[RFC v2 01/11] file: add callback for pre-mapping dmabuf

[Christoph Hellwig]

On Thu, Dec 04, 2025 at 11:46:45AM +0100, Christian König wrote:
> On 11/23/25 23:51, Pavel Begunkov wrote:
> > Add a file callback that maps a dmabuf for the given file and returns
> > an opaque token of type struct dma_token representing the mapping.
> 
> I'm really scratching my head what you mean with that?
> 
> And why the heck would we need to pass a DMA-buf to a struct file?

I find the naming pretty confusing a well.  But what this does is to
tell the file system/driver that it should expect a future
read_iter/write_iter operation that takes data from / puts data into
the dmabuf passed to this operation.