Re: [PATCH] lightnvm: introduce nvm_rq_to_ppa_list

[Matias Bjørling <mb@xxxxxxxxxxx>]

On 08/20/2018 02:38 PM, Javier Gonzalez wrote:
> > On 20 Aug 2018, at 14.12, Matias Bjørling <mb@xxxxxxxxxxx> wrote:
> >
> > There is a number of places in the lightnvm subsystem where the user
> > iterates over the ppa list. Before iterating, the user must know if it
> > is a single or multiple LBAs due to vector commands using either the
> > nvm_rq ->ppa_addr or ->ppa_list fields on command submission, which
> > leads to open-coding the if/else statement.
> >
> > Instead of having multiple if/else's, move it into a function that can
> > be called by its users.
> >
> > Signed-off-by: Matias Bjørling <mb@xxxxxxxxxxx>
> > ---
> > drivers/lightnvm/pblk-read.c  | 4 +---
> > drivers/lightnvm/pblk-write.c | 5 +----
> > drivers/lightnvm/pblk.h       | 4 +---
> > include/linux/lightnvm.h      | 5 +++++
> > 4 files changed, 8 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/lightnvm/pblk-read.c b/drivers/lightnvm/pblk-read.c
> > index f275c7e5abe4..696d3a9c9cf0 100644
> > --- a/drivers/lightnvm/pblk-read.c
> > +++ b/drivers/lightnvm/pblk-read.c
> > @@ -175,11 +175,9 @@ static void __pblk_read_put_line(struct pblk *pblk, struct ppa_addr ppa)
> >
> > static void pblk_read_put_line(struct pblk *pblk, struct nvm_rq *rqd)
> > {
> > -	struct ppa_addr *ppa_list;
> > +	struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);
> > 	int i;
> >
> > -	ppa_list = (rqd->nr_ppas > 1) ? rqd->ppa_list : &rqd->ppa_addr;
> > -
> > 	for (i = 0; i < rqd->nr_ppas; i++)
> > 		__pblk_read_put_line(pblk, ppa_list[i]);
> > }
> > diff --git a/drivers/lightnvm/pblk-write.c b/drivers/lightnvm/pblk-write.c
> > index df99c45778d4..a92450ec7698 100644
> > --- a/drivers/lightnvm/pblk-write.c
> > +++ b/drivers/lightnvm/pblk-write.c
> > @@ -212,10 +212,7 @@ static void pblk_submit_rec(struct work_struct *work)
> >
> > 	pblk_log_write_err(pblk, rqd);
> >
> > -	if (rqd->nr_ppas == 1)
> > -		ppa_list = &rqd->ppa_addr;
> > -	else
> > -		ppa_list = rqd->ppa_list;
> > +	ppa_list = nvm_rq_to_ppa_list(rqd);
> >
> > 	pblk_map_remaining(pblk, ppa_list);
> > 	pblk_queue_resubmit(pblk, c_ctx);
> > diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
> > index 64ae0c7ed3bb..bda098c7cc3b 100644
> > --- a/drivers/lightnvm/pblk.h
> > +++ b/drivers/lightnvm/pblk.h
> > @@ -1335,9 +1335,7 @@ static inline int pblk_boundary_ppa_checks(struct nvm_tgt_dev *tgt_dev,
> > static inline int pblk_check_io(struct pblk *pblk, struct nvm_rq *rqd)
> > {
> > 	struct nvm_tgt_dev *dev = pblk->dev;
> > -	struct ppa_addr *ppa_list;
> > -
> > -	ppa_list = (rqd->nr_ppas > 1) ? rqd->ppa_list : &rqd->ppa_addr;
> > +	struct ppa_addr *ppa_list = nvm_rq_to_ppa_list(rqd);
> >
> > 	if (pblk_boundary_ppa_checks(dev, ppa_list, rqd->nr_ppas)) {
> > 		WARN_ON(1);
> > diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h
> > index 0106984400bc..1497e275f90f 100644
> > --- a/include/linux/lightnvm.h
> > +++ b/include/linux/lightnvm.h
> > @@ -487,6 +487,11 @@ static inline struct ppa_addr dev_to_generic_addr(struct nvm_dev *dev,
> > 	return l;
> > }
> >
> > +static inline struct ppa_addr *nvm_rq_to_ppa_list(struct nvm_rq *rqd)
> > +{
> > +	return (rqd->nr_ppas > 1) ? rqd->ppa_list : &rqd->ppa_addr;
> > +}
> > +
> > typedef blk_qc_t (nvm_tgt_make_rq_fn)(struct request_queue *, struct bio *);
> > typedef sector_t (nvm_tgt_capacity_fn)(void *);
> > typedef void *(nvm_tgt_init_fn)(struct nvm_tgt_dev *, struct gendisk *,
> > --
> > 2.11.0
>
> Hans made a similar patch some time ago. There are a number of places
> where you want to use this helper too, also outside of pblk. You can
> look at it here [1]
>
> [1] https://github.com/OpenChannelSSD/linux/commits/for-4.20/pblk
>
>     fdd88185bfed
>     17609afb2db9
>
> Javier

I like Hans' better. Hans, could you please merge my patch with yours? I 
prefer the nvm_rq_to_ppa_list naming, rqdata -> rqd, and if short-hand.