linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: allocate HOT

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Message-ID: <887d9b30-0069-4f4d-8107-48662379fd30@kernel.org>
Date: Mon, 1 Sep 2025 10:15:24 +0800
From: Chao Yu <chao@...nel.org>
To: Jaegeuk Kim <jaegeuk@...nel.org>
Cc: chao@...nel.org, linux-kernel@...r.kernel.org,
 linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: allocate HOT_DATA for IPU writes

On 8/31/25 07:54, Jaegeuk Kim wrote:
> On 08/30, Chao Yu wrote:
>> On 8/30/2025 4:47 AM, Jaegeuk Kim wrote:
>>> On 08/29, Chao Yu wrote:
>>>> On 8/28/2025 11:23 PM, Jaegeuk Kim wrote:
>>>>> On 08/28, Chao Yu wrote:
>>>>>> On 8/28/25 05:52, Jaegeuk Kim via Linux-f2fs-devel wrote:
>>>>>>> Let's split IPU writes in hot data area to improve the GC efficiency.
>>>>>>
>>>>>> I didn't get it, IPU may be not friendly for migrating data along w/ write in
>>>>>> hot area?
>>>>>
>>>>> This deals with IPU in the LFS mode.
>>>>
>>>> Okay, so, we missed to add f2fs_lfs_mode() condition, right?
>>>
>>> Why do we need that?
>>
>> As you mentioned above, this deals w/ IPU in the LFS mode. Am I missing
>> something?
> 
> The IPU flag indicates the data is hot. In lfs_mode, we missed to allocate
> it into HOT_DATA. In normal mode, IPU will update the data in place, which
> doesn't affect anything, while newly create data is also good to store in
> HOT_DATA as well. So, I think we don't need other condition here.

It makes sense, thanks for the explanation.

Reviewed-by: Chao Yu <chao@...nel.org>

Thanks,

> 
>>
>> Thanks,
>>
>>>
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>>>
>>>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>>>>>> ---
>>>>>>>    fs/f2fs/segment.c | 3 ++-
>>>>>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>>>>>> index e0f6589c6a1c..bb79dad55ac9 100644
>>>>>>> --- a/fs/f2fs/segment.c
>>>>>>> +++ b/fs/f2fs/segment.c
>>>>>>> @@ -3688,7 +3688,8 @@ static int __get_segment_type_6(struct f2fs_io_info *fio)
>>>>>>>    		if (file_is_hot(inode) ||
>>>>>>>    				is_inode_flag_set(inode, FI_HOT_DATA) ||
>>>>>>> -				f2fs_is_cow_file(inode))
>>>>>>> +				f2fs_is_cow_file(inode) ||
>>>>>>> +				is_inode_flag_set(inode, FI_NEED_IPU))
>>>>>>>    			return CURSEG_HOT_DATA;
>>>>>>>    		return f2fs_rw_hint_to_seg_type(F2FS_I_SB(inode),
>>>>>>>    						inode->i_write_hint);