Re: [PATCH 1/3] drivers/gpu/drm/via: convert put_page() to put_user_page*()

[John Hubbard <jhubbard@nvidia.com>]

On 7/22/19 12:07 PM, Matthew Wilcox wrote:
> On Mon, Jul 22, 2019 at 11:53:54AM -0700, John Hubbard wrote:
>> On 7/22/19 2:33 AM, Christoph Hellwig wrote:
>>> On Sun, Jul 21, 2019 at 09:30:10PM -0700, john.hubbard@gmail.com wrote:
>>>>  		for (i = 0; i < vsg->num_pages; ++i) {
>>>>  			if (NULL != (page = vsg->pages[i])) {
>>>>  				if (!PageReserved(page) && (DMA_FROM_DEVICE == vsg->direction))
>>>> -					SetPageDirty(page);
>>>> -				put_page(page);
>>>> +					put_user_pages_dirty(&page, 1);
>>>> +				else
>>>> +					put_user_page(page);
>>>>  			}
>>>
>>> Can't just pass a dirty argument to put_user_pages?  Also do we really
>>
>> Yes, and in fact that would help a lot more than the single page case,
>> which is really just cosmetic after all.
>>
>>> need a separate put_user_page for the single page case?
>>> put_user_pages_dirty?
>>
>> Not really. I'm still zeroing in on the ideal API for all these call sites,
>> and I agree that the approach below is cleaner.
> 
> so enum { CLEAN = 0, DIRTY = 1, LOCK = 2, DIRTY_LOCK = 3 };
> ?
> 

Sure. In fact, I just applied something similar to bio_release_pages()
locally, in order to reconcile Christoph's and Jerome's approaches 
(they each needed to add a bool arg), so I'm all about the enums in the
arg lists. :)

I'm going to post that one shortly, let's see how it goes over. heh.

thanks,
-- 
John Hubbard
NVIDIA