linux-kernel - Re: [PATCH 3/3] f2fs: prevent waiter encountering incorrect discard states

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Date:   Tue, 28 Mar 2017 09:17:01 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>
Subject: Re: [PATCH 3/3] f2fs: prevent waiter encountering incorrect discard
 states

On 2017/3/28 7:56, Jaegeuk Kim wrote:
> On 03/27, Chao Yu wrote:
>> In f2fs_submit_discard_endio, we will wake up waiter before setting
>> discard command states, so waiter may use incorrect states. Change
>> the order between complete() and states setting to fix this issue.
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>>  fs/f2fs/segment.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 57a81f9c8c14..9f9542c9fe47 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -717,9 +717,9 @@ static void f2fs_submit_discard_endio(struct bio *bio)
>>  {
>>  	struct discard_cmd *dc = (struct discard_cmd *)bio->bi_private;
>>  
>> -	complete(&dc->wait);
>>  	dc->error = bio->bi_error;
>>  	dc->state = D_DONE;
>> +	complete(&dc->wait);
> 
> If we set D_DONE first, the object can be released by __remove_discard_cmd()?

Yes, I think so.

Thanks,

> 
> Thanks,
> 
>>  	bio_put(bio);
>>  }
>>  
>> -- 
>> 2.8.2.295.g3f1c1d0
> 
> .
>