[PATCH V5 2/6] nvmet: add lba to sect coversion helpers

[Damien Le Moal]

On 2020/12/10 15:27, Chaitanya Kulkarni wrote:
> In this preparation patch we add helpers to convert lbas to sectors and
> sectors to lba. This is needed to eliminate code duplication in the ZBD
> backend.
> 
> Use these helpers in the block device backennd.

s/backennd/backend

And in the title:

s/coversion/conversion

scripts/checkpatch.pl does spell checking...

> 
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> ---
>  drivers/nvme/target/io-cmd-bdev.c |  8 +++-----
>  drivers/nvme/target/nvmet.h       | 10 ++++++++++
>  2 files changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
> index 125dde3f410e..23095bdfce06 100644
> --- a/drivers/nvme/target/io-cmd-bdev.c
> +++ b/drivers/nvme/target/io-cmd-bdev.c
> @@ -256,8 +256,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
>  	if (is_pci_p2pdma_page(sg_page(req->sg)))
>  		op |= REQ_NOMERGE;
>  
> -	sector = le64_to_cpu(req->cmd->rw.slba);
> -	sector <<= (req->ns->blksize_shift - 9);
> +	sector = nvmet_lba_to_sect(req->ns, req->cmd->rw.slba);
>  
>  	if (req->transfer_len <= NVMET_MAX_INLINE_DATA_LEN) {
>  		bio = &req->b.inline_bio;
> @@ -345,7 +344,7 @@ static u16 nvmet_bdev_discard_range(struct nvmet_req *req,
>  	int ret;
>  
>  	ret = __blkdev_issue_discard(ns->bdev,
> -			le64_to_cpu(range->slba) << (ns->blksize_shift - 9),
> +			nvmet_lba_to_sect(ns, range->slba),
>  			le32_to_cpu(range->nlb) << (ns->blksize_shift - 9),
>  			GFP_KERNEL, 0, bio);
>  	if (ret && ret != -EOPNOTSUPP) {
> @@ -414,8 +413,7 @@ static void nvmet_bdev_execute_write_zeroes(struct nvmet_req *req)
>  	if (!nvmet_check_transfer_len(req, 0))
>  		return;
>  
> -	sector = le64_to_cpu(write_zeroes->slba) <<
> -		(req->ns->blksize_shift - 9);
> +	sector = nvmet_lba_to_sect(req->ns, write_zeroes->slba);
>  	nr_sector = (((sector_t)le16_to_cpu(write_zeroes->length) + 1) <<
>  		(req->ns->blksize_shift - 9));
>  
> diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
> index 592763732065..4cb4cdae858c 100644
> --- a/drivers/nvme/target/nvmet.h
> +++ b/drivers/nvme/target/nvmet.h
> @@ -603,4 +603,14 @@ static inline bool nvmet_ns_has_pi(struct nvmet_ns *ns)
>  	return ns->pi_type && ns->metadata_size == sizeof(struct t10_pi_tuple);
>  }
>  
> +static inline u64 nvmet_sect_to_lba(struct nvmet_ns *ns, sector_t sect)
> +{
> +	return sect >> (ns->blksize_shift - SECTOR_SHIFT);
> +}
> +
> +static inline sector_t nvmet_lba_to_sect(struct nvmet_ns *ns, __le64 lba)
> +{
> +	return le64_to_cpu(lba) << (ns->blksize_shift - SECTOR_SHIFT);
> +}
> +

One thing here that I am not a fan of is the inconsistency between the 2 helpers
regarding the LBA endianess: nvmet_lba_to_sect() takes LE lba value, but
nvmet_sect_to_lba() returns a CPU endian lba value. Can't we unify them to work
on CPU endian values, and then if needed add another helper like:

static inline sector_t nvmet_lelba_to_sect(struct nvmet_ns *ns, __le64 lba)
{
	return nvmet_lba_to_sect(ns, le64_to_cpu(lba));
}


>  #endif /* _NVMET_H */
> 


-- 
Damien Le Moal
Western Digital Research