATCH 7/9] jbd2: remove dead equality check of j_commit

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Message-ID: <90912168-9295-ac60-6a4c-687fe12ebd7a@huaweicloud.com>
Date: Thu, 9 May 2024 19:51:46 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: Kemeng Shi <shikemeng@...weicloud.com>
Cc: linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, tytso@....edu,
 jack@...e.com
Subject: Re: [PATCH 7/9] jbd2: remove dead equality check of
 j_commit_[sequence/request] in kjournald2

On 2024/5/6 22:17, Kemeng Shi wrote:
> In kjournald2, two equality checks of j_commit_[sequence/request] are
> under the same j_state_lock. As j_commit_[sequence/request] are updated
> concurrently with j_state_lock held during runtime, the second check is
> unnecessary.
> The j_commit_sequence is only updated concurrently in
> jbd2_journal_commit_transaction with j_state_lock held.
> The j_commit_request is only updated concurrently in
> __jbd2_log_start_commit with j_state_lock held.
> Also see comment in struct journal_s about lock rule of j_commit_sequence
> and j_commit_request.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>

Looks reasonable to me.

Reviewed-by: Zhang Yi <yi.zhang@...wei.com>

> ---
>  fs/jbd2/journal.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 01e33b643e4d..e8f592fbd6e1 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -224,8 +224,6 @@ static int kjournald2(void *arg)
>  
>  		prepare_to_wait(&journal->j_wait_commit, &wait,
>  				TASK_INTERRUPTIBLE);
> -		if (journal->j_commit_sequence != journal->j_commit_request)
> -			should_sleep = 0;
>  		transaction = journal->j_running_transaction;
>  		if (transaction && time_after_eq(jiffies,
>  						transaction->t_expires))
>