Re: [PATCH 06/13] lightnvm: pblk: Ensure that erase is chunk aligned

Matias Bjørling
2019-03-04T13:00:44Z

On 3/4/19 1:44 PM, Igor Konopko wrote:
>
>
> On 04.03.2019 12:43, Hans Holmberg wrote:
>> On Mon, Mar 4, 2019 at 10:11 AM Javier González <javier@javigon.com>
>> wrote:
>>>
>>>> On 4 Mar 2019, at 10.05, Hans Holmberg
>>>> <hans.ml.holmberg@owltronix.com> wrote:
>>>>
>>>> I strongly disagree with adding code that would mask implantation
>>>> errors.
>>>>
>>>> If we want more internal checks, we could add an if statement that
>>>> would only be compiled in if CONFIG_NVM_PBLK_DEBUG is enabled.
>>>>
>>>
>>> Not sure who this is for - better not to top post.
>>>
>>> In any case, this is a spec grey zone. I’m ok with cleaning the bits as
>>> they mean nothing for the reset command. If you feel that strongly about
>>> this, you can take if with Igor.
>>
>> Pardon the top-post. It was meant for both you and Igor.
>>
>
> OCSSD 2.0 spec for vector chunk reset (chapter 2.2.2) explicitly says
> "The addresses in the LBA list shall be the first logical block address
> of each chunk to be reset.". So in my understanding we suppose to clear
> the sectors bits of the PPA address in order to be spec compliant.
>

Agree. And since ppa_addr is allocated on the stack, it should be either
memset or the remaining fields should be set to 0. Maybe better to zero
initialize in declaration?

>>>
>>>>
>>>> On Mon, Mar 4, 2019 at 8:48 AM Javier González <javier@javigon.com>
>>>> wrote:
>>>>>> On 27 Feb 2019, at 18.14, Igor Konopko <igor.j.konopko@intel.com>
>>>>>> wrote:
>>>>>>
>>>>>> In current pblk implementation of erase command
>>>>>> there is a chance tha sector bits are set to some
>>>>>> random values for erase PPA. This is unexpected
>>>>>> situation, since erase shall be always chunk
>>>>>> aligned. This patch fixes that issue
>>>>>>
>>>>>> Signed-off-by: Igor Konopko <igor.j.konopko@intel.com>
>>>>>> ---
>>>>>> drivers/lightnvm/pblk-core.c | 1 +
>>>>>> drivers/lightnvm/pblk-map.c  | 2 ++
>>>>>> 2 files changed, 3 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/lightnvm/pblk-core.c
>>>>>> b/drivers/lightnvm/pblk-core.c
>>>>>> index a98b2255f963..78b1eea4ab67 100644
>>>>>> --- a/drivers/lightnvm/pblk-core.c
>>>>>> +++ b/drivers/lightnvm/pblk-core.c
>>>>>> @@ -978,6 +978,7 @@ int pblk_line_erase(struct pblk *pblk, struct
>>>>>> pblk_line *line)
>>>>>>
>>>>>>               ppa = pblk->luns[bit].bppa; /* set ch and lun */
>>>>>>               ppa.a.blk = line->id;
>>>>>> +             ppa.a.reserved = 0;
>>>>>>
>>>>>>               atomic_dec(&line->left_eblks);
>>>>>>               WARN_ON(test_and_set_bit(bit, line->erase_bitmap));
>>>>>> diff --git a/drivers/lightnvm/pblk-map.c
>>>>>> b/drivers/lightnvm/pblk-map.c
>>>>>> index 79df583ea709..aea46b4ec40f 100644
>>>>>> --- a/drivers/lightnvm/pblk-map.c
>>>>>> +++ b/drivers/lightnvm/pblk-map.c
>>>>>> @@ -161,6 +161,7 @@ int pblk_map_erase_rq(struct pblk *pblk,
>>>>>> struct nvm_rq *rqd,
>>>>>>
>>>>>>                       *erase_ppa = ppa_list[i];
>>>>>>                       erase_ppa->a.blk = e_line->id;
>>>>>> +                     erase_ppa->a.reserved = 0;
>>>>>>
>>>>>>                       spin_unlock(&e_line->lock);
>>>>>>
>>>>>> @@ -202,6 +203,7 @@ int pblk_map_erase_rq(struct pblk *pblk,
>>>>>> struct nvm_rq *rqd,
>>>>>>               atomic_dec(&e_line->left_eblks);
>>>>>>               *erase_ppa = pblk->luns[bit].bppa; /* set ch and lun */
>>>>>>               erase_ppa->a.blk = e_line->id;
>>>>>> +             erase_ppa->a.reserved = 0;
>>>>>>       }
>>>>>>
>>>>>>       return 0;
>>>>>> --
>>>>>> 2.17.1
>>>>>
>>>>> I’m fine with adding this, but note that there is actually no
>>>>> requirement for the erase to be chunk aligned - the only bits that
>>>>> should be looked at are group, PU and chunk.
>>>>>
>>>>> Reviewed-by: Javier González <javier@javigon.com>