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Date: Mon, 8 Apr 2024 19:30:57 +0200
From: Jan Kara <jack@suse.cz>
To: Ye Bin <yebin10@huawei.com>
Cc: tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org,
	linux-kernel@vger.kernel.org, jack@suse.cz
Subject: Re: [PATCH v2 1/2] jbd2: use shrink_type type instead of bool type
 for __jbd2_journal_clean_checkpoint_list()
Message-ID: <20240408173057.3wn4pnlzrxkai5fc@quack3>
References: <20240407065355.1528580-1-yebin10@huawei.com>
 <20240407065355.1528580-2-yebin10@huawei.com>
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In-Reply-To: <20240407065355.1528580-2-yebin10@huawei.com>

On Sun 07-04-24 14:53:54, Ye Bin wrote:
> "enum shrink_type" can clearly express the meaning of the parameter of
> __jbd2_journal_clean_checkpoint_list(), and there is no need to use the
> bool type.
> 
> Signed-off-by: Ye Bin <yebin10@huawei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/jbd2/checkpoint.c | 16 +++++++++-------
>  fs/jbd2/commit.c     |  2 +-
>  include/linux/jbd2.h |  4 +++-
>  3 files changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
> index 1c97e64c4784..80c0ab98bc63 100644
> --- a/fs/jbd2/checkpoint.c
> +++ b/fs/jbd2/checkpoint.c
> @@ -337,8 +337,6 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
>  
>  /* Checkpoint list management */
>  
> -enum shrink_type {SHRINK_DESTROY, SHRINK_BUSY_STOP, SHRINK_BUSY_SKIP};
> -
>  /*
>   * journal_shrink_one_cp_list
>   *
> @@ -472,21 +470,25 @@ unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
>   * journal_clean_checkpoint_list
>   *
>   * Find all the written-back checkpoint buffers in the journal and release them.
> - * If 'destroy' is set, release all buffers unconditionally.
> + * If 'type' is SHRINK_DESTROY, release all buffers unconditionally. If 'type'
> + * is SHRINK_BUSY_STOP, will stop release buffers if encounters a busy buffer.
> + * To avoid wasting CPU cycles scanning the buffer list in some cases, don't
> + * pass SHRINK_BUSY_SKIP 'type' for this function.
>   *
>   * Called with j_list_lock held.
>   */
> -void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
> +void __jbd2_journal_clean_checkpoint_list(journal_t *journal,
> +					  enum shrink_type type)
>  {
>  	transaction_t *transaction, *last_transaction, *next_transaction;
> -	enum shrink_type type;
>  	bool released;
>  
> +	WARN_ON_ONCE(type == SHRINK_BUSY_SKIP);
> +
>  	transaction = journal->j_checkpoint_transactions;
>  	if (!transaction)
>  		return;
>  
> -	type = destroy ? SHRINK_DESTROY : SHRINK_BUSY_STOP;
>  	last_transaction = transaction->t_cpprev;
>  	next_transaction = transaction;
>  	do {
> @@ -527,7 +529,7 @@ void jbd2_journal_destroy_checkpoint(journal_t *journal)
>  			spin_unlock(&journal->j_list_lock);
>  			break;
>  		}
> -		__jbd2_journal_clean_checkpoint_list(journal, true);
> +		__jbd2_journal_clean_checkpoint_list(journal, SHRINK_DESTROY);
>  		spin_unlock(&journal->j_list_lock);
>  		cond_resched();
>  	}
> diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
> index 5e122586e06e..78ebd04ac97d 100644
> --- a/fs/jbd2/commit.c
> +++ b/fs/jbd2/commit.c
> @@ -501,7 +501,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
>  	 * frees some memory
>  	 */
>  	spin_lock(&journal->j_list_lock);
> -	__jbd2_journal_clean_checkpoint_list(journal, false);
> +	__jbd2_journal_clean_checkpoint_list(journal, SHRINK_BUSY_STOP);
>  	spin_unlock(&journal->j_list_lock);
>  
>  	jbd2_debug(3, "JBD2: commit phase 1\n");
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index 971f3e826e15..58a961999d70 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -1434,7 +1434,9 @@ void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
>  extern void jbd2_journal_commit_transaction(journal_t *);
>  
>  /* Checkpoint list management */
> -void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy);
> +enum shrink_type {SHRINK_DESTROY, SHRINK_BUSY_STOP, SHRINK_BUSY_SKIP};
> +
> +void __jbd2_journal_clean_checkpoint_list(journal_t *journal, enum shrink_type type);
>  unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal, unsigned long *nr_to_scan);
>  int __jbd2_journal_remove_checkpoint(struct journal_head *);
>  int jbd2_journal_try_remove_checkpoint(struct journal_head *jh);
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR