On 2018/2/12 10:32, Jaegeuk Kim wrote:
> On 02/12, guoweichao wrote:
>> Hi Jaegeuk,
>>
>> On 2018/2/12 7:32, Jaegeuk Kim wrote:
>>> On 02/06, Weichao Guo wrote:
>>>> There is a potential inconsistent metadata case due to a cp block
>>>> crc invalid in the latest checkpoint caused by hardware issues:
>>>> 1) write nodes into segment x;
>>>> 2) write checkpoint A;
>>>> 3) remove nodes in segment x;
>>>> 4) write checkpoint B;
>>>> 5) issue discard or write datas into segment x;
>>>> 6) sudden power-cut;
>>>> 7) use checkpoint A after reboot as checkpoint B is invalid
>>>>
>>>> This inconsistency may be found after several reboots long time later
>>>> and the kernel log about cp block crc invalid has disappeared. This
>>>> makes the root cause of the inconsistency is hard to locate. Let us
>>>> separate such other part issues from f2fs logical bugs in debug version.
>>>>
>>>> Signed-off-by: Weichao Guo <guoweic...@huawei.com>
>>>> ---
>>>> fs/f2fs/checkpoint.c | 8 ++++++--
>>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>>>> index 8b0945b..16ba96a 100644
>>>> --- a/fs/f2fs/checkpoint.c
>>>> +++ b/fs/f2fs/checkpoint.c
>>>> @@ -737,13 +737,17 @@ static int get_checkpoint_version(struct
>>>> f2fs_sb_info *sbi, block_t cp_addr,
>>>> crc_offset = le32_to_cpu((*cp_block)->checksum_offset);
>>>> if (crc_offset > (blk_size - sizeof(__le32))) {
>>>> f2fs_msg(sbi->sb, KERN_WARNING,
>>>> - "invalid crc_offset: %zu", crc_offset);
>>>> + "invalid crc_offset: %zu at blk_addr: 0x%x",
>>>> + crc_offset, cp_addr);
>>>> + f2fs_bug_on(sbi, 1);
>>>
>>> I don't think we can use bug_on here, since we're easily getting this when
>>> power-cut happened in the middle of checkpoint pack writes, which is an
>>> expected
>>> behavior. Hmm, we need to consider another way to detect that.
>> We only check CP block crc here. The two CP blocks may have different CP
>> versions when
>> power-cut happened, but their crc value should be valid. IMO, this patch
>> will trigger a
>> bug_on only when some external issues cause CP block crc invalid as one 4K
>> page is
>> persisted atomically.
>
> Huh? This checks crc_offset, not crc? Unfortunately, my simple fault injection
> test gave this bug_on within a day. The below bug_on seems what you're saying
> about tho.
oh sorry, I didn't notice the code line carefully. But which fault injection
trigger
this bug_on? The crc_offset is also parts of the CP block, it seems power-cut
happened
in middle of writing checkpoint should not produce an invalid crc_offset.
Thanks,
>
>>
>> Thanks,
>>>
>>> Thanks,
>>>
>>>> return -EINVAL;
>>>> }
>>>>
>>>> crc = cur_cp_crc(*cp_block);
>>>> if (!f2fs_crc_valid(sbi, crc, *cp_block, crc_offset)) {
>>>> - f2fs_msg(sbi->sb, KERN_WARNING, "invalid crc value");
>>>> + f2fs_msg(sbi->sb, KERN_WARNING,
>>>> + "invalid crc value at blk_addr: 0x%x", cp_addr);
>>>> + f2fs_bug_on(sbi, 1);
>>>> return -EINVAL;
>>>> }
>>>>
>>>> --
>>>> 2.10.1
>>>
>>> .
>>>
>
> .
>
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
