linux-kernel - Re: [PATCH] f2fs: continuous counting for 'issued' in __issue_discard_cmd

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Message-ID: <7368c57a-141e-86b0-365f-8af795940483@kernel.org>
Date:   Sun, 11 Dec 2022 10:36:07 +0800
From:   Chao Yu <chao@...nel.org>
To:     Yuwei Guan <ssawgyw@...il.com>, jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Yuwei.Guan@...krlife.com
Subject: Re: [PATCH] f2fs: continuous counting for 'issued' in
 __issue_discard_cmd_orderly()

On 2022/11/22 0:11, Yuwei Guan wrote:
> As the 'dcc->discard_granularity' and 'dcc->max_ordered_discard' can be set
> at the user space, and if the 'dcc->max_ordered_discard' is set larger than
> 'dcc->discard_granularity' in DPOLICY_BG mode, or it's a volume device,
> discard_granularity can be tuned to 1 in f2fs_tuning_parameters(),
> it will may send more requests than the number of 'dpolicy->max_requests'
> in issue_discard_thread().
> 
> This patch will fix the issue.
> 
> Signed-off-by: Yuwei Guan <Yuwei.Guan@...krlife.com>
> ---
>   fs/f2fs/segment.c | 17 ++++++++---------
>   1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8b0b76550578..b0157bf392fb 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1379,8 +1379,8 @@ static int __queue_discard_cmd(struct f2fs_sb_info *sbi,
>   	return 0;
>   }
>   
> -static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
> -					struct discard_policy *dpolicy)
> +static int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
> +					struct discard_policy *dpolicy, int *issued)
>   {
>   	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
>   	struct discard_cmd *prev_dc = NULL, *next_dc = NULL;
> @@ -1388,7 +1388,6 @@ static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
>   	struct discard_cmd *dc;
>   	struct blk_plug plug;
>   	unsigned int pos = dcc->next_pos;
> -	unsigned int issued = 0;
>   	bool io_interrupted = false;
>   
>   	mutex_lock(&dcc->cmd_lock);
> @@ -1415,9 +1414,9 @@ static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
>   		}
>   
>   		dcc->next_pos = dc->lstart + dc->len;
> -		err = __submit_discard_cmd(sbi, dpolicy, dc, &issued);
> +		err = __submit_discard_cmd(sbi, dpolicy, dc, issued);
>   
> -		if (issued >= dpolicy->max_requests)
> +		if (*issued >= dpolicy->max_requests)
>   			break;
>   next:
>   		node = rb_next(&dc->rb_node);
> @@ -1433,10 +1432,10 @@ static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
>   
>   	mutex_unlock(&dcc->cmd_lock);
>   
> -	if (!issued && io_interrupted)
> -		issued = -1;
> +	if (!(*issued) && io_interrupted)
> +		*issued = -1;
>   
> -	return issued;
> +	return *issued;

A little weired that __issue_discard_cmd_orderly() will output the data
in both return value and @issued parameter.

How about changing type of return value __issue_discard_cmd_orderly()
from unsigned int to void.

Thanks,

>   }
>   static unsigned int __wait_all_discard_cmd(struct f2fs_sb_info *sbi,
>   					struct discard_policy *dpolicy);
> @@ -1465,7 +1464,7 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
>   			break;
>   
>   		if (i + 1 < dcc->max_ordered_discard && dpolicy->ordered)
> -			return __issue_discard_cmd_orderly(sbi, dpolicy);
> +			return __issue_discard_cmd_orderly(sbi, dpolicy, &issued);
>   
>   		pend_list = &dcc->pend_list[i];
>