linux-kernel - Re: [f2fs-dev] [PATCH 2/4] f2fs: allow wrong configure dio to buffered write

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Message-ID: <5ba170bb-8837-ce0a-87a9-b996b38eb1d8@huawei.com>
Date:   Tue, 10 Jul 2018 13:54:40 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH 2/4] f2fs: allow wrong configure dio to
 buffered write

On 2018/7/10 4:41, Jaegeuk Kim wrote:
> On 07/09, Chao Yu wrote:
>> On 2018/7/7 5:09, Jaegeuk Kim wrote:
>>> This fixes to support unaligned dio as buffered writes.
>>
>> Should we return -EINVAL as manual of write said:
>>
>> EINVAL fd is attached to an object which is unsuitable for writing; or the file
>> was opened with the O_DIRECT flag,  and  either  the  address
>> specified in buf, the value specified in count, or the current file offset is
>> not suitably aligned.
> 
> I came from many xfstests failures regarding to direct IO error. It seems other
> filesystems allow buffered writes as well.

But as I see, it allows unaligned DIO write like xfs_io -d -c "pwrite 1 512",
where ext4 returns failure.

I guess, we only need to expand to support DIO write aligns to sector (512
bytes) for these cases?

Thanks,

> 
>>
>> Thanks,
>>
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>> ---
>>>  fs/f2fs/data.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>> index e66379961804..6e8e78bb64a7 100644
>>> --- a/fs/f2fs/data.c
>>> +++ b/fs/f2fs/data.c
>>> @@ -2425,7 +2425,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
>>>  
>>>  	err = check_direct_IO(inode, iter, offset);
>>>  	if (err)
>>> -		return err;
>>> +		return 0;
>>>  
>>>  	if (f2fs_force_buffered_io(inode, rw))
>>>  		return 0;
>>>
> 
>