Re: btt ndctl question

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Tue, 2016-07-26 at 14:58 -0600, Vishal Verma wrote:
> On 07/26, Linda Knippers wrote:
> > 
> > My system has 4 8G NVDIMMs and I have them configured in different
> > ways, as you can
> > see from the ndctl output:
> > 
> > $ ndctl list
> > [
> >   {
> >     "dev":"namespace3.0",
> >     "mode":"raw",
> >     "size":8589934592,
> >     "blockdev":"pmem3"
> >   },
> >   {
> >     "dev":"namespace2.0",
> >     "mode":"memory",
> >     "size":8587837440,
> >     "uuid":"2567d762-68ae-486b-a6eb-2d3ab1b9dca9",
> >     "blockdev":"pmem2"
> >   },
> >   {
> >     "dev":"namespace1.0",
> >     "mode":"sector",
> >     "uuid":"44fb474e-7db8-4438-ad95-05ecb9f2075e",
> >     "sector_size":4096,
> >     "blockdev":"pmem1s"
> >   },
> >   {
> >     "dev":"namespace0.0",
> >     "mode":"memory",
> >     "size":8453619712,
> >     "uuid":"933ed54b-5b64-47f1-8409-c88f7c846522",
> >     "blockdev":"pmem0"
> >   }
> > ]
> > 
> > The two memory namespaces have different sizes because one is --
> > map=dev and the other is --map=mem.
> > It would be nice if the map option was displayed but my question is
> > about the size value for the
> > btt device, or lack of one.
> > 
> > All the namespaces show a size except for the btt.  The btt only
> > shows a sector size.  There
> > is no size value exposed by the btt sysfs information, which is
> > probably why it's not in ndctl.
> > 
> > I know the size can be gotten from the block device but it looks
> > like an omission here.
> > Is this a bug or a feature?
> 
> Probably an omission :)
> This patch should expose a size attribute in sysfs:
> 
> $ cat /sys/bus/nd/devices/btt7.0/size 
> 32440320
> 
> I can look at the 'ndctl list' enabling too if this looks good.
> 
> 8<------
> 
> From fb119bf4380d1d65d82754e581bbd41161c2100f Mon Sep 17 00:00:00 2001
> From: Vishal Verma <vishal.l.verma@intel.com>
> Date: Tue, 26 Jul 2016 14:54:39 -0600
> Subject: [PATCH] nvdimm, btt: add a size attribute for BTTs
> 
> To be consistent with other namespaces, expose a 'size' attribute for
> BTT devices also.
> 
> Cc: Dan Williams <dan.j.williams@intel.com>
> Reported-by: Linda Knippers <linda.knippers@hpe.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
>  drivers/nvdimm/btt.c      |  1 +
>  drivers/nvdimm/btt_devs.c | 15 +++++++++++++++
>  drivers/nvdimm/nd.h       |  1 +
>  3 files changed, 17 insertions(+)
> 
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index 68a7c3c..71ce0dc 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
> @@ -1270,6 +1270,7 @@ static int btt_blk_init(struct btt *btt)
>  		}
>  	}
>  	set_capacity(btt->btt_disk, btt->nlba * btt->sector_size >>
> 9);
> +	btt->nd_btt->size = btt->nlba * btt->sector_size;

Blargh, I think I was a bit hasty; I think this should be:

+	btt->nd_btt->size = btt->nlba * (u64)btt->sector_size;

Right? (I always get bit by integer promotion rules...)



>  	revalidate_disk(btt->btt_disk);
>  
>  	return 0;
> diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
> index 3fa7919..b54cfc7 100644
> --- a/drivers/nvdimm/btt_devs.c
> +++ b/drivers/nvdimm/btt_devs.c
> @@ -140,10 +140,25 @@ static ssize_t namespace_store(struct device
> *dev,
>  }
>  static DEVICE_ATTR_RW(namespace);
>  
> +
> +static ssize_t size_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct nd_btt *nd_btt = to_nd_btt(dev);
> +	ssize_t rc;
> +
> +	nvdimm_bus_lock(dev);
> +	rc = sprintf(buf, "%llu\n", nd_btt->size);
> +	nvdimm_bus_unlock(dev);
> +	return rc;
> +}
> +static DEVICE_ATTR_RO(size);
> +
>  static struct attribute *nd_btt_attributes[] = {
>  	&dev_attr_sector_size.attr,
>  	&dev_attr_namespace.attr,
>  	&dev_attr_uuid.attr,
> +	&dev_attr_size.attr,
>  	NULL,
>  };
>  
> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
> index 4047639..8024a0e 100644
> --- a/drivers/nvdimm/nd.h
> +++ b/drivers/nvdimm/nd.h
> @@ -143,6 +143,7 @@ struct nd_btt {
>  	struct nd_namespace_common *ndns;
>  	struct btt *btt;
>  	unsigned long lbasize;
> +	u64 size;
>  	u8 *uuid;
>  	int id;
>  };
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