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

[Changwei Ge]

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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