Re: [f2fs-dev] 答复: [PATCH v4] f2fs: compress: avoid unnecessary check in f2fs_prepare_compress_overwrite

[Chao Yu <yuchao0@huawei.com>]

On 2021/5/14 5:17, Eric Biggers wrote:
> On Wed, May 12, 2021 at 09:52:19AM +0800, Chao Yu wrote:
>> On 2021/5/12 5:50, Jaegeuk Kim wrote:
>>> On 05/11, changfengnan@vivo.com wrote:
>>>> Hi Jaegeuk:
>>>>
>>>> If there're existing clusters beyond i_size, may cause data corruption, but
>>>> will this happen in normal? maybe some error can cause this, if i_size is
>>>> error the data beyond size still can't handle properly.  Is there normal
>>>> case can casue existing clusters beyond i_size?
>>>
>>> We don't have a rule to sync between i_size and i_blocks.
>>
>> I can't image a case that compressed cluster may cross filesize, it looks it's
>> a bug if that happened, but I'm not sure I have considered all cases. So, I
>> prefer to add a check condition as below, then testing w/ xfstest/por_fsstress
>> for a while.
>>
>> Subject: [PATCH] f2fs: compress: compressed cluster should not cross i_size
>>
>> ---
>>   fs/f2fs/data.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index 06d1e58d3882..9acca358d578 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -3325,6 +3325,8 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
>>   			err = ret;
>>   			goto fail;
>>   		} else if (ret) {
>> +			f2fs_bug_on(sbi, index >=
>> +				DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
>>   			return 0;
>>   		}
>>   	}
> 
> If a file has both fs-verity and compression enabled, it can have compressed
> clusters past i_size.

Correct, any other case we missed for a writable file? let us know.

Thanks,

> 
> - Eric
> .
> 


_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel