Re: [PATCH 09/15] lightnvm: implement get log report chunk helpers

[Javier Gonzalez <javier@cnexlabs.com>]

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> On 1 Mar 2018, at 12.51, Matias Bjørling <mb@lightnvm.io> wrote:
> 
> On 03/01/2018 12:02 PM, Javier Gonzalez wrote:
>>> On 1 Mar 2018, at 11.40, Matias Bjørling <mb@lightnvm.io> wrote:
>>> 
>>> On 02/28/2018 04:49 PM, Javier González wrote:
>>>> The 2.0 spec provides a report chunk log page that can be retrieved
>>>> using the stangard nvme get log page. This replaces the dedicated
>>>> get/put bad block table in 1.2.
>>>> This patch implements the helper functions to allow targets retrieve the
>>>> chunk metadata using get log page. It makes nvme_get_log_ext available
>>>> outside of nvme core so that we can use it form lightnvm.
>>>> Signed-off-by: Javier González <javier@cnexlabs.com>
>>>> ---
>>>>  drivers/lightnvm/core.c      | 11 +++++++
>>>>  drivers/nvme/host/core.c     |  6 ++--
>>>>  drivers/nvme/host/lightnvm.c | 74 ++++++++++++++++++++++++++++++++++++++++++++
>>>>  drivers/nvme/host/nvme.h     |  3 ++
>>>>  include/linux/lightnvm.h     | 24 ++++++++++++++
>>>>  5 files changed, 115 insertions(+), 3 deletions(-)
>>>> diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
>>>> index ed33e0b11788..4141871f460d 100644
>>>> --- a/drivers/lightnvm/core.c
>>>> +++ b/drivers/lightnvm/core.c
>>>> @@ -712,6 +712,17 @@ static void nvm_free_rqd_ppalist(struct nvm_tgt_dev *tgt_dev,
>>>>  	nvm_dev_dma_free(tgt_dev->parent, rqd->ppa_list, rqd->dma_ppa_list);
>>>>  }
>>>>  +int nvm_get_chunk_meta(struct nvm_tgt_dev *tgt_dev, struct nvm_chk_meta *meta,
>>>> +		struct ppa_addr ppa, int nchks)
>>>> +{
>>>> +	struct nvm_dev *dev = tgt_dev->parent;
>>>> +
>>>> +	nvm_ppa_tgt_to_dev(tgt_dev, &ppa, 1);
>>>> +
>>>> +	return dev->ops->get_chk_meta(tgt_dev->parent, meta,
>>>> +						(sector_t)ppa.ppa, nchks);
>>>> +}
>>>> +EXPORT_SYMBOL(nvm_get_chunk_meta);
>>>>    int nvm_set_tgt_bb_tbl(struct nvm_tgt_dev *tgt_dev, struct ppa_addr *ppas,
>>>>  		       int nr_ppas, int type)
>>>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>>>> index 2e9e9f973a75..af642ce6ba69 100644
>>>> --- a/drivers/nvme/host/core.c
>>>> +++ b/drivers/nvme/host/core.c
>>>> @@ -2127,9 +2127,9 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
>>>>  	return ret;
>>>>  }
>>>>  -static int nvme_get_log_ext(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>>>> -			    u8 log_page, void *log,
>>>> -			    size_t size, size_t offset)
>>>> +int nvme_get_log_ext(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>>>> +		     u8 log_page, void *log,
>>>> +		     size_t size, size_t offset)
>>>>  {
>>>>  	struct nvme_command c = { };
>>>>  	unsigned long dwlen = size / 4 - 1;
>>>> diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
>>>> index f7135659f918..a1796241040f 100644
>>>> --- a/drivers/nvme/host/lightnvm.c
>>>> +++ b/drivers/nvme/host/lightnvm.c
>>>> @@ -35,6 +35,10 @@ enum nvme_nvm_admin_opcode {
>>>>  	nvme_nvm_admin_set_bb_tbl	= 0xf1,
>>>>  };
>>>>  +enum nvme_nvm_log_page {
>>>> +	NVME_NVM_LOG_REPORT_CHUNK	= 0xca,
>>>> +};
>>>> +
>>>>  struct nvme_nvm_ph_rw {
>>>>  	__u8			opcode;
>>>>  	__u8			flags;
>>>> @@ -236,6 +240,16 @@ struct nvme_nvm_id20 {
>>>>  	__u8			vs[1024];
>>>>  };
>>>>  +struct nvme_nvm_chk_meta {
>>>> +	__u8	state;
>>>> +	__u8	type;
>>>> +	__u8	wi;
>>>> +	__u8	rsvd[5];
>>>> +	__le64	slba;
>>>> +	__le64	cnlb;
>>>> +	__le64	wp;
>>>> +};
>>>> +
>>>>  /*
>>>>   * Check we didn't inadvertently grow the command struct
>>>>   */
>>>> @@ -252,6 +266,9 @@ static inline void _nvme_nvm_check_size(void)
>>>>  	BUILD_BUG_ON(sizeof(struct nvme_nvm_bb_tbl) != 64);
>>>>  	BUILD_BUG_ON(sizeof(struct nvme_nvm_id20_addrf) != 8);
>>>>  	BUILD_BUG_ON(sizeof(struct nvme_nvm_id20) != NVME_IDENTIFY_DATA_SIZE);
>>>> +	BUILD_BUG_ON(sizeof(struct nvme_nvm_chk_meta) != 32);
>>>> +	BUILD_BUG_ON(sizeof(struct nvme_nvm_chk_meta) !=
>>>> +						sizeof(struct nvm_chk_meta));
>>>>  }
>>>>    static void nvme_nvm_set_addr_12(struct nvm_addr_format_12 *dst,
>>>> @@ -555,6 +572,61 @@ static int nvme_nvm_set_bb_tbl(struct nvm_dev *nvmdev, struct ppa_addr *ppas,
>>>>  	return ret;
>>>>  }
>>>>  +/*
>>>> + * Expect the lba in device format
>>>> + */
>>>> +static int nvme_nvm_get_chk_meta(struct nvm_dev *ndev,
>>>> +				 struct nvm_chk_meta *meta,
>>>> +				 sector_t slba, int nchks)
>>>> +{
>>>> +	struct nvm_geo *geo = &ndev->geo;
>>>> +	struct nvme_ns *ns = ndev->q->queuedata;
>>>> +	struct nvme_ctrl *ctrl = ns->ctrl;
>>>> +	struct nvme_nvm_chk_meta *dev_meta = (struct nvme_nvm_chk_meta *)meta;
>>>> +	struct ppa_addr ppa;
>>>> +	size_t left = nchks * sizeof(struct nvme_nvm_chk_meta);
>>>> +	size_t log_pos, offset, len;
>>>> +	int ret, i;
>>>> +
>>>> +	/* Normalize lba address space to obtain log offset */
>>>> +	ppa.ppa = slba;
>>>> +	ppa = dev_to_generic_addr(ndev, ppa);
>>>> +
>>>> +	log_pos = ppa.m.chk;
>>>> +	log_pos += ppa.m.pu * geo->num_chk;
>>>> +	log_pos += ppa.m.grp * geo->num_lun * geo->num_chk;
>>> 
>>> Why is this done?
>> The log page does not map to the lba space. You need to convert it to
>> get one chunk at a time in the format.
>>    GRP:PU:CHK
>> I can see why taking a lba as argument is better than a ppa, since users
>> might use the lbas directly, but the conversion needs to be done
>> somewhere.
> 
> Good point. I guess this is clash between the two APIs. Chunk metadata
> being laid out sequentially, while the address space is sparse.

Exactly.

> I'm good with the conversion being in the fn.

Cool. I think it is good here too, as it hides the ppa format from the
upper layers. It requires a double conversion from pblk, but it is not
on the fast path anyway...

Javier

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