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

[piaojun]

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.

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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>