Re: [PATCH v5 17/21] libnvdimm: infrastructure for btt devices

[Jeff Moyer]

Dan Williams <dan.j.williams@xxxxxxxxx> writes:

> On Wed, Jun 17, 2015 at 9:47 AM, Jeff Moyer <jmoyer@xxxxxxxxxx> wrote:
>> Christoph Hellwig <hch@xxxxxx> writes:
>>
>>> On Wed, Jun 10, 2015 at 02:46:16PM -0400, Matthew Wilcox wrote:
>>>> Don't screw up rw_page.  The point of rw_page is to read or write a page
>>>> cache page.  It can sleep, and it indicates success by using the page
>>>> flags.  Don't try and scqueeze rw_bytes into it.  If you want rw_bytes
>>>> to be a queue operation, that's one thing, but don't mess with rw_page.
>>>
>>> Oh, I forgot about the page manipulating nature.  Yes, we'll need a different
>>> operation in this case.
>>
>> I didn't see this addressed in the new patch set.  I'm also concerned
>> about the layering, but I haven't put enough time into it to really make
>> a better suggestion.  I really dislike the idea of yet another device
>> stacking model in the kernel and I'm worried the code will go in, and the
>> sysfs interface will end up as a "user abi" and we won't be able to
>> change it in the future.
>>
>> Dan, have you made any progress on this, or do you have plans to?
>
> ? in v6 ->rw_bytes() moved from libnvdimm local hackery to a top-level
> block device operation.  Is that your concern or something else?

Hmm, I guess I was conflating two things.  I see now that you did move
the rw_bytes into the block device operations, that looks good.  I'll
table my concerns over yet another stacking model until I can say
something intelligent about it.

Cheers,
Jeff
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/