On Tue, Jul 26, 2016 at 2:24 PM, Verma, Vishal L
<[email protected]> wrote:
> 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 <[email protected]>
>> 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 <[email protected]>
>> Reported-by: Linda Knippers <[email protected]>
>> Signed-off-by: Vishal Verma <[email protected]>
>> ---
>>  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...)

...but at this point we're identical to what the block layer is
reporting.  The other 'size' attributes are communicating the raw
byte-aligned capacity of the namespace minus local driver overhead.
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