Re: [PATCH 3/3] lightnvm: pblk: take write semaphore on metadata

[Matias BjÃrling]

On 08/29/2018 03:21 PM, Javier Gonzalez wrote:
> > On 29 Aug 2018, at 15.08, Matias BjÃrling <mb@xxxxxxxxxxx> wrote:
> >
> > On 08/29/2018 10:56 AM, Javier GonzÃlez wrote:
> > > pblk guarantees write ordering at a chunk level through a per open chunk
> > > semaphore. At this point, since we only have an open I/O stream for both
> > > user and GC data, the semaphore is per parallel unit.
> > > For the metadata I/O that is synchronous, the semaphore is not needed as
> > > ordering is guaranteed. However, if the metadata scheme changes or
> > > multiple streams are open, this guarantee might not be preserved.
> > > This patch makes sure that all writes go through the semaphore, even for
> > > synchronous I/O. This is consistent with pblk's write I/O model. It also
> > > simplifies maintenance since changes in the metadata scheme could cause
> > > ordering issues.
> > > Signed-off-by: Javier GonzÃlez <javier@xxxxxxxxxxxx>
> > > ---
> > >   drivers/lightnvm/pblk-core.c | 16 +++++++++++++++-
> > >   drivers/lightnvm/pblk.h      |  1 +
> > >   2 files changed, 16 insertions(+), 1 deletion(-)
> > > diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
> > > index 767178185f19..1e4dc0c1ed88 100644
> > > --- a/drivers/lightnvm/pblk-core.c
> > > +++ b/drivers/lightnvm/pblk-core.c
> > > @@ -558,6 +558,20 @@ int pblk_submit_io_sync(struct pblk *pblk, struct nvm_rq *rqd)
> > >   	return ret;
> > >   }
> > >   +int pblk_submit_io_sync_sem(struct pblk *pblk, struct nvm_rq *rqd)
> > > +{
> > > +	struct ppa_addr *ppa_list;
> > > +	int ret;
> > > +
> > > +	ppa_list = (rqd->nr_ppas > 1) ? rqd->ppa_list : &rqd->ppa_addr;
> > > +
> > > +	pblk_down_page(pblk, ppa_list, rqd->nr_ppas);
> >
> > If the debug stuff is killed inside __pblk_down_page, then ppa_list
> > and rqd->nr_ppas does not need to be passed, and this function can be
> > inlined in its caller. Can we kill it? I'll make the patch if you
> > like.
>
> Sounds good. Sure, please send - should I wait to resend this series?

Will do. Yes, wait a bit. I'll post asap.