linux-kernel - Re: [f2fs-dev] [PATCH] f2fs-tools: allocate logs after conventional area for HM zoned devices

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Date: Fri, 26 Jan 2024 09:27:10 +0800
From: Chao Yu <chao@...nel.org>
To: Daeho Jeong <daeho43@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
 kernel-team@...roid.com, Daeho Jeong <daehojeong@...gle.com>,
 Yongpeng Yang <yangyongpeng1@...o.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs-tools: allocate logs after conventional
 area for HM zoned devices

On 2024/1/26 0:25, Daeho Jeong wrote:
> On Wed, Jan 24, 2024 at 7:34 PM Chao Yu <chao@...nel.org> wrote:
>>
>> +Cc Yongpeng Yang
>>
>> Daeho,
>>
>> Yongpeng reports a potential issue: if c.devices[0].total_segments is
>> larger than segments of mainarea, c.cur_seg[CURSEG_HOT_NODE] will exceed
>> end boundary of mainarea. Could you please check that? though it's a corner
>> case.
> 
> Can you elaborate more?

Since c.cur_seg[CURSEG_HOT_NODE] is an offset started from main_blkaddr.
If c.cur_seg[CURSEG_HOT_NODE] was assigned w/ c.devices[0].total_segments,
and c.devices[0].total_segments is larger than segments of mainare,
c.cur_seg[CURSEG_HOT_NODE] will exceed the end boundary of mainarea.

	c.cur_seg[CURSEG_HOT_NODE] = c.zoned_model == F2FS_ZONED_HM ?
			c.devices[0].total_segments : 0;

> In the case of F2FS_ZONED_HM, we have the devices[1].
> Do you mean the case we format the filesystem intentionally smaller
> than what devices have?

I mean blew case:
device[0]: conventional device size = 10240 MB
device[1]: zone device size = 2 MB

Thanks,

> 
>>
>> On 2024/1/18 7:00, Daeho Jeong wrote:
>>> From: Daeho Jeong <daehojeong@...gle.com>
>>>
>>> Make to allocate logs after conventional area for HM zoned devices to
>>> spare them for file pinning support.
>>>
>>> Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
>>> ---
>>>    mkfs/f2fs_format.c | 3 ++-
>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
>>> index f2840c8..91a7f4b 100644
>>> --- a/mkfs/f2fs_format.c
>>> +++ b/mkfs/f2fs_format.c
>>> @@ -557,7 +557,8 @@ static int f2fs_prepare_super_block(void)
>>>                c.cur_seg[CURSEG_COLD_DATA] = 0;
>>>                c.cur_seg[CURSEG_WARM_DATA] = next_zone(CURSEG_COLD_DATA);
>>>        } else if (c.zoned_mode) {
>>> -             c.cur_seg[CURSEG_HOT_NODE] = 0;
>>> +             c.cur_seg[CURSEG_HOT_NODE] = c.zoned_model == F2FS_ZONED_HM ?
>>> +                     c.devices[0].total_segments : 0;
>>>                c.cur_seg[CURSEG_WARM_NODE] = next_zone(CURSEG_HOT_NODE);
>>>                c.cur_seg[CURSEG_COLD_NODE] = next_zone(CURSEG_WARM_NODE);
>>>                c.cur_seg[CURSEG_HOT_DATA] = next_zone(CURSEG_COLD_NODE);