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Date: Fri, 13 Jul 2018 16:35:59 -0400
From: Luiz Capitulino <lcapitulino@...hat.com>
To: Pankaj Gupta <pagupta@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
qemu-devel@...gnu.org, linux-nvdimm@...1.01.org, jack@...e.cz,
stefanha@...hat.com, dan.j.williams@...el.com, riel@...riel.com,
haozhong.zhang@...el.com, nilal@...hat.com, kwolf@...hat.com,
pbonzini@...hat.com, ross.zwisler@...el.com, david@...hat.com,
xiaoguangrong.eric@...il.com, hch@...radead.org, mst@...hat.com,
niteshnarayanlal@...mail.com, imammedo@...hat.com,
eblake@...hat.com
Subject: Re: [RFC v3 1/2] libnvdimm: Add flush callback for virtio pmem
On Fri, 13 Jul 2018 13:22:30 +0530
Pankaj Gupta <pagupta@...hat.com> wrote:
> This patch adds functionality to perform flush from guest to host
> over VIRTIO. We are registering a callback based on 'nd_region' type.
> As virtio_pmem driver requires this special flush interface, for rest
> of the region types we are registering existing flush function.
> Also report the error returned by virtio flush interface.
This patch doesn't apply against latest upstream. A few more comments
below.
>
> Signed-off-by: Pankaj Gupta <pagupta@...hat.com>
> ---
> drivers/nvdimm/nd.h | 1 +
> drivers/nvdimm/pmem.c | 4 ++--
> drivers/nvdimm/region_devs.c | 24 ++++++++++++++++++------
> include/linux/libnvdimm.h | 5 ++++-
> 4 files changed, 25 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
> index 32e0364..1b62f79 100644
> --- a/drivers/nvdimm/nd.h
> +++ b/drivers/nvdimm/nd.h
> @@ -159,6 +159,7 @@ struct nd_region {
> struct badblocks bb;
> struct nd_interleave_set *nd_set;
> struct nd_percpu_lane __percpu *lane;
> + int (*flush)(struct device *dev);
> struct nd_mapping mapping[0];
> };
>
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index 9d71492..29fd2cd 100644
> --- a/drivers/nvdimm/pmem.c
> +++ b/drivers/nvdimm/pmem.c
> @@ -180,7 +180,7 @@ 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_FLUSH)
> - nvdimm_flush(nd_region);
> + bio->bi_status = nvdimm_flush(nd_region);
>
> do_acct = nd_iostat_start(bio, &start);
> bio_for_each_segment(bvec, bio, iter) {
> @@ -196,7 +196,7 @@ 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 = nvdimm_flush(nd_region);
>
> bio_endio(bio);
> return BLK_QC_T_NONE;
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index a612be6..124aae7 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -1025,6 +1025,7 @@ 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;
> + nd_region->flush = ndr_desc->flush;
> nd_device_register(dev);
>
> return nd_region;
> @@ -1065,13 +1066,10 @@ struct nd_region *nvdimm_volatile_region_create(struct nvdimm_bus *nvdimm_bus,
> }
> 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)
> +void pmem_flush(struct device *dev)
> {
> - struct nd_region_data *ndrd = dev_get_drvdata(&nd_region->dev);
> + struct nd_region_data *ndrd = dev_get_drvdata(dev);
> + struct nd_region *nd_region = to_nd_region(dev);
> int i, idx;
>
> /*
> @@ -1094,6 +1092,20 @@ void nvdimm_flush(struct nd_region *nd_region)
> writeq(1, ndrd_get_flush_wpq(ndrd, i, idx));
> wmb();
> }
> +
> +/**
> + * nvdimm_flush - flush any posted write queues between the cpu and pmem media
> + * @nd_region: blk or interleaved pmem region
> + */
> +int nvdimm_flush(struct nd_region *nd_region)
> +{
> + if (nd_region->flush)
> + return(nd_region->flush(&nd_region->dev));
> +
> + pmem_flush(&nd_region->dev);
IMHO, a better way of doing this would be to allow nvdimm_flush() to
be overridden. That is, in nd_region_create() you set nd_region->flush
to the original nvdimm_flush() if ndr_desc->flush is NULL. And then
always call nd_region->flush() where nvdimm_flush() is called today.
> +
> + return 0;
> +}
> EXPORT_SYMBOL_GPL(nvdimm_flush);
>
> /**
> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
> index 097072c..33b617f 100644
> --- a/include/linux/libnvdimm.h
> +++ b/include/linux/libnvdimm.h
> @@ -126,6 +126,7 @@ struct nd_region_desc {
> int numa_node;
> unsigned long flags;
> struct device_node *of_node;
> + int (*flush)(struct device *dev);
> };
>
> struct device;
> @@ -201,7 +202,9 @@ 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);
> +void pmem_set_flush(struct nd_region *nd_region, void (*flush)
> + (struct device *));
It seems pmem_set_flush() doesn't exist.
> int nvdimm_has_flush(struct nd_region *nd_region);
> int nvdimm_has_cache(struct nd_region *nd_region);
>
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