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

From: Jeff Moyer
Date: Wed Jun 17 2015 - 12:47:45 EST

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?

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