[Ocfs2-devel] [PATCH] ocfs2: submit another bio if current bio is full

[Changwei Ge]

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,
>>>>>
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>