Re: [PATCH 2/3] libnvdimm: nd_region flush callback support

Pankaj Gupta
2018-09-24T11:07:27Z

> > This patch adds functionality to perform flush from guest
> > to host over VIRTIO. We are registering a callback based
> > on 'nd_region' type. virtio_pmem driver requires this special
> > flush function. For rest of the region types we are registering
> > existing flush function. Report error returned by host fsync
> > failure to userspace.
> >
> > Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
>
> This looks ok to me, just some nits below.
>
> > ---
> > drivers/acpi/nfit/core.c | 7 +++++--
> > drivers/nvdimm/claim.c | 3 ++-
> > drivers/nvdimm/pmem.c | 12 ++++++++----
> > drivers/nvdimm/region_devs.c | 12 ++++++++++--
> > include/linux/libnvdimm.h | 4 +++-
> > 5 files changed, 28 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> > index b072cfc..cd63b69 100644
> > --- a/drivers/acpi/nfit/core.c
> > +++ b/drivers/acpi/nfit/core.c
> > @@ -2216,6 +2216,7 @@ static void write_blk_ctl(struct nfit_blk *nfit_blk,
> > unsigned int bw,
> > {
> > u64 cmd, offset;
> > struct nfit_blk_mmio *mmio = &nfit_blk->mmio[DCR];
> > + struct nd_region *nd_region = nfit_blk->nd_region;
> >
> > enum {
> > BCW_OFFSET_MASK = (1ULL << 48)-1,
> > @@ -2234,7 +2235,7 @@ static void write_blk_ctl(struct nfit_blk *nfit_blk,
> > unsigned int bw,
> > offset = to_interleave_offset(offset, mmio);
> >
> > writeq(cmd, mmio->addr.base + offset);
> > - nvdimm_flush(nfit_blk->nd_region);
> > + nd_region->flush(nd_region);
>
> I would keep the indirect function call override inside of
> nvdimm_flush. Then this hunk can go away...

Sure. Will change.

>
> >
> > if (nfit_blk->dimm_flags & NFIT_BLK_DCR_LATCH)
> > readq(mmio->addr.base + offset);
> > @@ -2245,6 +2246,7 @@ static int acpi_nfit_blk_single_io(struct nfit_blk
> > *nfit_blk,
> > unsigned int lane)
> > {
> > struct nfit_blk_mmio *mmio = &nfit_blk->mmio[BDW];
> > + struct nd_region *nd_region = nfit_blk->nd_region;
> > unsigned int copied = 0;
> > u64 base_offset;
> > int rc;
> > @@ -2283,7 +2285,8 @@ static int acpi_nfit_blk_single_io(struct nfit_blk
> > *nfit_blk,
> > }
> >
> > if (rw)
> > - nvdimm_flush(nfit_blk->nd_region);
> > + nd_region->flush(nd_region);
> > +
> >
>
> ...ditto, no need to touch this code.

Sure.

>
> > rc = read_blk_stat(nfit_blk, lane) ? -EIO : 0;
> > return rc;
> > diff --git a/drivers/nvdimm/claim.c b/drivers/nvdimm/claim.c
> > index fb667bf..49dce9c 100644
> > --- a/drivers/nvdimm/claim.c
> > +++ b/drivers/nvdimm/claim.c
> > @@ -262,6 +262,7 @@ static int nsio_rw_bytes(struct nd_namespace_common
> > *ndns,
> > {
> > struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
> > unsigned int sz_align = ALIGN(size + (offset & (512 - 1)), 512);
> > + struct nd_region *nd_region = to_nd_region(ndns->dev.parent);
> > sector_t sector = offset >> 9;
> > int rc = 0;
> >
> > @@ -301,7 +302,7 @@ static int nsio_rw_bytes(struct nd_namespace_common
> > *ndns,
> > }
> >
> > memcpy_flushcache(nsio->addr + offset, buf, size);
> > - nvdimm_flush(to_nd_region(ndns->dev.parent));
> > + nd_region->flush(nd_region);
>
> For this you would need to teach nsio_rw_bytes() that the flush can fail.

Sure.

>
> >
> > return rc;
> > }
> > diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> > index 6071e29..ba57cfa 100644
> > --- a/drivers/nvdimm/pmem.c
> > +++ b/drivers/nvdimm/pmem.c
> > @@ -201,7 +201,8 @@ static blk_qc_t pmem_make_request(struct request_queue
> > *q, struct bio *bio)
> > struct nd_region *nd_region = to_region(pmem);
> >
> > if (bio->bi_opf & REQ_PREFLUSH)
> > - nvdimm_flush(nd_region);
> > + bio->bi_status = nd_region->flush(nd_region);
> > +
>
> Let's have nvdimm_flush() return 0 or -EIO if it fails since thats
> what nsio_rw_bytes() expects, and you'll need to translate that to:
> BLK_STS_IOERR

o.k. Will change it as per suggestion.

>
> >
> > do_acct = nd_iostat_start(bio, &start);
> > bio_for_each_segment(bvec, bio, iter) {
> > @@ -216,7 +217,7 @@ static blk_qc_t pmem_make_request(struct request_queue
> > *q, struct bio *bio)
> > nd_iostat_end(bio, start);
> >
> > if (bio->bi_opf & REQ_FUA)
> > - nvdimm_flush(nd_region);
> > + bio->bi_status = nd_region->flush(nd_region);
>
> Same comment.

Sure.

>
> >
> > bio_endio(bio);
> > return BLK_QC_T_NONE;
> > @@ -517,6 +518,7 @@ static int nd_pmem_probe(struct device *dev)
> > static int nd_pmem_remove(struct device *dev)
> > {
> > struct pmem_device *pmem = dev_get_drvdata(dev);
> > + struct nd_region *nd_region = to_region(pmem);
> >
> > if (is_nd_btt(dev))
> > nvdimm_namespace_detach_btt(to_nd_btt(dev));
> > @@ -528,14 +530,16 @@ static int nd_pmem_remove(struct device *dev)
> > sysfs_put(pmem->bb_state);
> > pmem->bb_state = NULL;
> > }
> > - nvdimm_flush(to_nd_region(dev->parent));
> > + nd_region->flush(nd_region);
>
> Not needed if the indirect function call moves inside nvdimm_flush().

o.k

>
> >
> > return 0;
> > }
> >
> > static void nd_pmem_shutdown(struct device *dev)
> > {
> > - nvdimm_flush(to_nd_region(dev->parent));
> > + struct nd_region *nd_region = to_nd_region(dev->parent);
> > +
> > + nd_region->flush(nd_region);
> > }
> >
> > static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)
> > diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> > index fa37afc..a170a6b 100644
> > --- a/drivers/nvdimm/region_devs.c
> > +++ b/drivers/nvdimm/region_devs.c
> > @@ -290,7 +290,7 @@ static ssize_t deep_flush_store(struct device *dev,
> > struct device_attribute *att
> > return rc;
> > if (!flush)
> > return -EINVAL;
> > - nvdimm_flush(nd_region);
> > + nd_region->flush(nd_region);
>
> Let's pass the error code through if the flush fails.

o.k

>
> >
> > return len;
> > }
> > @@ -1065,6 +1065,11 @@ static struct nd_region *nd_region_create(struct
> > nvdimm_bus *nvdimm_bus,
> > dev->of_node = ndr_desc->of_node;
> > nd_region->ndr_size = resource_size(ndr_desc->res);
> > nd_region->ndr_start = ndr_desc->res->start;
> > + if (ndr_desc->flush)
> > + nd_region->flush = ndr_desc->flush;
> > + else
> > + nd_region->flush = nvdimm_flush;
> > +
>
> We'll need to rename the existing nvdimm_flush() to generic_nvdimm_flush().

Sure.

>
> > nd_device_register(dev);
> >
> > return nd_region;
> > @@ -1109,7 +1114,7 @@ EXPORT_SYMBOL_GPL(nvdimm_volatile_region_create);
> > * nvdimm_flush - flush any posted write queues between the cpu and pmem
> > media
> > * @nd_region: blk or interleaved pmem region
> > */
> > -void nvdimm_flush(struct nd_region *nd_region)
> > +int nvdimm_flush(struct nd_region *nd_region)
> > {
> > struct nd_region_data *ndrd = dev_get_drvdata(&nd_region->dev);
> > int i, idx;
> > @@ -1133,7 +1138,10 @@ void nvdimm_flush(struct nd_region *nd_region)
> > if (ndrd_get_flush_wpq(ndrd, i, 0))
> > writeq(1, ndrd_get_flush_wpq(ndrd, i, idx));
> > wmb();
> > +
> > + return 0;
> > }
> > +
>
> Needless newline.

Will remove this.

>
> > EXPORT_SYMBOL_GPL(nvdimm_flush);
> >
> > /**
> > diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
> > index 097072c..3af7177 100644
> > --- a/include/linux/libnvdimm.h
> > +++ b/include/linux/libnvdimm.h
> > @@ -115,6 +115,7 @@ struct nd_mapping_desc {
> > int position;
> > };
> >
> > +struct nd_region;
> > struct nd_region_desc {
> > struct resource *res;
> > struct nd_mapping_desc *mapping;
> > @@ -126,6 +127,7 @@ struct nd_region_desc {
> > int numa_node;
> > unsigned long flags;
> > struct device_node *of_node;
> > + int (*flush)(struct nd_region *nd_region);
> > };
> >
> > struct device;
> > @@ -201,7 +203,7 @@ unsigned long nd_blk_memremap_flags(struct
> > nd_blk_region *ndbr);
> > unsigned int nd_region_acquire_lane(struct nd_region *nd_region);
> > void nd_region_release_lane(struct nd_region *nd_region, unsigned int
> > lane);
> > u64 nd_fletcher64(void *addr, size_t len, bool le);
> > -void nvdimm_flush(struct nd_region *nd_region);
> > +int nvdimm_flush(struct nd_region *nd_region);
> > int nvdimm_has_flush(struct nd_region *nd_region);
> > int nvdimm_has_cache(struct nd_region *nd_region);
> >
> > --
> > 2.9.3
> >
>

Thanks,
Pankaj