linux-kernel - Re: [PATCH 1/2] lightnvm: use rrpc->nr_luns to calculate the rrpc area size

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Date:	Thu, 31 Mar 2016 17:51:53 +0800
From:	Wenwei Tao <ww.tao0320@...il.com>
To:	Matias Bjørling <mb@...htnvm.io>
Cc:	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH 1/2] lightnvm: use rrpc->nr_luns to calculate the rrpc
 area size

This could be work, but it needs more steps when rrpc_area_init fails.
If rrpc_area_init fail we may come to rrpc_free and call
rrpc_area_free, we find and put the area by the rrpc->soffset value,
this value is zero when we fail to get an area, we may put an exist
area that really start from zero by mistake. If we move rrpc_area_init
call under the rrpc_luns_init call instead, we need a way to avoid it.

2016-03-31 16:57 GMT+08:00 Matias Bjørling <mb@...htnvm.io>:
>
>
> On 03/31/2016 10:31 AM, Wenwei Tao wrote:
>>
>> 2016-03-30 22:28 GMT+08:00 Wenwei Tao <ww.tao0320@...il.com>:
>>>
>>> rrpc->nr_sects is calculated after rrpc init luns succeeds,
>>> before that the value of rrpc->nr_sects is zero, so we cannot
>>> use it to calcuate rrpc area size, we use rrpc->nr_luns instead.
>>>
>>> Signed-off-by: Wenwei Tao <ww.tao0320@...il.com>
>>> ---
>>>   drivers/lightnvm/rrpc.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/lightnvm/rrpc.c b/drivers/lightnvm/rrpc.c
>>> index 3ab6495..516a045 100644
>>> --- a/drivers/lightnvm/rrpc.c
>>> +++ b/drivers/lightnvm/rrpc.c
>>> @@ -1223,7 +1223,7 @@ static int rrpc_area_init(struct rrpc *rrpc,
>>> sector_t *begin)
>>>   {
>>>          struct nvm_dev *dev = rrpc->dev;
>>>          struct nvmm_type *mt = dev->mt;
>>> -       sector_t size = rrpc->nr_sects * dev->sec_size;
>>> +       sector_t size = dev->sec_size * dev->sec_per_lun * rrpc->nr_luns;
>>
>>
>> dev->sec_size * dev->sec_per_lun * rrpc->nr_luns could be oveflow,
>> should use (sector_t)dev->sec_size * dev->sec_per_lun * rrpc->nr_luns
>> instead. Will submit another patch to fix it.
>
>
> Hi Wenwei,
>
> How about moving rrpc_area_init call under the rrpc_luns_init call instead.
> Then nr_sects will have been initialized?
>
>
>>>
>>>          size >>= 9;
>>>
>>> --
>>> 2.7.2.333.g70bd996
>>>
>