Re: [PATCH] f2fs: allocate hot_data for atomic write more strictly

[heyunlei <heyunlei@huawei.com>]

>-----Original Message-----
>From: Yuchao (T)
>Sent: Tuesday, April 17, 2018 4:31 PM
>To: heyunlei; jaegeuk@kernel.org; linux-f2fs-devel@lists.sourceforge.net
>Cc: Wangbintian; Zhangdianfang (Euler)
>Subject: Re: [f2fs-dev][PATCH] f2fs: allocate hot_data for atomic write more strictly
>
>On 2018/4/16 19:34, Yunlei He wrote:
>> If a file not set type as hot, has dirty pages more than
>> threshold 64 before starting atomic write, may be lose hot
>> flag.
>>
>> Signed-off-by: Yunlei He <heyunlei@huawei.com>
>> ---
>>  fs/f2fs/file.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 79eeed5..bf61e20 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -1685,7 +1685,6 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
>>  		goto out;
>>
>>  	set_inode_flag(inode, FI_ATOMIC_FILE);
>
>How about moving this below inc_stat tag? If there is still dirty page, for
>reclaim path, we may redirty page with atomic write mode, we need to avoid that.
>
With it，maybe still has dirty pages after filemap_write_and_wait_range，
which are not inmem pages and maybe affect atomicity?

Thanks.

>> -	set_inode_flag(inode, FI_HOT_DATA);
>>  	f2fs_update_time(F2FS_I_SB(inode), REQ_TIME);
>
>Ditto.
>
>Thanks,
>
>>
>>  	if (!get_dirty_pages(inode))
>> @@ -1697,11 +1696,11 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
>>  	ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
>>  	if (ret) {
>>  		clear_inode_flag(inode, FI_ATOMIC_FILE);
>> -		clear_inode_flag(inode, FI_HOT_DATA);
>>  		goto out;
>>  	}
>>
>>  inc_stat:
>> +	set_inode_flag(inode, FI_HOT_DATA);
>>  	F2FS_I(inode)->inmem_task = current;
>>  	stat_inc_atomic_write(inode);
>>  	stat_update_max_atomic_write(inode);
>>

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