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Subject: Re: [PATCH 1/7] fs/writeback: avoid to writeback non-expired inode in
 kupdate writeback
To: Tim Chen <tim.c.chen@linux.intel.com>, viro@zeniv.linux.org.uk,
 brauner@kernel.org, jack@suse.cz
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240208172024.23625-1-shikemeng@huaweicloud.com>
 <20240208172024.23625-2-shikemeng@huaweicloud.com>
 <ba75294dfb5bf4dd046d54de6c3e57698592dacc.camel@linux.intel.com>
From: Kemeng Shi <shikemeng@huaweicloud.com>
Message-ID: <4364e9bc-2d29-120d-4837-7f5620585508@huaweicloud.com>
Date: Sun, 18 Feb 2024 10:01:42 +0800
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on 2/9/2024 2:29 AM, Tim Chen wrote:
> On Fri, 2024-02-09 at 01:20 +0800, Kemeng Shi wrote:
>>
>>  
>> +static void filter_expired_io(struct bdi_writeback *wb)
>> +{
>> +	struct inode *inode, *tmp;
>> +	unsigned long expired_jiffies = jiffies -
>> +		msecs_to_jiffies(dirty_expire_interval * 10);
> 
> We have kupdate trigger time hard coded with a factor of 10 to expire interval here.
> The kupdate trigger time "mssecs_to_jiffies(dirty_expire_interval * 10)" is
> also used in wb_writeback().  It will be better to have a macro or #define
> to encapsulate the trigger time so if for any reason we need
> to tune the trigger time, we just need to change it at one place.
Hi Tim. Sorry for the late reply, I was on vacation these days.
I agree it's better to have a macro and I will add it in next version.
Thanks!
> 
> Tim
> 
>> +
>> +	spin_lock(&wb->list_lock);
>> +	list_for_each_entry_safe(inode, tmp, &wb->b_io, i_io_list)
>> +		if (inode_dirtied_after(inode, expired_jiffies))
>> +			redirty_tail(inode, wb);
>> +
>> +	list_for_each_entry_safe(inode, tmp, &wb->b_more_io, i_io_list)
>> +		if (inode_dirtied_after(inode, expired_jiffies))
>> +			redirty_tail(inode, wb);
>> +	spin_unlock(&wb->list_lock);
>> +}
>> +
>>  /*
>>   * Explicit flushing or periodic writeback of "old" data.
>>   *
>> @@ -2070,6 +2087,9 @@ static long wb_writeback(struct bdi_writeback *wb,
>>  	long progress;
>>  	struct blk_plug plug;
>>  
>> +	if (work->for_kupdate)
>> +		filter_expired_io(wb);
>> +
>>  	blk_start_plug(&plug);
>>  	for (;;) {
>>  		/*
>