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Subject: Re: [f2fs-dev] [PATCH 6/7] f2fs: flush quota blocks after turnning it
 off
To:     Jaegeuk Kim <jaegeuk@kernel.org>, Chao Yu <chao@kernel.org>
CC:     <linux-kernel@vger.kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>
References: <20190128234717.77225-1-jaegeuk@kernel.org>
 <20190128234717.77225-6-jaegeuk@kernel.org>
 <629f4b34-381e-7860-c717-3fe54ee15694@kernel.org>
 <20190204165934.GB15646@jaegeuk-macbookpro.roam.corp.google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <499c3f3c-3ef4-5412-d4df-8bcfc7a558be@huawei.com>
Date:   Wed, 13 Feb 2019 11:27:25 +0800
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On 2019/2/5 0:59, Jaegeuk Kim wrote:
> On 02/02, Chao Yu wrote:
>> On 2019-1-29 7:47, Jaegeuk Kim wrote:
>>> After quota_off, we'll get some dirty blocks. If put_super don't have a chance
>>> to flush them by checkpoint, it causes NULL pointer exception in end_io after
>>> iput(node_inode). (e.g., by checkpoint=disable)
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>> ---
>>>  fs/f2fs/super.c | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>> index 5e1f8573a17f..7694cb350734 100644
>>> --- a/fs/f2fs/super.c
>>> +++ b/fs/f2fs/super.c
>>> @@ -2026,6 +2026,12 @@ void f2fs_quota_off_umount(struct super_block *sb)
>>>  			set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR);
>>>  		}
>>>  	}
>>> +	/*
>>> +	 * In case of checkpoint=disable, we must flush quota blocks.
>>
>> checkpoint=disable is one of the cases, right? e.g. IO error can be another case?
>>
>> So here I guess we need to change the comments a bit for that.
> 
> I didn't test other cases, but checkpoint=disable could give real errors through
> some tests. So, basically, I'd like to keep known cases only here.

Alright, not a big deal. :)

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,

> 
>>
>> Thanks,
>>
>>> +	 * This can cause NULL exception for node_inode in end_io, since
>>> +	 * put_super already dropped it.
>>> +	 */
>>> +	sync_filesystem(sb);
>>>  }
>>>  
>>>  static void f2fs_truncate_quota_inode_pages(struct super_block *sb)
>>>
> 
> 
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