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.
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
>
> .
>
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