linux-kernel - Re: [f2fs-dev] [PATCH 1/4] f2fs: flush journal nat entries for nat

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Date:   Tue, 10 Jul 2018 14:01:22 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH 1/4] f2fs: flush journal nat entries for
 nat_bits during unmount

On 2018/7/10 4:43, Jaegeuk Kim wrote:
> On 07/09, Chao Yu wrote:
>> On 2018/7/7 5:09, Jaegeuk Kim wrote:
>>> Let's flush journal nat entries for speed up in the next run.
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>> ---
>>>  fs/f2fs/node.c | 7 +++++++
>>>  1 file changed, 7 insertions(+)
>>>
>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>> index 29237aeca041..0f076fb0d828 100644
>>> --- a/fs/f2fs/node.c
>>> +++ b/fs/f2fs/node.c
>>> @@ -2613,6 +2613,13 @@ void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>>>  	nid_t set_idx = 0;
>>>  	LIST_HEAD(sets);
>>>  
>>> +	/* during unmount, let's flush nat_bits before checking dirty_nat_cnt */
>>> +	if (enabled_nat_bits(sbi, cpc)) {
>>> +		down_write(&nm_i->nat_tree_lock);
>>> +		remove_nats_in_journal(sbi);
>>> +		up_write(&nm_i->nat_tree_lock);
>>> +	}
>>
>> The case will cover that nm_i->dirty_nat_cnt is zero and there is cached nats in
>> journal?
> 
> Yes.
> 
>>
>> So enabled_nat_bits() below should be removed?
> 
> It's out of lock, nm_i->nat_tree_lock, logically..

CP_NAT_BITS_FLAG modification should be happened in mount or checkpoint, so
there should be no contention.

Anyway, keep it here is okay to me.

Reviewed-by: Chao Yu <yuchao0@...wei.com>

Thanks,

> 
>>
>> 	if (enabled_nat_bits(sbi, cpc) ||
>> 		!__has_cursum_space(journal, nm_i->dirty_nat_cnt, NAT_JOURNAL))
>> 		remove_nats_in_journal(sbi);
>>
>> Thanks,
>>
>>> +
>>>  	if (!nm_i->dirty_nat_cnt)
>>>  		return;
>>>  
>>>
> 
> .
>