[Ocfs2-devel] [PATCH] ocfs2: submit another bio if current bio is full
piaojun
piaojun at huawei.com
Mon May 14 18:06:29 PDT 2018
On 2018/5/14 15:05, Changwei Ge wrote:
> Hi Jun,
>
> IMO, o2hb_issue_node_write() just needs _one_ vec so there is no problem
> in it.
>
> Calculating bio number might be get related code more complicated which
> I think is not necessary.
>
> It doesn't solve any existed problem or improve performance or clean
> code. :(
OK, it sounds reasonable, thanks for your correction.
Thanks,
Jun
>
> Thanks,
> Changwei
>
> On 2018/5/14 14:26, piaojun wrote:
>> Hi Changwei,
>>
>> I got your point, we should let the caller retry if bio is not enough,
>> right? But some caller like o2hb_issue_node_write() won't retry once error
>> happens, though the bio will always be enough. I think if we could
>> calculate the number of bio we need before calling bio_add_page()?
>>
>> Thanks
>> Jun
>>
>> On 2018/5/14 11:21, Changwei Ge wrote:
>>> Hi Jun,
>>>
>>> Right now, I am afraid that the easiest and fasted way to fix this issue
>>> is to revert your patch.
>>>
>>> From comments before function bio_add_page(), we can see that it only
>>> fails if either ::bi_vcnt == ::bi_max_vecs or it's a cloned bio.
>>>
>>>
>>> So we can judge if bio is full from its return value is zero or not.
>>>
>>>
>>> Thanks,
>>>
>>> Changwei
>>>
>>>
>>> On 2018/5/10 9:13, Changwei Ge wrote:
>>>>
>>>> On 2018/5/10 8:24, piaojun wrote:
>>>>> On 2018/5/9 20:01, Changwei Ge wrote:
>>>>>> Hi Jun,
>>>>>>
>>>>>>
>>>>>> On 2018/5/9 18:08, piaojun wrote:
>>>>>>> Hi Changwei,
>>>>>>>
>>>>>>> On 2018/4/13 13:51, Changwei Ge wrote:
>>>>>>>> If cluster scale exceeds 16 nodes, bio will be full and
>>>>>>>> bio_add_page()
>>>>>>>> returns 0 when adding pages to bio. Returning -EIO to
>>>>>>>> o2hb_read_slots()
>>>>>>>> from o2hb_setup_one_bio() will lead to losing chance to allocate more
>>>>>>>> bios to present all heartbeat region.
>>>>>>>>
>>>>>>>> So o2hb_read_slots() fails.
>>>>>>>>
>>>>>>>> In my test, making fs fails in starting o2cb service.
>>>>>>>>
>>>>>>>> Attach error log:
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 0, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 1, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 2, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 3, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 4, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 5, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 6, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 7, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 8, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 9, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 10, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 11, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 12, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 13, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 14, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 15, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:463 page 16, vec_len =
>>>>>>>> 4096, vec_start = 0
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_setup_one_bio:471 ERROR: Adding page[16]
>>>>>>>> to bio failed, page ffffea0002d7ed40, len 0, vec_len 4096,
>>>>>>>> vec_start 0, bi_sector 8192
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_read_slots:500 ERROR: status = -5
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_populate_slot_data:1911 ERROR: status = -5
>>>>>>>> (mkfs.ocfs2,27479,2):o2hb_region_dev_write:2012 ERROR: status = -5
>>>>>>>>
>>>>>>>> Fixes: ba16ddfbeb9d ("ocfs2/o2hb: check len for bio_add_page() to
>>>>>>>> avoid getting incorrect bio"
>>>>>>>>
>>>>>>>> Signed-off-by: Changwei Ge <ge.changwei at h3c.com>
>>>>>>>> ---
>>>>>>>> fs/ocfs2/cluster/heartbeat.c | 8 ++++++--
>>>>>>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/fs/ocfs2/cluster/heartbeat.c
>>>>>>>> b/fs/ocfs2/cluster/heartbeat.c
>>>>>>>> index 91a8889abf9b..2809e29d612d 100644
>>>>>>>> --- a/fs/ocfs2/cluster/heartbeat.c
>>>>>>>> +++ b/fs/ocfs2/cluster/heartbeat.c
>>>>>>>> @@ -540,11 +540,12 @@ static struct bio *o2hb_setup_one_bio(struct
>>>>>>>> o2hb_region *reg,
>>>>>>>> struct bio *bio;
>>>>>>>> struct page *page;
>>>>>>>> +#define O2HB_BIO_VECS 16
>>>>>>>> /* Testing has shown this allocation to take long enough under
>>>>>>>> * GFP_KERNEL that the local node can get fenced. It would be
>>>>>>>> * nicest if we could pre-allocate these bios and avoid this
>>>>>>>> * all together. */
>>>>>>>> - bio = bio_alloc(GFP_ATOMIC, 16);
>>>>>>>> + bio = bio_alloc(GFP_ATOMIC, O2HB_BIO_VECS);
>>>>>>>> if (!bio) {
>>>>>>>> mlog(ML_ERROR, "Could not alloc slots BIO!\n");
>>>>>>>> bio = ERR_PTR(-ENOMEM);
>>>>>>>> @@ -570,7 +571,10 @@ static struct bio *o2hb_setup_one_bio(struct
>>>>>>>> o2hb_region *reg,
>>>>>>>> current_page, vec_len, vec_start);
>>>>>>> Should we check the validity of 'current_page' before
>>>>>>> bio_add_page()? And
>>>>>>> that will prevent error happen. Others looks OK.
>>>>>> If I understand correctly, you mean we should check current page is
>>>>>> NULL or not?
>>>>>> If so I think there is no need since o2hb should guarantee that it has
>>>>>> already reserved enough pages for disk heartbeat read/write behalf.
>>>>> I mean we could check if 'current_page' equals O2HB_BIO_VECS before
>>>>> bio_add_page() to avoid NULL pointer referrence.
>>>> Yes, that might work.
>>>> I find another problem within this patch.
>>>> I will post v2 patch later to fix them all with consideration about
>>>> your suggestion.
>>>>
>>>> Thanks,
>>>> Changwei
>>>>
>>>>> thanks,
>>>>> Jun
>>>>>
>>>>>> Thanks,
>>>>>> Changwei
>>>>>>> thanks,
>>>>>>> Jun
>>>>>>>> len = bio_add_page(bio, page, vec_len, vec_start);
>>>>>>>> - if (len != vec_len) {
>>>>>>>> + if (len == 0 && current_page == O2HB_BIO_VECS) {
>>>>>>>> + /* bio is full now. */
>>>>>>>> + goto bail;
>>>>>>>> + } else if (len != vec_len) {
>>>>>>>> mlog(ML_ERROR, "Adding page[%d] to bio failed, "
>>>>>>>> "page %p, len %d, vec_len %u, vec_start %u, "
>>>>>>>> "bi_sector %llu\n", current_page, page, len,
>>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Ocfs2-devel mailing list
>>>>>>> Ocfs2-devel at oss.oracle.com
>>>>>>> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>
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