Re: [f2fs-dev] f2fs_symlink bug

[Chao Yu <chao@kernel.org>]

On 2019-8-23 23:04, Jaegeuk Kim wrote:
> On 08/23, Chao Yu wrote:
>> On 2019/8/23 3:49, Jaegeuk Kim wrote:
>>> On 08/21, Chao Yu wrote:
>>>> Ping,
>>>>
>>>> On 2019/8/12 20:01, Chao Yu wrote:
>>>>> Hi Jaegeuk,
>>>>>
>>>>> In por_fsstress testcase, fsck reports below inconsistent status, I found one
>>>>> path can cause this case.
>>>>>
>>>>> [FIX] (fsck_chk_inode_blk:1002)  --> Symlink: recover 0x1425 with i_size=4096
>>>>> [ASSERT] (fsck_chk_inode_blk:1030)  --> ino: 0x1425 chksum:0x6983d47, but
>>>>> calculated one is: 0xdb284b35
>>>>> [FIX] (fsck_chk_inode_blk:1036)  --> ino: 0x1425 recover, i_inode_checksum=
>>>>> 0x6983d47 -> 0xdb284b35
>>>>>
>>>>> - f2fs_symlink
>>>>>  - page_symlink failed -> f2fs_write_failed() will truncate size to zero
>>>>>   - f2fs_unlink failed -> symlink inode w/o data will remain in fs
>>>>>
>>>>> Not sure, but one choice of fix is to treat symlink as fs meta like we did for
>>>>> directory, so that checkpoint can take care of all data/node of symlink, any
>>>>> thoughts?
>>>
>>> Hmm, how's the possible to get very long path name requiring another data block?
>>
>> It can with below script, which is actually existed case in fsstress.
>>
>> #!/bin/bash
>>
>> for (( i = 0; i < 4095; i++ )); do
>>         if [ $((i % 255)) -eq 0 ]
>>         then
>>                 filename=$filename"/"
>>         else
>>                 filename=$filename"0"
>>         fi
>> done
>>
>> ln -s $filename /f2fs_mount_point/symlink
>>
>>> If it's fitted in inline_data, it's more easy to guarantee that, right?
>>
>> If the length of symlink is 4095, not sure inline space is enough even we can
>> compress symlink...
> 
> I meant real usecases larger than 3.5KB. There's no posix rule to guarantee
> this. IOWs, it's known behavior across filesystems.

Correct, it looks not a big deal that whether we truncate i_size of symlink to
zero or not? how about avoiding such assert in fsck?

Thanks,

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