linux-kernel - Re: [PATCH v1] f2fs: Fix discard bug on zoned block devices with 2MiB zone size

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Date:   Sun, 26 Mar 2023 11:49:37 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     yonggil.song@...sung.com,
        "linux-f2fs-devel@...ts.sourceforge.net" 
        <linux-f2fs-devel@...ts.sourceforge.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] f2fs: Fix discard bug on zoned block devices with 2MiB
 zone size

On 2023/3/25 0:54, Jaegeuk Kim wrote:
> On 03/24, Chao Yu wrote:
>> On 2023/3/24 6:03, Jaegeuk Kim wrote:
>>> On 03/23, Chao Yu wrote:
>>>> On 2023/3/13 17:48, Yonggil Song wrote:
>>>>> When using f2fs on a zoned block device with 2MiB zone size, IO errors
>>>>> occurs because f2fs tries to write data to a zone that has not been reset.
>>>>>
>>>>> The cause is that f2fs tries to discard multiple zones at once. This is
>>>>> caused by a condition in f2fs_clear_prefree_segments that does not check
>>>>> for zoned block devices when setting the discard range. This leads to
>>>>> invalid reset commands and write pointer mismatches.
>>>>>
>>>>> This patch fixes the zoned block device with 2MiB zone size to reset one
>>>>> zone at a time.
>>>>>
>>>>> Signed-off-by: Yonggil Song <yonggil.song@...sung.com>
>>>>> ---
>>>>>     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 acf3d3fa4363..2b6cb6df623b 100644
>>>>> --- a/fs/f2fs/segment.c
>>>>> +++ b/fs/f2fs/segment.c
>>>>> @@ -1953,7 +1953,8 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
>>>>>     					(end - 1) <= cpc->trim_end)
>>>>>     				continue;
>>>>> -		if (!f2fs_lfs_mode(sbi) || !__is_large_section(sbi)) {
>>>>> +		if (!f2fs_sb_has_blkzoned(sbi) &&
>>>>
>>>> Could you please add one line comment here for this change?
>>>
>>> This was merged in -dev a while ago. I don't think this would be critical
>>> to rebase it again.
>>
>> Yes, it's not critical, fine to me.
> 
> Added:
> 
> /* Should cover 2MB zoned device for zone-based reset */

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

Thanks,

> 
> So lucky since I had to rebase to fix other patch. :(
> 
> "f2fs: factor out discard_cmd usage from general rb_tree use"
> 
> 
>>
>> Thanks,
>>
>>>
>>>>
>>>> Otherwise it looks good to me.
>>>>
>>>> Thanks,
>>>>
>>>>> +		    (!f2fs_lfs_mode(sbi) || !__is_large_section(sbi))) {
>>>>>     			f2fs_issue_discard(sbi, START_BLOCK(sbi, start),
>>>>>     				(end - start) << sbi->log_blocks_per_seg);
>>>>>     			continue;