Hi Changwei,
On 2018/1/26 9:00, Changwei Ge wrote:
> Hi Jun,
> Good morning:-)
>
> On 2018/1/25 20:45, piaojun wrote:
>> Hi Changwei,
>>
>> On 2018/1/25 20:30, Changwei Ge wrote:
>>> Hi Jun,
>>>
>>> On 2018/1/25 20:18, piaojun wrote:
>>>> Hi Changwei,
>>>>
>>>> On 2018/1/25 19:59, Changwei Ge wrote:
>>>>> Hi Jun,
>>>>>
>>>>> On 2018/1/25 10:41, piaojun wrote:
>>>>>> We should not reuse the dirty bh in jbd2 directly due to the following
>>>>>> situation:
>>>>>>
>>>>>> 1. When removing extent rec, we will dirty the bhs of extent rec and
>>>>> Quick questions:
>>>>> Do you mean current code puts modifying extent records belonging to a
>>>>> certain file and modifying truncate log into the same transaction?
>>>>> If so, forgive me since I didn't figure it out. Could you point out in
>>>>> your following sequence diagram?
>>>>>
>>>>> Afterwards, I can understand the issue your change log is describing
>>>>> better.
>>>>>
>>>>> Thanks,
>>>>> Changwei
>>>>>
>>>> Yes, I mean they are in the same transaction as below:
>>>>
>>>> ocfs2_remove_btree_range
>>>> ocfs2_remove_extent // modify extent records
>>>> ocfs2_truncate_log_append // modify truncate log
>>>
>>> If so I think the transaction including operations on extent and truncate
>>> log won't be committed.
>>> And journal should already be aborted if interval transaction commit thread
>>> has been woken.
>>> So no metadata will be changed.
>>> And later, ocfs2_truncate_log_worker shouldn't see any inode on truncate
>>> log.
>>> Are you sure this is the root cause of your problem?
>>> I feel a little strange for it.
>>>
>>> Thanks,
>>> Changwei
>>>
>> As you said, the transaction was not committed, but after a while the
>> bh of truncate log was committed in another transaction. I'm sure for
>> the cause and after applying this patch, the duplicate cluster problem
>> is gone. I have tested it a few month.
>
> I think we are talking about two jbd2/transactions. right?
yes, two transactions involved.
> One is for moving clusters from extent to truncate log. Let's name it T1.
> Anther is for declaiming clusters from truncate log and returning them back
> to global bitmap. Let's name it T2.
>
> If jbd2 fails to commit T1 due to an IO error, the whole jbd2/journal will be
> aborted which means it can't work any more.
> All following starting transaction and commit transaction will fail.
>
> So, how can the T2 be committed while T1 fails?
>From my testing jbd2 won't be aborted when encounter IO error, and I
print the bh->b_state = 0x44828 = 1000100100000101000. That means the
bh has been submitted but write IO, and still in jbd2 according to
'bh_state_bits' and 'jbd_state_bits'.
>
> Otherwise, did you ever try to recover jbd2/journal? If so, I think your
> patch here is not fit for mainline yet.
>
Currently this problem needs user umount and mount again to recover,
and I'm glad to hear your advice.
thanks,
Jun
> Thanks,
> Changwei
>
>>
>> thanks,
>> Jun
>>
>>>>
>>>> thanks,
>>>> Jun
>>>>
>>>>>> truncate log at the same time, and hand them over to jbd2.
>>>>>> 2. The bhs are not flushed to disk due to abnormal storage link.
>>>>>> 3. After a while the storage link become normal. Truncate log flush
>>>>>> worker triggered by the next space reclaiming found the dirty bh of
>>>>>> truncate log and clear its 'BH_Write_EIO' and then set it uptodate
>>>>>> in __ocfs2_journal_access():
>>>>>>
>>>>>> ocfs2_truncate_log_worker
>>>>>> ocfs2_flush_truncate_log
>>>>>> __ocfs2_flush_truncate_log
>>>>>> ocfs2_replay_truncate_records
>>>>>> ocfs2_journal_access_di
>>>>>> __ocfs2_journal_access // here we clear io_error and set
>>>>>> 'tl_bh' uptodata.
>>>>>>
>>>>>> 4. Then jbd2 will flush the bh of truncate log to disk, but the bh of
>>>>>> extent rec is still in error state, and unfortunately nobody will
>>>>>> take care of it.
>>>>>> 5. At last the space of extent rec was not reduced, but truncate log
>>>>>> flush worker have given it back to globalalloc. That will cause
>>>>>> duplicate cluster problem which could be identified by fsck.ocfs2.
>>>>>>
>>>>>> So we should return -EIO in case of ruining atomicity and consistency
>>>>>> of space reclaim.
>>>>>>
>>>>>> Fixes: acf8fdbe6afb ("ocfs2: do not BUG if buffer not uptodate in
>>>>>> __ocfs2_journal_access")
>>>>>>
>>>>>> Signed-off-by: Jun Piao <piao...@huawei.com>
>>>>>> Reviewed-by: Yiwen Jiang <jiangyi...@huawei.com>
>>>>>> ---
>>>>>> fs/ocfs2/journal.c | 45 +++++++++++++++++++++++++++++++++++----------
>>>>>> 1 file changed, 35 insertions(+), 10 deletions(-)
>>>>>>
>>>>>> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
>>>>>> index 3630443..d769ca2 100644
>>>>>> --- a/fs/ocfs2/journal.c
>>>>>> +++ b/fs/ocfs2/journal.c
>>>>>> @@ -666,21 +666,46 @@ static int __ocfs2_journal_access(handle_t *handle,
>>>>>> /* we can safely remove this assertion after testing. */
>>>>>> if (!buffer_uptodate(bh)) {
>>>>>> mlog(ML_ERROR, "giving me a buffer that's not
>>>>>> uptodate!\n");
>>>>>> - mlog(ML_ERROR, "b_blocknr=%llu\n",
>>>>>> - (unsigned long long)bh->b_blocknr);
>>>>>> + mlog(ML_ERROR, "b_blocknr=%llu, b_state=0x%lx\n",
>>>>>> + (unsigned long long)bh->b_blocknr, bh->b_state);
>>>>>>
>>>>>> lock_buffer(bh);
>>>>>> /*
>>>>>> - * A previous attempt to write this buffer head failed.
>>>>>> - * Nothing we can do but to retry the write and hope for
>>>>>> - * the best.
>>>>>> + * We should not reuse the dirty bh directly due to the
>>>>>> + * following situation:
>>>>>> + *
>>>>>> + * 1. When removing extent rec, we will dirty the bhs of
>>>>>> + * extent rec and truncate log at the same time, and
>>>>>> + * hand them over to jbd2.
>>>>>> + * 2. The bhs are not flushed to disk due to abnormal
>>>>>> + * storage link.
>>>>>> + * 3. After a while the storage link become normal.
>>>>>> + * Truncate log flush worker triggered by the next
>>>>>> + * space reclaiming found the dirty bh of truncate
>>>>>> log
>>>>>> + * and clear its 'BH_Write_EIO' and then set it
>>>>>> uptodate
>>>>>> + * in __ocfs2_journal_access():
>>>>>> + *
>>>>>> + * ocfs2_truncate_log_worker
>>>>>> + * ocfs2_flush_truncate_log
>>>>>> + * __ocfs2_flush_truncate_log
>>>>>> + * ocfs2_replay_truncate_records
>>>>>> + * ocfs2_journal_access_di
>>>>>> + * __ocfs2_journal_access
>>>>>> + *
>>>>>> + * 4. Then jbd2 will flush the bh of truncate log to
>>>>>> disk,
>>>>>> + * but the bh of extent rec is still in error state,
>>>>>> and
>>>>>> + * unfortunately nobody will take care of it.
>>>>>> + * 5. At last the space of extent rec was not reduced,
>>>>>> + * but truncate log flush worker have given it back
>>>>>> to
>>>>>> + * globalalloc. That will cause duplicate cluster
>>>>>> problem
>>>>>> + * which could be identified by fsck.ocfs2.
>>>>>> + *
>>>>>> + * So we should return -EIO in case of ruining atomicity
>>>>>> + * and consistency of space reclaim.
>>>>>> */
>>>>>> if (buffer_write_io_error(bh) && !buffer_uptodate(bh)) {
>>>>>> - clear_buffer_write_io_error(bh);
>>>>>> - set_buffer_uptodate(bh);
>>>>>> - }
>>>>>> -
>>>>>> - if (!buffer_uptodate(bh)) {
>>>>>> + mlog(ML_ERROR, "A previous attempt to write
>>>>>> this "
>>>>>> + "buffer head failed\n");
>>>>>> unlock_buffer(bh);
>>>>>> return -EIO;
>>>>>> }
>>>>>>
>>>>> .
>>>>>
>>>>
>>> .
>>>
>>
> .
>
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