Re: [patch][cft] zero-copy dma cd writing and ripping

From: Jens Axboe (axboe@suse.de)
Date: Mon Oct 28 2002 - 10:08:32 EST

On Mon, Oct 28 2002, David S. Miller wrote:
> On Mon, 2002-10-28 at 04:42, Jens Axboe wrote:
> > > This work reminds me that get_user_pages() (or it's callers)
> > > need to be doing some flush_dcache_page()
> >
> > Was wondering about that. Can you tell me what it needs? And what about
> > bio_unmap_user(), surely that needs to flush cache as well for reads?
>
> Documentation/cachetlb.txt describes where flush_dcache_page is needed.
> If that doesn't describe it enough for you, that is a bug and please
> tell me what part is confusing so I may make the document better.

Ok what I make of this is that from bio_map_user() (which does a
get_user_pages() I need to do a

        if (write_to_vm)
                flush_dcache_page(page);

and in bio_unmap_user() I do

        if (!write_to_vm)
                flush_dcache_page(page);

is that correct? 

-- 
Jens Axboe

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