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Subject: Re: [PATCH 5/7] fs/writeback: only calculate dirtied_before when b_io
 is empty
To: Jan Kara <jack@suse.cz>
Cc: viro@zeniv.linux.org.uk, brauner@kernel.org,
 linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240208172024.23625-1-shikemeng@huaweicloud.com>
 <20240208172024.23625-6-shikemeng@huaweicloud.com>
 <20240223135809.5bvyl7ex3zm6bnta@quack3>
From: Kemeng Shi <shikemeng@huaweicloud.com>
Message-ID: <115755e5-9c4f-8aea-1bc0-41868926c527@huaweicloud.com>
Date: Mon, 26 Feb 2024 19:50:24 +0800
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on 2/23/2024 9:58 PM, Jan Kara wrote:
> On Fri 09-02-24 01:20:22, Kemeng Shi wrote:
>> The dirtied_before is only used when b_io is not empty, so only calculate
>> when b_io is not empty.
>>
>> Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
>> ---
>>  fs/fs-writeback.c | 25 +++++++++++++------------
>>  1 file changed, 13 insertions(+), 12 deletions(-)
> 
> OK, but please wrap the comment at 80 columns as well.
Sorry for missing this as I rely too much on checkpatch.pl to report this
while the script didn't catch it. Will fix it in next version. Thanks for
review.
> 
> 								Honza
> 
>>
>> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
>> index b61bf2075931..e8868e814e0a 100644
>> --- a/fs/fs-writeback.c
>> +++ b/fs/fs-writeback.c
>> @@ -2118,20 +2118,21 @@ static long wb_writeback(struct bdi_writeback *wb,
>>  
>>  		spin_lock(&wb->list_lock);
>>  
>> -		/*
>> -		 * Kupdate and background works are special and we want to
>> -		 * include all inodes that need writing. Livelock avoidance is
>> -		 * handled by these works yielding to any other work so we are
>> -		 * safe.
>> -		 */
>> -		if (work->for_kupdate) {
>> -			dirtied_before = jiffies -
>> -				msecs_to_jiffies(dirty_expire_interval * 10);
>> -		} else if (work->for_background)
>> -			dirtied_before = jiffies;
>> -
>>  		trace_writeback_start(wb, work);
>>  		if (list_empty(&wb->b_io)) {
>> +			/*
>> +			 * Kupdate and background works are special and we want to
>> +			 * include all inodes that need writing. Livelock avoidance is
>> +			 * handled by these works yielding to any other work so we are
>> +			 * safe.
>> +			 */
>> +			if (work->for_kupdate) {
>> +				dirtied_before = jiffies -
>> +					msecs_to_jiffies(dirty_expire_interval *
>> +							 10);
>> +			} else if (work->for_background)
>> +				dirtied_before = jiffies;
>> +
>>  			queue_io(wb, work, dirtied_before);
>>  			queued = true;
>>  		}
>> -- 
>> 2.30.0
>>