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Subject: Re: [PATCH] f2fs: fix to align to section for fallocate() on pinned
 file
To:     Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>
CC:     <linux-f2fs-devel@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>
References: <20210305095601.96591-1-yuchao0@huawei.com>
 <d9c118eb-45b3-7f35-70bd-cb016957e6e8@kernel.org>
 <YFo0Tz1zl4tw7lUP@google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <d08a10bb-d6ac-1dde-7e61-836030c96f34@huawei.com>
Date:   Wed, 24 Mar 2021 09:23:29 +0800
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On 2021/3/24 2:32, Jaegeuk Kim wrote:
> On 03/23, Chao Yu wrote:
>> On 2021/3/5 17:56, Chao Yu wrote:
>>> Now, fallocate() on a pinned file only allocates blocks which aligns
>>> to segment rather than section, so GC may try to migrate pinned file's
>>> block, and after several times of failure, pinned file's block could
>>> be migrated to other place, however user won't be aware of such
>>> condition, and then old obsolete block address may be readed/written
>>> incorrectly.
>>>
>>> To avoid such condition, let's try to allocate pinned file's blocks
>>> with section alignment.
>>>
>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>
>> Jaegeuk,
>>
>> Could you please check and apply below diff into original patch?
>>
>> ---
>>   fs/f2fs/file.c | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 236f3f69681a..24fa68fdcaa0 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -1648,13 +1648,13 @@ static int expand_inode_data(struct inode *inode, loff_t offset,
>>   		return 0;
>>
>>   	if (f2fs_is_pinned_file(inode)) {
>> -		block_t len = (map.m_len >> sbi->log_blocks_per_seg) <<
>> -					sbi->log_blocks_per_seg;
>> +		block_t sec_blks = BLKS_PER_SEC(sbi);
>> +		block_t len = rounddown(map.m_len, sec_blks);
> 
> len is declared above, so let me rephrase this as well.

Oh, right.

> 
>>
>> -		if (map.m_len % sbi->blocks_per_seg)
>> -			len += sbi->blocks_per_seg;
>> +		if (map.m_len % sec_blks)
>> +			len += sec_blks;
> 
> is this roundup()?

More clean.

> 
> Could you check this?
> https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=e1175f02291141bbd924fc578299305fcde35855

Looks good to me. :)

Thanks,

> 
>>
>> -		map.m_len = sbi->blocks_per_seg;
>> +		map.m_len = sec_blks;
>>   next_alloc:
>>   		if (has_not_enough_free_secs(sbi, 0,
>>   			GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))) {
>> -- 
>> 2.22.1
>>
> .
>